Role Of Innate Immunity to NeuroHIV in the cART Era

PROJECT SUMMARY A significant percentage of people living with HIV/AIDS (PLWHA) exhibit HIV associated neurocognitive disorders (HAND). With the development and improvement of combination antiretroviral therapies (cART) there was a substantial decrease of the death and morbidity rates of PLWHA. Despite the cART progress, PLWHA still present a high prevalence as chronic neuroinflammation, where the cellular mechanism(s) that drive such inflammation have not been entirely defined. Certain models of neuroinflammation define inter-cellular cytokine signalling as a major player in neuroinflammation. These models propose that activation of microglia results in the production of inflammatory cytokines and metabolites (e.g. IL-1α, TNFα, IL-6, C1q) that are recognized by astrocytes, leading to a modification from non-reactive astrocytes to a range of pro-inflammatory or repair phenotypes. In this proposal we aim to identify the molecular mechanisms that trigger the activation of intracellular innate immunity in microglia, as well to characterize the cellular crosstalk between HIV infected and non-infected cells in the brain under physiological concentrations of cART. Our preliminary data from gene expression and viral interaction with innate sensing immune complexes points to an activation of the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway in microglia under cART. Thus, we hypothesize that the activation of the cGAS/STING pathway leads to episodes of chronic neuroinflamation in the context of HIV and cART therapy . We will determine the impact of cART on HIV cytoplasmic trafficking and the activation of innate immune sensing. We will characterize the biologic consequences to HIV-mediated innate sensing in astrocytes and neurons under brain physiologic cART concentrations. We will carry out an experimental plan to characterize the impact of activation of the cGAS/STING in the brain with funcional assays, cyclic multiplex immunofluorescence and super-resolution fluorescence imaging, machine learning analysis, single cell and bulk RNAseq, and multiplexed cytokine profiling in iPSC-derived microglia and cerebral brain organoids. These studies will define the activation of HIV mediated innate immunity in cells from the brain that are known to be infected by HIV and the impact of this activation in the disruption of normal brain homeostasis by inflammatory processes. At the heart of this proposal is the clarification and identification of the mechanism(s) that drive and/or contribute to persistent neuroinflammation under cART that culminate in HAND. Knowledge gained from this research plan can inform therapeutic potential to ameliorate and/or reduce HAND in PLWHA.