Involvement of Fas system-mediated apoptosis in pathogenesis of viral hepatitis

Enhanced Fas system-mediated hepatocyte apoptosis is observed in hepatitis C virus (HCV)- and hepatitis B virus (HBV)-associated chronic liver disease s, In these forms of viral hepatitis, liver-infiltrating lymphocytes that r ecognize the viral antigen on hepatocytes become activated and express cyto lytic Fas ligand (FasL) molecules. In contrast, hepatocytes exhibit enhance d Fas expression and become susceptible to FasL-mediated death. Augmentatio n of the Fas system has also been observed in other liver diseases and bili ary disorders. Moreover, the Fas system is involved in removing aged hepato cytes. Thus, Fas-mediated apoptosis plays an important role in several live r diseases and in maintaining normal liver homeostasis.