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HCV and the hepatic lipid pathway as a potential treatment target

Open AccessPublished:June 28, 2011DOI:https://doi.org/10.1016/j.jhep.2011.06.004
      Atherosclerosis has been described as a liver disease of the heart [
      • Davis R.A.
      • Hui Y.
      George Lyman Duff Memorial Lecture: atherosclerosis is a liver disease of the heart.
      ]. The liver is the central regulatory organ of lipid pathways but since dyslipidaemias are major contributors to cardiovascular disease and type 2 diabetes rather than liver disease, research in this area has not been a major focus for hepatologists. Virus–host interaction is a continuous co-evolutionary process [
      • Pang P.S.
      • Planet P.J.
      • Glenn J.S.
      The evolution of the major hepatitis C genotypes correlates with clinical response to interferon therapy.
      ] involving the host immune system and viral escape mechanisms [
      • Virgin H.W.
      • Wherry E.J.
      • Ahmed R.
      Redefining chronic viral infection.
      ]. One of the strategies HCV has adopted to escape immune clearance and establish persistent infection is to make use of hepatic lipid pathways. This review aims to:
      • update the hepatologist on lipid metabolism
      • review the evidence that HCV exploits hepatic lipid pathways to its advantage
      • discuss approaches to targeting host lipid pathways as adjunctive therapy.

      Keywords

      The hepatic lipid pathway

      Lipids act as energy sources for cells. Mammals have evolved a sophisticated mechanism to enable hydrophobic fat to be made soluble in the form of lipoproteins for delivery to peripheral tissues. The role of hepatically-derived very-low-density lipoprotein (VLDL) is thus to deliver energy, in the form of triglyceride (TG) to cells requiring energy (skeletal muscle) or to cells that store energy (adipose tissue). Lipoproteins can be characterised by their densities related to their core lipid (TG and cholesteryl ester) composition; the five main classes according to their density are chylomicrons (CM), VLDL, intermediate-density lipoproteins (IDL), low-density lipoprotein (LDL), and high-density lipoproteins (HDL). Lipoproteins can also be characterised by the major apolipoproteins present on their surfaces, some of which are structural (apolipoproteins B and AI), whilst others exchange between different lipoprotein particles (apolipoproteins AII, C, and E).

      Apolipoprotein B (apoB)

      Apolipoprotein B (apoB) exists as two distinct forms, apoB100 and apoB48 (the amino-terminal 48% of apoB100).
      ApoB100 is the full length protein produced by the liver and contains the low-density lipoprotein receptor (LDL-R)-binding domain. ApoB100 is essential for VLDL assembly in hepatocytes and is the structural lipoprotein present in VLDLs, IDL (also called VLDL remnants), and LDL. The number of secreted VLDL is regulated primarily by multiple degradative pathways for apoB within the cell which are, in turn, regulated by metabolic factors and pathways [
      • Ginsberg H.N.
      • Fisher E.A.
      The ever-expanding role of degradation in the regulation of apolipoprotein B metabolism.
      ].
      ApoB48, which lacks the LDL receptor-binding domain, is primarily synthesized by the postnatal small intestine and is essential for chylomicron assembly in enterocytes. Hence apoB48 is the intestinally-derived isoform of apoB100 on CM which transport dietary lipids [
      • Rutledge A.C.
      • Su Q.
      • Adeli K.
      Apolipoprotein B100 biogenesis: a complex array of intracellular mechanisms regulating folding, stability, and lipoprotein assembly.
      ].

      Apolipoprotein E (apoE)

      Apolipoprotein E (apoE) is a multifunctional protein that is synthesized by the liver and several peripheral tissues and cell types, including macrophages [
      • Getz G.S.
      • Reardon C.A.
      Apoprotein E as a lipid transport and signaling protein in the blood, liver, and artery wall.
      ]. Insight into its multiple roles in lipid and energy metabolism has been provided by the transgenic ApoE (−/−) mouse model [
      • Pendse A.A.
      • Arbones-Mainar J.M.
      • Johnson L.A.
      • Altenburg M.K.
      • Maeda N.
      Apolipoprotein E knock-out and knock-in mice. atherosclerosis, metabolic syndrome, and beyond.
      ]. ApoE is a critical ligand for the receptor mediated removal of TG-rich lipoprotein (TRL) remnants (VLDL and CM remnants) by the liver. ApoE not only acts as a high affinity ligand for multiple members of the LDL receptor family including the LDL-R, the LDL receptor-related protein (LRP), and the VLDL receptor but also binds to heparan sulphate proteoglycans (HSPG), which act as hepatic receptors for TRL remnant clearance. In addition, apoE participates in the biogenesis of discoidal HDL particles which are then converted to the spherical form, by the action of lecithin:cholesterol acyltransferase (LCAT) allowing the recognition of HDL by the scavenger receptor-B1 (SR-B1) [
      • Kypreos K.E.
      • Zannis V.I.
      Pathway of biogenesis of apolipoprotein E-containing HDL in vivo with the participation of ABCA1 and LCAT.
      ]. ApoE also has an immune function and mediates the presentation of serum-borne lipid antigens [
      • van den Elzen P.
      • Garg S.
      • Leon L.
      • Brigl M.
      • Leadbetter E.A.
      • Gumperz J.E.
      • et al.
      Apolipoprotein-mediated pathways of lipid antigen presentation.
      ].
      Human apoE has three common isoforms (apoE2, apoE3, and apoE4) which differ only by a single amino acid at two residues. These differences affect structural and biophysical properties of apoE resulting in different effects on lipid homeostasis. For example apoE2 binds LDL-R with reduced affinity [
      • Eichner J.E.
      • Dunn S.T.
      • Perveen G.
      • Thompson D.M.
      • Stewart K.E.
      • Stroehla B.C.
      Apolipoprotein E polymorphism and cardiovascular disease: a HuGE review.
      ] whilst apoE4 preferentially associates with VLDL.

      Apolipoprotein Cs (apoCs)

      The apoCs are a family of small exchangeable lipoproteins (Table 1) which are important for the regulation of lipolysis. ApoCI is a basic apolipoprotein that is mainly secreted by the liver as a component of VLDLs. It can dissociate from the VLDL surface to rapidly associate with HDLs and promote discoidal particle morphology [
      • James P.F.
      • Dogovski C.
      • Dobson R.C.
      • Bailey M.F.
      • Goldie K.N.
      • Karas J.A.
      • et al.
      Aromatic residues in the C-terminal helix of human apoC-I mediate phospholipid interactions and particle morphology.
      ]. ApoC-I has multiple regulatory actions in plasma TRL metabolism including inhibiting the binding and/or uptake of VLDL by LDL-R and LRP. This is believed to be due to the ability of apoC-I to displace significant amounts of apoE from TRL, or alternatively to mask or alter the conformation of apoE on these particles [
      • Cohn J.S.
      • Tremblay M.
      • Batal R.
      • Jacques H.
      • Veilleux L.
      • Rodriguez C.
      • et al.
      Plasma kinetics of VLDL and HDL apoC-I in normolipidemic and hypertriglyceridemic subjects.
      ]. ApoCI also functions as an activator of LCAT and an inhibitor of plasma cholesteryl ester transfer protein (CETP) [
      • de Barros J.P.
      • Boualam A.
      • Gautier T.
      • Dumont L.
      • Verges B.
      • Masson D.
      • et al.
      Apolipoprotein CI is a physiological regulator of cholesteryl ester transfer protein activity in human plasma but not in rabbit plasma.
      ].
      Table 1Distribution of major apolipoproteins among the lipoprotein particle family.
      B48 is exclusive to chylomicrons and chylomicrons remnants. St, structural apolipoprotein; Ex, exchangeable apolipoprotein. Other apolipoproteins (AIV, AV, D, F, G, H, J, (a)) are beyond the scope of this review.
      Apolipoprotein CII (apoCII) is a necessary activator for lipoprotein lipase [
      • Shen Y.
      • Lookene A.
      • Zhang L.
      • Olivecrona G.
      Site-directed mutagenesis of apolipoprotein CII to probe the role of its secondary structure for activation of lipoprotein lipase.
      ].
      ApoCIII is synthesised by the liver and, in the fasting state, is mainly associated with high-density lipoprotein (HDL) whereas in the fed state, or in hyperlipidaemic individuals, it preferentially redistributes to VLDL and CM (Fig. 1). ApoCIII is an important regulator of lipoprotein metabolism [
      • Kawakami A.
      • Yoshida M.
      Apolipoprotein CIII links dyslipidemia with atherosclerosis.
      ]; it impairs the lipolysis of TRLs by inhibiting lipoprotein lipase and the hepatic uptake of TRLs by remnant receptors. VLDL particles rich in apoCIII have a reduced clearance rate whereas those rich in apoE rapidly clear from the circulation [
      • Zheng C.
      • Khoo C.
      • Furtado J.
      • Sacks F.M.
      Apolipoprotein C-III and the metabolic basis for hypertriglyceridemia and the dense low-density lipoprotein phenotype.
      ,
      • Mendivil C.O.
      • Zheng C.
      • Furtado J.
      • Lel J.
      • Sacks F.M.
      Metabolism of very-low-density lipoprotein and low-density lipoprotein containing apolipoprotein C-III and not other small apolipoproteins.
      ]. It has also been shown that apoCIII stimulates VLDL synthesis [
      • Ooi E.M.
      • Barrett P.H.
      • Chan D.C.
      • Watts G.F.
      Apolipoprotein C-III: understanding an emerging cardiovascular risk factor.
      ]. Hence total plasma apoCIII concentrations causally correlate with plasma TG concentrations.
      Figure thumbnail gr1
      Fig. 1Pictorial representation of the transfer of exchangeable apolipoproteins (ApoCs, apoAII, § and apoE) between apoB-containing lipoprotein particles (very-low density lipoprotein [VLDL], intermediate density lipoprotein [IDL], low density lipoprotein [LDL], and chlymicrons [CM]) and apoAI-containing high-density lipoprotein [HDL] particles in the circulation. For example in the fed state apoCIII preferentially redistributes to VLDL and CM. Similarly HDL serves as a plasma reservoir of apoAII that transfers to TRLs in much the same way as apoCs
      [
      • Castellani L.W.
      • Nguyen C.N.
      • Charugundla S.
      • Weinstein M.M.
      • Doan C.X.
      • Blaner W.S.
      • et al.
      Apolipoprotein AII is a regulator of very low density lipoprotein metabolism and insulin resistance.
      ]
      . Discoidal HDL particles are converted to the spherical form by the action of lecithin:cholesterol acyltransferase (LCAT)
      [
      • Kypreos K.E.
      • Zannis V.I.
      Pathway of biogenesis of apolipoprotein E-containing HDL in vivo with the participation of ABCA1 and LCAT.
      ]
      . [Adapted from Ooi et al.
      [
      • Ooi E.M.
      • Barrett P.H.
      • Chan D.C.
      • Watts G.F.
      Apolipoprotein C-III: understanding an emerging cardiovascular risk factor.
      ]
      ].

      Apolipoprotein As (ApoAs)

      ApoAI is the principal apolipoprotein in HDL and has the ability to interact with the SR-B1 hepatic receptor as well as activate LCAT [
      • Scanu A.M.
      • Edelstein C.
      HDL: bridging past and present with a look at the future.
      ]. ApoAII is also associated with HDL where it is the second most abundant protein (Table 1). ApoAII exchanges from HDL to VLDL resulting in VLDL that is a poorer substrate for lipolytic activity (Fig. 1). It is thus a regulator of VLDL metabolism and apoAII levels in humans are associated with plasma concentrations of TGs [
      • Castellani L.W.
      • Nguyen C.N.
      • Charugundla S.
      • Weinstein M.M.
      • Doan C.X.
      • Blaner W.S.
      • et al.
      Apolipoprotein AII is a regulator of very low density lipoprotein metabolism and insulin resistance.
      ].

      High-density lipoproteins (HDLs)

      HDLs are small, dense, particles [density range of 1.063–1.210 g/ml], some of which carry only ApoAI, whereas others contain both ApoAI and ApoAII. Other apolipoprotein species found in HDL particles include ApoAIV, Apo C (CI, CII, and CIII), and Apo E. The physical heterogeneity of HDLs is associated with multiple functions that involve both the protein and the lipid components of these particles [
      • Scanu A.M.
      • Edelstein C.
      HDL: bridging past and present with a look at the future.
      ]. A major role of HDL is in the reverse cholesterol transport process where cholesterol in peripheral tissues is transported to the liver for reuse or bile acid synthesis. In addition, recent data indicate that HDL participates in a mechanism of intercellular communication involving the transport and delivery of microRNAs [
      • Vickers K.C.
      • Palmisano B.T.
      • Shoucri B.M.
      • Shamburek R.D.
      • Remaley A.T.
      MicroRNAs are transported in plasma and delivered to recipient cells by high-density lipoproteins.
      ].

      VLDL assembly and secretion

      VLDL particles secreted from the liver vary in size and composition and can be classified not only by their density (0.94–1.06 g/ml), but also by their diameter (20–75 nm), and flotation rate [Svedberg flotation rate (Sf) 20–400]. VLDL can be separated into two main classes: large, buoyant VLDL1 particles (Sf 60–400) which contain more TG and smaller denser VLDL2 particles (Sf 20–60).
      Each VLDL contains a single non-exchangeable apoB100 molecule, which serves as its scaffolding, and exchangeable apolipoproteins including apoE and apoCs. The processes involved in the assembly and secretion of VLDL have been studied extensively in vitro and in vivo for the past two to three decades [
      • Rutledge A.C.
      • Su Q.
      • Adeli K.
      Apolipoprotein B100 biogenesis: a complex array of intracellular mechanisms regulating folding, stability, and lipoprotein assembly.
      ,
      • Blasiole D.A.
      • Davis R.A.
      • Attie A.D.
      The physiological and molecular regulation of lipoprotein assembly and secretion.
      ]. VLDL assembly occurs via a two-step mechanism (Fig. 2), involving the formation of apoB-containing VLDL precursor particles in the lumen of the endoplasmic reticulum (ER), a step which requires microsomal triglyceride-transfer protein (MTP) (reviewed in [
      • Hussain M.M.
      • Shi J.
      • Dreizen P.
      Microsomal triglyceride transfer protein and its role in apoB-lipoprotein assembly.
      ]). This initial lipidation of apoB prevents proteosome-mediated degradation. The VLDL precursor particles are then loaded with neutral lipids by lipid droplets (LDs) [
      • Olofsson S.O.
      • Bostrom P.
      • Andersson L.
      • Rutberg M.
      • Perman J.
      • Boren J.
      Lipid droplets as dynamic organelles connecting storage and efflux of lipids.
      ,
      • Hodges B.D.
      • Wu C.C.
      Proteomic insights into an expanded cellular role for cytoplasmic lipid droplets.
      ] to form TG rich VLDL1. It is thought that interplay between the length of apoB polypeptide and palmitoylation of apoB regulates TG-rich lipoprotein assembly and secretion. In addition, apoE appears to play a role in the formation of fully lipidated VLDL, whilst apoCIII plays an intracellular role in stimulating VLDL assembly and secretion.
      Figure thumbnail gr2
      Fig. 2Schematic representation of the two-stage VLDL assembly in hepatocytes. ApoB is translocated to the lumen of the ER and lipidated by microsomal triglyceride transfer protein [MTP] to form pre-VLDL. Pre-VLDL is further lipidated to form VLDL2 or misfolded apoB can be degraded in the cell. VLDL2 is transferred to the Golgi and is either secreted or further lipidated with a major load of triglyceride (TG) from the lipid droplet to form VLDL1. [Adapted from Olofsson et al.
      [
      • Olofsson S.O.
      • Wiklund O.
      • Boren J.
      Apolipoproteins A–I and B: biosynthesis, role in the development of atherosclerosis and targets for intervention against cardiovascular disease.
      ]
      ].
      Both the hepatic production rate and the circulating number of VLDL1 particles are significantly and strongly related to HOMA-estimated insulin resistance (IR) in normoglycaemic adults [
      • Gill J.M.
      • Brown J.C.
      • Bedford D.
      • Wright D.M.
      • Cooney J.
      • Hughes D.A.
      • et al.
      Hepatic production of VLDL1 but not VLDL2 is related to insulin resistance in normoglycaemic middle-aged subjects.
      ,
      • Adiels M.
      • Boren J.
      • Caslake M.J.
      • Stewart P.
      • Soro A.
      • Westerbacka J.
      • et al.
      Overproduction of VLDL1 driven by hyperglycemia is a dominant feature of diabetic dyslipidemia.
      ]. Disease phenotypes (e.g., type II diabetes, obesity) also dramatically alter the total numbers and size of LDs, the dynamic cellular structures involved in lipid homeostasis [
      • Hodges B.D.
      • Wu C.C.
      Proteomic insights into an expanded cellular role for cytoplasmic lipid droplets.
      ]. In contrast, the production rate and number of VLDL2 are not significantly related to insulin resistance.

