Critical role of CD44 in hepatotoxin-mediated liver injury☆

Background/Aims

Blocking of adhesion molecules is considered to be one of the therapeutic strategies inflammatory diseases, although it remains unclear whether this strategy is beneficial.

Methods

We used CD44-deficient mice to assess whether inhibition of CD44 could control liver injury caused by carbon tetrachloride (CCl₄).

Results

CD44-deficient mice exhibited suppressed liver inflammation during the early phase (within 6h) after CCl₄ injection due to reduced inflammatory cell infiltration and cytokine production, but showed severe liver inflammation with increased numbers of apoptotic hepatocytes at the late phase (after 12h). The induction of hepatocyte apoptosis was triggered by reduced NF-κB activity, which was induced by the low inflammatory cytokine concentrations. Furthermore, macrophages contributed to the induction of hepatocyte apoptosis, since neutralization by an anti-CD11b antibody significantly protected against hepatocyte apoptosis. Finally, we found that blocking of MIP-2 and TNF-α reduced hepatocyte apoptosis with decreased numbers of intrahepatic leukocytes and reduced inflammatory cytokine production.

Conclusions

These findings suggest that targeting of CD44 as a therapeutic approach for inflammatory liver diseases may require caution for particular immune systems in the liver.

Abbreviations: sALT, serum alanine aminotransferase, IHL, intrahepatic leukocyte, RPA, ribonuclease protection assay, CCl₄, carbon tetrachloride, EMSA, electrophoretic mobility shift assay, FADD, Fas-associated death domain, TRADD, TNF receptor-associated death domain, HA, hyaluronic acid, MIP-2, macrophage inflammatory protein 2

Keywords: CD44, MIP-2, Liver inflammation, NF-κB, Macrophage