Elucidating the role of Akkermansia muciniphila in Group B Streptococcal vaginal colonization and ascending infection - PROJECT SUMMARY Group B Streptococcus (GBS) is a Gram-positive pathobiont that asymptomatically colonizes the female genital tract (FGT) of up to 30% of healthy women. However, during pregnancy it is associated with adverse pregnancy outcomes, including premature rupture of membranes (PROM), chorioamnionitis, stillbirth, and preterm birth; notably 10% of preterm births are caused by GBS. Further, GBS can be transmitted to the fetus in utero, or the newborn during vaginal birth, resulting in invasive neonatal disease. GBS is the leading cause of meningitis and bloodstream infections in newborns, leaving them at risk for long-term problems. During pregnancy, GBS colonization of the FGT is intermittent and can be transient. However, the bacterial and host determinants that promote GBS vaginal colonization and ascending infection, as well as the role of native microbiota are largely unknown and remain important questions to be studied. Previous microbiome studies have demonstrated that GBS colonization impacts vaginal microbial diversity. Using a mouse model of GBS vaginal colonization, we found that GBS persistence is driven by computationally predictable changes in certain taxa, including Akkermansia muciniphila, a Gram-negative obligate anaerobe that degrades mucin. We have further shown that co-colonization with A. muciniphila increases GBS vaginal persistence, however, the specific mechanism(s) for this synergy is unknown. To date, we demonstrate that GBS adherence to human vaginal and endocervical epithelial cells increases in the presence of A. muciniphila. To further explore this synergism, we performed dual and triple RNA sequencing with human vaginal epithelial cells (hVECs) in order to observe the effect of each organism during infection. Upon analysis, we identified 225 unique GBS genes that were differentially expressed in the presence of hVECs and A. muciniphila. Interestingly, our data showed significant increase in expression of genes encoding for GBS pili, and preliminary data suggest that the observed increase in adherence to hVECs is occurring in a pili-dependent manner. Additionally, the host transcriptome demonstrated major changes in numerous cellular processes in the presence of GBS and A. muciniphila, including innate immune responses. We hypothesize that the observed increase in GBS burden during co-culture with A. muciniphila may be due to: 1) induction of GBS pili production; 2) alteration of mucin abundance; 3) modulation of host immune responses. In my proposed studies, I will focus on identifying the specific mechanisms by which A. muciniphila promotes GBS host cell interaction, as prolonged GBS vaginal persistence may potentiate the risk of invasive infection in utero and in the newborn.