      Chylomicrons

      Dietary fat is absorbed by the enterocyte, where a unique assembly process similar to that of VLDL produces a “package” of lipid and cholesterol with phospholipids and apoB-48 to form a chylomicron that is stable in the aqueous environment of the bloodstream. Chylomicrons are the largest lipoproteins; CM access the circulation via the thoracic duct where they are converted to remnants by the TG hydrolysing action of lipoprotein lipase, with apoCII acting as a co-factor and activator. The resultant relatively TG-depleted, cholesterol-enriched CM remnant particle is then cleared by the liver via an apoE dependent receptor-mediated process. Thus, chylomicrons facilitate delivery of dietary lipid and cholesterol to the liver [
      • Williams K.J.
      Molecular processes that handle–and mishandle–dietary lipids.
      ].

      Intravascular re-modelling of lipoproteins and removal of lipid

      Intravascular re-modelling of lipoproteins

      Re-modelling entails the exchange of core and surface lipids and apolipoproteins, mediated largely by the action of plasma lipid transfer enzymes [lipoprotein lipase, hepatic lipase (HL), lipid transfer proteins (CETP and phospholipid transfer protein (PLTP)) and LCAT].
      Lipoprotein lipase (LPL) is the enzyme responsible for the hydrolysis of core TG in VLDL and CM, producing IDL and chylomicron remnants, respectively. LPL is made in tissue parenchymal cells and then translocated to functional binding sites at the luminal surface of endothelial cells. LPL is anchored by ion interaction with heparin sulphate proteoglycans (HSPG) and/or glycosyl phosphatidylinositol. Once TRLs are bound to this platform, LPL mediates TG hydrolysis, causing the release of fatty acids that are then taken up by receptors located on the plasma membrane of cells. Within these cells, the fatty acids are re-esterified and used for storage in adipocytes or for energy production in muscle. LPL requires a specific co-factor, apoCII, to be fully active [
      • Shen Y.
      • Lookene A.
      • Zhang L.
      • Olivecrona G.
      Site-directed mutagenesis of apolipoprotein CII to probe the role of its secondary structure for activation of lipoprotein lipase.
      ,
      • Kinnunen P.K.
      • Jackson R.L.
      • Smith L.C.
      • Gotto Jr., A.M.
      • Sparrow J.T.
      Activation of lipoprotein lipase by native and synthetic fragments of human plasma apolipoprotein C-II.
      ]. The enzymatic activity of LPL is regulated in a complex manner in response to energy requirements and hormonal changes. For example insulin not only increases the level of LPL mRNA in mature adipocytes but also regulates LPL activity through post-transcriptional and post-translational mechanisms. Conversely, interferon (IFN) decreases LPL activity resulting in an increase in plasma TG [
      • Ehnholm C.
      • Aho K.
      • Huttunen J.K.
      • Kostiainen E.
      • Mattila K.
      • Pakkarainen J.
      • et al.
      Effect of interferon on plasma lipoproteins and on the activity of postheparin plasma lipases.
      ,
      • Shinohara E.
      • Yamashita S.
      • Kihara S.
      • Hirano K.
      • Ishigami M.
      • Arai T.
      • et al.
      Interferon alpha induces disorder of lipid metabolism by lowering postheparin lipases and cholesteryl ester transfer protein activities in patients with chronic hepatitis C.
      ,
      • Feingold K.R.
      • Hardardottir I.
      • Grunfeld C.
      Beneficial effects of cytokine induced hyperlipidemia.
      ,
      • Andrade R.J.
      • Garcia-Escano M.D.
      • Valdivielso P.
      • Alcantara R.
      • Sanchez-Chaparro M.A.
      • Gonzalez-Santos P.
      Effects of interferon-beta on plasma lipid and lipoprotein composition and post-heparin lipase activities in patients with chronic hepatitis C.
      ]. Hepatic lipase plays a major role in lipoprotein metabolism as a lipolytic enzyme that hydrolyses TG and phospholipids in VLDL2, IDL, CM remnants, and HDL [
      • Perret B.
      • Mabile L.
      • Martinez L.
      • Terce F.
      • Barbaras R.
      • Collet X.
      Hepatic lipase: structure/function relationship, synthesis, and regulation.
      ].
      CETP primarily transfers TG from VLDL in exchange for cholesteryl esters from other lipoproteins, especially HDL [
      • Masson D.
      • Jiang X.C.
      • Lagrost L.
      • Tall A.R.
      The role of plasma lipid transfer proteins in lipoprotein metabolism and atherogenesis.
      ].
      Low-density lipoprotein is thus not directly secreted from hepatocytes but is produced by VLDL catabolism. The lipolytic cascade produces LDL particles which are depleted of TG and enriched with cholesterol. During lipolysis of TRLs, apolipoproteins in their surface phospholipid coats are released and recycled into HDL in serum. HDL particles are also secreted de novo from hepatocytes.

      Clearance of TRLs

      The size of VLDL is a critical determinant in deciding the fate of the particles in the circulation [
      • Adiels M.
      • Olofsson S.O.
      • Taskinen M.R.
      • Boren J.
      Overproduction of very low-density lipoproteins is the hallmark of the dyslipidemia in the metabolic syndrome.
      ]. Thus, most of the large TG-rich VLDL1 are cleared directly from the plasma [
      • Packard C.J.
      • Munro A.
      • Lorimer A.R.
      • Gotto A.M.
      • Shepherd J.
      Metabolism of apolipoprotein B in large triglyceride-rich very low density lipoproteins of normal and hypertriglyceridemic subjects.
      ] and less than 20% of VLDL1 undergoes lipolysis all the way to LDL [
      • Demant T.
      • Packard C.
      In vivo studies of VLDL metabolism and LDL heterogeneity.
      ] (Fig. 3).
      Figure thumbnail gr3
      Fig. 3Schematic representation of the life cycle of apoB-containing lipoprotein particles. Triglyceride-rich lipoproteins (VLDL1 and chylomicron (CM)) remnants undergo rapid apoE-mediated clearance from the plasma (see ). The lipolytic cascade produces low-density lipoprotein (LDL) particles largely from VLDL2 catabolism. Statins have the largest LDL-cholesterol lowering effect among current licensed drugs by inhibiting the rate-limiting step in hepatic cholesterol synthesis, 3-hydroxy-3-methylglutaryl CoA reductase (HMG-CoA).
      Once TG-rich lipoproteins (VLDL1 and CM) are hydrolysed by LPL, the resultant apoE-enriched TG-rich lipoprotein remnant particles are removed in the liver by the concerted action of a number of receptors [
      • Mahley R.W.
      • Ji Z.S.
      Remnant lipoprotein metabolism: key pathways involving cell-surface heparan sulfate proteoglycans and apolipoprotein E.
      ,
      • Williams K.J.
      • Chen K.
      Recent insights into factors affecting remnant lipoprotein uptake.
      ]. Hepatic lipase on the basolateral surface of hepatocytes not only functions as a lipase but also serves as a bridge/ligand that facilitates lipoprotein uptake. The lipase-lipoprotein complex can then undergo internalisation, a process that is independent of lipolysis and can be mediated by HSPG, LDL-R, and LRP (Fig. 4), as well as SR-B1 (reviewed in [
      • Williams K.J.
      • Chen K.
      Recent insights into factors affecting remnant lipoprotein uptake.
      ,
      • Santamarina-Fojo S.
      • Gonzalez-Navarro H.
      • Freeman L.
      • Wagner E.
      • Nong Z.
      Hepatic lipase, lipoprotein metabolism, and atherogenesis.
      ]). Syndecan1 is a HSPG that is essential for the binding and clearance of TG-rich remnant lipoproteins [
      • Stanford K.I.
      • Bishop J.R.
      • Foley E.M.
      • Gonzales J.C.
      • Niesman I.R.
      • Witztum J.L.
      • et al.
      Syndecan-1 is the primary heparan sulfate proteoglycan mediating hepatic clearance of triglyceride-rich lipoproteins in mice.
      ,
      • Dallinga-Thie G.M.
      • Franssen R.
      • Mooij H.L.
      • Visser M.E.
      • Hassing H.C.
      • Peelman F.
      • et al.
      The metabolism of triglyceride-rich lipoproteins revisited: new players, new insight.
      ]. SR-B1 might function as an initial recognition site for CM remnants with subsequent internalisation by additional receptors such as LDL-R [
      • Out R.
      • Kruijt J.K.
      • Rensen P.C.
      • Hildebrand R.B.
      • de Vos P.
      • Van Eck M.
      • et al.
      Scavenger receptor BI plays a role in facilitating chylomicron metabolism.
      ]. Thus SRB1 not only promotes cellular uptake of cholesteryl esters from HDL but also binds and facilitates the catabolism of VLDL and CM [
      • Williams K.J.
      • Chen K.
      Recent insights into factors affecting remnant lipoprotein uptake.
      ,
      • Van Eck M.
      • Hoekstra M.
      • Out R.
      • Bos I.S.
      • Kruijt J.K.
      • Hildebrand R.B.
      • et al.
      Scavenger receptor BI facilitates the metabolism of VLDL lipoproteins in vivo.
      ]. Recent data confirm complexity in the interactions of lipoproteins with SR-B1 [
      • Nieland T.J.
      • Xu S.
      • Penman M.
      • Krieger M.
      Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI.
      ].
      Figure thumbnail gr4
      Fig. 4Hepatic TRL remnant clearance involves sequestration of the particles through the fenestrae in the endothelium into the space of Disse. Two endocytic receptors, the syndecan-1 heparan sulfate proteoglycan (HSPG) and the LDL receptor, plus one docking receptor, SR-BI, significantly contribute to normal hepatic remnant catabolism
      [
      • Williams K.J.
      • Chen K.
      Recent insights into factors affecting remnant lipoprotein uptake.
      ]
      , all of which have been implicated as cellular receptors for HCV (red box). Hepatic lipase (HL) and apoE, secreted by the hepatocytes (H), appear to bind to the HSPG and be available to enrich the remnant lipoproteins and facilitate their uptake. [Adapted from Van Eck et al.
      [
      • Van Eck M.
      • Pennings M.
      • Hoekstra M.
      • Out R.
      • Van Berkel T.J.
      Scavenger receptor BI and ATP-binding cassette transporter A1 in reverse cholesterol transport and atherosclerosis.
      ]
      ].
      The ligand for these receptors is likely to be apoE since apoB appears not to be in a receptor competent conformation on large triglyceride-rich VLDL1. ApoCIII strongly inhibits hepatic uptake of VLDL and IDL overriding the opposite influence of apoE when both are present [
      • Mendivil C.O.
      • Zheng C.
      • Furtado J.
      • Lel J.
      • Sacks F.M.
      Metabolism of very-low-density lipoprotein and low-density lipoprotein containing apolipoprotein C-III and not other small apolipoproteins.
      ].

      HCV co-opts the hepatic lipid pathway

      HCV infection is a highly dynamic process with a viral half life in plasma of less than 3 h and production/clearance of an estimated 1012 virions per day in an infected individual [
      • Neumann A.U.
      • Lam N.P.
      • Dahari H.
      • Gretch D.R.
      • Wiley T.E.
      • Layden T.J.
      • et al.
      Hepatitis C viral dynamics in vivo and the antiviral efficacy of interferon-alpha therapy.
      ]. Currently, it is believed that HCV co-opts the VLDL assembly, maturation, degradation, and secretory machinery of the cell [
      • Ye J.
      Reliance of host cholesterol metabolic pathways for the life cycle of hepatitis C virus.
      ,
      • Gastaminza P.
      • Cheng G.
      • Wieland S.
      • Zhong J.
      • Liao W.
      • Chisari F.V.
      Cellular determinants of hepatitis C virus assembly, maturation, degradation, and secretion.
      ] and that the production of infectious HCV virions coincides with the pathway for producing VLDL/TRLs (reviewed in [
      • Bartenschlager R.
      • Penin F.
      • Lohmann V.
      • Andre P.
      Assembly of infectious hepatitis C virus particles.
      ]. This virus–host interaction impacts on host lipid metabolism in ways which may be HCV genotype (G) specific, such as induction of hepatic steatosis and hypobetalipoproteinaemia, both of which are more frequent and severe in HCV G3 infection [
      • Negro F.
      Abnormalities of lipid metabolism in hepatitis C virus infection.
      ,

      Cai T, Dufour J-F, Muellhaupt B, Gerlach T, Heim M, Moradpour D, et al. Viral Genotype-Specific Role of PNPLA3, PPARG, MTTP and IL28B in Hepatitis C Virus-Associated Steatosis. J Hepatol 2011.

      ].
      The in vitro study of HCV replication has benefitted from the use of the replicon system and, more recently from the infection competent HCV cell culture (HCVcc) system (reviewed in [
      • Moradpour D.
      • Penin F.
      • Rice C.M.
      Replication of hepatitis C virus.
      ]). However, the hepatoma cell lines used secrete relatively dense lipid-poor apoB-containing particles, unlike the buoyant VLDL particles secreted in vivo by the human liver [
      • Meex S.J.
      • Andreo U.
      • Sparks J.D.
      • Fisher E.A.
      Huh-7 or HepG2 cells: which is the better model for studying human apolipoprotein-B100 assembly and secretion?.
      ]. The density profile of HCVcc particles shows an HCV RNA distribution from 1.0 to 1.18 g/ml with no infectivity at densities >1.12 g/ml [
      • Lindenbach B.D.
      • Meuleman P.
      • Ploss A.
      • Vanwolleghem T.
      • Syder A.J.
      • McKeating J.A.
      • et al.
      Cell culture-grown hepatitis C virus is infectious in vivo and can be recultured in vitro.
      ]. It appears that HCV has evolved a mechanism of replication in which lipid droplets, the intracellular storage sites for TG and cholesteryl esters, are used to produce infectious virus. Association of replication complexes with LDs occurs in a core and NS5A-dependent manner [
      • Boulant S.
      • Targett-Adams P.
      • McLauchlan J.
      Disrupting the association of hepatitis C virus core protein with lipid droplets correlates with a loss in production of infectious virus.
      ,
      • Miyanari Y.
      • Atsuzawa K.
      • Usuda N.
      • Watashi K.
      • Hishiki T.
      • Zayas M.
      • et al.
      The lipid droplet is an important organelle for hepatitis C virus production.
      ,
      • Shavinskaya A.
      • Boulant S.
      • Penin F.
      • McLauchlan J.
      • Bartenschlager R.
      The lipid droplet binding domain of hepatitis C virus core protein is a major determinant for efficient virus assembly.
      ], (reviewed in [

      Jones DM, McLauchlan J. Hepatitis C virus: assembly and release of virus particles. J Biol Chem 2010.

