Identification of Aryl Hydrocarbon Receptor as a Barrier to HIV-1 Infection and Outgrowth in CD4+T-Cells

ABSTRACT The Aryl hydrocarbon receptor (AhR) identifies “ non-pathogenic ” Th17-polarized CD4 + T-cells in autoimmune models. Thus, we explored whether AhR restricts HIV-1 in Th17-cells, consistent with its antiviral role in macrophages. AhR-specific CRISPR/Cas9-mediated knockout and pharmacological blockade decreased AhR target gene expression (CYP1A1/IL-22/IL-17A/IL-10/ ITGB7), while increasing HIV-1 replication in CD4 + T-cells. Pharmacological AhR activation caused opposite effects. AhR agonism/antagonism modulated HIV-1 replication mainly in Th17/Th22-polarized CCR6 + CD4 + T-cells. Single-round VSV-G-pseudotyped HIV-1 infection demonstrated that AhR acts at post-entry levels, with AhR blockade increasing the efficacy of early/late reverse transcription steps and subsequently integration/translation. In viral outgrowth assay, the AhR blockade boosted the detection of replication-competent viral reservoirs in CD4 + T-cells of people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Finally, RNA-Sequencing revealed genes/pathways modulated by AhR blockade in CD4 + T-cells of ART-treated PLWH, with known HIV-1 interactor activities (NCBI HIV Interactor Database) and AhR responsive elements in their promoters (ENCODE). Among them, HIC1, a repressor of Tat-mediated HIV-1 transcription and a tissue-residency inducer, represents a putative AhR mechanism of action. These results demonstrate that AhR governs an antiviral transcriptional program in CD4 + T-cells and point to the use of AhR inhibitors to boost viral outgrowth in “ shock and kill ” HIV-1 remission/cure strategies. Model of AhR-mediated transcriptional reprogramming with implications for “ silent ” HIV-1 reservoir persistence and gut homing/residency. RNA-Sequencing revealed genes sets modulated by AhR blockade in CD4 + T-cells of ART-treated PLWH, with known HIV-1 interactor activities (NCBI HIV Interactor Database) and AhR responsive elements in their promoters (ENCODE). Among them, HIC1, a repressor of Tat-mediated HIV-1 transcription and a tissue-residency regulator, represents a putative AhR mechanism of action. These results support a model in which AhR activation favors the gut homing and residency via the induction of ITGB7 and CXCR6 expression, respectively, and fuels the persistence of ‘ silent ” HIV-1 reservoirs in CD4 + T-cells of ART-treated PLWH. At the opposite, pharmacological AhR blockade facilitates viral outgrowth, and by interfering with tissue residency, likely promotes the mobilization of « reactivated » reservoir cells from deep tissues into the circulations. BRIEF SUMMARY We identified the aryl hydrocarbon receptor as a barrier to HIV-1 infection/outgrowth in Th17-polarized CD4 + T-cells and a novel therapeutic target in HIV-1 cure/remission interventions.