CrmA gene expression protects mice against concanavalin-A-induced hepatitis by inhibiting IL-18 secretion and hepatocyte apoptosis

Activated cytotoxic T-cell-mediated hepatocyte apoptosis via Fas/Fas-ligand and perforin/granzyme pathways are believed to involve the model of concanavalin A (ConA)induced hepatitis. The purpose of the present study is to investigate whether the cytokine response modifier A (crmA) gene effectively inhibits the hepatocyte apoptosis of ConA-induced hepatitis. We examined survival rates, liver pathology, immune histological changes, and cytokine profiles from mice receiving the recombinant adenovirus vectors containing cre and/or crmA genes, transferred to the liver 3 days before ConA injection, and a crmA gene nonexpression control group. Injection of ConA into mice rapidly led to massive hepatocyte apoptosis, and infiltration of leukocytes, especially CD11b(+) inflammatory cells. In contrast, liver damage was dramatically reduced in the mice that expressed the crmA gene. However, infiltration by CD4(+) cells was not affected. The survival of the mice increased significantly to 100% in the treated group versus the control group. Furthermore, we demonstrated that interleukin (IL)-18 plays an important role in ConA-induced hepatitis, and that crmA expression significantly inhibited IL-18 secretion. Our results showed that the crmA gene effectively inhibits apoptosis induced by ConA hepatitis. This indicates a potential therapeutic usage of crmA for protection from cellular damage due to hepatitis.