      ]). Recently, it has been shown that the triglyceride-synthesizing enzyme diacylglycerol acyltransferase-1 (DGAT1), an enzyme involved in lipid droplet biogenesis, is another key host factor for HCV infectious particle production [
      • Herker E.
      • Harris C.
      • Hernandez C.
      • Carpentier A.
      • Kaehlcke K.
      • Rosenberg A.R.
      • et al.
      Efficient hepatitis C virus particle formation requires diacylglycerol acyltransferase-1.
      ].
      Although apoB is essential for production of infectious virus [
      • Nahmias Y.
      • Goldwasser J.
      • Casali M.
      • van Poll D.
      • Wakita T.
      • Chung R.T.
      • et al.
      Apolipoprotein B-dependent hepatitis C virus secretion is inhibited by the grapefruit flavonoid naringenin.
      ], HCV infectivity is closely related to the level of apoE present in HCVcc particles [
      • Chang K.S.
      • Jiang J.
      • Cai Z.
      • Luo G.
      Human apolipoprotein e is required for infectivity and production of hepatitis C virus in cell culture.
      ] and biochemical analysis shows that these particles have 290 ± 41 apoE molecules per viral RNA [
      • Merz A.
      • Long G.
      • Hiet M.S.
      • Bruegger B.
      • Chlanda P.
      • Andre P.
      • et al.
      Biochemical and morphological properties of hepatitis C virus particles and determination of their lipidome.
      ]. Knockdown of apoE by a specific siRNA results in reductions in infectious HCV [
      • Jiang J.
      • Luo G.
      Apolipoprotein E but not B is required for the formation of infectious hepatitis C virus particles.
      ] and an interaction between apoE and NS5A is required for assembly of infectious HCV particles [
      • Cun W.
      • Jiang J.
      • Luo G.
      The C-terminal alpha-helix domain of apolipoprotein E is required for interaction with nonstructural protein 5A and assembly of hepatitis C virus.
      ,
      • Benga W.J.
      • Krieger S.E.
      • Dimitrova M.
      • Zeisel M.B.
      • Parnot M.
      • Lupberger J.
      • et al.
      Apolipoprotein E interacts with hepatitis C virus nonstructural protein 5A and determines assembly of infectious particles.
      ]. Virion associated cholesterol contributes to the interaction between HCV particles and apoE [
      • Yamamoto M.
      • Aizaki H.
      • Fukasawa M.
      • Teraoka T.
      • Miyamura M.
      • Wakita T.
      • et al.
      Apolipoprotein E interacts with hepatitis C virus nonstructural protein 5A and determines assembly of infectious particles.
      ]. Production of HCVcc from serum free culture has shown that these viral particles have a lower level of associated apoE and that lipids conjugated with HCV affect infection and neutralization [
      • Akazawa D.
      • Morikawa K.
      • Omi N.
      • Takahashi H.
      • Nakamura N.
      • Mochizuki H.
      • et al.
      Production and characterization of HCV particles from serum-free culture.
      ]. Recently, it has also been shown that specific siRNA-mediated downregulation of apoAI leads to a reduction of HCV RNA and viral particles in vitro [
      • Mancone C.
      • Steindler C.
      • Santangelo L.
      • Simonte G.
      • Vlassi C.
      • Longo M.A.
      • et al.
      Hepatitis C virus production requires apolipoprotein A-I and affects its association with nascent low-density lipoproteins.
      ].
      Infectious HCV particles can also be produced in primary hepatocytes (HCVpc) [
      • Podevin P.
      • Carpentier A.
      • Pene V.
      • Aoudjehane L.
      • Carriere M.
      • Zaidi S.
      • et al.
      Production of infectious hepatitis C virus in primary cultures of human adult hepatocytes.
      ]. Compared with HCVcc, HCVpc had lower average buoyant density and higher specific infectivity, similar to the characteristics of virus particles associated with VLDL that are produced during in vivo infection.
      The infectivity of hepatitis C viral particles is thus inversely related to their density and low density particles have been termed lipo-viral particles (LVP). LVPs in vivo are TG-rich and contain at least viral RNA, HCV core protein, and the VLDL components apoB and apoE [
      • Andre P.
      • Komurian P.F.
      • Deforges S.
      • Perret M.
      • Berland J.L.
      • Sodoyer M.
      • et al.
      Characterization of low- and very-low-density hepatitis C virus RNA containing particles.
      ,
      • Diaz O.
      • Delers F.
      • Maynard M.
      • Demignot S.
      • Zoulim F.
      • Chambaz J.
      • et al.
      Preferential association of Hepatitis C virus with apolipoprotein B48-containing lipoproteins.
      ,
      • Nielson S.U.
      • Bassendine M.F.
      • Burt A.D.
      • Martin C.
      • Pumeechockchai W.
      • Toms G.L.
      Association between hepatitis C virus and very-low-density lipoprotein (VLDL)/LDL analysed in iodixanol density gradients.
      ]. It has long been recognised that HCV in serum has a wide range of buoyant densities due to this association with lipoproteins and immunoglobulins [
      • Thomssen R.
      • Bonk S.
      • Thiele A.
      Density heterogeneities of Hepatitis C virus in human sera due to binding of beta-lipoproteins and immunoglobulins.
      ,
      • Kanto T.
      • Hayashi N.
      • Takehara T.
      • Hagiwara H.
      • Mita E.
      • Naito Kashara A.
      • et al.
      Density analysis of Hepatitis-C Virus particle-population in the circulation of infected hosts – implications for virus neutralization or persistence.
      ]. The contribution of LVP to total HCV viral load varies widely in a cohort of fasting chronic HCV G1 patients and correlates not only with TG:HDL ratio and HOMA-IR but also with non-response to anti-viral therapy [
      • Bridge S.H.
      • Sheridan D.A.
      • Felmlee D.J.
      • Nielsen S.U.
      • Thomas H.C.
      • Taylor-Robinson S.D.
      • et al.
      Insulin resistance and low-density apolipoprotein B-associated lipoviral particles in hepatitis C virus genotype 1 infection.
      ]. The buoyant density of HCV particles in human plasma is not only heterogeneous, but also dynamic and dependent on TRL in circulation [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ]. Very-low-density HCV (density <1.025 g/ml) associated with TRLs (VLDL1, IDL, CM, and CM remnants) rise 26-fold after a fatty meal and are rapidly cleared from the circulation, rather than entering the lipolytic cascade, suggesting removal via the hepatic TRL receptors [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ]. These post-prandial LVP are associated with both apoB100 and apoB48 TRLs [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ], confirming a previous study [
      • Diaz O.
      • Delers F.
      • Maynard M.
      • Demignot S.
      • Zoulim F.
      • Chambaz J.
      • et al.
      Preferential association of Hepatitis C virus with apolipoprotein B48-containing lipoproteins.
      ]. The marked increase in these putative infectious LVP after a fatty meal appears to be due not only to de novo production from infected hepatocytes but also to intravascular transfer onto TRLs in a manner similar to exchangeable lipoproteins (Fig. 5). These studies in patients with chronic HCV suggest that HCV has not only co-opted the VLDL assembly, maturation, degradation, and secretory machinery of the hepatocyte but also utilises the intravascular remodelling of lipoproteins and the rapid removal of TRL remnants by the liver to its advantage (Fig. 6).
      Figure thumbnail gr5
      Fig. 5The buoyant density of HCV particles in human plasma is heterogenous. High density HCV is associated with immunoglobulins, whilst low density infectious HCV-lipo-viral particles (LVP) contain at least HCV RNA, HCV core protein, TG and VLDL components apoB and apoE. HCV is able to transfer onto TRLs in a manner similar to exchangeable lipoproteins
      [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ]
      . Antibodies to apoCI are able to neutralise >75% of infectious particles in vitro
      [
      • Meunier J.-C.
      • Russell R.S.
      • Engle R.E.
      • Faulk K.N.
      • Purcell R.H.
      • Emerson S.U.
      Apolipoprotein c1 association with hepatitis C virus.
      ]
      . It is not known whether immunoglobulin-loaded HCV can be exchanged.
      Figure thumbnail gr6
      Fig. 6HCV co-opts the hepatic TRL remnant pathway. After a fatty meal, there is a 26-fold increase in very-low density lipo-viral particles (LVP) which are rapidly cleared from the plasma (t1/2 of 95 min)
      [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ]
      .

      HCV entry

      The current model for HCV entry involves the initial docking of the virus onto the cell surface through interactions of LVP with cell surface HSPG and lipoprotein receptors (e.g. LDL-R, SR-B1) which lead to conformational change(s) in the viral particle allowing the engagement of other hepatocyte membrane co-receptors (CD81, Claudin 1 (CLDN1) and Occludin (OCLN) (reviewed in [
      • Farquhar M.J.
      • McKeating J.A.
      Primary hepatocytes as targets for hepatitis C virus replication.
      ,
      • Burlone M.E.
      • Budkowska A.
      Hepatitis C virus cell entry: role of lipoproteins and cellular receptors.
      ,
      • Bartenschlager R.
      • Cosset F.L.
      • Lohmann V.
      Hepatitis C virus replication cycle.
      ]). HCVcc infectivity is increased 18-fold in Huh-7 cells over-expressing SR-B1 [
      • Grove J.
      • Nielsen S.
      • Zhong J.
      • Bassendine M.F.
      • Drummer H.E.
      • Balfe P.
      • et al.
      Identification of a residue in hepatitis C virus E2 glycoprotein that determines scavenger receptor BI and CD81 receptor dependency and sensitivity to neutralising antibodies.
      ] and SR-BI appears to be an essential HCV entry factor [
      • Dreux M.
      • Dao Thi V.L.
      • Fresquet J.
      • Guerin M.
      • Julia Z.
      • Verney G.
      • et al.
      Receptor complementation and mutagenesis reveal SR-BI as an essential HCV entry factor and functionally imply its intra- and extra-cellular domains.
      ]. Thus, cellular receptors involved in the uptake of VLDL and CM remnants in vivo (HSPG, SR-B1 and LDL-R; Fig. 4) are also implicated as receptors for infectious HCVcc particles. Blocking experiments show that VLDL itself or anti-apoE antibody can block HCV LVP entry [
      • Owen D.M.
      • Huang H.
      • Ye J.
      • Gale Jr, M.
      Apolipoprotein E on hepatitis C virion facilitates infection through interaction with low-density lipoprotein receptor.
      ]. ApoE isoforms have been found to influence infectivity with the suggestion that the apoE2 isoform, which has low affinity for LDL-R, being associated with poor infectivity both in vitro [
      • Hishiki T.
      • Shimizu Y.
      • Tobita R.
      • Sugiyama K.
      • Ogawa K.
      • Funami K.
      • et al.
      Infectivity of hepatitis C virus is influenced by association with apolipoprotein E isoforms.
      ] and in vivo [

      Price DA, Bassendine MF, Norris SN, Golding C, Toms GL, Schmid ML, et al. The Apolipoprotein e3 allele is associated with persistent Hepatitis C Virus infection. Gut 2006.

      ]. It is likely that the balance of apoE and apoCs on LVPs is involved in cell entry. ApoCI appears to be involved in infectivity; it is recruited by HCV glycoproteins on the viral surface and promotes fusion of HCV particles with membranes [
      • Dreux M.
      • Boson B.
      • Ricard-Blum S.
      • Molle J.
      • Lavillette D.
      • Bartosch B.
      • et al.
      The exchangeable apolipoprotein ApoC-I promotes membrane fusion of hepatitis C virus.
      ]. ApoCI also enhances HCVpp infectivity [
      • Meunier J.-C.
      • Russell R.S.
      • Engle R.E.
      • Faulk K.N.
      • Purcell R.H.
      • Emerson S.U.
      Apolipoprotein c1 association with hepatitis C virus.
      ].

      The lipid pathway as a therapeutic target in chronic HCV

      The current standard of care (SoC) for the treatment of hepatitis C virus (HCV) infection is a combination of pegylated IFN and ribavirin (Peg-IFN/RBV) [
      • Aghemo A.
      • Rumi M.G.
      • Colombo M.
      Pegylated interferons alpha2a and alpha2b in the treatment of chronic hepatitis C.
      ], but this cures around 50% (sustained virological response (SVR) = undetectable HCV RNA for greater than 24 weeks after cessation of therapy). There is hence an urgent need for better treatment and a huge array of potential targets for the development of new classes of HCV therapies [
      • Lemon S.M.
      • McKeating J.A.
      • Pietschmann T.
      • Frick D.N.
      • Glenn J.S.
      • Tellinghuisen T.L.
      • et al.
      Development of novel therapies for hepatitis C.
      ], which has focused initially on “direct-acting anti-virals” (DAAs) [
      • Lange C.M.
      • Sarrazin C.
      • Zeuzem S.
      Review article: specifically targeted anti-viral therapy for hepatitis C – a new era in therapy.
      ]. These represent a major step forward but the emergence of drug-resistant virus in patients with viral breakthrough on treatment needs to be addressed [
      • Thompson A.J.
      • McHutchison J.G.
      Antiviral resistance and specifically targeted therapy for HCV (STAT-C).
      ,
      • Milazzo L.
      • Antinori S.
      STAT-C: a full revolution or just a step forward?.
      ].
      HCV–lipid interactions represent attractive targets for indirect-acting antiviral (IDAA) development because it is more difficult for the virus to develop escape mutations against therapeutics that target host cell factors. In addition, as dyslipidaemia in the metabolic syndrome is central to cardiovascular disease, a number of therapeutic interventions are already in use or under development for this indication [
      • Watts G.F.
      • Ooi E.M.
      • Chan D.C.
      Therapeutic regulation of apoB100 metabolism in insulin resistance in vivo.
      ]. An understanding of how HCV genotypes interact with lipid pathways is thus central to the use of these treatments “off-label” for a condition not approved in the marketing authorization [
      • Kairuz T.E.
      • Gargiulo D.
      • Bunt C.
      • Garg S.
      Quality, safety and efficacy in the ‘off-label’ use of medicines.
      ].

      Diet and lifestyle modifications

      Obesity may be associated with decreased efficacy of current SOC [
      • Charlton M.R.
      • Pockros P.J.
      • Harrison S.A.
      Impact of obesity on treatment of chronic hepatitis C.
      ]. Modest weight loss optimally decreases plasma TG and LDL-cholesterol via reduction in hepatic apoB secretion [
      • Watts G.F.
      • Chan D.C.
      • Ooi E.M.
      • Nestel P.J.
      • Beilin L.J.
      • Barrett P.H.
      Fish oils, phytosterols and weight loss in the regulation of lipoprotein transport in the metabolic syndrome: lessons from stable isotope tracer studies.
      ]. One small unconfirmed study in patients with chronic hepatitis C (CHC) has reported an association of a mean weight loss of only 5.9 kg with a reduction in steatosis and abnormal liver enzymes and an improvement in fibrosis, despite the persistence of HCV [
      • Hickman I.J.
      • Clouston A.D.
      • Macdonald G.A.
      • Purdie D.M.
      • Prins J.B.
      • Ash S.
      • et al.
      Effect of weight reduction on liver histology and biochemistry in patients with chronic hepatitis C.
      ]. Conversely, high visceral adiposity is associated with both steatosis and high viral load in G1-CHC [
      • Petta S.
      • Amato M.
      • Cabibi D.
      • Camma C.
      • Di Marco V.
      • Giordano C.
      • et al.
      Visceral adiposity index is associated with histological findings and high viral load in patients with chronic hepatitis C due to genotype 1.
      ]. Hence, management of dyslipidaemia with diet and exercise may provide an adjunct treatment strategy for obese patients with CHC [
      • Testino G.
      • Sumberaz A.
      • Ancarani A.O.
      • Borro P.
      • Ravetti G.
      • Ansaldi F.
      • et al.
      Influence of body mass index, cholesterol, triglycerides and steatosis on pegylated interferon alfa-2a and ribavirin treatment for recurrent hepatitis C in patients transplanted for HCV and alcoholic cirrhosis.
      ].

