Staphylococcal enterotoxin B and α‑toxin induce the apoptosis of ECV304 cells via similar mechanisms.

Staphylococcal enterotoxin B (SEB) and α‑toxin produced by Staphylococcus aureus (S. aureus) are important in the pathogenesis of diseases. In the present study, we investigated the effects of SEB and α‑toxin on ECV304 cells. It was identified that both SEB and α‑toxin were capable of inducing the apoptosis of ECV304 cells in a dose‑ and time‑dependent manner. In addition, SEB and α‑toxin were able to induce the expression of TNF‑α and the activation of caspase‑3 and ‑8 in the ECV304 cells. The inhibition of TNF‑α (with its neutralizing antibody) and caspase‑3 and ‑8 [with the corresponding inhibitory peptides; z-N-acetyl-Asp-Glu-Val-Asp-aminomethyl-coumarin (DEVD)-fluoromethyl ketone (FMK) for inhibition of caspase‑3 and z-N-acetyl-Ile-Glu-Thr-Asp (IETD)-FMK) for inhibition of caspase‑8] significantly decreased the rates of cell apoptosis induced by SEB and α‑toxin, but was not able to completely block the induced cell apoptosis. These data suggest that SEB and α‑toxin induce ECV304 cell apoptosis via a similar mechanism, which is partially mediated by the extrinsic death pathway involving TNF‑α and caspase‑8. These results provide insights into the synergistic pathogenicity of SEB and α‑toxin during S. aureus infection.