Pathways modulating memory-like properties in NK cells and their impact on HIV control

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Project Summary Natural Killer (NK) cells are part of the innate immune system and play an important role in controlling HIV infection. NK cells have been shown to control of SIV replication in the B cell follicles of African Green Monkeys and in the decrease in acquisition of SHIV in macaques in a vaccination study. Furthermore, studies presented at CROI2015 and AIDS2018 highlight the importance of NK cells controlling HIV infection in humans. These studies showed stronger NK responses in post-treatment controllers from the VISCONTI study. All these previous studies highlight the importance of harnessing NK cells to develop a protective HIV vaccine or a cure. Recently NK cells have been shown to have ‘adaptive’ or ‘memory-like’ properties. These properties include a quantitatively and qualitatively increased effector response upon restimulation; enhanced proliferation in response to low levels of IL-2 or IL-15; enhanced survival in vivo; and enhanced cytolytic response against different malignancies. In the context of HIV, pre-existing memory-like NK cells have been shown to control viremia during primary infection. To that end, understanding the signaling pathways and mechanisms promoting the generation of memory-like NK cells could lead to the development of therapeutic strategies to enhance HIV control mediated by memory-like NK cells both in the context of vaccine development and cure interventions. Our preliminary data supports the hypothesis that memory-like NK cells have an enhanced ability to control HIV infection relative to conventional NK cells. In Aim 1, we will define the signaling pathways that promote the generation of memory-like NK cells. Specifically, we will investigate the role of cytokines, antibodies and Toll-like receptor agonists inducing memory-like NK cells. One of the hallmarks of memory-like NK cells is the epigenetic remodeling of the IFN-γ locus characterized by reduced DNA methylation and enhanced IFN-γ upon restimulation. As such, we will investigate how DNA methylation as well as other epigenetic marks such as histone acetylation and histone methylation regulate the generation of memory-like NK cells. In Aim 2, we will further investigate the ability of memory-like NK cells to control HIV infection using both in vitro and in vivo models. We will expand our studies to include different viral strains and evaluate both natural cytotoxicity and antibody-dependent cellular toxicity. The ultimate goal of these research proposal will be to elucidate signaling pathways that lead to the enhancement of the generation of memory-like NK cells. If successful, we will provide preclinical data to develop interventions to enhance memory-like NK effector functions in the context of HIV vaccination and/or cure strategies.