      Omega-3-fatty acids

      Fish oils are a rich source of omega-3-fatty acids, eicosapentaenoic acid and docosahexanoic acid. Fish oils diminish hepatic secretion of VLDL-apoB [
      • Watts G.F.
      • Chan D.C.
      • Ooi E.M.
      • Nestel P.J.
      • Beilin L.J.
      • Barrett P.H.
      Fish oils, phytosterols and weight loss in the regulation of lipoprotein transport in the metabolic syndrome: lessons from stable isotope tracer studies.
      ]. Several polyunsaturated fatty acids (PUFA) including eicosapentaenoic acid and docosahexanoic acid dramatically inhibit HCV replication in vitro using the HCV RNA replicon system [
      • Kapadia S.B.
      • Chisari F.V.
      Hepatitis C virus RNA replication is regulated by host geranylgeranylation and fatty acids.
      ]. When combined with IFN-alpha, PUFAs have a strong synergistic anti-HCV effect in vitro [
      • Leu G.Z.
      • Lin T.Y.
      • Hsu J.T.
      Anti-HCV activities of selective polyunsaturated fatty acids.
      ], but no studies have evaluated whether omega-3-fatty acids can provide synergistic antiviral effects when given as food supplements during IFN-based anti-HCV therapy in patients.

      Pharmacological interventions

      Targeting LVP assembly, maturation and secretion

      Lipid lowering drugs differ strongly with respect to the types of lipids or lipoproteins that they predominantly affect. The major classes of drugs that lower cholesterol are statins and cholesterol absorption inhibitors, whilst those that lower triglycerides are fibrates and omega-3 fatty acids. Nicotinic acid has a hybrid position in that it decreases both TG and cholesterol. As a rule, TG lowering drugs increase HDL-cholesterol and nicotinic acid is the strongest HDL raising drug in current clinical use.

      Statins

      Statins inhibit the de novo synthesis of cholesterol in the liver by blocking mevalonate production via inhibition of 3-hydroxy-3-methylglutaryl CoA reductase (HMG CoA reductase) (Fig. 3) and have other pleiotropic effects. Initial in vitro studies in genomic and sub-genomic HCV RNA replicons showed that lovastatin markedly reduced HCV RNA levels [
      • Ye J.
      • Wang C.
      • Sumpter R.
      • Brown M.S.
      • Goldstein J.L.
      • Gale M.
      Disruption of hepatitis C RNA replication through inhibition of host protein geranylgeranylation.
      ]. This effect was shown to be mediated by inhibiting geranylgeranylation of a host protein FBL2 required for HCV replication [
      • Kapadia S.B.
      • Chisari F.V.
      Hepatitis C virus RNA replication is regulated by host geranylgeranylation and fatty acids.
      ]. In vitro, different statins show a hierarchy of inhibition of HCV replication, with pravastatin being devoid of an anti-viral effect [
      • Ikeda M.
      • Kato N.
      Life style-related diseases of the digestive system: cell culture system for the screening of anti-hepatitis C virus (HCV) reagents: suppression of HCV replication by statins and synergistic action with interferon.
      ,
      • Delang L.
      • Paeshuyse J.
      • Vliegen I.
      • Leyssen P.
      • Obeid S.
      • Durantel D.
      • et al.
      Statins potentiate the in vitro anti-hepatitis C virus activity of selective hepatitis C virus inhibitors and delay or prevent resistance development.
      ]. The sensitivity of HCV to an individual statin may also vary [
      • Nishimura G.
      • Ikeda M.
      • Mori K.
      • Nakazawa T.
      • Ariumi Y.
      • Dansako H.
      • et al.
      Replicons from genotype 1b HCV-positive sera exhibit diverse sensitivities to anti-HCV reagents.
      ].
      In combination with IFN-α, both fluvastatin and pitavastatin show strong synergistic activity and enhance the anti-HCV effect of IFN-α [
      • Ikeda M.
      • Kato N.
      Life style-related diseases of the digestive system: cell culture system for the screening of anti-hepatitis C virus (HCV) reagents: suppression of HCV replication by statins and synergistic action with interferon.
      ,
      • Ikeda M.
      • Abe K.
      • Yamada M.
      • Dansako H.
      • Naka K.
      • Kato N.
      Different anti-HCV profiles of statins and their potential for combination therapy with interferon.
      ]. Statins may be a useful adjunctive therapy with HCV polymerase or protease inhibitors as an additive antiviral effect has been reported with mevastatin or simvastatin in vitro in short-term (3 days) antiviral assays [
      • Delang L.
      • Paeshuyse J.
      • Vliegen I.
      • Leyssen P.
      • Obeid S.
      • Durantel D.
      • et al.
      Statins potentiate the in vitro anti-hepatitis C virus activity of selective hepatitis C virus inhibitors and delay or prevent resistance development.
      ]. However, the potential for clinically relevant drug–drug interactions between statins and DAAs via CYP450-dependent metabolism [
      • Feidt D.M.
      • Klein K.
      • Hofmann U.
      • Riedmaier S.
      • Knobeloch D.
      • Thasler W.E.
      • et al.
      Profiling induction of cytochrome p450 enzyme activity by statins using a new liquid chromatography-tandem mass spectrometry cocktail assay in human hepatocytes.
      ] could present a problem, similar to that encountered in the treatment of HIV infection with “ritonovir-boosted” protease inhibitors [
      • Josephson F.
      Drug–drug interactions in the treatment of HIV infection: focus on pharmacokinetic enhancement through CYP3A inhibition.
      ].
      The clinical data with statins are limited, but indicate that statin monotherapy has little anti-viral effect [
      • Bader T.
      • Fazili J.
      • Madhoun M.
      • Aston C.
      • Hughes D.
      • Rizvi S.
      • et al.
      Fluvastatin inhibits hepatitis C replication in humans.
      ,
      • Mihaila R.
      • Nedelcu L.
      • Fratila O.
      • Rezi E.C.
      • Domnariu C.
      • Ciuca R.
      • et al.
      Lovastatin and fluvastatin reduce viremia and the pro-inflammatory cytokines in the patients with chronic hepatitis C.
      ,
      • Milazzo L.
      • Meroni L.
      • Galazzi M.
      • Cesari M.
      • Caramma I.
      • Marchetti G.
      • et al.
      Does fluvastatin favour HCV replication in vivo? A pilot study on HIV-HCV coinfected patients.
      ,
      • O’Leary J.G.
      • Chan J.L.
      • McMahon C.M.
      • Chung R.T.
      Atorvastatin does not exhibit antiviral activity against HCV at conventional doses: a pilot clinical trial.
      ,
      • Forde K.A.
      • Law C.
      • O’Flynn R.
      • Kaplan D.E.
      Do statins reduce hepatitis C RNA titers during routine clinical use?.
      ], although combination therapy is more promising and adequately powered randomised controlled trials are needed.
      The disappointing and sometimes contradictory results using statin monotherapy in vivo may be partially explained by dose effects. With conventional doses, the serum concentration of the statin may be 10-fold lower than that found be effective in the HCV replicon systems. Also, besides their effect on HCV replication, statins cause up-regulation of LDL-R and hence may enhance HCV infectivity of hepatocytes, abrogating or even reversing any beneficial effects of monotherapy in vivo.
      Combining a statin with Peg-IFN/RBV appears more promising [
      • Sezaki H.
      • Suzuki F.
      • Akuta N.
      • Yatsuji H.
      • Hosaka T.
      • Kobayashi M.
      • et al.
      An open pilot study exploring the efficacy of fluvastatin, pegylated interferon and ribavirin in patients with hepatitis C virus genotype 1b in high viral loads.
      ] (Table 2). In HCV/HIVco-infection, combination of fluvastatin with Peg-IFN/RBV significantly improved the rapid virological response (RVR) rate [
      • Milazzo L.
      • Caramma I.
      • Mazzali C.
      • Cesari M.
      • Olivetti M.
      • Galli M.
      • et al.
      Fluvastatin as an adjuvant to pegylated interferon and ribavirin in HIV/hepatitis C virus genotype 1 co-infected patients: an open-label randomized controlled study.
      ]. In patients with HCV-G1 infection treated in the IDEAL study [
      • McHutchison J.G.
      • Lawitz E.J.
      • Shiffman M.L.
      • Muir A.J.
      • Galler G.W.
      • McCone J.
      • et al.
      Peginterferon alfa-2b or alfa-2a with ribavirin for treatment of hepatitis C infection.
      ], multivariate logistic regression analysis showed that pre-emptive statin use was independently associated with SVR. This has been confirmed by a large retrospective study utilising the USA Veterans Affairs administrative database where statin use was associated with an improved SVR among both diabetic patients and nondiabetic patients receiving combination antiviral therapy [
      • Rao G.A.
      • Pandya P.K.
      Statin therapy improves sustained virologic response among diabetic patients with chronic hepatitis C.
      ].
      Table 2Examples of studies evaluating lipid-modulating therapies in vivo and their effect on HCV.
      SoC, standard of care

      EASL Clinical Practice Guidelines: Management of hepatitis C virus infection. J Hepatol 2011.

      : NR, non-responder; RVR, rapid virological response; SVR, sustained virological response.

      Peroxisome proliferator-activated receptor (PPAR) agonists

      PPARs belong to the steroid/thyroid/retinoid receptor superfamily and are nuclear lipid-activable receptors that control a variety of genes in several pathways of lipid metabolism [
      • Desvergne B.
      • Wahli W.
      Peroxisome proliferator-activated receptors: nuclear control of metabolism.
      ]. In addition to being activated by fatty acids, they respond to fibric acid derivatives and thiazolidinediones.

      PPARα agonists

      Fibrates decrease hepatic VLDL secretion and enhance clearance, hence reducing plasma TG by 30–50% [
      • Shah A.
      • Rader D.J.
      • Millar J.S.
      The effect of PPAR-alpha agonism on apolipoprotein metabolism in humans.
      ]. They are particularly beneficial in overweight people with high plasma TG levels and low levels of HDL cholesterol (HDL-C). Lower TGs associate with higher rates of SVR in CHC-G1 [
      • Ramcharran D.
      • Wahed A.S.
      • Conjeevaram H.S.
      • Evans R.W.
      • Wang T.
      • Belle S.H.
      • et al.
      Associations between serum lipids and hepatitis C antiviral treatment efficacy.
      ], but there is conflicting data on the use of fibrates in HCV. One in vitro study showing binding of HCV core protein to apoAII reported that fenofibrate treatment resulted in a parallel increase in apoAII and core protein secretion [
      • Sabile A.
      • Perlemuter G.
      • Bono F.
      • Kohara K.
      • Demaugre F.
      • Kohara M.
      • et al.
      Hepatitis C virus core protein binds to apolipoprotein AII and its secretion is modulated by fibrates.
      ]. Another found that use of a PPAR-α antagonist resulted in disruption of HCV replication complexes [
      • Lyn R.K.
      • Kennedy D.C.
      • Sagan S.M.
      • Blais D.R.
      • Rouleau Y.
      • Pegoraro A.F.
      • et al.
      Direct imaging of the disruption of hepatitis C virus replication complexes by inhibitors of lipid metabolism.
      ]. However, a recent study in a sub-genomic replicon model for HCV-induced steatosis shows that fenofibrate reduced ER stress [
      • Rahman S.M.
      • Qadri I.
      • Janssen R.C.
      • Friedman J.E.
      Fenofibrate and PBA prevent fatty acid-induced loss of adiponectin receptor and pAMPK in human hepatoma cells and in hepatitis C virus-induced steatosis.
      ] whilst a pilot study in patients has suggested that bezafibrate may be useful in combination with Peg-IFN/RBV [
      • Fujita N.
      • Kaito M.
      • Kai M.
      • Sugimoto R.
      • Tanaka H.
      • Horiike S.
      • et al.
      Effects of bezafibrate in patients with chronic hepatitis C virus infection: combination with interferon and ribavirin.
      ].

      PPAR-γ agonists

      Both pioglitazone and rosiglitazone are effective in reducing liver fat content by 30–50% and sensitizing the liver to insulin but they have different effects on serum lipids [
      • Yki-Jarvinen H.
      Thiazolidinediones and the liver in humans.
      ]. Pioglitazone has a beneficial effect on fasting and post-prandial plasma triglycerides and reduces hepatic de novo lipogenesis [
      • Chappuis B.
      • Braun M.
      • Stettler C.
      • Allemann S.
      • Diem P.
      • Lumb P.J.
      • et al.
      Differential effect of pioglitazone (PGZ) and rosiglitazone (RGZ) on postprandial glucose and lipid metabolism in patients with type 2 diabetes mellitus: a prospective, randomized crossover study.
      ,
      • Beysen C.
      • Murphy E.J.
      • Nagaraja H.
      • Decaris M.
      • Riiff T.
      • Fong A.
      • et al.
      A pilot study of the effects of pioglitazone and rosiglitazone on de novo lipogenesis in type 2 diabetes.
      ]. Pioglitazone has been used in chronic HCV with the rationale that insulin resistance affects SVR. A study in treatment naïve HCV genotype 4 patients with HOMA-IR >2 has reported increased RVR, SVR and decreased IR in those receiving triple combination therapy (pioglitazone/Peg-IFN/RBV) (Table 2) [
      • Khattab M.
      • Emad M.
      • Abdelaleem A.
      • Eslam M.
      • Atef R.
      • Shaker Y.
      • et al.
      Pioglitazone improves virological response to peginterferon alpha-2b/ribavirin combination therapy in hepatitis C genotype 4 patients with insulin resistance.
      ]. The dose and schedule of use of pioglitazone may be important [
      • Overbeck K.
      • Genne D.
      • Golay A.
      • Negro F.
      Pioglitazone in chronic hepatitis C not responding to pegylated interferon-alpha and ribavirin.
      ], with the suggestion that sequential rather than concomitant use is preferable [
      • Serfaty L.
      • Fartoux L.
      • Poupon R.
      Pioglitazone as adjuvant therapy in chronic hepatitis C: sequential rather than concomitant administration with pegylated interferon and ribavirin?.
      ]. In addition the response may be affected by genotype-dependent HCV–host interactions [
      • del Campo J.A.
      • Lopez R.A.
      • Romero-Gomez M.
      Insulin resistance and response to antiviral therapy in chronic hepatitis C: mechanisms and management.
      ]. Further understanding of the effect of these compounds on HCV–lipid interaction in addition to simple insulin sensitisation is required to inform trial design. Measurement of LVP [
      • Bridge S.H.
      • Sheridan D.A.
      • Felmlee D.J.
      • Nielsen S.U.
      • Thomas H.C.
      • Taylor-Robinson S.D.
      • et al.
      Insulin resistance and low-density apolipoprotein B-associated lipoviral particles in hepatitis C virus genotype 1 infection.
      ] in addition to total HCV viral load and HOMA-IR is likely to be informative.

