Tissue-specific differences in HIV DNA levels and mechanisms that govern HIV transcription in blood, gut, genital tract and liver in ART-treated women

Introduction: Sex-specific differences affect multiple aspects of HIV infection, yet few studies have quantified HIV levels in tissues from women. Since an HIV functional cure will likely require a major reduction of infected cells from most tissues, we measured total and intact HIV DNA and the HIV transcription profile in blood, gut, genital tract and liver from HIV-positive antiretroviral therapy (ART) -treated women.

Methods: Peripheral blood mononuclear cells (PBMC) and biopsies from the gastrointestinal (ileum, colon, rectosigmoid +/- liver) and genital (ectocervix, endocervix and endometrium) tracts were collected from 6 ART-treated (HIV RNA < 200 copies/mL) women. HIV DNA (total and intact) and levels of read-through, initiated (total), 5'elongated, polyadenylated and multiply spliced HIV transcripts were measured by droplet digital PCR. Immunophenotyping of cells was performed using Cytometry by time of flight (CyTOF).

Results: We detected total HIV DNA in all tissues and intact HIV DNA in blood, ileum, colon, rectosigmoid and ectocervix. Initiated HIV transcripts per provirus were higher in PBMC and endometrium than in ileum, colon, rectosigmoid, ectocervix or endocervix, and higher in the rectum than either ileum or colon. 5'Elongated HIV transcripts per provirus were comparable in PBMC and endometrium, but higher than in gut or cervical samples. Polyadenylated and multiply spliced HIV transcripts were detected in PBMC (6/6 and 3/6 individuals respectively), but rarely in the tissues.

Conclusions: These results suggest tissue-specific differences in the mechanisms that govern HIV expression, with lower HIV transcription in most tissues than blood. Therapies aimed at disrupting latency, such as latency-reversing or latency-silencing agents, will be required to penetrate into multiple tissues and target different blocks to HIV transcription.