PROJECT SUMMARY In aging HIV-infected populations comorbid diseases are important determinants of morbidity and mortality. Lung diseases such as bacterial pneumonia, COPD and pulmonary hypertension are emerging as significant comorbidities in the people living with HIV. COPD continues to be an important comorbidity in HIV- infected patients even though anti-retroviral therapy has succeeded in restoring CD4 cell counts and decreasing infections by pneumocystis. HIV is an independent risk factor for COPD even when compensated for smoking status. Senescence associated proinflammatory cytokines play and important role in the chronic inflammation which is a hallmark of COPD. Impaired mitophagy leads to accumulation of depolarized defective mitochondria that demonstrates increased ROS production and release of Damage associated Molecular patterns (DAMPs) with a concomitant increase in senescence associated secretory phenotype (SASP) associated cytokines. Cigarette smoking is the primary means of nicotine addiction in people living with HIV. The pharmacologic effects of nicotine-mediated release of dopamine, glutamate and GABA cause nicotine dependence. A disproportionately high number of HIV infected people are addicted to nicotine and smoke tobacco compared to the general population in the United States. We show that HIV Tat and cigarette smoke mediate some of their effects via a common pathway involving TGF-? signaling. Tat and TGF-? alter the microRNAome of bronchial epithelial cells leading to suppression of some of the key genes involved in mitophagy and general macroautophagy. Taken together with our reports that HIV Tat and Cigarette smoke increase lung inflammation, this suggests that the altered microRNAome may manifest as the initiating event in HIV and CS associated COPD with increased severity of onset observed in HIV smokers. Hence neutralizing HIV tat and modulating TGF-? signaling in the airway can arrest or even reverse lung ?inflammaging? thereby preventing or slowing down the onset of clinical disease. Based on these observations, Aim 1 will determine the role of miRNAs involved in HIV Tat and cigarette smoke associated impaired mitophagy. Aim 2 will relate altered mitophagy and consequent senescence with increased secretion in SASP associated cytokines and DAMPs in primary small airway epithelial cells (SAECs) in vitro and in small animal lung-specific Tat transgenic models and donor lungs from HIV smokers/nonsmokers. Aim 3 will determine therapeutic approaches to rescue the effects of Tat and TGF-? to rescue mitophagy and consequently inhibit stress induced senescence and aberrant SASP cytokines and DAMPs. The proposal aims will address one of the major high priority areas identified for HIV research namely comorbidities in people living with HIV and substance abuse.