Bacterial vaginosis is associated with transcriptomic changes but not higher concentrations of cervical leukocytes in a study of women at high risk for HIV acquisition

Background The association between bacterial vaginosis (BV) and increased HIV acquisition risk may be related to concentrations of HIV-susceptible immune cells in the cervix. Methods Participants (31 with BV and 30 with normal microbiota) underwent cervical biopsy at a single visit. Immune cells were quantified and sorted using flow cytometry (N=55), localization assessed by immunofluorescence (N=16), and function determined by bulk RNA sequencing (RNA-seq) of live CD45+ cells (N=21). Results Linear regression analyses demonstrated no differences in mean log2 [cells/mg tissue] between women with BV vs normal microbiota for antigen presenting cell (APC) subtypes linked to HIV risk (including CD1a+HLA-DR+ Langerhans cells, CD11c+CD14+ dendritic cells [DCs], and CD11c+HLA-DR+ DCs) and CD4+ T cells. Women with BV had a higher median proportion of CD11c+HLA-DR+ APCs (out of total cells) in cervical epithelium (0.1% vs 0.0%; p=0.03 using Mann-Whitney testing). RNA-seq identified 1,032 differentially expressed genes (adjusted p-value <0.05) in CD45+ cells between women with BV vs normal microbiota. Women with BV demonstrated downregulation of pathways linked to translation, metabolism, cell stress, and immune signaling. Conclusions BV alters immune cell localization and function; future studies are needed to address how these changes may mediate HIV acquisition risk.