Opioid-abusing individuals are in the top three risk-factor groups for Human Immunodeficiency Virus (HIV) infection. In fact, almost 30% of HIV-infected individuals in the USA are reported to abuse opioids, highlighting the intersection of drugs of abuse with HIV/AIDS. Opioid-abusers are cognitively impaired and suffer from neurological dysfunctions that may lead to high-risk sexual behavior, poor adherence to antiretroviral regimens and promote onset of co-morbid conditions such as hepatitis-C virus infection. Collectively, these circumstances accelerate HIV disease progression. Inflammation and oxidative stress are some of the well- characterized reactions induced by these pathologic (HIV) and biochemical (opioids) insults to the central nervous system (CNS). However, there is a newly recognized paradigm through which cells and organisms adapt to such environmental stimuli. This recently identified genomic adaptive mechanism involves dynamic changes in the genome reflected in altered transcription and translation. Such genomic adaptation involves RNA interference (RNAi) and is mediated by microRNA (miRNA). Our recent study corroborates the notion of genomic adaptation, as alterations in miRNA expression were correlated with morphine treatment. When human monocyte-derived macrophages (h-mdms) were treated with morphine, differential expression of 26 miRNAs (p<0.01) was induced. A direct correlation was observed between miRNA, hsa-miR15b (strongest induction) and suppression of its target gene expression fibroblast growth factor-2 (FGF-2). As well, computational modeling predicted several inflammatory and T-cell activation pathway targets for hsa-miR-181b (strongest suppression). Interestingly, our ongoing studies with human fetal CNS cells suggest that morphine and HIV induce comparable but not additive inflammation and oxidative stress. Hence, we hypothesize that differential miRNA expression is a form of genomic adaptation to HIV infection and opioid exposure. This hypothesis makes two testable predictions (a) alterations in miRNA expression levels are the result of the pathological (HIV) or biochemical (opioids) insult and (b) the extent of the adaptive response reflects on the disease outcome. To test this hypothesis, in the first specific aim we will perform miRNA microarray analyses to characterize miRNA expression profiles in human fetal brain derived cultures of microglia, astrocytes, oligodendrocytes, endothelial cells, and neurons infected with HIV and/or treated with morphine. We will then computationally predict gene targets and biochemical pathways in which these miRNAs may function. To complement these studies, we will analyze the miRNA-mediated genomic adaptive response in brain autopsy tissues from HIV patients with or without opioid-abuse disorder. The second specific aim will assess the biological consequences of miRNA-mediated genomic adaptation in response to specific miRNA precursors or inhibitors. Results from these studies will increase our understanding of genomic adaptation to HIV infection in opioid abusers and determine the predictive value of miRNA in HIV disease outcome in opioid-abusers. PUBLIC HEALTH RELEVANCE: The two public health concerns, HIV epidemic and opioid-abuse have a substantial overlap. This grant application seeks to understand the molecular mechanisms of the genomic adaptive responses. Knowledge thus gained will help us to advance towards our long-term objective to develop RNA interference based therapies to treat HIV infection and counteract the deleterious effects of opioid-abuse.