Role of α-toxin-induced apoptosis of umbilical vein endothelial cells in vertical infection of Staphylococcus aureus L-form / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate α-toxin-induced apoptosis of umbilical vein endothelial cells and explore its role in vertical infection of Staphylococcus aureus L-form.</p><p><b>METHODS</b>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).</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Effect of maternal staphylococcal enterotoxin B administration during pregnancy on CD3⁺ TCR Vβ8⁺T cells of adult offspring rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the influence of maternal staphylococcal enterotoxin B (SEB) administration during pregnancy on CD3⁺ TCR Vβ8⁺T cells of adult offspring rats.</p><p><b>METHODS</b>Pregnant maternal rats at gestational day (GD) 16 were injected intravenously with 15 µg SEB in 0.2 ml PBS (SEB group), and the control rats receive the same volume of PBS. Flow cytometry was used to determine the levels of CD3⁺ TCR Vβ8⁺T cells in both the thymus and peripheral blood of adult offspring rats and the response of these cells to a secondary SEB administration.</p><p><b>RESULTS</b>Maternal SEB administration during pregnancy significantly decreased the percentages of CD3⁺TCR Vβ8⁺T cells in the thymus in adult female (1.760-2.714) and male (1.098-2.088) offspring rats (P<0.05). The change of CD3⁺TCR Vβ8⁺T cells in the peripheral blood was similar to that in the thymus. In the control adult offspring rats, SEB administration at adulthood significantly reduced the percentages of CD3⁺TCR Vβ8⁺T cells in both the thymus and peripheral blood (P<0.05). But in SEB group, a secondary SEB administration in adult offspring rats significantly increased the percentage of CD3⁺TCR Vβ8⁺T cells in the peripheral blood (P<0.05) but not in the thymus (P>0.05).</p><p><b>CONCLUSION</b>Maternal SEB administration during pregnancy can change the response of CD3⁺ TCR Vβ8⁺T cells of adult offspring rats to a secondary SEB administration.</p>