Abstract 17308: Effect of HIV Protein-Tat & Cocaine on Hippo-YAP Signaling Axis in Pulmonary Arterial Smooth Muscle Cells

Introduction and hypothesis: Intravenous drug use (IVDU) is considered to be one of the important risk factors in the development of HIV-associated pulmonary arterial hypertension (HPAH). Our previous findings demonstrate that the exposure of cocaine to HIV infected individuals has an additive effect in enhancing the proliferation of pulmonary smooth muscle cells, thus further amplifying the development of pulmonary arteriopathy. Furthermore, various studies suggest the failure of Hippo pathway and increased YAP/TAZ activity in pulmonary hypertension (PH). Based on this, we hypothesized that YAP axis might be having a role in HIV and cocaine mediated smooth muscle hyperplasia. Methods: Primary human pulmonary arterial smooth muscle cells (HPASMCs) were grown and treated with cocaine hydrochloride (1μM) and/or HIV-Tat protein (25ng/mL) for 6h. In addition, primary HPASMC were treated for 24h with extracellular vesicles (EVs) transfected with miR-130a antagomir or scrambled miR followed by treatment of EVs isolated from supernatants of monocyte derived macrophage infected with HIV-Bal (5ng/ml) in the presence or absence of cocaine for 4 days. The expression of Hippo proteins was determined using western blot. Results: Combined treatment of HPASMCs with HIV-Tat and cocaine for 6h showed no change in the expression of MST proteins, however reduced expression of phosphorylated LATS1 relative to total LATS1 was observed. This correlated with the decline in the phosphorylated YAP to total YAP ratio. Pre-treatment of HPASMCs with YAP/TAZ inhibitor attenuated the HIV-Tat and cocaine mediated augmentation of cell proliferation. Furthermore, our recent findings demonstrate that EVs derived from HIV infected and cocaine treated MDMs (H+C EVs) when added to HPASMC result in increased proliferation on transfer of miR-130a. We now found that this H+C EVs mediated hyper-proliferation of smooth muscle cells is associated with the increased levels of total YAP protein. In addition, H+C EVs mediated increase in total YAP was prevented on the pretreatment of HPASMCs with EVs carrying anti-miR-130a. Conclusion: In conclusion, our preliminary findings suggest increased activation of Hippo-YAP signaling in pulmonary smooth muscle cells on the direct treatment with HIV protein and cocaine and also on exposure to EVs derived from HIV infected and cocaine treated macrophages.