Zhang Yuan-Li, Li Qing-Quan, Guo Wei, Huang Yi, Yang Jiong
Division of Intensive Care Unit, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong, China.
Zhongguo Wei Zhong Bing Ji Jiu Yi Xue. 2008 Feb;20(2):95-9.
To investigate the effects of chronic ethanol ingestion and lipopolysaccharide (LPS) on airway epithelium barrier function and the expression of tight junction protein occludin and adherens junction protein E-cadherin.
Forty Sprague-Dawley (SD) rats were assigned to control, ethanol, LPS and ethanol+LPS groups. The bronchoalveolar epithelial permeability was assessed by the bronchoalveolar lavage fluid (BALF): serum fluorescein isothiocyanate (FITC)-dextran (FD(4)) fluorescence ratio. Protein localization and expression of occludin and E-cadherin in airway epithelium of rats lung were examined by immunofluorescence. The protein, messenger RNA expression of occludin and E-cadherin in the lung were examined by Western blotting and reverse transcription-polymerase chain reaction (RT-PCR).
The bronchoalveolar epithelial permeability in the ethanol group and LPS group were approximately 2-fold higher than those in the control group (both P<0.05). The permeability in the ethanol+LPS group was increased further (P<0.01). Occludin and E-cadherin appeared as a continuous and uniform expression in the airway epithelium of control rats. In ethanol group and LPS group partial breakdown of membrane staining and decreased cytoplasm staining of occludin and E-cadherin were seen in the airway epithelium. In ethanol plus LPS group, there was breakdown of epithelial membrane and obvious disappearance of cytoplasm staining pattern of occludin and E-cadherin. Western blotting and RT-PCR showed that both in ethanol and LPS groups protein levels of occludin and E-cadherin were depressed in lung. Treatment with ethanol together with LPS further depressed the protein and mRNA levels of occludin and E-cadherin in lung. RT-PCR showed that messenger RNA levels of occludin and E-cadherin in ethanol group and LPS group were lower than those in the control group (both P< 0.05). Treatment with ethanol plus LPS had the greatest depressive effect on these messenger RNA levels (ethanol+LPS group vs. the other groups, all P<0.01).
These data suggest that chronic ethanol ingestion impairs the airway epithelial barrier function through down-regulation the messenger RNA expression and disruption of membrane localization of occludin and E-cadherin. Those deterioration of occludin and E-cadherin predisposes to acute lung injury induced by LPS.
探讨慢性乙醇摄入和脂多糖（LPS）对气道上皮屏障功能以及紧密连接蛋白闭合蛋白和黏附连接蛋白E-钙黏蛋白表达的影响。
将40只Sprague-Dawley（SD）大鼠分为对照组、乙醇组、LPS组和乙醇+LPS组。通过支气管肺泡灌洗液（BALF）与血清异硫氰酸荧光素（FITC）-葡聚糖（FD(4)）荧光比值评估支气管肺泡上皮通透性。采用免疫荧光法检测大鼠肺气道上皮中闭合蛋白和E-钙黏蛋白的蛋白定位及表达。通过蛋白质印迹法和逆转录-聚合酶链反应（RT-PCR）检测肺组织中闭合蛋白和E-钙黏蛋白的蛋白质及信使核糖核酸表达。
乙醇组和LPS组的支气管肺泡上皮通透性比对照组高约2倍（均P<0.05）。乙醇+LPS组的通透性进一步升高（P<0.01）。对照组大鼠气道上皮中闭合蛋白和E-钙黏蛋白呈连续且均匀的表达。乙醇组和LPS组气道上皮中可见闭合蛋白和E-钙黏蛋白的膜染色部分破坏及细胞质染色减少。乙醇加LPS组出现上皮细胞膜破坏，闭合蛋白和E-钙黏蛋白的细胞质染色模式明显消失。蛋白质印迹法和RT-PCR显示，乙醇组和LPS组肺组织中闭合蛋白和E-钙黏蛋白的蛋白水平均降低。乙醇与LPS共同处理进一步降低了肺组织中闭合蛋白和E-钙黏蛋白的蛋白质及信使核糖核酸水平。RT-PCR显示，乙醇组和LPS组中闭合蛋白和E-钙黏蛋白的信使核糖核酸水平低于对照组（均P<0.05）。乙醇加LPS处理对这些信使核糖核酸水平的抑制作用最大（乙醇+LPS组与其他组相比，均P<0.01）。
这些数据表明，慢性乙醇摄入通过下调信使核糖核酸表达以及破坏闭合蛋白和E-钙黏蛋白的膜定位来损害气道上皮屏障功能。闭合蛋白和E-钙黏蛋白功能的这些恶化易引发LPS诱导的急性肺损伤。
