Changes in vaginal bacteria and inflammatory mediators from periconception through early-postpartum in a cohort of HIV-negative Kenyan women

Women’s increased risk of HIV acquisition during pregnancy and the postpartum period maybe mediated by changes in vaginal microbiota and/or cytokines. Methods: A cohort of HIV-1-seronegative Kenyan women contributed vaginal fluid samples at six pregnancy time points: periconception, positive pregnancy test, first trimester, second trimester, third trimester and postpartum. Concentrations of vaginal bacteria previously associated with HIV risk and cytokines were measured using quantitative polymerase chain reaction and immunoassays, respectively. Results: Eighty women contributed 409 samples. Using Tobit regression, later pregnancy time points were associated with lower concentrations of Sneathia spp. (p=0.01), Eggerthella sp. Type 1 (p=0.002) and Parvimonas sp. Type 2 (p=0.02), and higher concentrations of IL-6 (p=3×10-5), TNF (p=0.004), CXCL10 (p=1×10-4), CCL3 (0.009), CCL4 (p=4.8×10-7), CCL5 (p=0.002), IL-1b (p=0.02), and IL-8 (p=0.002). Most cervicovaginal cytokines and vaginal bacteria clustered separately in principal components analysis, except for CXCL10, which did not group with either the cytokine or bacterial clusters. The shift toward a more Lactobacillus dominated microbiota during pregnancy appeared to mediate the relationship between pregnancy time point and CXCL10. Conclusions: Increases in proinflammatory cytokines, but not vaginal bacterial taxa previously associated with HIV risk, could provide an explanation for increased HIV susceptibility during pregnancy and postpartum.