PROJECT ABSTRACT People living with HIV-1 (PLWH) on long-term antiretroviral therapy (ART) still present with cognitive and behavioral deficits and the prevalence of HIV-1 associated neurocognitive disorders (HANDs) is 30%-50%. The mechanisms underlying HIV-induced central nervous system (CNS) dysfunction in these patients are complex and challenging to study using current methods. In this proposal, we will investigate modifiable mechanistic pathways of neurocognitive impairment in PLWH using personalized, physiologically relevant, participant- derived cell models. In recent years, the ability to generate directly induced neurons (iNs) from patient-derived fibroblasts has been demonstrated. Unlike the immature neuronal populations generated from induced pluripotent stem cells (iPSCs), iNs retain neuron-specific, aging-associated gene-expression characteristics of the donor. As a result, these iNs represent a major technological advance. Our preliminary data demonstrates our ability to generate iNs from the skin biopsies of PLWH. To our knowledge, this makes us the first group to apply this technology to study of neuronal health in HIV-1. We now propose to use these tools to determine if differences in gene expression reflective of neurocognitive impairment are evident through the transcriptional phenotyping of iNs derived from age, sex and race-matched cohorts of PLWH enriched for individuals > 60 years of age. Functional analyses of the iNs will test hypothesized pathomechanisms of neuronal dysfunction. We will investigate our hypotheses in two specific aims. In AIM 1, we will generate patient-derived iNs from clinically well-characterized participants. We will generate iNs as per Mertens et al. (Cell Stem Cell, 2015) from the skin biopsies of 3 clinically well-defined cohorts with low comorbid conditions stratified by degree of neurocognitive impairment (NCI) as determined by comprehensive neuropsychological examination and HIV-1. In AIM 2, we will determine neuronal-associated gene-expression pathways modulated by neurocognitive impairment and HIV-1 status through transcriptional profiling of iNs from well-defined clinical cohorts. Differential gene expression analysis will be performed across cohorts in attempts to determine, neurocognitive (normal vs. impaired), and HIV-1 (positive vs. negative) effects on gene transcription. In vitro experiments will test the hypothesis that impairments in nucleocytoplasmic compartmentalization and apoptosis in derived iNs positively correlate with the degree of donor NCI. Our novel application of this iNs technology to the translational study of PLWH allows us the opportunity to fill a gap in our understanding of neuronal dysfunction in HIV-1 and identify therapeutic targets for improved cognition.