Chen Qing, de Vries Maaike, Nwozor Kingsley Okechukwu, Noordhoek Jacobien A, Brandsma Corry-Anke, Boezen H Marike, Heijink Irene H
Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Front Physiol. 2021 Jun 7;12:690936. doi: 10.3389/fphys.2021.690936. eCollection 2021.
Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung disease characterized by chronic inflammation upon inhalation of noxious particles, e.g., cigarette smoke. FAM13A is one of the genes often found to be associated with COPD, however its function in the pathophysiology of COPD is incompletely understood. We studied its role in airway epithelial barrier integrity and cigarette smoke-induced epithelial responses.
Protein level and localization of FAM13A was assessed with immunohistochemistry in lung tissue from COPD patients and non-COPD controls. , FAM13A expression was determined in the absence or presence of cigarette smoke extract (CSE) in primary airway epithelial cells (AECs) from COPD patients and controls by western blotting. FAM13A was overexpressed in cell line 16HBE14o- and its effect on barrier function was monitored real-time by electrical resistance. Expression of junctional protein E-cadherin and β-catenin was assessed by western blotting. The secretion of neutrophil attractant CXCL8 upon CSE exposure was measured by ELISA.
FAM13A was strongly expressed in airway epithelium, but significantly weaker in airways of COPD patients compared to non-COPD controls. In COPD-derived AECs, but not those of controls, FAM13A was significantly downregulated by CSE. 16HBE14o- cells overexpressing FAM13A built up epithelial resistance significantly more rapidly, which was accompanied by higher E-cadherin expression and reduced CSE-induced CXCL8 levels.
Our data indicate that the expression of FAM13A is lower in airway epithelium of COPD patients compared to non-COPD controls. In addition, cigarette smoking selectively downregulates airway epithelial expression of FAM13A in COPD patients. This may have important consequences for the pathophysiology of COPD, as the more rapid build-up of epithelial resistance upon FAM13A overexpression suggests improved (re)constitution of barrier function. The reduced epithelial secretion of CXCL8 upon CSE-induced damage suggests that lower FAM13A expression upon cigarette smoking may facilitate epithelial-driven neutrophilia.
慢性阻塞性肺疾病（COPD）是一种进行性肺部疾病，其特征是吸入有害颗粒（如香烟烟雾）后发生慢性炎症。FAM13A是常被发现与COPD相关的基因之一，然而其在COPD病理生理学中的功能尚未完全明确。我们研究了其在气道上皮屏障完整性及香烟烟雾诱导的上皮反应中的作用。
采用免疫组织化学方法评估COPD患者和非COPD对照者肺组织中FAM13A的蛋白水平和定位。通过蛋白质印迹法测定COPD患者和对照者原代气道上皮细胞（AECs）在有无香烟烟雾提取物（CSE）情况下FAM13A的表达。在细胞系16HBE14o-中过表达FAM13A，并通过电阻实时监测其对屏障功能的影响。通过蛋白质印迹法评估连接蛋白E-钙黏蛋白和β-连环蛋白的表达。采用酶联免疫吸附测定法（ELISA）检测CSE刺激后中性粒细胞趋化因子CXCL8的分泌。
FAM13A在气道上皮中高表达，但与非COPD对照者相比，COPD患者气道中的表达明显较弱。在源自COPD的AECs中，而非对照者的AECs中，FAM13A被CSE显著下调。过表达FAM13A的16HBE14o-细胞上皮电阻增加明显更快，同时伴有E-钙黏蛋白表达升高及CSE诱导的CXCL8水平降低。
我们的数据表明，与非COPD对照者相比，COPD患者气道上皮中FAM13A的表达较低。此外，吸烟可选择性下调COPD患者气道上皮中FAM13A的表达。这可能对COPD的病理生理学产生重要影响，因为FAM13A过表达时上皮电阻增加更快表明屏障功能改善（重建）。CSE诱导损伤后上皮CXCL8分泌减少表明吸烟时较低的FAM13A表达可能促进上皮驱动的中性粒细胞增多。
