HIV-Nef Protein Persists in the Lungs of Aviremic HIV Patients and Induces Endothelial Cell Death

Science and Research

It remains a mystery why HIV-associated end-organ pathologies persist in the era of combined antiretroviral therapy (ART). One possible mechanism is the continued production of HIV encoded proteins in latently HIV-infected T cells and macrophages. The pro-apoptotic protein HIV-Nef persists in the blood of ART treated patients within extracellular vesicles (EV) and PBMC. Here we demonstrate that HIV-Nef is present in cells and extracellular vesicles (EV) isolated from bronchoalveolar lavage (BAL) of patients on ART. We hypothesize that HIV-Nef persistence in lung induces endothelial apoptosis leading to endothelial dysfunction and further pulmonary vascular pathologies. HIV-Nef presence in HIV patients correlates with the surface expression of the pro-apoptotic Endothelial-Monocyte Activating Polypeptide II (EMAPII), which was implicated in progression of pulmonary emphysema via mechanisms involving endothelial cell death. HIV-Nef protein induces EMAPII surface expression in HEK293T, T cells, and human and mouse lung endothelial cells. HIV-Nef packages itself into EV and increases the amount of EV secreted from Nef-expressing T cells and Nef-transfected HEK293T cells. EV from BAL of HIV-positive patients and Nef-transfected cells induce apoptosis in lung microvascular endothelial cells by upregulating EMAPII surface expression in a PAK2-dependent fashion. Transgenic expression of HIV-Nef in VE-Cadherin-positive endothelial cells leads to lung rarefaction, characterized by reduced alveoli and overall increase in lung inspiratory capacity. These changes occur concomitantly with lung endothelial cell apoptosis. Together, these data suggest that HIV-Nef induces endothelial cell apoptosis using an EMAPII dependent mechanism that is sufficient to cause pulmonary vascular pathologies even in the absence of inflammation.