Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Atlanta Veterans Affairs Health Care System, Decatur, GA, 30033, United States; Emory University, Atlanta, GA, 30322, United States.
Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Atlanta Veterans Affairs Health Care System, Decatur, GA, 30033, United States; Emory University, Atlanta, GA, 30322, United States.
Alcohol. 2019 Nov;80:65-72. doi: 10.1016/j.alcohol.2018.08.006. Epub 2018 Aug 22.
Excessive alcohol users have a higher risk for developing respiratory infections compared to individuals who do not chronically misuse alcohol, due to impaired host immune defense. In the lung, alveolar epithelial cells play a critical role in host immune defense against invading pathogens in the lower respiratory tract due to their capacity to maintain barrier integrity, and alveolar macrophages play a key role in pulmonary innate immunity by phagocytizing and clearing infiltrating microbes. Chronic alcohol misuse induces mitochondrial damage that results in release of mitochondrial DNA (mtDNA) in exosomes. We hypothesized that alcohol-induced cellular damage leads to release of exosomes containing damaged mtDNA, which can mediate injurious crosstalk between lung epithelial cells and macrophages. The mouse alveolar epithelial cell line, MLE-12, and the mouse alveolar macrophage cell line, MH-S, were transfected with a damaged mtDNA overexpression plasmid or exposed to ethanol in vitro. Overexpression of damaged mtDNA impaired MLE-12 barrier function and MH-S phagocytic capacity. Ethanol induced damage of mtDNA in MLE-12 and MH-S cells, and promoted release of exosomes enriched with damaged mtDNA from these cells. Exosomes from ethanol-exposed MH-S cells caused mtDNA damage and barrier dysfunction in MLE-12 cells, and exosomes from ethanol-exposed MLE-12 cells caused mtDNA damage and phagocytic dysfunction in MH-S cells. Collectively, these data show that ethanol-induced mtDNA damage in MLE-12 and MH-S cells stimulates release of damaged mtDNA-enriched exosomes and contributes to injurious crosstalk between the alveolar epithelium and macrophages, potentially leading to impaired host immune defense against respiratory infections.
酗酒者比不滥用酒精的个体更容易发生呼吸道感染,因为他们的宿主免疫防御受损。在肺部,肺泡上皮细胞由于能够维持屏障完整性,在宿主对下呼吸道入侵病原体的免疫防御中起着至关重要的作用,肺泡巨噬细胞通过吞噬和清除浸润的微生物在肺部先天免疫中起着关键作用。慢性酒精滥用会导致线粒体损伤,从而导致外泌体中释放线粒体 DNA(mtDNA)。我们假设,酒精引起的细胞损伤导致释放含有受损 mtDNA 的外泌体,这可能介导肺上皮细胞和巨噬细胞之间的有害串扰。我们用损伤的 mtDNA 过表达质粒转染小鼠肺泡上皮细胞系 MLE-12 和小鼠肺泡巨噬细胞系 MH-S,或在体外用乙醇处理这些细胞。过表达损伤的 mtDNA 会损害 MLE-12 的屏障功能和 MH-S 的吞噬能力。乙醇诱导 MLE-12 和 MH-S 细胞中的 mtDNA 损伤,并促进这些细胞释放富含损伤 mtDNA 的外泌体。来自乙醇暴露的 MH-S 细胞的外泌体导致 MLE-12 细胞中的 mtDNA 损伤和屏障功能障碍,来自乙醇暴露的 MLE-12 细胞的外泌体导致 MH-S 细胞中的 mtDNA 损伤和吞噬功能障碍。总的来说,这些数据表明,MLE-12 和 MH-S 细胞中乙醇诱导的 mtDNA 损伤刺激富含损伤 mtDNA 的外泌体的释放,并有助于肺泡上皮细胞和巨噬细胞之间的有害串扰,可能导致宿主对呼吸道感染的免疫防御受损。