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

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 proapoptotic protein HIV-Nef persists in the blood of ART-treated patients within extracellular vesicles (EVs) and peripheral blood mononuclear cells. Here we demonstrate that HIV-Nef is present in cells and EVs isolated from BAL of patients on ART. We hypothesize that HIV-Nef persistence in the lung induces endothelial apoptosis leading to endothelial dysfunction and further pulmonary vascular pathologies. The presence of HIV-Nef in patients with HIV correlates with the surface expression of the proapoptotic 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 human embryonic kidney 293T cells, T cells, and human and mouse lung endothelial cells. HIV-Nef packages itself into EVs and increases the amount of EVs secreted from Nef-expressing T cells and Nef-transfected human embryonic kidney 293T cells. EVs from BAL of HIV+ 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 vascular endothelial–cadherin+ 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 via an EMAPII-dependent mechanism that is sufficient to cause pulmonary vascular pathologies even in the absence of inflammation

Cigarette Smoke-Induced Emphysema and Pulmonary Hypertension Can Be Prevented by Phosphodiesterase 4 and 5 Inhibition in Mice

<div><p>Rationale</p><p>Chronic obstructive pulmonary disease (COPD) is a widespread disease, with no curative therapies available. Recent findings suggest a key role of NO and sGC-cGMP signaling for the pathogenesis of the disease. Previous data suggest a downregulation/inactivation of the cGMP producing soluble guanylate cyclase, and sGC stimulation prevented cigarette smoke-induced emphysema and pulmonary hypertension (PH) in mice. We thus aimed to investigate if the inhibition of the cGMP degrading phosphodiesterase (PDE)5 has similar effects. Results were compared to the effects of a PDE 4 inhibitor (cAMP elevating) and a combination of both.</p><p>Methods</p><p>C57BL6/J mice were chronically exposed to cigarette smoke and in parallel either treated with Tadalafil (PDE5 inhibitor), Piclamilast (PDE4 inhibitor) or both. Functional measurements (lung compliance, hemodynamics) and structural investigations (alveolar and vascular morphometry) as well as the heart ratio were determined after 6 months of tobacco smoke exposure. In addition, the number of alveolar macrophages in the respective lungs was counted.</p><p>Results</p><p>Preventive treatment with Tadalafil, Piclamilast or a combination of both almost completely prevented the development of emphysema, the increase in lung compliance, tidal volume, structural remodeling of the lung vasculature, right ventricular systolic pressure, and right ventricular hypertrophy induced by cigarette smoke exposure. Single, but not combination treatment prevented or reduced smoke-induced increase in alveolar macrophages.</p><p>Conclusion</p><p>Cigarette smoke-induced emphysema and PH could be prevented by inhibition of the phosphodiesterases 4 and 5 in mice.</p></div

Systemic effects of smoke exposure and treatment with Piclamilast and/or Tadalafil in mice.

<p>Mice were exposed to cigarette smoke for 6 months and treated in parallel with Piclamilast (10 mg/kg body weight/day) and/or Tadalafil (10 mg/kg body weight/day). Time matched controls were received solvent only. Systemic arterial pressure determined by <i>A</i>. <i>carotis</i> catheterization and quantified in anesthetized animals. Data are given as mean ± SEM from n = 5–8, each. Bars indicate significant differences using ANOVA followed by Student-Newman-Keuls post hoc test (**<i>P</i><0.01; ***<i>P</i><0.001).</p

Effect of Piclamilast and/or Tadalafil on cigarette smoke-induced lung emphysema development assessed by structural parameters.

<p>Mice were exposed to cigarette smoke for 6 months and treated in parallel with Piclamilast (10 mg/kg body weight/day) and/or Tadalafil (10 mg/kg body weight/day). Time matched controls received solvent only. <b>(A)</b> Air space, <b>(B)</b> septal wall thickness and <b>(C)</b> mean linear intercept. <b>(D)</b> Representative histology from mice lung sections stained with hematoxylin and eosin. Data are given as mean ± SEM from n = 5–6, each. Bars indicate significant differences using ANOVA followed by Student-Newman-Keuls post hoc test (*<i>P</i><0.05;** <i>P</i><0.01; ***<i>P</i><0.001).</p

Effect of Piclamilast and/or Tadalafil on cigarette smoke-induced pulmonary hypertension in mice assessed by functional parameters.

<p>Mice were exposed to cigarette smoke for 6 months and treated in parallel with Piclamilast (10 mg/kg body weight/day) and/or Tadalafil (10 mg/kg body weight/day). Time matched controls received solvent only. <b>(A)</b> Right ventricular systolic pressure quantified by right heart catheterization in anesthetized animals. <b>(B)</b> Right heart hypertrophy, given as the ratio of right ventricular (RV) mass to left ventricular plus septum (LV+S) mass, from dried heart tissue; left ventricular weights did not differ between the different groups. Data are given as mean ± SEM from n = 5–8, each. Bars indicate significant differences using ANOVA followed by Student-Newman-Keuls post hoc test (**<i>P</i><0.01; ***<i>P</i><0.001).</p

Additional file 1: of Increased S100A4 expression in the vasculature of human COPD lungs and murine model of smoke-induced emphysema

Supplemental information about data collecion, material and methods. (PDF 567 kb