Tnf-a production and apoptosis in hepatocytes after listeria monocytogenes and salmonella typhimurium invasion

invasion of hepatocytes by listeria monocytogenes (lm) and salmonella typhimurium (st) can stimulate tumor necrosis factor alpha (tnf-α) release and induce apoptosis. in this study, we compared the behavior of hepatocytes invaded by three l. monocytogenes serotypes (lm-4a, lm-4b and lm-1/2a) and by st to understand which bacterium is more effective in the infectious process. we quantified tnf-α release by elisa, apoptosis rates by annexin v (early apoptosis) and tunel (late apoptosis) techniques. the cell morphology was studied too. tnf-α release rate was highest in st-invaded hepatocytes. st and lm-1/2a induced the highest apoptosis production rates evaluated by tunel. lm-4b produced the highest apoptosis rate measured by annexin. invaded hepatocytes presented various morphological alterations. overall, lm-4b and lm-1/2a proved to be the most efficient at cell invasion, although st adapted faster to the environment and induced earlier hepatocyte tnf-α release.