Hydrogen from intestinal bacteria is protective for Concanavalin A-induced hepatitis

It is well known that some intestinal bacteria, such as Escherichia coli, can produce a remarkable amount of molecular hydrogen (H 2). Although the antioxidant effects of H 2 are well documented, the present study examined whether H 2 released from intestinally colonized bacteria could affect Concanavalin A (ConA)-induced mouse hepatitis. Systemic antibiotics significantly decreased the level of H 2 in both liver and intestines along with suppression of intestinal bacteria. As determined by the levels of AST, ALT, TNF-α and IFN-γ in serum, suppression of intestinal bacterial flora by antibiotics increased the severity of ConA-induced hepatitis, while reconstitution of intestinal flora with H 2-producing E. coli, but not H 2-deficient mutant E. coli, down-regulated the ConA-induced liver inflammation. Furthermore, in vitro production of both TNF-α and IFN-γ by ConA-stimulated spleen lymphocytes was significantly inhibited by the introduction of H 2. These results indicate that H 2 released from intestinal bacteria can suppress inflammation induced in liver by ConA.