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Idiopathic pulmonary arterial hypertension (PAH) is characterized by proliferation of pulmonary vascular endothelial and smooth muscle cells causing increased vascular resistance and right heart failure. Mutations in the bone morphogenetic protein receptor type 2 (BMPR2) are believed to cause the familial form of the disease. Reduced expression of BMPR2 is also noted in secondary PAH. Recent advances in the therapy of PAH have improved quality of life and survival, but many patients continue to do poorly. The possibility of treating PAH via improving BMPR2 signaling is thus a rational consideration. Such an approach could be synergistic with or additive to current treatments. We developed adenoviral vectors containing the BMPR2 gene. Transfection of cells in vitro resulted in upregulation of SMAD signaling and reduced cell proliferation. Targeted delivery of vector to the pulmonary vascular endothelium of rats substantially reduced the pulmonary hypertensive response to chronic hypoxia, as reflected by reductions in pulmonary artery and right ventricular pressures, fight ventricular hypertrophy, and muscularization of distal pulmonary arterioles. These data provide further evidence for a role for BMPR2 in PAH and provide a rationale for the development of therapies aimed at improving BMPR2 signaling. hypoxia; growth substances; endothelium doi:10.1152/ajplung.00020.2006

Background and objective: E‐cigarettes are often marketed and thought of as emitting harmless vapour; however, verification of their safety for non‐smokers is scarce. We have previously shown that E‐cigarettes cause decreased phagocytosis of bacteria by macrophages via reductions in surface bacterial recognition receptors. This study assessed the effect of E‐cigarette constituents, 3 E‐liquid apple flavours, nicotine, vegetable glycerine and propylene glycol, on bronchial epithelial cell viability, apoptosis and cytokine secretion and macrophage phagocytosis of apoptotic airway cells and phagocytic recognition molecules. Methods: Cell necrosis and apoptosis were measured by Sytox Green stain and Annexin V. Efferocytosis was measured by internalization of pHrodo Green labelled apoptotic airway cells by macrophages. Expression of macrophage cell surface apoptotic cell receptors was measured by flow cytometry. Cytokine release by E‐cigarette‐exposed airway cells was measured by cytokine bead array. Results: E‐cigarette vapour increased primary bronchial epithelial necrosis and apoptosis. E‐cigarette vapour reduced efferocytosis (lowest flavour 12.1%) versus control (20.2%, P = 0.032). The efferocytosis receptor CD44 was reduced by one flavour (MFI 1863 vs 2332 control, P = 0.016) and all components reduced expression of CD36, including the glycol bases (MFI 1067–12 274 vs 1415 control). Reduced secretion of TNF‐α, IL‐6, IP‐10, MIP‐1α and MIP‐1β was observed for all flavour variants. Conclusion: E‐cigarettes can cause bronchial epithelial apoptosis and macrophage efferocytosis dysfunction via reduced expression of apoptotic cell recognition receptors. These data further show that E‐cigarettes should not be considered harmless to non‐smokers and their effects may go far beyond cytotoxicity to cells. [ABSTRACT FROM AUTHOR]

Our previous studies have shown that nutritional zinc restriction exacerbates airway inflammation accompanied by an increase in caspase-3 activation and an accumulation of apoptotic epithelial cells in the bronchioles of the mice. Normally, apoptotic cells are rapidly cleared by macrophage efferocytosis, limiting any secondary necrosis and inflammation. We therefore hypothesized that zinc deficiency is not only pro-apoptotic but also impairs macrophage efferocytosis. Impaired efferocytic clearance of apoptotic epithelial cells by alveolar macrophages occurs in chronic obstructive pulmonary disease (COPD), cigarette-smoking and other lung inflammatory diseases. We now show that zinc is a factor in impaired macrophage efferocytosis in COPD. Concentrations of zinc were significantly reduced in the supernatant of bronchoalveolar lavage fluid of patients with COPD who were current smokers, compared to healthy controls, smokers or COPD patients not actively smoking. Lavage zinc was positively correlated with AM efferocytosis and there was decreased efferocytosis in macrophages depleted of Zn in vitro by treatment with the membrane-permeable zinc chelator TPEN. Organ and cell Zn homeostasis are mediated by two families of membrane ZIP and ZnT proteins. Macrophages of mice null for ZIP1 had significantly lower intracellular zinc and efferocytosis capability, suggesting ZIP1 may play an important role. We investigated further using the human THP-1 derived macrophage cell line, with and without zinc chelation by TPEN to mimic zinc deficiency. There was no change in ZIP1 mRNA levels by TPEN but a significant 3-fold increase in expression of another influx transporter ZIP2, consistent with a role for ZIP2 in maintaining macrophage Zn levels. Both ZIP1 and ZIP2 proteins were localized to the plasma membrane and cytoplasm in normal human lung alveolar macrophages. We propose that zinc homeostasis in macrophages involves the coordinated action of ZIP1 and ZIP2 transporters responding differently to zinc deficiency signals and that these play important roles in macrophage efferocytosis. [ABSTRACT FROM AUTHOR]