Sakhatskyy Pavlo, Gabino Miranda Gustavo Andres, Newton Julie, Lee Chun Geun, Choudhary Gaurav, Vang Alexander, Rounds Sharon, Lu Qing
Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Department of Medicine, Alpert Medical School of Brown University, Providence, RI 02908, USA.
Pulmonary, Critical Care and Sleep Medicine, School of Medicine, Yale University, New Haven, CT 06520, USA.
Microvasc Res. 2014 Jul;94:80-9. doi: 10.1016/j.mvr.2014.05.003. Epub 2014 May 20.
Lung endothelial cell (EC) apoptosis has been implicated in the pathogenesis of emphysema. However, the mechanism underlying cigarette smoke (CS)-induced lung EC apoptosis and emphysema is not well defined. We have previously shown that cigarette smoke extract (CSE) decreased focal adhesion kinase (FAK) activity via oxidative stress in cultured lung EC. In this study, we compared FAK activation in the lungs of highly susceptible AKR mice and mildly susceptible C57BL/6 mice after exposure to CS for three weeks. We found that three weeks of CS exposure caused mild emphysema and increased lung EC apoptosis in AKR mice (room air: 12.8±5.6%; CS: 30.7±3.7%), but not in C57BL/6 mice (room air: 0±0%; CS: 3.5±1.7%). Correlated with increased lung EC apoptosis and early onset of emphysema, FAK activity was reduced in the lungs of AKR mice, but not of C57BL/6 mice. Additionally, inhibition of FAK caused lung EC apoptosis, whereas over-expression of FAK prevented CSE-induced lung EC apoptosis. These results suggest that FAK inhibition may contribute to CS-induced lung EC apoptosis and emphysema. Unfolded protein response (UPR) and autophagy have been shown to be activated by CS exposure in lung epithelial cells. In this study, we noted that CSE activated UPR and autophagy in cultured lung EC, as indicated by enhanced eIF2α phosphorylation and elevated levels of GRP78 and LC3B-II. However, eIF2α phosphorylation was significantly reduced by three-weeks of CS exposure in the lungs of AKR mice, but not of C57BL/6 mice. Markers for autophagy activation were not significantly altered in the lungs of either AKR or C57BL/6 mice. These results suggest that CS-induced impairment of eIF2α signaling may increase the susceptibility to lung EC apoptosis and emphysema. Taken together, our data suggest that inhibition of eIF2α and FAK signaling may play an important role in CS-induced lung EC apoptosis and emphysema.
肺内皮细胞（EC）凋亡与肺气肿的发病机制有关。然而，香烟烟雾（CS）诱导肺EC凋亡和肺气肿的潜在机制尚未完全明确。我们之前已经表明，香烟烟雾提取物（CSE）通过氧化应激降低了培养的肺EC中粘着斑激酶（FAK）的活性。在本研究中，我们比较了高度易感的AKR小鼠和轻度易感的C57BL/6小鼠在暴露于CS三周后的肺中FAK的激活情况。我们发现，暴露于CS三周导致AKR小鼠出现轻度肺气肿并增加肺EC凋亡（室内空气：12.8±5.6%；CS：30.7±3.7%），但C57BL/6小鼠未出现（室内空气：0±0%；CS：3.5±1.7%）。与肺EC凋亡增加和肺气肿早期发作相关，AKR小鼠肺中的FAK活性降低，但C57BL/6小鼠未降低。此外，抑制FAK导致肺EC凋亡，而FAK的过表达可预防CSE诱导的肺EC凋亡。这些结果表明，FAK抑制可能导致CS诱导的肺EC凋亡和肺气肿。未折叠蛋白反应（UPR）和自噬已被证明在肺上皮细胞中被CS暴露激活。在本研究中，我们注意到CSE激活了培养的肺EC中的UPR和自噬，这表现为eIF2α磷酸化增强以及GRP78和LC3B-II水平升高。然而，在AKR小鼠的肺中，暴露于CS三周后eIF2α磷酸化显著降低，但C57BL/6小鼠未降低。在AKR或C57BL/6小鼠的肺中，自噬激活标记物没有显著改变。这些结果表明，CS诱导的eIF2α信号传导受损可能增加对肺EC凋亡和肺气肿的易感性。综上所述，我们的数据表明，抑制eIF2α和FAK信号传导可能在CS诱导的肺EC凋亡和肺气肿中起重要作用。
