Modulation of Immune and Barrier Functions of Epithelial Cells from the Female Reproductive Tract by Vaginal Microbiota Metabolites: Implications for HIV Susceptibility

The female genital tract is colonised by bacteria known as the vaginal microbiota. An optimal microbiota is associated with favourable sexual and reproductive health outcomes, including being at a lower risk of HIV acquisition. Lactic acid is the main metabolic product of these optimal bacteria and here we show it helps maintaining a non-inflamed state and supports the barrier function of the vagina, which protects against HIV infection. In contrast, we found factors produced by non-optimal bacteria increased inflammation in cells from the vagina, suggesting they may contribute to increased risk of HIV acquisition in women with non-optimal vaginal microbiota.