Mitochondria-Dependent Apoptosis of Con A-Activated T Lymphocytes Induced by Asiatic Acid for Preventing Murine Fulminant Hepatitis

Abstract

Selectively facilitating apoptosis of activated T cells is essential for the clearance of pathogenic injurious cells and subsequent efficient resolution of inflammation. However, few chemicals have been reported to trigger apoptosis of activated T cells for the treatment of hepatitis without affecting quiescent T cells. In the present study, we found that asiatic acid, a natural triterpenoid, selectively triggered apoptosis of concanavalin A (Con A)-activated T cells in a mitochondria-dependent manner indicated by the disruption of the mitochondrial transmembrane potential, release of cytochrome c from mitochondria to cytosol, caspases activation, and cleavage of PARP. In addition, asiatic acid also induced the cleavage of caspase 8 and Bid and augmented Fas expression in Con A-activated T cells. However, following activation of T cells from MRL(lpr/lpr) mice with mutation of Fas demonstrated a similar susceptibility to asiatic acid-induced apoptosis compared with normal T cells, suggesting that Fas-mediated death-receptor apoptotic pathway does not mainly contribute to asiatic acid-induced cell death. Furthermore, asiatic acid significantly alleviated Con A-induced T cell-dependent fulminant hepatitis in mice, as assessed by reduced serum transaminases, pro-inflammatory cytokines, and pathologic parameters. Consistent with the in vitro results, asiatic acid also induced apoptosis of activated CD4(+) T cells in vivo. Taken together, our results demonstrated that the ability of asiatic acid to induce apoptosis of activated T cells and its potential use in the treatment of T-cell-mediated inflammatory diseases.