Search

The genital tract of African women has been shown to differ from what is currently accepted as 'normal', defined by a pH≤4.5 and lactobacilli-dominated microbiota. Adolescent girls and young women (AGYW) from sub-Saharan Africa are at high risk for HIV, and we hypothesized that specific biological factors are likely to be influential. This study aimed to compare characteristics of vaginal health in HIV-negative AGYW (16-22-years-old), from two South African communities, to international norms. We measured plasma hormones, vaginal pH, presence of BV (Nugent scoring), sexually transmitted infections (multiplex PCR for Chlamydia trachomatis, Neisseria gonorrhoea, Trichomonas vaginalis, Mycoplasma genitalium) and candidiasis (Gram stain) in AGYW (n = 298) from Cape Town and Soweto. Cervicovaginal microbiota was determined by 16S pyrosequencing; 44 genital cytokines were measured by Luminex; and cervical T-cell activation/proliferation (CCR5, HLA-DR, CD38, Ki67) was measured by multiparametric flow cytometry. 90/298 (30.2%) AGYW were negative for BV, candidiasis and bacterial STIs. L. crispatus and L. iners were the dominant bacteria in cervicovaginal swabs, and the median vaginal pH was 4.7. AGYW with L. crispatus-dominant microbiota (42.4%) generally had the lowest cytokine concentrations compared to women with more diverse microbiota (34/44 significantly upregulated cytokines). Frequencies of CCR5+CD4+ T-cells co-expressing CD38 and HLA-DR correlated positively with interleukin (IL)-6, TNF-α, GRO-α, macrophage inflammatory protein (MIP)-1α, and IL-9. While endogenous oestrogen had an immune-dampening effect on IL-6, TNF-related apoptosis-inducing ligand (TRAIL) and IL-16, injectable hormone contraceptives (DMPA and Net-EN) were associated with significantly lower endogenous hormone concentrations (p<0.0001 for oestrogen and progesterone) and upregulation of 34/44 cytokines. Since genital inflammation and the presence of activated CD4+ T cells in the genital tract have been implicated in increased HIV risk in South African women, the observed high levels of genital cellular activation and cytokines from AGYW may point towards biological factors increasing HIV risk in this region., Competing Interests: The authors have declared that no competing interests exist.

Background: Early life microbiota is an important determinant of immune and metabolic development and may have lasting consequences. The maternal gut microbiota during pregnancy or breastfeeding is important for defining infant gut microbiota. We hypothesized that maternal gut microbiota during pregnancy and breastfeeding is a critical determinant of infant immunity. To test this, pregnant BALB/c dams were fed vancomycin for 5 days prior to delivery (gestation; Mg), 14 days postpartum during nursing (Mn), or during gestation and nursing (Mgn), or no vancomycin (Mc). We analyzed adaptive immunity and gut microbiota in dams and pups at various times after delivery., Results: In addition to direct alterations to maternal gut microbial composition, pup gut microbiota displayed lower α-diversity and distinct community clusters according to timing of maternal vancomycin. Vancomycin was undetectable in maternal and offspring sera, therefore the observed changes in the microbiota of stomach contents (as a proxy for breastmilk) and pup gut signify an indirect mechanism through which maternal intestinal microbiota influences extra-intestinal and neonatal commensal colonization. These effects on microbiota influenced both maternal and offspring immunity. Maternal immunity was altered, as demonstrated by significantly higher levels of both total IgG and IgM in Mgn and Mn breastmilk when compared to Mc. In pups, lymphocyte numbers in the spleens of Pg and Pn were significantly increased compared to Pc. This increase in cellularity was in part attributable to elevated numbers of both CD4+ T cells and B cells, most notable Follicular B cells., Conclusion: Our results indicate that perturbations to maternal gut microbiota dictate neonatal adaptive immunity.

The relevance of specific microbial colonisation to colorectal cancer (CRC) disease pathogenesis is increasingly recognised, but our understanding of possible underlying molecular mechanisms that may link colonisation to disease in vivo remains limited. Here, we investigate the relationships between the most commonly studied CRC-associated bacteria (Enterotoxigenic Bacteroides fragilis, pks+ Escherichia coli, Fusobacterium spp., afaC+ E. coli, Enterococcus faecalis & Enteropathogenic E. coli) and altered transcriptomic and methylation profiles of CRC patients, in order to gain insight into the potential contribution of these bacteria in the aetiopathogenesis of CRC. We show that colonisation by E. faecalis and high levels of Fusobacterium is associated with a specific transcriptomic subtype of CRC that is characterised by CpG island methylation, microsatellite instability and a significant increase in inflammatory and DNA damage pathways. Analysis of the significant, bacterially-associated changes in host gene expression, both at the level of individual genes as well as pathways, revealed a transcriptional remodeling that provides a plausible mechanistic link between specific bacterial colonisation and colorectal cancer disease development and progression in this subtype; these included upregulation of REG3A, REG1A and REG1P in the case of high-level colonization by Fusobacterium, and CXCL10 and BMI1 in the case of colonisation by E. faecalis. The enrichment of both E. faecalis and Fusobacterium in this CRC subtype suggests that polymicrobial colonisation of the colonic epithelium may well be an important aspect of colonic tumourigenesis., Competing Interests: The authors have declared that no competing interests exist.