Local immune innate markers and vaginal microbiota composition are influenced by hormonal cycle phases.

The female reproductive tract (FRT) is rich in environmental factors, including immune and non-immune components such as the vaginal microbiota. These factors can modulate local inflammation therefore sexually transmitted infection susceptibility. Moreover, menstrual cycle induces important modifications within the FRT mucosa and affects these factors. Unfortunately, very few information are known about the interaction between local inflammatory factors and vaginal microbiota as well as their combining effect on local inflammation. The menstrual cycle and FRT morphology are similar between women and cynomolgus macaque. Moreover, their microbiota is dominated by anaerobic bacteria that are associated with a dysbiotic environment in women. Therefore, a longitudinal study covering three menstrual cycles was performed in cynomolgus macaques. The evolution of the vaginal microbiota composition and the inflammation (cytokine/chemokine profiles and neutrophil phenotype) in the FRT and in the blood was determined throughout the menstrual cycle