Translating the vaginal microbial landscape: a connecting link between bacterial vaginosis and preeclampsia

The human vaginal microbiome plays a pivotal role in maintaining female reproductive health through its Lactobacillus-dominated microbial ecology. These bacteria contribute to the acidic pH of the vagina by producing lactic acid, ultimately preventing the colonization of pathogens. Additionally, they produce bacteriocins and hydrogen peroxide, which are detrimental to other microorganisms. Human vaginal microbiota is subjected to alterations with advancement in age, hormonal status, puberty, menstruation cycle, pregnancy and gestation, vaginal tract diseases, exposure to antibiotics, etc. Diet, lifestyle factors, obesity, and gestational diabetes are also reported to cause a shift in vaginal microbiota. This review thoroughly illustrates the perpetually changing dynamics of vaginal microbiota throughout women’s lives, as well as focuses on the impact of dysbiosis in bacterial vaginosis. More emphasis is given on immunological changes observed during bacterial vaginosis, mainly IL-1β, and its involvement in the development of preeclampsia. Thereby, this review highlights a mechanistic link between lower genital tract disease, bacterial vaginosis, and a hypertensive disorder of pregnancy, preeclampsia, via IL-1β–ROR-γt–Th17 axis, which is regulated by vitamin D, with a suggestion on how shifts in vaginal microbial community may pose a risk for preeclampsia.