Apoptotic effect of bacterial toxins on cardiac myocytes

Rat embryonic cardiac myocytes ( H9c2 ) were incubated with different concentrations of bacterial toxins, such as cholerae toxin, diphtheriae toxin, Staphylococcus Enterotoxin B, Lipopolysaccharide for 24hs. The cytotoxic effect of bacterial toxins was analysed by MTT assay for the percentage of cell viability.There was no statistical significance for the effects of cholerae toxin, Staphylococcus Enterotoxin B, Lipopolysaccharide on viability in H9c2 cells. The effect of Diphtheriae toxin on the viability of H9c2 cells was dose-dependent. Diphtheriae toxin in the concentration of 50 ? g/ml affected the percentage of viability in H9c2 cells significantly.H9c2 cells were incubated with Diphtheriae toxin in the concentration of 50mikrog/ml for 24hs. The percentage of apoptotic cells were analysed by Flow Cytometry. H9c2 cells were incubated with different concentrations of diphtheriae toxin for 24hs. Production of Reactive Oxygen Species were analysed by DCF assay. H9c2 cells were incubated with diphtheriae toxin in the concentration of 50mikrog/ml for 5hs. mRNA levels of Caspase 2, Caspase 8, Caspase 9 , Caspase 3, Caspase 6, Caspase 7, Fas, Tnfrsf11b, Apaf1, Traf1, Bax were analysed by RT-PCR . H9c2 cells were incubated with diphtheriae toxin in the concentration of 50mikrog/ml for 24hs. İnternucleosomal DNA fragmentation, which is known as terminal stage of Apoptosis, was analysed by Apo-BRDU assay, nuclear morphology was analysed by Hoechst Dye assay.According to the percentage of Apoptotic cells, the cytotoxic effect of Diphtheriae toxin on H9c2 cells results from apoptotic effect of toxin itself.Diphtheriae toxin increased production of ROS in a dose-dependent manner and increased mRNA levels of Caspase 2, Caspase 9, Caspase 7, Tnfrsf11b, Traf1 in H9c2 cells. Diphtheriae toxin decreased mRNA levels of Apaf1 in H9c2 cells.In conclusion; Diphtheriae toxin increased apoptotic effect through dose-dependent production of ROS and increased apoptotic effect by augmentation of mRNA levels of Caspase 2, Caspase 9, Caspase 7 in H9c2 cells. Diphtheriae toxin decreased Apoptotic effect by reducing of mRNA levels of Apaf1, Traf1 in H9c2 cells.