Summary The abuse of opioid drugs is associated with treatment non-compliance, greater risk of viral transmission, and more rapid clinical progression of HIV disease. The overarching hypothesis behind the present project is that the analysis of molecular profiles of neuronal and glia cells at the single cell level in drug abuse-relevant brain regions by single nucleus RNA-Seq (snRNA-Seq) will reveal key genes that are dysregulated by the interaction of HIV with opioid abuse, resulting in neurodegeneration and cognitive impairment. To test the present hypothesis, we propose to use validated systems biology strategies for the reconstruction and interrogation of a genome-scale integrated gene regulatory network in conjunction with snRNA-Seq from HIV transgenic (Tg) rats, which harbor a non-replicating HIV-1 transgene expressing chronic low-levels of multiple HIV-1 proteins in disease-relevant cell types, and wild-type rats. The occasional but limited use of a drug is clinically distinct from dependent drug use, which is characterized by the emergence of dependence and a negative emotional state when access to the drug is prevented that drives negative reinforcement, a powerful source of motivation for drug seeking. Therefore, we will use a state-of-the-art paradigm of voluntary intravenous opioid self-administration under short access (ShA) conditions, which is characterized by a non-dependent, “recreational” pattern of drug use, and long access (LgA) conditions, which leads to dependent drug intake. Escalated drug intake under LgA conditions is highly relevant to human substance use disorder (SUD) as it has been suggested that it models all 7 of the criteria for drug addiction in the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV and 7 of the 11 criteria in the DSM-V. We showed that HIV Tg rats self-administering oxycodone in this LgA paradigm of escalated self-administration display increased neural injury and cognitive impairment. The project will address the following vexing question about opioid abuse in the setting of HIV infection: what are the cell types and cell states that drive neuroinflammation, neurodegeneration, virus expression, and escalated (dependent) opioid self-administration and cognitive impairment in the setting of HIV? Overall, this collaborative interdisciplinary proposal integrating single cell level transcriptomics, state-of-the- art behavior methods in HIV Tg and wild-type rats, and computational strategies for the deconvolution of the gene regulatory network at the single cell level will elucidate key mechanisms that underlie the effects of HIV and opioid abuse and their detrimental interactions on neuroHIV progression, virus expression and persistence. The results will indicate transformative new mechanistic hypotheses that may lead to novel therapeutic concepts for opioid use disorder (OUD) in the setting of HIV and will establish key resources for the neuroHIV field to be made publicly available through the SCORCH data coordination center and other public repositories.

Public Health Relevance Opioid abuse in HIV-infected individuals is associated with treatment non-compliance, greater risk of viral transmission, and more rapid disease progression. To investigate the molecular mechanisms behind the interactions of HIV and opioid use disorder (OUD), this interdisciplinary project will profile gene expression at the single cell level in key brain regions relevant to the effects of persistent HIV infection and OUD in a small animal model of neuroHIV in a behavioral paradigm of voluntary intravenous drug self-administration. We will bring to bear computational methods to elucidate the key genes driving the altered gene expression at the single cell level, which will provide a framework for new testable hypotheses on the mechanisms underlying the neuropathogenesis of the neuronal damage and neuroinflammation in the context of OUD in HIV infection that can reveal new pathogenic concepts and more effective therapeutic targets to improve neuropsychological functioning in people with HIV and OUD comorbidity.