ABSTRACT
Staphylococcal enterotoxin B (SEB) and αtoxin produced by Staphylococcus aureus (S. aureus) are important in the pathogenesis of diseases. In the present study, we investigated the effects of SEB and αtoxin on ECV304 cells. It was identified that both SEB and αtoxin were capable of inducing the apoptosis of ECV304 cells in a dose and timedependent manner. In addition, SEB and αtoxin were able to induce the expression of TNFα and the activation of caspase3 and 8 in the ECV304 cells. The inhibition of TNFα (with its neutralizing antibody) and caspase3 and 8 [with the corresponding inhibitory peptides; z-N-acetyl-Asp-Glu-Val-Asp-aminomethyl-coumarin (DEVD)-fluoromethyl ketone (FMK) for inhibition of caspase3 and z-N-acetyl-Ile-Glu-Thr-Asp (IETD)-FMK) for inhibition of caspase8] significantly decreased the rates of cell apoptosis induced by SEB and αtoxin, but was not able to completely block the induced cell apoptosis. These data suggest that SEB and αtoxin induce ECV304 cell apoptosis via a similar mechanism, which is partially mediated by the extrinsic death pathway involving TNFα and caspase8. These results provide insights into the synergistic pathogenicity of SEB and αtoxin during S. aureus infection.