      Niacin (Nicotinic acid)

      Niacin is a water-soluble B vitamin (B3) which decreases plasma triglycerides by 25%, increases HDL-C and reduces LDL cholesterol modestly [
      • Brown B.G.
      • Zhao X.Q.
      Nicotinic acid, alone and in combinations, for reduction of cardiovascular risk.
      ]. Its use has been hampered because it can cause frequent flushing of the skin, but addition of a prostaglandin receptor blocker, laropiprant, improves this side effect [
      • Cheng K.
      • Wu T.J.
      • Wu K.K.
      • Sturino C.
      • Metters K.
      • Gottesdiener K.
      • et al.
      Antagonism of the prostaglandin D2 receptor 1 suppresses nicotinic acid-induced vasodilation in mice and humans.
      ,
      • Maccubbin D.
      • Bays H.E.
      • Olsson A.G.
      • Elinoff V.
      • Elis A.
      • Mitchel Y.
      • et al.
      Lipid-modifying efficacy and tolerability of extended-release niacin/laropiprant in patients with primary hypercholesterolaemia or mixed dyslipidaemia.
      ]. In patients with CHC G1 there is a strong correlation between fasting LVP and TG:HDL ratio [
      • Bridge S.H.
      • Sheridan D.A.
      • Felmlee D.J.
      • Nielsen S.U.
      • Thomas H.C.
      • Taylor-Robinson S.D.
      • et al.
      Insulin resistance and low-density apolipoprotein B-associated lipoviral particles in hepatitis C virus genotype 1 infection.
      ] and a post-prandial surge in TG-rich LVPs [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ], suggesting that niacin may be beneficial as an adjunct to SoC. This is supported by a recent cross-sectional and longitudinal analysis of HCV RNA viral loads in chronic HCV patients with dyslipidaemia in which hypertriglycerideamia was found to correlate with HCV titres and niacin exposure was associated with significantly lower viral titres [
      • Forde K.A.
      • Law C.
      • O’Flynn R.
      • Kaplan D.E.
      Do statins reduce hepatitis C RNA titers during routine clinical use?.
      ]. Another study has also reported significant differences in niacin intake between responders and non-responders to interferon therapy [
      • Loguercio C.
      • Federico A.
      • Masarone M.
      • Torella R.
      • Blanco Cdel V.
      • Persico M.
      The impact of diet on liver fibrosis and on response to interferon therapy in patients with HCV-related chronic hepatitis.
      ]. Niacin warrants further evaluation, either alone or in combination with a statin [
      • Vittone F.
      • Chait A.
      • Morse J.S.
      • Fish B.
      • Brown B.G.
      • Zhao X.Q.
      Niacin plus simvastatin reduces coronary stenosis progression among patients with metabolic syndrome despite a modest increase in insulin resistance. a subgroup analysis of the HDL-Atherosclerosis treatment study (HATS).
      ] as adjunctive therapy, particularly in patients with HCV genotype 1, body weight ⩾ 85 kg, and high baseline viral load who respond poorly to Peg-IFN/RBV [
      • Reddy K.R.
      • Shiffman M.L.
      • Rodriguez-Torres M.
      • Cheinquer H.
      • Abdurakhmanov D.
      • Bakulin I.
      • et al.
      Induction pegylated interferon alfa-2a and high dose ribavirin do not increase SVR in heavy patients with HCV genotype 1 and high viral loads.
      ].

      Silymarin

      Silymarin, a mixture of flavolignans extracted from the milk thistle plant Silybum marianum, is widely used as a traditional herbal remedy for self-treatment of chronic HCV. The main component of silymarin is silibinin which has been shown to inhibit HCV infection both in vitro and in vivo [
      • Ferenci P.
      • Scherzer T.M.
      • Kerschner H.
      • Rutter K.
      • Beinhardt S.
      • Hofer H.
      • et al.
      Silibinin is a potent antiviral agent in patients with chronic hepatitis C not responding to pegylated interferon/ribavirin therapy.
      ].The mechanism of action of silymarin is complex but it includes decreasing infectious virion production by blocking MTP-dependent apoB secretion [
      • Wagoner J.
      • Negash A.
      • Kane O.J.
      • Martinez L.E.
      • Nahmias Y.
      • Bourne N.
      • et al.
      Multiple effects of silymarin on the hepatitis C virus lifecycle.
      ]. The plant flavanoid taxifolin, also present in milk thistle, has likewise been shown to decrease hepatic lipid synthesis by decreasing apoB and increasing apoAI secretion [
      • Theriault A.
      • Wang Q.
      • Van Iderstine S.C.
      • Chen B.
      • Franke A.A.
      • Adeli K.
      Modulation of hepatic lipoprotein synthesis and secretion by taxifolin, a plant flavonoid.
      ]. As silymarin-derived compounds may influence HCV disease course in some patients [
      • Polyak S.J.
      • Morishima C.
      • Lohmann V.
      • Pal S.
      • Lee D.Y.
      • Liu Y.
      • et al.
      Identification of hepatoprotective flavonolignans from silymarin.
      ], studies where standardized compounds are dosed to identify specific clinical endpoints are urgently needed. Initial case reports using silibinin to prevent graft reinfection after orthotopic liver transplantation are encouraging [
      • Neumann U.P.
      • Biermer M.
      • Eurich D.
      • Neuhaus P.
      • Berg T.
      Successful prevention of hepatitis C virus (HCV) liver graft reinfection by silibinin mono-therapy.
      ,
      • Beinhardt S.
      • Rasoul-Rockenschaub S.
      • Scherzer T.M.
      • Ferenci P.
      Silibinin monotherapy prevents graft infection after orthotopic liver transplantation in a patient with chronic hepatitis C.
      ].

      ApoB antisense

      An antisense inhibitor of apoB synthesis, mipomersen, has recently been shown to be effective and safe as an adjunctive agent to lower LDL cholesterol concentrations in patients with familial hypercholesterolaemia [
      • Raal F.J.
      • Santos R.D.
      • Blom D.J.
      • Marais A.D.
      • Charng M.J.
      • Cromwell W.C.
      • et al.
      Mipomersen, an apolipoprotein B synthesis inhibitor, for lowering of LDL cholesterol concentrations in patients with homozygous familial hypercholesterolaemia: a randomised, double-blind, placebo-controlled trial.
      ,
      • Visser M.E.
      • Kastelein J.J.
      • Stroes E.S.
      Apolipoprotein B synthesis inhibition: results from clinical trials.
      ]. Mipomersen contains an endonuclease resistant modified sequence of nucleotides complementary to ApoB mRNA which binds to and inhibits the translation of the encoded sequence into the mature protein, reducing the synthesis and secretion of the apolipoprotein B lipoproteins VLDL and LDL [
      • Neely R.D.
      • Bassendine M.F.
      Antisense technology to lower LDL cholesterol.
      ]. As silencing ApoB mRNA in the HCVcc system causes a 70% reduction in the secretion of both ApoB100 and HCV [
      • Gastaminza P.
      • Cheng G.
      • Wieland S.
      • Zhong J.
      • Liao W.
      • Chisari F.V.
      Cellular determinants of hepatitis C virus assembly, maturation, degradation, and secretion.
      ,
      • Nahmias Y.
      • Goldwasser J.
      • Casali M.
      • van Poll D.
      • Wakita T.
      • Chung R.T.
      • et al.
      Apolipoprotein B-dependent hepatitis C virus secretion is inhibited by the grapefruit flavonoid naringenin.
      ,
      • Huang H.
      • Sun F.
      • Owen D.M.
      • Li W.
      • Chen Y.
      • Gale M.J.
      • et al.
      Hepatitis C virus production by human hepatocytes dependent on assembly and secretion of very low-density lipoproteins.
      ], this novel drug may warrant evaluation in chronic HCV infection.

      MicroRNA-122 inhibition

      MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at post-transcriptional level. Some miRNAs have been associated with lipid metabolism; for example miR-122 inhibition in normal mice results in reduced plasma cholesterol levels [
      • Esau C.
      • Davis S.
      • Murray S.F.
      • Yu X.X.
      • Pandey S.K.
      • Pear M.
      • et al.
      MiR-122 regulation of lipid metabolism revealed by in vivo antisense targeting.
      ]. Recent work has shown that therapeutic silencing of miRNA-122 in primates with CHC leads to long lasting suppression of HCV viraemia [
      • Lanford R.E.
      • Hildebrandt-Eriksen E.S.
      • Petri A.
      • Persson R.
      • Lindow M.
      • Munk M.E.
      • et al.
      Therapeutic silencing of microRNA-122 in primates with chronic hepatitis C virus infection.
      ].

      Novel targets

      3β-Hydroxysterol Δ24-reductase (DHCR24) inhibitors

      DHCR24 is an enzyme in the cholesterol biosynthetic pathway, converting desmosterol to cholesterol [
      • Waterham H.R.
      • Koster J.
      • Romeijn G.J.
      • Hennekam R.C.
      • Vreken P.
      • Andersson H.C.
      • et al.
      Mutations in the 3beta-hydroxysterol Delta24-reductase gene cause desmosterolosis, an autosomal recessive disorder of cholesterol biosynthesis.
      ]. This enzyme is induced by HCV infection in human hepatocytes in vitro and an inhibitor of DHCR24 has recently been shown to have an anti-viral effect in chimeric mice with HCV infection in their humanised liver [

      Takano T, Tsukiyama-Kohara K, Hayashi M, Hirata Y, Satoh M, Tokunaga Y, et al. Augmentation of DHCR24 expression by hepatitis C virus infection facilitates viral replication in hepatocytes. J Hepatol 2011.

      ].

      Diacylglycerol acyltransferase 1 (DGAT1) inhibitors

      DGAT1 interacts with HCV core and is required for its trafficking to lipid droplets. Inhibition of DGAT1 activity or RNAi-mediated knockdown of DGAT1 severely impairs infectious virion production, implicating DGAT1 as a new target for antiviral therapy [
      • Herker E.
      • Harris C.
      • Hernandez C.
      • Carpentier A.
      • Kaehlcke K.
      • Rosenberg A.R.
      • et al.
      Efficient hepatitis C virus particle formation requires diacylglycerol acyltransferase-1.
      ].

      Long chain acyl-CoA synthetase 3 (ACSL3) inhibitors

      ACSL3 is required for incorporation of fatty acids into phosphatidylcholine, a reaction that is essential for VLDL assembly. It has been shown that secretion of VLDL as well as HCV is inhibited when expression of ACSL3 is reduced by RNA interference [
      • Yao H.
      • Ye J.
      Long chain acyl-CoA synthetase 3-mediated phosphatidylcholine synthesis is required for assembly of very low density lipoproteins in human hepatoma Huh7 cells.
      ]. This study identified ACSL3 as a new enzyme required for VLDL assembly, confirmed the link between VLDL assembly and HCV production and suggested that ACSL3 is a new enzymatic target for limiting both VLDL secretion and HCV infection.

      Polyunsaturated liposomes (PERLS)

      Liposomes capable of ER-targeted drug delivery have been developed [
      • Pollock S.
      • Antrobus R.
      • Newton L.
      • Kampa B.
      • Rossa J.
      • Latham S.
      • et al.
      Uptake and trafficking of liposomes to the endoplasmic reticulum.
      ] and polyunsaturated ER-targeting liposomes have been reported to decrease secretion and infectivity of HCVcc [
      • Pollock S.
      • Nichita N.B.
      • Bohmer A.
      • Radulescu C.
      • Dwek R.A.
      • Zitzmann N.
      Polyunsaturated liposomes are antiviral against hepatitis B and C viruses and HIV by decreasing cholesterol levels in infected cells.
      ]. PERLS may target multiple points in the lipid pathway, not only lowering intracellular cholesterol and LD number but also competing with lipoproteins for cell entry.

      Targeting intravascular re-modelling of LVP and clearance via TRL receptors

      The demonstration that HCV particles behave in a manner similar to exchangeable lipoproteins and transfer onto TRLs [
      • Felmlee D.J.
      • Sheridan D.A.
      • Bridge S.H.
      • Nielsen S.U.
      • Milne R.W.
      • Packard C.J.
      • et al.
      Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
      ] opens up further potential targets once the pathophysiology of this process is understood. Drugs that lower TG such as niacin or target LD biogenesis may be more effective in vivo than interventions aimed at lowering LDL via the cholesterol pathway such as statins. Indeed high LDL-cholesterol is associated with SVR in patients receiving Peg-IFN/RBV [
      • Sheridan D.A.
      • Price D.A.
      • Schmid M.
      • Toms G.L.
      • Donaldson P.
      • Neely D.
      • et al.
      Apolipoprotein B associated cholesterol is a determinant of treatment outcome in patients with chronic hepatitis C virus (HCV) infection receiving anti-viral agents interferon-alpha and ribavirin.
      ,
      • Harrison S.A.
      • Rossaro L.
      • Hu K.Q.
      • Patel K.
      • Tillmann H.
      • Dhaliwal S.
      • et al.
      Serum cholesterol and statin use predict virological response to peginterferon and ribavirin therapy.
      ] whilst high TG is associated with both viral load and hepatic steatosis [
      • Ramcharran D.
      • Wahed A.S.
      • Conjeevaram H.S.
      • Evans R.W.
      • Wang T.
      • Belle S.H.
      • et al.
      Associations between serum lipids and hepatitis C antiviral treatment efficacy.
      ].

      CETP inhibitors

      Successful HCV infection of SCID/uPA mice transplanted with human hepatocytes correlates with expression of markers of human lipoprotein biosynthesis, human apoB and CETP, suggesting that CETP may be involved in the infectious cycle of HCV [
      • Steenbergen R.H.
      • Joyce M.A.
      • Lund G.
      • Lewis J.
      • Chen R.
      • Barsby N.
      • et al.
      Lipoprotein profiles in SCID/uPA mice transplanted with human hepatocytes become human-like and correlate with HCV infection success.
      ]. This raises the intriguing question of whether small-molecule CETP inhibitors (dalcetrapib, torcetrapib, and anacetrapib) which have been or are being tested in phase 3 clinical studies, may be of benefit in chronic HCV [
      • Davidson M.H.
      Update on CETP inhibition.
      ].

      HCV entry inhibitors

      HCV entry inhibitors would limit the expansion of the infected cell reservoir and complement other approaches to therapy. SR-BI appears to be an essential HCV entry factor [
      • Dreux M.
      • Dao Thi V.L.
      • Fresquet J.
      • Guerin M.
      • Julia Z.
      • Verney G.
      • et al.
      Receptor complementation and mutagenesis reveal SR-BI as an essential HCV entry factor and functionally imply its intra- and extra-cellular domains.
      ]. SR-B1 residues involved in HCV recognition are not required for HDL binding or SR-BI-mediated cholesterol efflux, suggesting that the development of agents selectively inhibiting HCV infection, but with no or low impact on the reverse cholesterol pathway, is a feasible task [
      • Nieland T.J.
      • Xu S.
      • Penman M.
      • Krieger M.
      Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI.
      ,
      • Catanese M.T.
      • Ansuini H.
      • Graziani R.
      • Huby T.
      • Moreau M.
      • Ball J.K.
      • et al.
      Role of scavenger receptor class B type I in hepatitis C virus entry: kinetics and molecular determinants.
      ]. Recently a small molecule SR-BI antagonist, ITX 5061, has been shown to have potent antiviral activity against HCVpp and HCVcc [
      • Syder A.J.
      • Lee H.
      • Zeisel M.B.
      • Grove J.
      • Soulier E.
      • Macdonald J.
      • et al.
      Small molecule scavenger receptor BI antagonists are potent HCV entry inhibitors.
      ]. This orally active agent is now being evaluated in the clinic in chronic HCV patients and patients undergoing liver transplantation.

