HIV Tat and Opiate-mediated aberrations in glial-neuronal crosstalk: Implications for the role of extracellular RNA in HAND - Project Summary: Currently, there are over 40 million people living with HIV-1 worldwide. Although combination antiretroviral therapy (cART) has improved the health and lifespan of millions of those living with HIV-1, long-term use of antiretrovirals coupled with limited penetration of some of these medications into the CNS, is often accompanied with neurocognitive impairments in at least 50% of infected individuals, commonly referred to as NeuroHIV. Additionally, while cART can successfully suppress peripheral viremia, persistence of cytotoxicity viral protein such as Transactivator of transcription (Tat) in tissues such as the brain, remains a significant concern. Adding further complexity is the co-morbidity of drug use disorder in those infected with HIV-1, especially that of opiates. While the direct combined effects of HIV Tat and Opiates involving astrocytic cytokines and chemokines on neuronal injury are well studied, how morphine exacerbates aberrant glial-neuronal responses to Tat & HIV-1, involving shuttling of microRNAs and reprogramming the neurons to a synaptically injured phenotype in is an unmet need in the field and warrants investigation. Our preliminary findings suggest in human primary astrocytes/ A172 cells exposure to HIV Tat mediated the induction and release of miRNA-7 and exposure to morphine mediated the upregulation and release of miR-23a in extracellular vesicles (EVs). Furthermore, neuronal uptake of Tat and Morphine stimulated astrocyte EVs (containing miR-7 and 23a) resulted in exacerbated synaptic injury compared to uptake by EVs with individual miR. These findings are backed by strong in vivo data demonstrating morphine-mediated potentiation of synaptodegeneration induced by HIV Tat and also, reversal of synatic injury by anti-miR. Taken together, the scientific hypothesis of this proposal is that HIV Tat/HIV-1 & morphine co- operate to mediate exacerbated synaptic alterations involving: a) HIV Tat/ HIV-1-mediated release of astrocytic EV miR-7 that downregulates its targets (NLGN2, GRIN2A, PBX3), & b) Morphine-mediated release of astrocytic EV miR-23a downregulates its targets (NRGN, PCLO, NLGN1), in neurons. We will test the efficacy of engineered, astrocyte specific AAVs expressing short hairpin RNA for -miR7 & -23a to restore HIV-1 Tat & morphine-mediated synaptic impairments in two complementary in vivo rodent models of NeuroHIV: a) Inducible brain Tat transgenic & b) infectious humanized mice administered opiates along with validation in archival macaque brain tissues. These studies will make a significant contribution to our understanding of glial-neuronal crosstalk, and the role of miRNAs in HIV and opiate-mediated synaptic neurodegeneration and will set a stage for a future development of RNA therapeutics for these comorbid conditions.
