In vivo targeting of T cells to Enable an HIV Cure

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Abstract CHALLENGE: Autologous cytolytic T cell responses, while effective in killing HIV-infected cells, cannot clear tissue-residing HIV reservoirs. One hurdle for T cell mediated killing is their restriction to the peripheral blood and absence from secondary lymphoid tissue (SLT). Recent attempts by investigators in this application to trap cytolytic cells in the tissue using a tissue egress inhibitor, FTY720, proved ineffective. Although CD8+ T lymphocytes were retained, expanded, and activated in SLT, they were non-cytotoxic and did not impact viral rebound. From this, we conclude that tissue microenvironment features inhibit CD8+ T cell cytotoxicity and/or T cell intrinsic mechanisms prevent trafficking of cytotoxic cells to SLT. Either or both of these issues must be overcome to enable CD8+ T cell clearance of abundant tissue-residing viral reservoirs. APPROACH: In Project 2 we propose reciprocal and synergistic strategies to modulate cellular immune responses for reservoir clearance in SLT by applying a cutting-edge mRNA lipid nanoparticle (mRNA-LNP) technology. We have found that chemical modification of mRNA-LNPs with cytokines, like CX3CL1 and interleukin-7 (IL7), efficiently redirects mRNA to immune cell subsets that express those ligands’ cognate receptors, CX3CR1 and IL7-receptor (CD127). These approaches may permit transient mRNA delivery to cytolytic (CX3CR1+) and naive/memory subsets (CD127+), respectively. Here we propose to transiently reprogram cytotoxic immune cells to overcome viral escape within autologous T cell epitopes and SLT exclusion through mRNA delivery of an HIV-specific chimeric antigen receptor (CAR) and trafficking marker, respectively. Alternatively, we propose to apply IL7-mRNA-LNPs to reprogram CD127+ naïve and memory T cells, which at baseline express SLT trafficking markers, with mRNA encoding a CAR and a cytotoxicity associated transcription factor. Following in vitro optimization, these interventions will be tested for in vivo efficacy in pilot nonhuman primate experiments and the best candidate approach will then be applied in the setting of SHIV infection. INNOVATION: These complementary and non-overlapping approaches test two nonexclusive means of enhancing cytolytic immune control of primate lentiviruses and develop an immunotherapy platform with possible application to other tissue- residing pathogens. They have the potential to rapidly translate fundamental observations of T cell immunology to in vivo testing of interventions using the clinically approved mRNA-LNP platform. Finally, they test whether known barriers to T cell-mediated control of HIV infection can be overcome, which may prove important in the development of an HIV cure.