      Double filtration plasmaphoresis (DFPP)

      Heparin-induced extracorporeal low-density lipoprotein precipitation (HELP) apheresis is an effective tool to eliminate apoB containing lipoproteins from the circulation and has been found to reduce HCV–RNA by 77% [
      • Schettler V.
      • Monazahian M.
      • Wieland E.
      • Ramadori G.
      • Grunewald R.W.
      • Thomssen R.
      • et al.
      Reduction of hepatitis C virus load by H.E.L.P.-LDL apheresis.
      ]. DFPP is a similar technique which uses a plasma separator (first filter) to separate plasma and blood cells from blood and a plasma fractionator (second filter) to eliminate high-molecular-weight substances. DFPP can mechanically eliminate not only lipoproteins but also HCV from the blood. It was approved in Japan in 2008 for the retreatment of chronic HCV G1b patients with high viral loads but has similar effects in chronic HCV G2 infection [
      • Ohara T.
      • Oteki T.
      • Suzuki T.
      • Suzuki M.
      • Matsuzaki Y.
      Efficacy of double filtration plasmapheresis with pegylated interferon/ribavirin therapy for intractable chronic hepatitis C patients and hepatitis C patients with combined liver cirrhosis by HBV, leading to early viral elimination.
      ]. DFPP may be useful in combination with IFN in some patients, especially those with cryoglobulinaemia [
      • Kim S.R.
      • Imoto S.
      • Kudo M.
      • Mita K.
      • Taniguchi M.
      • Kim K.I.
      • et al.
      Double-filtration plasmapheresis plus IFN for HCV-1b patients with non-sustained virological response to previous combination therapy: early viral dynamics.
      ,
      • Namba T.
      • Shiba R.
      • Yamamoto T.
      • Hirai Y.
      • Moriwaki T.
      • Matsuda J.
      • et al.
      Successful treatment of HCV-related cryoglobulinemic glomerulonephritis with double-filtration plasmapheresis and interferon combination therapy.
      ] but there are safety issues as DFPP also decreases other plasma proteins including factor XIII [
      • Hanafusa N.
      • Satonaka H.
      • Doi K.
      • Noiri E.
      • Fujita T.
      Virus removal and eradication by modified double filtration plasmapheresis decreases factor XIII levels.
      ].
      In summary, HCV–host interaction is a continuous co-evolutionary process and phylogenetic analysis of 345 full-length HCV genomic sequences suggests different evolutionary ages of the major HCV genotypes [
      • Pang P.S.
      • Planet P.J.
      • Glenn J.S.
      The evolution of the major hepatitis C genotypes correlates with clinical response to interferon therapy.
      ]. It is now clear that the equilibrium established between HCV and the host in chronic infection involves not only the immune response but also lipid pathways, some of which may be genotype-specific. Better understanding of how HCV utilises these pathways in its life cycle will lead to more options for therapy. These include not only lipid-modulating drugs already in use or in development for other indications [e.g. statins, niacin, CETP inhibitors, apoB antisense, miRNA-122 inhibitors] but also entry inhibitors [e.g. SR-BI antagonists] and novel targets [e.g. diacylglycerol acyltransferase 1 inhibitors, long chain acyl-CoA synthetase 3 inhibitors].

      References

        • Davis R.A.
        • Hui Y.
        George Lyman Duff Memorial Lecture: atherosclerosis is a liver disease of the heart.
        Arterioscler Thromb Vasc Biol. 2001; 21: 887-898
        • Pang P.S.
        • Planet P.J.
        • Glenn J.S.
        The evolution of the major hepatitis C genotypes correlates with clinical response to interferon therapy.
        PLoS ONE. 2009; 4: e6579
        • Virgin H.W.
        • Wherry E.J.
        • Ahmed R.
        Redefining chronic viral infection.
        Cell. 2009; 138: 30-50
        • Ginsberg H.N.
        • Fisher E.A.
        The ever-expanding role of degradation in the regulation of apolipoprotein B metabolism.
        J Lipid Res. 2009; 50: S162-S166
        • Rutledge A.C.
        • Su Q.
        • Adeli K.
        Apolipoprotein B100 biogenesis: a complex array of intracellular mechanisms regulating folding, stability, and lipoprotein assembly.
        Biochem Cell Biol. 2010; 88: 251-267
        • Getz G.S.
        • Reardon C.A.
        Apoprotein E as a lipid transport and signaling protein in the blood, liver, and artery wall.
        J Lipid Res. 2009; 50: S156-S161
        • Pendse A.A.
        • Arbones-Mainar J.M.
        • Johnson L.A.
        • Altenburg M.K.
        • Maeda N.
        Apolipoprotein E knock-out and knock-in mice. atherosclerosis, metabolic syndrome, and beyond.
        J Lipid Res. 2009; 50: S178-S182
        • Kypreos K.E.
        • Zannis V.I.
        Pathway of biogenesis of apolipoprotein E-containing HDL in vivo with the participation of ABCA1 and LCAT.
        Biochem J. 2007; 403: 359-367
        • van den Elzen P.
        • Garg S.
        • Leon L.
        • Brigl M.
        • Leadbetter E.A.
        • Gumperz J.E.
        • et al.
        Apolipoprotein-mediated pathways of lipid antigen presentation.
        Nature. 2005; 437: 906-910
        • Eichner J.E.
        • Dunn S.T.
        • Perveen G.
        • Thompson D.M.
        • Stewart K.E.
        • Stroehla B.C.
        Apolipoprotein E polymorphism and cardiovascular disease: a HuGE review.
        Am J Epidemiol. 2002; 155: 487-495
        • James P.F.
        • Dogovski C.
        • Dobson R.C.
        • Bailey M.F.
        • Goldie K.N.
        • Karas J.A.
        • et al.
        Aromatic residues in the C-terminal helix of human apoC-I mediate phospholipid interactions and particle morphology.
        J Lipid Res. 2009; 50: 1384-1394
        • Cohn J.S.
        • Tremblay M.
        • Batal R.
        • Jacques H.
        • Veilleux L.
        • Rodriguez C.
        • et al.
        Plasma kinetics of VLDL and HDL apoC-I in normolipidemic and hypertriglyceridemic subjects.
        J Lipid Res. 2002; 43: 1680-1687
        • de Barros J.P.
        • Boualam A.
        • Gautier T.
        • Dumont L.
        • Verges B.
        • Masson D.
        • et al.
        Apolipoprotein CI is a physiological regulator of cholesteryl ester transfer protein activity in human plasma but not in rabbit plasma.
        J Lipid Res. 2009; 50: 1842-1851
        • Shen Y.
        • Lookene A.
        • Zhang L.
        • Olivecrona G.
        Site-directed mutagenesis of apolipoprotein CII to probe the role of its secondary structure for activation of lipoprotein lipase.
        J Biol Chem. 2010; 285: 7484-7492
        • Kawakami A.
        • Yoshida M.
        Apolipoprotein CIII links dyslipidemia with atherosclerosis.
        J Atheroscler Thromb. 2009; 16: 6-11
        • Zheng C.
        • Khoo C.
        • Furtado J.
        • Sacks F.M.
        Apolipoprotein C-III and the metabolic basis for hypertriglyceridemia and the dense low-density lipoprotein phenotype.
        Circulation. 2010; 121: 1722-1734
        • Mendivil C.O.
        • Zheng C.
        • Furtado J.
        • Lel J.
        • Sacks F.M.
        Metabolism of very-low-density lipoprotein and low-density lipoprotein containing apolipoprotein C-III and not other small apolipoproteins.
        Arterioscler Thromb Vasc Biol. 2010; 30: 239-245
        • Ooi E.M.
        • Barrett P.H.
        • Chan D.C.
        • Watts G.F.
        Apolipoprotein C-III: understanding an emerging cardiovascular risk factor.
        Clin Sci (Lond). 2008; 114: 611-624
        • Scanu A.M.
        • Edelstein C.
        HDL: bridging past and present with a look at the future.
        Faseb J. 2008; 22: 4044-4054
        • Castellani L.W.
        • Nguyen C.N.
        • Charugundla S.
        • Weinstein M.M.
        • Doan C.X.
        • Blaner W.S.
        • et al.
        Apolipoprotein AII is a regulator of very low density lipoprotein metabolism and insulin resistance.
        J Biol Chem. 2008; 283: 11633-11644
        • Vickers K.C.
        • Palmisano B.T.
        • Shoucri B.M.
        • Shamburek R.D.
        • Remaley A.T.
        MicroRNAs are transported in plasma and delivered to recipient cells by high-density lipoproteins.
        Nat. Cell Biol. 2011; 13: 423-433
        • Blasiole D.A.
        • Davis R.A.
        • Attie A.D.
        The physiological and molecular regulation of lipoprotein assembly and secretion.
        Mol BioSyst. 2007; 3: 608-619
        • Hussain M.M.
        • Shi J.
        • Dreizen P.
        Microsomal triglyceride transfer protein and its role in apoB-lipoprotein assembly.
        J. Lipid Res. 2003; 44: 22-32
        • Olofsson S.O.
        • Bostrom P.
        • Andersson L.
        • Rutberg M.
        • Perman J.
        • Boren J.
        Lipid droplets as dynamic organelles connecting storage and efflux of lipids.
        Biochim Biophys Acta. 2009; 1791: 448-458
        • Hodges B.D.
        • Wu C.C.
        Proteomic insights into an expanded cellular role for cytoplasmic lipid droplets.
        J Lipid Res. 2010; 51: 262-273
        • Gill J.M.
        • Brown J.C.
        • Bedford D.
        • Wright D.M.
        • Cooney J.
        • Hughes D.A.
        • et al.
        Hepatic production of VLDL1 but not VLDL2 is related to insulin resistance in normoglycaemic middle-aged subjects.
        Atherosclerosis. 2004; 176: 49-56
        • Adiels M.
        • Boren J.
        • Caslake M.J.
        • Stewart P.
        • Soro A.
        • Westerbacka J.
        • et al.
        Overproduction of VLDL1 driven by hyperglycemia is a dominant feature of diabetic dyslipidemia.
        Arterioscler Thromb Vasc Biol. 2005; 25: 1697-1703
        • Williams K.J.
        Molecular processes that handle–and mishandle–dietary lipids.
        J Clin Investig. 2008; 118: 3247-3259
        • Kinnunen P.K.
        • Jackson R.L.
        • Smith L.C.
        • Gotto Jr., A.M.
        • Sparrow J.T.
        Activation of lipoprotein lipase by native and synthetic fragments of human plasma apolipoprotein C-II.
        Proc Natl Acad Sci USA. 1977; 74: 4848-4851
        • Ehnholm C.
        • Aho K.
        • Huttunen J.K.
        • Kostiainen E.
        • Mattila K.
        • Pakkarainen J.
        • et al.
        Effect of interferon on plasma lipoproteins and on the activity of postheparin plasma lipases.
        Arteriosclerosis. 1982; 2: 68-73
        • Shinohara E.
        • Yamashita S.
        • Kihara S.
        • Hirano K.
        • Ishigami M.
        • Arai T.
        • et al.
        Interferon alpha induces disorder of lipid metabolism by lowering postheparin lipases and cholesteryl ester transfer protein activities in patients with chronic hepatitis C.
        Hepatology. 1997; 25: 1502-1506
        • Feingold K.R.
        • Hardardottir I.
        • Grunfeld C.
        Beneficial effects of cytokine induced hyperlipidemia.
        Z Ernahrungswiss. 1998; 37: 66-74
        • Andrade R.J.
        • Garcia-Escano M.D.
        • Valdivielso P.
        • Alcantara R.
        • Sanchez-Chaparro M.A.
        • Gonzalez-Santos P.
        Effects of interferon-beta on plasma lipid and lipoprotein composition and post-heparin lipase activities in patients with chronic hepatitis C.
        Aliment Pharmacol Ther. 2000; 14: 929-935
        • Perret B.
        • Mabile L.
        • Martinez L.
        • Terce F.
        • Barbaras R.
        • Collet X.
        Hepatic lipase: structure/function relationship, synthesis, and regulation.
        J Lipid Res. 2002; 43: 1163-1169
        • Masson D.
        • Jiang X.C.
        • Lagrost L.
        • Tall A.R.
        The role of plasma lipid transfer proteins in lipoprotein metabolism and atherogenesis.
        J Lipid Res. 2009; 50: S201-S206
        • Adiels M.
        • Olofsson S.O.
        • Taskinen M.R.
        • Boren J.
        Overproduction of very low-density lipoproteins is the hallmark of the dyslipidemia in the metabolic syndrome.
        Arterioscler Thromb Vasc Biol. 2008; 28: 1225-1236
        • Packard C.J.
        • Munro A.
        • Lorimer A.R.
        • Gotto A.M.
        • Shepherd J.
        Metabolism of apolipoprotein B in large triglyceride-rich very low density lipoproteins of normal and hypertriglyceridemic subjects.
        J Clin Invest. 1984; 74: 2178-2192
        • Demant T.
        • Packard C.
        In vivo studies of VLDL metabolism and LDL heterogeneity.
        Eur Heart J. 1998; 19: H7-H10
        • Mahley R.W.
        • Ji Z.S.
        Remnant lipoprotein metabolism: key pathways involving cell-surface heparan sulfate proteoglycans and apolipoprotein E.
        J Lipid Res. 1999; 40: 1-16
        • Williams K.J.
        • Chen K.
        Recent insights into factors affecting remnant lipoprotein uptake.
        Curr Opin Lipidol. 2010; 21: 218-228
        • Santamarina-Fojo S.
        • Gonzalez-Navarro H.
        • Freeman L.
        • Wagner E.
        • Nong Z.
        Hepatic lipase, lipoprotein metabolism, and atherogenesis.
        Arterioscler Thromb Vasc Biol. 2004; 24: 1750-1754
        • Stanford K.I.
        • Bishop J.R.
        • Foley E.M.
        • Gonzales J.C.
        • Niesman I.R.
        • Witztum J.L.
        • et al.
        Syndecan-1 is the primary heparan sulfate proteoglycan mediating hepatic clearance of triglyceride-rich lipoproteins in mice.
        J Clin Investig. 2009; 119: 3236-3245
        • Dallinga-Thie G.M.
        • Franssen R.
        • Mooij H.L.
        • Visser M.E.
        • Hassing H.C.
        • Peelman F.
        • et al.
        The metabolism of triglyceride-rich lipoproteins revisited: new players, new insight.
        Atherosclerosis. 2010; 211: 1-8
        • Out R.
        • Kruijt J.K.
        • Rensen P.C.
        • Hildebrand R.B.
        • de Vos P.
        • Van Eck M.
        • et al.
        Scavenger receptor BI plays a role in facilitating chylomicron metabolism.
        J Biol Chem. 2004; 279: 18401-18406
        • Van Eck M.
        • Hoekstra M.
        • Out R.
        • Bos I.S.
        • Kruijt J.K.
        • Hildebrand R.B.
        • et al.
        Scavenger receptor BI facilitates the metabolism of VLDL lipoproteins in vivo.
        J Lipid Res. 2008; 49: 136-146
        • Nieland T.J.
        • Xu S.
        • Penman M.
        • Krieger M.
        Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI.
        Biochemistry. 2011; 50: 1818-1830
        • Neumann A.U.
        • Lam N.P.
        • Dahari H.
        • Gretch D.R.
        • Wiley T.E.
        • Layden T.J.
        • et al.
        Hepatitis C viral dynamics in vivo and the antiviral efficacy of interferon-alpha therapy.
        Science. 1998; 282: 103-107
        • Ye J.
        Reliance of host cholesterol metabolic pathways for the life cycle of hepatitis C virus.
        PLoS Pathog. 2007; 3: 1017-1022
        • Gastaminza P.
        • Cheng G.
        • Wieland S.
        • Zhong J.
        • Liao W.
        • Chisari F.V.
        Cellular determinants of hepatitis C virus assembly, maturation, degradation, and secretion.
        J Virol. 2008; 82: 2120-2129
        • Bartenschlager R.
        • Penin F.
        • Lohmann V.
        • Andre P.
        Assembly of infectious hepatitis C virus particles.
        Trends Microbiol. 2011; 19 ([Epub 2010 Dec 14]): 95-103
        • Negro F.
        Abnormalities of lipid metabolism in hepatitis C virus infection.
        Gut. 2010; 59: 1279-1287
      1. Cai T, Dufour J-F, Muellhaupt B, Gerlach T, Heim M, Moradpour D, et al. Viral Genotype-Specific Role of PNPLA3, PPARG, MTTP and IL28B in Hepatitis C Virus-Associated Steatosis. J Hepatol 2011.

