The BCL-2 pro-survival protein has been implicated in HIV persistence, and we have previously demonstrated that the clinically used BCL-2 inhibitor Venetoclax augments HIV induced killing of the reactivating cell, in vitro. It is unknown whether Venetoclax impacts HIV dynamics in vivo. We hypothesized that Venetoclax would reduce HIV replication in a murine model of HIV, and increase clearance of HIV infected cells by cytotoxic T Cells.
Primary CD4 T-Cells isolated from HIV infected, ART suppressed, donors were infected in vitro with HIV IIIB, subsequently treated with the BCL2-specific inhibitor Venetoclax, and co-cultured with HIV Pepmix expanded, CD8 T Cells, in the presence of ART. The CD8-negative target cells were analyzed by flow cytometry to measure cell death by Live/Dead staining and intracellular p24 expression. Supernatant p24 was measured by ELISA to estimate viral production. Using NOD/Shi-scid/IL-2R?null immunodeficient (NCG) mice, humanized using CD34+ cells isolated from human cord blood, we treated HIV infected CD34 + cell humanized mice with or without Venetoclax and assessed viral dynamics in the absence of ART, measured by HIV RNA PCR.
Treatment of acutely HIV-infected CD4 T-Cells with the BCL-2 inhibitor Venetoclax significantly increased susceptibility to Cytotoxic T lymphocyte killing at E:T ratios of 1:2 and 1:5 (p <0.05), accompanied by significant reductions in levels of supernatant p24 (p <0.05). Within our in-vivo mouse model, BCL-2 inhibition resulted in significant, log fold decreases in HIV RNA with Venetoclax (p = 0.002), accompanied by significant decreases in CD4 cells (p <0.0001) compared to control.
Taken together, these findings suggest that Venetoclax augments host immune function against HIV, in the setting of active HIV infection, both in an in-vitro and in-vivo setting. These findings represent a significant step forward in our understanding of the clinical applicability and feasibility of BCL-2 inhibition for HIV therapy.