The association between obesity and weight loss after bariatric surgery on the vaginal microbiota

BackgroundObesity and vaginal microbiome (VMB) dysbiosis are each risk factors for adverse reproductive and oncological health outcomes in women. Here, we investigated the relationship between obesity, vaginal bacterial composition, local inflammation and bariatric surgery.MethodsVaginal bacterial composition assessed by high-throughput sequencing of bacterial 16S rRNA genes and local cytokine levels measured using a multiplexed Magnetic Luminex Screening Assay were compared between 67 obese and 42 non-obese women. We further assessed temporal changes in the microbiota and cytokines in a subset of 27 women who underwent bariatric surgery.ResultsThe bacterial component of the vaginal microbiota in obese women was characterised by a lower prevalence of aLactobacillus-dominant VMB and higher prevalence of a high diversity (Lactobacillusspp., andGardnerella- spp. depleted) VMB, compared with non-obese subjects (pDialisterspecies (pAnaerococcus vaginalis(p=0.021), andPrevotella timonensis(p=0.020) and decreased relative abundance ofLactobacillus crispatus(p=0.014). Local vaginal IL-1β, IL-4, IL-6, IL-8, IFNγ, MIP-1α and TNFα levels were all higher among obese women, however, only IL-1β and IL-8 correlated with VMB species diversity. In a subset of obese women undergoing bariatric surgery, there were no significant overall differences in VMB following surgery; however, 75% of these women remained obese at 6 months. Prior to surgery, there was no relationship between body mass index (BMI) and VMB structure; however, post-surgery women with aLactobacillus-dominant VMB had a significantly lower BMI than those with a high diversity VMB.ConclusionsObese women have a significantly different vaginal microbiota composition with increased levels of local inflammation compared to non-obese women. Bariatric surgery does not change the VMB; however, those with the greatest weight loss 6-month post-surgery are most likely to have aLactobacillus-dominant VMB.