Mitochondrial DNA content in blood extracellular vesicles as a biomarker of neuronal mitochondrial DNA damage induced by cigarette smoking in virally suppressed, HIV-positive African Americans

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Project Summary/Abstract Antiretroviral therapy (ART) drastically reduces the incidence of opportunistic infections and improves life expectancy among HIV-infected individuals. HIV-associated neurocognitive disorders (HAND) related to the use of ART remain highly prevalent (15–50%). Meanwhile, the diagnosis of HAND is often challenging. Moreover, there are no validated surrogate markers and definitive adjunctive treatment for HAND. Since the prevalence of smoking is three- to four-fold higher among HIV-infected individuals than in the general population, and that HIV-infected African Americans (AAs) represent 42% of individuals living with HIV in the U.S., there is an urgent need to address the effect of smoking on neuronal dysfunction in AAs living with HIV. Mitochondrial dysfunction is a hallmark of various neurological disorders. Mitochondrial damage and mitochondrial DNA (mtDNA) content reduction often occur prior to neuronal degeneration. Our long-term goal is to develop a clinically applicable, non-invasive test to monitor the effects of cigarette smoking on neuronal mtDNA content in HIV-positive individuals. This test will allow clinicians to monitor changes in neuronal mtDNA content in HIV-infected cigarette smokers on ART in order to facilitate early medical intervention. Our overall objective is to determine the effect of cigarette smoking on mtDNA content in neuron-derived extracellular vesicles (NEVs) isolated from the peripheral blood of AAs, according to smoking and HIV status. Our central hypothesis is that cigarette smoking exacerbates neuronal mtDNA damage in virally suppressed HIV-positive AAs, leading to increased release of mtDNA in peripheral blood NEVs. Our rationale is that mtDNA content in NEVs is a novel and non-invasive biomarker for early detection of mtDNA damage in neurons. Our specific aims are: 1) To quantify mtDNA content in NEVs isolated from the peripheral blood of AA non-smokers, including virally suppressed HIV-positive and HIV-negative subjects; and 2) To compare the mtDNA content in NEVs isolated from the peripheral blood of virally suppressed HIV-positive AA smokers with the mtDNA content in NEVs isolated from virally suppressed HIV-positive non-smokers, as well as HIV-negative smokers and non-smokers. In Aim #1, we will measure mtDNA content in NEVs isolated from the peripheral blood of HIV-negative and HIV-positive non-smokers by real-time quantitative PCR (qPCR) using intravesicular DNA extracted from NEVs. In Aim #2, we will analyze quantitative changes in mtDNA content in NEVs that may reflect mtDNA damage associated with cigarette smoking and ART. Our proposal is innovative because it proposes using mtDNA content in peripheral blood NEVs as a novel surrogate biomarker for monitoring neuronal mtDNA damage. Our findings from this proposed study will be significant they will establish mtDNA content in NEVs as a novel, non-invasive biomarker for real-time monitoring of neuronal dysfunction associated with mtDNA damage in HIV-positive individuals on ART and cigarette smokers.