        • Moradpour D.
        • Penin F.
        • Rice C.M.
        Replication of hepatitis C virus.
        Nat Rev Microbiol. 2007; 5: 453-463
        • Meex S.J.
        • Andreo U.
        • Sparks J.D.
        • Fisher E.A.
        Huh-7 or HepG2 cells: which is the better model for studying human apolipoprotein-B100 assembly and secretion?.
        J Lipid Res. 2011; 52: 152-158
        • Lindenbach B.D.
        • Meuleman P.
        • Ploss A.
        • Vanwolleghem T.
        • Syder A.J.
        • McKeating J.A.
        • et al.
        Cell culture-grown hepatitis C virus is infectious in vivo and can be recultured in vitro.
        Proc Natl Acad Sci USA. 2006; 103: 3805-3809
        • Boulant S.
        • Targett-Adams P.
        • McLauchlan J.
        Disrupting the association of hepatitis C virus core protein with lipid droplets correlates with a loss in production of infectious virus.
        J General Virol. 2007; 88: 2204-2213
        • Miyanari Y.
        • Atsuzawa K.
        • Usuda N.
        • Watashi K.
        • Hishiki T.
        • Zayas M.
        • et al.
        The lipid droplet is an important organelle for hepatitis C virus production.
        Nat Cell Biol. 2007; 9: 1089-1097
        • Shavinskaya A.
        • Boulant S.
        • Penin F.
        • McLauchlan J.
        • Bartenschlager R.
        The lipid droplet binding domain of hepatitis C virus core protein is a major determinant for efficient virus assembly.
        J Biol Chem. 2007; 282: 37158-37169
      2. Jones DM, McLauchlan J. Hepatitis C virus: assembly and release of virus particles. J Biol Chem 2010.

        • Herker E.
        • Harris C.
        • Hernandez C.
        • Carpentier A.
        • Kaehlcke K.
        • Rosenberg A.R.
        • et al.
        Efficient hepatitis C virus particle formation requires diacylglycerol acyltransferase-1.
        Nat Med. 2010; 16: 1295-1298
        • Nahmias Y.
        • Goldwasser J.
        • Casali M.
        • van Poll D.
        • Wakita T.
        • Chung R.T.
        • et al.
        Apolipoprotein B-dependent hepatitis C virus secretion is inhibited by the grapefruit flavonoid naringenin.
        Hepatology. 2008; 47: 1437-1445
        • Chang K.S.
        • Jiang J.
        • Cai Z.
        • Luo G.
        Human apolipoprotein e is required for infectivity and production of hepatitis C virus in cell culture.
        J Virol. 2007; 81: 13783-13793
        • Merz A.
        • Long G.
        • Hiet M.S.
        • Bruegger B.
        • Chlanda P.
        • Andre P.
        • et al.
        Biochemical and morphological properties of hepatitis C virus particles and determination of their lipidome.
        J Virol. 2010;
        • Jiang J.
        • Luo G.
        Apolipoprotein E but not B is required for the formation of infectious hepatitis C virus particles.
        J Virol. 2009; 83: 12680-12691
        • Cun W.
        • Jiang J.
        • Luo G.
        The C-terminal alpha-helix domain of apolipoprotein E is required for interaction with nonstructural protein 5A and assembly of hepatitis C virus.
        J Virol. 2010; 84: 11532-11541
        • Benga W.J.
        • Krieger S.E.
        • Dimitrova M.
        • Zeisel M.B.
        • Parnot M.
        • Lupberger J.
        • et al.
        Apolipoprotein E interacts with hepatitis C virus nonstructural protein 5A and determines assembly of infectious particles.
        Hepatology. 2010; 51: 43-53
        • Yamamoto M.
        • Aizaki H.
        • Fukasawa M.
        • Teraoka T.
        • Miyamura M.
        • Wakita T.
        • et al.
        Apolipoprotein E interacts with hepatitis C virus nonstructural protein 5A and determines assembly of infectious particles.
        J General Virol. 2011;
        • Akazawa D.
        • Morikawa K.
        • Omi N.
        • Takahashi H.
        • Nakamura N.
        • Mochizuki H.
        • et al.
        Production and characterization of HCV particles from serum-free culture.
        Vaccine. 2011;
        • Mancone C.
        • Steindler C.
        • Santangelo L.
        • Simonte G.
        • Vlassi C.
        • Longo M.A.
        • et al.
        Hepatitis C virus production requires apolipoprotein A-I and affects its association with nascent low-density lipoproteins.
        Gut. 2011; 60: 378-386
        • Podevin P.
        • Carpentier A.
        • Pene V.
        • Aoudjehane L.
        • Carriere M.
        • Zaidi S.
        • et al.
        Production of infectious hepatitis C virus in primary cultures of human adult hepatocytes.
        Gastroenterology. 2010; 139: 1355-1364
        • Andre P.
        • Komurian P.F.
        • Deforges S.
        • Perret M.
        • Berland J.L.
        • Sodoyer M.
        • et al.
        Characterization of low- and very-low-density hepatitis C virus RNA containing particles.
        J Virol. 2002; 76: 6919-6928
        • Diaz O.
        • Delers F.
        • Maynard M.
        • Demignot S.
        • Zoulim F.
        • Chambaz J.
        • et al.
        Preferential association of Hepatitis C virus with apolipoprotein B48-containing lipoproteins.
        J General Virol. 2006; 87: 2983-2991
        • Nielson S.U.
        • Bassendine M.F.
        • Burt A.D.
        • Martin C.
        • Pumeechockchai W.
        • Toms G.L.
        Association between hepatitis C virus and very-low-density lipoprotein (VLDL)/LDL analysed in iodixanol density gradients.
        J Virol. 2006; 80: 2418-2428
        • Thomssen R.
        • Bonk S.
        • Thiele A.
        Density heterogeneities of Hepatitis C virus in human sera due to binding of beta-lipoproteins and immunoglobulins.
        Med Microbiol Immunol. 1993; 182: 329-334
        • Kanto T.
        • Hayashi N.
        • Takehara T.
        • Hagiwara H.
        • Mita E.
        • Naito Kashara A.
        • et al.
        Density analysis of Hepatitis-C Virus particle-population in the circulation of infected hosts – implications for virus neutralization or persistence.
        J Hepatol. 1995; 22: 440-448
        • Bridge S.H.
        • Sheridan D.A.
        • Felmlee D.J.
        • Nielsen S.U.
        • Thomas H.C.
        • Taylor-Robinson S.D.
        • et al.
        Insulin resistance and low-density apolipoprotein B-associated lipoviral particles in hepatitis C virus genotype 1 infection.
        Gut. 2011; 60: 680-687
        • Felmlee D.J.
        • Sheridan D.A.
        • Bridge S.H.
        • Nielsen S.U.
        • Milne R.W.
        • Packard C.J.
        • et al.
        Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles.
        Gastroenterology. 2010; 139 (83 e1-6): 1774-1783
        • Farquhar M.J.
        • McKeating J.A.
        Primary hepatocytes as targets for hepatitis C virus replication.
        J Viral Hepat. 2008; 15: 849-854
        • Burlone M.E.
        • Budkowska A.
        Hepatitis C virus cell entry: role of lipoproteins and cellular receptors.
        J General Virol. 2009; 90: 1055-1070
        • Bartenschlager R.
        • Cosset F.L.
        • Lohmann V.
        Hepatitis C virus replication cycle.
        J Hepatol. 2010; 53: 583-585
        • Grove J.
        • Nielsen S.
        • Zhong J.
        • Bassendine M.F.
        • Drummer H.E.
        • Balfe P.
        • et al.
        Identification of a residue in hepatitis C virus E2 glycoprotein that determines scavenger receptor BI and CD81 receptor dependency and sensitivity to neutralising antibodies.
        J Virol. 2008; 82: 12020-12029
        • Dreux M.
        • Dao Thi V.L.
        • Fresquet J.
        • Guerin M.
        • Julia Z.
        • Verney G.
        • et al.
        Receptor complementation and mutagenesis reveal SR-BI as an essential HCV entry factor and functionally imply its intra- and extra-cellular domains.
        PLoS Pathog. 2009; 5: e1000310
        • Owen D.M.
        • Huang H.
        • Ye J.
        • Gale Jr, M.
        Apolipoprotein E on hepatitis C virion facilitates infection through interaction with low-density lipoprotein receptor.
        Virology. 2009; 394: 99-108
        • Hishiki T.
        • Shimizu Y.
        • Tobita R.
        • Sugiyama K.
        • Ogawa K.
        • Funami K.
        • et al.
        Infectivity of hepatitis C virus is influenced by association with apolipoprotein E isoforms.
        J Virol. 2010; 84: 12048-12057
      3. Price DA, Bassendine MF, Norris SN, Golding C, Toms GL, Schmid ML, et al. The Apolipoprotein e3 allele is associated with persistent Hepatitis C Virus infection. Gut 2006.

