Molecular Pathways of Innate Immunity and Substance Abuse in NeuroHIV

PROJECT SUMMARY A significant percentage of people living with HIV/AIDS (PLWH) 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 PLWH. HAND and neuroinflammation are exacerbated by Methamphetamine (Meth) abuse. PLWH abusing Meth present a high prevalence of chronic neuroinflammation and the cellular mechanism(s) that drive such inflammation have not been entirely defined. Certain models of neuroinflammation define inter-cellular cytokine signaling as a major player in neuroinflammation. These models propose that activation of microglia results in the production of inflammatory cytokines and metabolites 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 and astrocytes in the context of NeuroHIV and Meth, and characterize the cellular crosstalk between HIV infected and non-infected brain cells under physiological concentrations of cART. Our preliminary data from gene expression and microscopy of innate sensing immune complexes points to an activation of the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway in microglia with Meth and HIV infection. Thus, we hypothesize that HIV-triggered activation of the cGAS/STING pathway leads to episodes of chronic neuroinflamation. We also hypothesize that Meth-mediated DNA damage is additive to the activation of the inflammation pathway. In the R61 phase, we aim to determine the impact of HIV post-entry events and Meth-mediated DNA damage on innate immune sensing of glial cells. During the R33 phase, we will characterize the biological consequences of HIV/Meth-mediated innate sensing to brain organoids under brain physiologic cART concentrations. We aim to assess the potential of cGAS/STING antagonists to reduce neuroinflammation in the context of HIV/Meth. We will carry out an experimental plan using functional assays, cyclic multiplex immunofluorescence and super-resolution fluorescence imaging, machine learning analysis, next-generation sequencing, and multiplexed cytokine profiling in iPSC-derived microglia, astrocytes, cerebral brain organoids and a chimeric human/mouse animal model. These studies will define the activation of HIV/Meth-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 by HIV and Meth under cART that culminate in HAND. Knowledge gained from this research plan can inform therapeutic potential to ameliorate and/or reduce HAND in PLWH.