Transcriptomic profiling of TSST-1–induced cytotoxicity and inflammatory responses in human vaginal epithelial cells

Toxic shock syndrome toxin-1 (TSST-1) is a critical superantigen produced by certain staphylococcal strains, closely associated with menstrual toxic shock syndrome and mucosal inflammation. While the systemic superantigenic function of TSST-1 is well-established, its early cytotoxic and inflammatory effects on human vaginal epithelial cells (HVEC) remain poorly characterized. This study, therefore, sought to investigate the initial temporal dynamics of TSST-1-induced changes in cell viability, inflammatory cytokine responses, epithelial stress-related responses, and barrier-associated transcriptional changes in a human vaginal epithelial cell model, along with transcriptomic analysis. We evaluated the impact of recombinant TSST-1 on HVEC at different doses and treatment durations. Subsequent exposure assessments included cell viability, apoptosis, and cell cycle distribution via flow cytometry, alongside inflammatory gene expression and transcriptomic profiling. TSST-1 reduced cell viability and proliferation in a dose-and time-dependent manner due to increased apoptosis and G1-phase accumulation. Notably, early exposure did not result in a uniform upregulation of all inflammatory mediators; rather, multiple cytokines exhibited dose-dependent segmented response patterns instead of a linear increase. RNA sequencing analysis of samples treated with 125 or 1000 ng/mL TSST-1 for 48 h revealed dose-associated transcriptional changes involving chemokine signaling, cytokine-receptor interactions, epithelial stress-related pathways, and glycolysis-related pathways. Notably the moderate-dose group showed a higher number of statistically defined differentially expressed genes than the high-dose group, suggesting a non-linear dose-associated transcriptional pattern. These findings demonstrate that TSST-1 can trigger cytotoxicity, apoptosis, cell cycle disruption, and a graded inflammatory response in vaginal epithelial cells, providing a systematic transcriptomic framework for understanding the early mucosal responses induced by TSST-1.