Short-term oral pre-exposure prophylaxis against HIV-1 modulates the transcriptome of foreskin tissue in young men in Africa

Bacterial microbiome and host inflammatory gene expression in foreskin tissue

The penile epithelial microbiome remains underexplored. We sequenced human RNA and a segment of the bacterial 16S rRNA gene from the foreskin tissue of 144 adolescents from South Africa and Uganda collected during penile circumcision after receipt of 1-2 doses of placebo, emtricitabine + tenofovir disoproxil fumarate, or emtricitabine + tenofovir alafenamide to investigate the microbiome of foreskin tissue and its potential changes with antiretroviral use. We identified a large number of anaerobic species, including Corynebacterium acnes, which was detected more frequently in participants from South Africa than Uganda. Bacterial populations did not differ by treatment received, and no differentially abundant taxa were identified between placebo versus active drug recipients. The relative abundance of specific bacterial taxa was negatively correlated with expression of genes downstream of the innate immune response to bacteria and regulation of inflammation. Our results show no difference in the tissue microbiome of the foreskin with short-course antiretroviral use but that bacterial taxa were largely inversely correlated with inflammatory gene expression, consistent with commensal colonization.

A randomized clinical trial of on-demand oral pre-exposure prophylaxis does not modulate lymphoid/myeloid HIV target cell density in the foreskin

OBJECTIVES

As topical pre-exposure prophylaxis (PrEP) has been shown to cause immune modulation in rectal or cervical tissue, our aim was to examine the impact of oral PrEP on lymphoid and myeloid changes in the foreskin in response to dosing and timing of drug administration.

DESIGN

HIV-negative male individuals ( n  = 144) were recruited in South Africa and Uganda into an open-label randomized controlled trial in a 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 ratio to control arm (with no PrEP) or one of eight arms receiving emtricitabine-tenofovir disoproxil fumarate (F/TDF) or emtricitabine-tenofovir alafenamide (F/TAF) at one of two different doses, 5 or 21 h before undergoing voluntary medical male circumcision (VMMC).

METHODS

After dorsal-slit circumcision, foreskin tissue sections were embedded into Optimal Cutting Temperature media and analysed, blinded to trial allocation, to determine numbers of CD4 + CCR5 + , CD1a + cells and claudin-1 expression. Cell densities were correlated with tissue-bound drug metabolites and p24 production after ex-vivo foreskin challenge with HIV-1 bal .

RESULTS

There was no significant difference in CD4 + CCR5 + or CD1a + cell numbers in foreskins between treatment arms compared with the control arm. Claudin-1 expression was 34% higher ( P  = 0.003) in foreskin tissue from participants receiving PrEP relative to controls, but was no longer statistically significant after controlling for multiple comparisons. There was neither correlation of CD4 + CCR5 + , CD1a + cell numbers, or claudin-1 expression with tissue-bound drug metabolites, nor with p24 production after ex-vivo viral challenge.

CONCLUSION

Oral doses and timing of on-demand PrEP and in-situ drug metabolite levels in tissue have no effect on numbers or anatomical location of lymphoid or myeloid HIV target cells in foreskin tissue.