Abstract: Objective To investigate α-toxin-induced apoptosis of umbilical vein endothelial cells and explore its role in vertical
infection of Staphylococcus aureus L-form. Methods HUV-EC-C cells exposed to different concentrations (0, 10, 30, 90, and 270
ng/ml) of α-toxin for different time lengths (0, 2, 4, 6, and 8 h) were examined for apoptosis using flow cytometry with
Annexin V-PI staining. The levels of tumor necrosis factor-α (TNF-α) and the activities of, caspase-3 and caspase-8 in the cell
culture were detected by ELISA and colorimetric method, respectively. α-Toxin-induced cell apoptosis was also analyzed in
HUV-EC-C cells treated with a neutralizing antibody of TNF-α or with the inhibitory peptides of caspase-3 (zDEVD-FMK) and
caspase-8 (zIETD-fmk). Results α-Toxin induced apoptosis of HUV-EC-C cells in a dose- and time-dependent manner and
caused significantly enhanced expression of TNF-α and the activation of both caspase-3 and caspase-8. Inhibition of TNF-α
with its neutralizing antibody and the inhibitory peptides of caspase-3 or -8 all significantly decreased α-toxin-induced cell
apoptosis, and the caspase-3 inhibitor completely blocked α-toxin-induced cell apoptosis. Conclusion α-Toxin-induced
apoptosis is partially mediated by the extrinsic cell death pathway of TNF-α and caspase-8 and plays an important role in the
vertical infection of S. aureus L-form to affect fetal growth and development.