        • Dreux M.
        • Boson B.
        • Ricard-Blum S.
        • Molle J.
        • Lavillette D.
        • Bartosch B.
        • et al.
        The exchangeable apolipoprotein ApoC-I promotes membrane fusion of hepatitis C virus.
        J Biol Chem. 2007; 282: 32357-32369
        • Meunier J.-C.
        • Russell R.S.
        • Engle R.E.
        • Faulk K.N.
        • Purcell R.H.
        • Emerson S.U.
        Apolipoprotein c1 association with hepatitis C virus.
        J Virol. 2008; 82: 9647-9656
        • Aghemo A.
        • Rumi M.G.
        • Colombo M.
        Pegylated interferons alpha2a and alpha2b in the treatment of chronic hepatitis C.
        Nat Rev. 2010; 7: 485-494
        • Lemon S.M.
        • McKeating J.A.
        • Pietschmann T.
        • Frick D.N.
        • Glenn J.S.
        • Tellinghuisen T.L.
        • et al.
        Development of novel therapies for hepatitis C.
        Antiviral Res. 2010; 86: 79-92
        • Lange C.M.
        • Sarrazin C.
        • Zeuzem S.
        Review article: specifically targeted anti-viral therapy for hepatitis C – a new era in therapy.
        Aliment Pharmacol Ther. 2010; 32: 14-28
        • Thompson A.J.
        • McHutchison J.G.
        Antiviral resistance and specifically targeted therapy for HCV (STAT-C).
        J Viral Hepatol. 2009; 16: 377-387
        • Milazzo L.
        • Antinori S.
        STAT-C: a full revolution or just a step forward?.
        Lancet. 2010; 376: 662-663
        • Watts G.F.
        • Ooi E.M.
        • Chan D.C.
        Therapeutic regulation of apoB100 metabolism in insulin resistance in vivo.
        Pharmacol Ther. 2009; 123: 281-291
        • Kairuz T.E.
        • Gargiulo D.
        • Bunt C.
        • Garg S.
        Quality, safety and efficacy in the ‘off-label’ use of medicines.
        Curr Drug Safety. 2007; 2: 89-95
        • Charlton M.R.
        • Pockros P.J.
        • Harrison S.A.
        Impact of obesity on treatment of chronic hepatitis C.
        Hepatology. 2006; 43: 1177-1186
        • Watts G.F.
        • Chan D.C.
        • Ooi E.M.
        • Nestel P.J.
        • Beilin L.J.
        • Barrett P.H.
        Fish oils, phytosterols and weight loss in the regulation of lipoprotein transport in the metabolic syndrome: lessons from stable isotope tracer studies.
        Clin Exp Pharmacol Physiol. 2006; 33: 877-882
        • Hickman I.J.
        • Clouston A.D.
        • Macdonald G.A.
        • Purdie D.M.
        • Prins J.B.
        • Ash S.
        • et al.
        Effect of weight reduction on liver histology and biochemistry in patients with chronic hepatitis C.
        Gut. 2002; 51: 89-94
        • Petta S.
        • Amato M.
        • Cabibi D.
        • Camma C.
        • Di Marco V.
        • Giordano C.
        • et al.
        Visceral adiposity index is associated with histological findings and high viral load in patients with chronic hepatitis C due to genotype 1.
        Hepatology. 2010; 52: 1543-1552
        • Testino G.
        • Sumberaz A.
        • Ancarani A.O.
        • Borro P.
        • Ravetti G.
        • Ansaldi F.
        • et al.
        Influence of body mass index, cholesterol, triglycerides and steatosis on pegylated interferon alfa-2a and ribavirin treatment for recurrent hepatitis C in patients transplanted for HCV and alcoholic cirrhosis.
        Hepatogastroenterology. 2009; 56: 501-503
        • Kapadia S.B.
        • Chisari F.V.
        Hepatitis C virus RNA replication is regulated by host geranylgeranylation and fatty acids.
        Proc Natl Acad Sci USA. 2005; 102: 2561-2566
        • Leu G.Z.
        • Lin T.Y.
        • Hsu J.T.
        Anti-HCV activities of selective polyunsaturated fatty acids.
        Biochem Biophys Res Commun. 2004; 318: 275-280
        • Ye J.
        • Wang C.
        • Sumpter R.
        • Brown M.S.
        • Goldstein J.L.
        • Gale M.
        Disruption of hepatitis C RNA replication through inhibition of host protein geranylgeranylation.
        Proc Natl Acad Sci USA. 2003; 100: 15865-15870
        • Ikeda M.
        • Kato N.
        Life style-related diseases of the digestive system: cell culture system for the screening of anti-hepatitis C virus (HCV) reagents: suppression of HCV replication by statins and synergistic action with interferon.
        J Pharmacol Sci. 2007; 105: 145-150
        • Delang L.
        • Paeshuyse J.
        • Vliegen I.
        • Leyssen P.
        • Obeid S.
        • Durantel D.
        • et al.
        Statins potentiate the in vitro anti-hepatitis C virus activity of selective hepatitis C virus inhibitors and delay or prevent resistance development.
        Hepatology. 2009; 50: 6-16
        • Nishimura G.
        • Ikeda M.
        • Mori K.
        • Nakazawa T.
        • Ariumi Y.
        • Dansako H.
        • et al.
        Replicons from genotype 1b HCV-positive sera exhibit diverse sensitivities to anti-HCV reagents.
        Antiviral Res. 2009; 82: 42-50
        • Ikeda M.
        • Abe K.
        • Yamada M.
        • Dansako H.
        • Naka K.
        • Kato N.
        Different anti-HCV profiles of statins and their potential for combination therapy with interferon.
        Hepatology. 2006; 44: 117-125
        • Feidt D.M.
        • Klein K.
        • Hofmann U.
        • Riedmaier S.
        • Knobeloch D.
        • Thasler W.E.
        • et al.
        Profiling induction of cytochrome p450 enzyme activity by statins using a new liquid chromatography-tandem mass spectrometry cocktail assay in human hepatocytes.
        Drug Metab Dispos: Biol Fate Chem. 2010; 38: 1589-1597
        • Josephson F.
        Drug–drug interactions in the treatment of HIV infection: focus on pharmacokinetic enhancement through CYP3A inhibition.
        J Intern Med. 2010; 268: 530-539
        • Bader T.
        • Fazili J.
        • Madhoun M.
        • Aston C.
        • Hughes D.
        • Rizvi S.
        • et al.
        Fluvastatin inhibits hepatitis C replication in humans.
        Am J Gastroenterol. 2008; 103: 1383-1389
        • Mihaila R.
        • Nedelcu L.
        • Fratila O.
        • Rezi E.C.
        • Domnariu C.
        • Ciuca R.
        • et al.
        Lovastatin and fluvastatin reduce viremia and the pro-inflammatory cytokines in the patients with chronic hepatitis C.
        Hepatogastroenterology. 2009; 56: 1704-1709
        • Milazzo L.
        • Meroni L.
        • Galazzi M.
        • Cesari M.
        • Caramma I.
        • Marchetti G.
        • et al.
        Does fluvastatin favour HCV replication in vivo? A pilot study on HIV-HCV coinfected patients.
        J Viral Hepatol. 2009; 16: 479-484
        • O’Leary J.G.
        • Chan J.L.
        • McMahon C.M.
        • Chung R.T.
        Atorvastatin does not exhibit antiviral activity against HCV at conventional doses: a pilot clinical trial.
        Hepatology. 2007; 45: 895-898
        • Forde K.A.
        • Law C.
        • O’Flynn R.
        • Kaplan D.E.
        Do statins reduce hepatitis C RNA titers during routine clinical use?.
        World J Gastroenterol. 2009; 15: 5020-5027
        • Sezaki H.
        • Suzuki F.
        • Akuta N.
        • Yatsuji H.
        • Hosaka T.
        • Kobayashi M.
        • et al.
        An open pilot study exploring the efficacy of fluvastatin, pegylated interferon and ribavirin in patients with hepatitis C virus genotype 1b in high viral loads.
        Intervirology. 2009; 52: 43-48
        • Milazzo L.
        • Caramma I.
        • Mazzali C.
        • Cesari M.
        • Olivetti M.
        • Galli M.
        • et al.
        Fluvastatin as an adjuvant to pegylated interferon and ribavirin in HIV/hepatitis C virus genotype 1 co-infected patients: an open-label randomized controlled study.
        J Antimicrob Chemother. 2010; 65: 735-740
        • McHutchison J.G.
        • Lawitz E.J.
        • Shiffman M.L.
        • Muir A.J.
        • Galler G.W.
        • McCone J.
        • et al.
        Peginterferon alfa-2b or alfa-2a with ribavirin for treatment of hepatitis C infection.
        N Engl J Med. 2009; 361: 580-593
        • Rao G.A.
        • Pandya P.K.
        Statin therapy improves sustained virologic response among diabetic patients with chronic hepatitis C.
        Gastroenterology. 2011; 140: 144-152
        • Desvergne B.
        • Wahli W.
        Peroxisome proliferator-activated receptors: nuclear control of metabolism.
        Endocr Rev. 1999; 20: 649-688
        • Shah A.
        • Rader D.J.
        • Millar J.S.
        The effect of PPAR-alpha agonism on apolipoprotein metabolism in humans.
        Atherosclerosis. 2010; 210: 35-40
        • Ramcharran D.
        • Wahed A.S.
        • Conjeevaram H.S.
        • Evans R.W.
        • Wang T.
        • Belle S.H.
        • et al.
        Associations between serum lipids and hepatitis C antiviral treatment efficacy.
        Hepatology. 2010; 52: 854-863
        • Sabile A.
        • Perlemuter G.
        • Bono F.
        • Kohara K.
        • Demaugre F.
        • Kohara M.
        • et al.
        Hepatitis C virus core protein binds to apolipoprotein AII and its secretion is modulated by fibrates.
        Hepatology. 1999; 30: 1064-1076
        • Lyn R.K.
        • Kennedy D.C.
        • Sagan S.M.
        • Blais D.R.
        • Rouleau Y.
        • Pegoraro A.F.
        • et al.
        Direct imaging of the disruption of hepatitis C virus replication complexes by inhibitors of lipid metabolism.
        Virology. 2009; 394: 130-142
        • Rahman S.M.
        • Qadri I.
        • Janssen R.C.
        • Friedman J.E.
        Fenofibrate and PBA prevent fatty acid-induced loss of adiponectin receptor and pAMPK in human hepatoma cells and in hepatitis C virus-induced steatosis.
        J Lipid Res. 2009; 50: 2193-2202
        • Fujita N.
        • Kaito M.
        • Kai M.
        • Sugimoto R.
        • Tanaka H.
        • Horiike S.
        • et al.
        Effects of bezafibrate in patients with chronic hepatitis C virus infection: combination with interferon and ribavirin.
        J Viral Hepatol. 2006; 13: 441-448
        • Yki-Jarvinen H.
        Thiazolidinediones and the liver in humans.
        Curr Opin Lipidol. 2009; 20: 477-483
        • Chappuis B.
        • Braun M.
        • Stettler C.
        • Allemann S.
        • Diem P.
        • Lumb P.J.
        • et al.
        Differential effect of pioglitazone (PGZ) and rosiglitazone (RGZ) on postprandial glucose and lipid metabolism in patients with type 2 diabetes mellitus: a prospective, randomized crossover study.
        Diabetes/Metabol Res Rev. 2007; 23: 392-399
        • Beysen C.
        • Murphy E.J.
        • Nagaraja H.
        • Decaris M.
        • Riiff T.
        • Fong A.
        • et al.
        A pilot study of the effects of pioglitazone and rosiglitazone on de novo lipogenesis in type 2 diabetes.
        J Lipid Res. 2008; 49: 2657-2663
        • Khattab M.
        • Emad M.
        • Abdelaleem A.
        • Eslam M.
        • Atef R.
        • Shaker Y.
        • et al.
        Pioglitazone improves virological response to peginterferon alpha-2b/ribavirin combination therapy in hepatitis C genotype 4 patients with insulin resistance.
        Liver Int. 2010; 30: 447-454
        • Overbeck K.
        • Genne D.
        • Golay A.
        • Negro F.
        Pioglitazone in chronic hepatitis C not responding to pegylated interferon-alpha and ribavirin.
        J Hepatol. 2008; 49: 295-298
        • Serfaty L.
        • Fartoux L.
        • Poupon R.
        Pioglitazone as adjuvant therapy in chronic hepatitis C: sequential rather than concomitant administration with pegylated interferon and ribavirin?.
        J Hepatol. 2009; 50: 1269-1271
        • del Campo J.A.
        • Lopez R.A.
        • Romero-Gomez M.
        Insulin resistance and response to antiviral therapy in chronic hepatitis C: mechanisms and management.
        Digest Dis (Basel, Switzerland). 2010; 28: 285-293
        • Brown B.G.
        • Zhao X.Q.
        Nicotinic acid, alone and in combinations, for reduction of cardiovascular risk.
        Am J Cardiol. 2008; 101: 58B-62B
        • Cheng K.
        • Wu T.J.
        • Wu K.K.
        • Sturino C.
        • Metters K.
        • Gottesdiener K.
        • et al.
        Antagonism of the prostaglandin D2 receptor 1 suppresses nicotinic acid-induced vasodilation in mice and humans.
        Proc Natl Acad Sci USA. 2006; 103: 6682-6687
        • Maccubbin D.
        • Bays H.E.
        • Olsson A.G.
        • Elinoff V.
        • Elis A.
        • Mitchel Y.
        • et al.
        Lipid-modifying efficacy and tolerability of extended-release niacin/laropiprant in patients with primary hypercholesterolaemia or mixed dyslipidaemia.
        Int J Clin Pract. 2008; 62: 1959-1970
        • Loguercio C.
        • Federico A.
        • Masarone M.
        • Torella R.
        • Blanco Cdel V.
        • Persico M.
        The impact of diet on liver fibrosis and on response to interferon therapy in patients with HCV-related chronic hepatitis.
        Am J Gastroenterol. 2008; 103: 3159-3166
        • Vittone F.
        • Chait A.
        • Morse J.S.
        • Fish B.
        • Brown B.G.
        • Zhao X.Q.
        Niacin plus simvastatin reduces coronary stenosis progression among patients with metabolic syndrome despite a modest increase in insulin resistance. a subgroup analysis of the HDL-Atherosclerosis treatment study (HATS).
        J Clin Lipidol. 2007; 1: 203-210
        • Reddy K.R.
        • Shiffman M.L.
        • Rodriguez-Torres M.
        • Cheinquer H.
        • Abdurakhmanov D.
        • Bakulin I.
        • et al.
        Induction pegylated interferon alfa-2a and high dose ribavirin do not increase SVR in heavy patients with HCV genotype 1 and high viral loads.
        Gastroenterology. 2010; 139: 1972-1983
        • Ferenci P.
        • Scherzer T.M.
        • Kerschner H.
        • Rutter K.
        • Beinhardt S.
        • Hofer H.
        • et al.
        Silibinin is a potent antiviral agent in patients with chronic hepatitis C not responding to pegylated interferon/ribavirin therapy.
        Gastroenterology. 2008; 135: 1561-1567
        • Wagoner J.
        • Negash A.
        • Kane O.J.
        • Martinez L.E.
        • Nahmias Y.
        • Bourne N.
        • et al.
        Multiple effects of silymarin on the hepatitis C virus lifecycle.
        Hepatology. 2010; 51: 1912-1921
        • Theriault A.
        • Wang Q.
        • Van Iderstine S.C.
        • Chen B.
        • Franke A.A.
        • Adeli K.
        Modulation of hepatic lipoprotein synthesis and secretion by taxifolin, a plant flavonoid.
        J Lipid Res. 2000; 41: 1969-1979
        • Polyak S.J.
        • Morishima C.
        • Lohmann V.
        • Pal S.
        • Lee D.Y.
        • Liu Y.
        • et al.
        Identification of hepatoprotective flavonolignans from silymarin.
        Proc Natl Acad Sci USA. 2010; 107: 5995-5999
        • Neumann U.P.
        • Biermer M.
        • Eurich D.
        • Neuhaus P.
        • Berg T.
        Successful prevention of hepatitis C virus (HCV) liver graft reinfection by silibinin mono-therapy.
        J Hepatol. 2010; 52: 951-952
        • Beinhardt S.
        • Rasoul-Rockenschaub S.
        • Scherzer T.M.
        • Ferenci P.
        Silibinin monotherapy prevents graft infection after orthotopic liver transplantation in a patient with chronic hepatitis C.
        J Hepatol. 2011; 54 (author reply 2-3): 591-592
        • Raal F.J.
        • Santos R.D.
        • Blom D.J.
        • Marais A.D.
        • Charng M.J.
        • Cromwell W.C.
        • et al.
        Mipomersen, an apolipoprotein B synthesis inhibitor, for lowering of LDL cholesterol concentrations in patients with homozygous familial hypercholesterolaemia: a randomised, double-blind, placebo-controlled trial.
        Lancet. 2010; 375: 998-1006
        • Visser M.E.
        • Kastelein J.J.
        • Stroes E.S.
        Apolipoprotein B synthesis inhibition: results from clinical trials.
        Curr Opin Lipidol. 2010; 21: 319-323
        • Neely R.D.
        • Bassendine M.F.
        Antisense technology to lower LDL cholesterol.
        Lancet. 2010; 375: 959-961
        • Huang H.
        • Sun F.
        • Owen D.M.
        • Li W.
        • Chen Y.
        • Gale M.J.
        • et al.
        Hepatitis C virus production by human hepatocytes dependent on assembly and secretion of very low-density lipoproteins.
        Proc Natl Acad Sci USA. 2007; 104: 5848-5853
        • Esau C.
        • Davis S.
        • Murray S.F.
        • Yu X.X.
        • Pandey S.K.
        • Pear M.
        • et al.
        MiR-122 regulation of lipid metabolism revealed by in vivo antisense targeting.
        Cell Metab. 2006; 3: 87-98
        • Lanford R.E.
        • Hildebrandt-Eriksen E.S.
        • Petri A.
        • Persson R.
        • Lindow M.
        • Munk M.E.
        • et al.
        Therapeutic silencing of microRNA-122 in primates with chronic hepatitis C virus infection.
        Science. 2010; 327: 198-201
        • Waterham H.R.
        • Koster J.
        • Romeijn G.J.
        • Hennekam R.C.
        • Vreken P.
        • Andersson H.C.
        • et al.
        Mutations in the 3beta-hydroxysterol Delta24-reductase gene cause desmosterolosis, an autosomal recessive disorder of cholesterol biosynthesis.
        Am J Hum Genet. 2001; 69: 685-694
      4. Takano T, Tsukiyama-Kohara K, Hayashi M, Hirata Y, Satoh M, Tokunaga Y, et al. Augmentation of DHCR24 expression by hepatitis C virus infection facilitates viral replication in hepatocytes. J Hepatol 2011.

        • Yao H.
        • Ye J.
        Long chain acyl-CoA synthetase 3-mediated phosphatidylcholine synthesis is required for assembly of very low density lipoproteins in human hepatoma Huh7 cells.
        J Biol Chem. 2008; 283: 849-854
        • Pollock S.
        • Antrobus R.
        • Newton L.
        • Kampa B.
        • Rossa J.
        • Latham S.
        • et al.
        Uptake and trafficking of liposomes to the endoplasmic reticulum.
        Faseb J. 2010; 24: 1866-1878
        • Pollock S.
        • Nichita N.B.
        • Bohmer A.
        • Radulescu C.
        • Dwek R.A.
        • Zitzmann N.
        Polyunsaturated liposomes are antiviral against hepatitis B and C viruses and HIV by decreasing cholesterol levels in infected cells.
        Proc Natl Acad Sci USA. 2010; 107: 17176-17181
        • Sheridan D.A.
        • Price D.A.
        • Schmid M.
        • Toms G.L.
        • Donaldson P.
        • Neely D.
        • et al.
        Apolipoprotein B associated cholesterol is a determinant of treatment outcome in patients with chronic hepatitis C virus (HCV) infection receiving anti-viral agents interferon-alpha and ribavirin.
        Aliment Pharmacol Ther. 2009; : 29 1282-90
        • Harrison S.A.
        • Rossaro L.
        • Hu K.Q.
        • Patel K.
        • Tillmann H.
        • Dhaliwal S.
        • et al.
        Serum cholesterol and statin use predict virological response to peginterferon and ribavirin therapy.
        Hepatology. 2010; 52: 864-874
        • Steenbergen R.H.
        • Joyce M.A.
        • Lund G.
        • Lewis J.
        • Chen R.
        • Barsby N.
        • et al.
        Lipoprotein profiles in SCID/uPA mice transplanted with human hepatocytes become human-like and correlate with HCV infection success.
        Am J Physiol. 2010; 299: G844-G854
        • Davidson M.H.
        Update on CETP inhibition.
        J Clin Lipidol. 2010; 4: 394-398
        • Catanese M.T.
        • Ansuini H.
        • Graziani R.
        • Huby T.
        • Moreau M.
        • Ball J.K.
        • et al.
        Role of scavenger receptor class B type I in hepatitis C virus entry: kinetics and molecular determinants.
        J Virol. 2010; 84: 34-43