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

BACKGROUND: Women's increased risk of HIV acquisition during pregnancy and postpartum may be mediated by changes in vaginal microbiota and/or cytokines.

METHODS: A cohort of 80 HIV-1-seronegative Kenyan women contributed 409 vaginal samples at six pregnancy timepoints: periconception, positive pregnancy test, first trimester, second trimester, third trimester, and postpartum. Concentrations of vaginal bacteria linked with HIV risk and Lactobacillus species were measured using quantitative polymerase chain reaction. Cytokines were measured by immunoassay.

RESULTS: Using Tobit regression, later pregnancy timepoints 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 L iners (p < 0.001), L. crispatus (p=<0.001), L. vaginalis (p < 0.001), IL-6 (p < 0.001), TNF (p = 0.004), CXCL10 (p < 0.001), CCL3 (p = 0.009), CCL4 (p < 0.001), CCL5 (p = 0.002), IL-1β (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 cytokines or bacteria. The shift toward a Lactobacillus dominated microbiota during pregnancy mediated the relationship between pregnancy timepoint and CXCL10.

CONCLUSIONS: Increases in proinflammatory cytokines, but not vaginal bacterial taxa linked with higher HIV risk, could provide an explanation for increased HIV susceptibility during pregnancy and postpartum.