The gut microbiome and sexual behaviors are associated with immunologic alterations in the colonic mucosa and blood of HIV positive and negative Men who have Sex with Men

HIV infection and other factors related to sexual activity among men who have sex with men (MSM) can dysregulate relationships between the gut microbiome and immune system. To deeply explore these relationships, we subjected blood and colonic samples from HIV+ and HIV- MSM and non-MSM to deep immune phenotyping using mass cytometry (CyTOF); We then related immune data to gut microbiome composition and MSM behaviors. HIV-infection status drove immune population differences in colonic biopsy, but MSM status had a greater influence in blood, including reduced naïve T and CD8+ Mucosal-Associated Invariant T (MAIT) cells. Correlations between immune cell populations and gut microbial taxa were impacted by both HIV infection and MSM status, and network analysis indicated that colonic tissue resident T cells and blood MAITs were associated with diverse gut microbes. This study provides novel information on host:microbe interactions with implications for HIV control and transmission among MSM.