The goal of this proposal is to understand cellular stress responses in HIV infection, and their relationship to circulating exosome cargo. In preliminary studies using samples and clinical data from cohorts of predominantly male African-American subjects with HIV infection, cocaine use was associated with increased markers of inflammation, oxidative stress, mitochondrial dysfunction, and altered monoamine metabolism. Plasma exosomes and exosome-associated HSP70 were also increased in HIV+ cocaine users compared to HIV- controls. Furthermore, we identified plasma exosome miRNAs in HIV+ cocaine users that were also induced during cell stress responses in cell culture models. Based on preliminary data and predicted network models, we hypothesize that HIV infection induces cellular stress responses as a consequence of inflammation, oxidative stress, mitochondrial dysfunction, and altered monoamine metabolism. Cocaine augments these cellular stress responses through effects on catecholamines and dopamine, which increase energy demands, mitochondrial dysfunction, and oxidative stress. Transcriptional and epigenetic regulators including REST, PGC-1alpha, and sirtuins are predicted to play key roles in regulating these cellular stress response networks and modulating cocaine-related effects on cells. Exosomes and other microvesicles released during cell stress responses contain protein and RNA cargo that represent potential biomarkers of these stress responses. To address this hypothesis, we propose integrated biology approaches using clinical samples and data to characterize exosomes and cellular stress responses in racially diverse cohorts of HIV+ subjects with and without cocaine use, and their relationship to clinical data. Integrative analysis of plasma exosome cargo, gene and miRNA expression profiles, inflammation and oxidative stress markers, metabolomics, and virological and immunological data along with targeted experimentation will be used to build, test, and refine models of networks and pathways involved in mediating cellular stress responses in HIV infection and their relationship to exosome cargo.