HIV-Resistant and HIV-Specific CAR-Modified CD4+ T Cells Mitigate HIV Disease Progression and Confer CD4+ T Cell Help In Vivo

Abstract

HIV infection preferentially depletes HIV-specific CD4⁺ T cells, thereby impairing antiviral immunity. In this study, we explored the therapeutic utility of adoptively transferred CD4⁺ T cells expressing an HIV-specific chimeric antigen receptor (CAR₄) to restore CD4⁺ T cell function to the global HIV-specific immune response. We demonstrated that CAR₄ T cells directly suppressed in vitro HIV replication and eliminated virus-infected cells. Notably, CAR₄ T cells containing intracellular domains (ICDs) derived from the CD28 receptor family (ICOS and CD28) exhibited superior effector functions compared to the tumor necrosis factor receptor (TNFR) family ICDs (CD27, OX40, and 4-1BB). However, despite demonstrating limited in vitro efficacy, only HIV-resistant CAR₄ T cells expressing the 4-1BBζ ICD exhibited profound expansion, concomitant with reduced rebound viremia after antiretroviral therapy (ART) cessation and protection of CD4⁺ T cells (CAR^-) from HIV-induced depletion in humanized mice. Moreover, CAR₄ T cells enhanced the in vivo persistence and efficacy of HIV-specific CAR-modified CD8⁺ T cells expressing the CD28ζ ICD, which alone exhibited poor survival. Collectively, these studies demonstrate that HIV-resistant CAR₄ T cells can directly control HIV replication and augment the virus-specific CD8⁺ T cell response, highlighting the therapeutic potential of engineered CD4⁺ T cells to engender a functional HIV cure.

Keywords: C34-CXCR4; IL-2; IL-21; T cell help; TIGIT; chimeric antigen receptor; costimulation; in vivo model of HIVPD-1.