Chan Tze Khee, Tan W S Daniel, Peh Hong Yong, Wong W S Fred
Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore 117600, Singapore.
Immunology Program, Life Science Institute, National University of Singapore, Singapore 117456, Singapore.
J Immunol. 2017 Jul 1;199(1):39-47. doi: 10.4049/jimmunol.1600657. Epub 2017 May 19.
Exposure to environmental allergens is a major risk factor for asthma development. Allergens possess proteolytic activity that is capable of disrupting the airway epithelium. Although there is increasing evidence pointing to asthma as an epithelial disease, the underlying mechanism that drives asthma has not been fully elucidated. In this study, we investigated the direct DNA damage potential of aeroallergens on human bronchial epithelial cells and elucidated the mechanisms mediating the damage. Human bronchial epithelial cells, BEAS-2B, directly exposed to house dust mites (HDM) resulted in enhanced DNA damage, as measured by the CometChip and the staining of DNA double-strand break marker, γH2AX. HDM stimulated cellular reactive oxygen species production, increased mitochondrial oxidative stress, and promoted nitrosative stress. Notably, expression of nuclear factor erythroid 2-related factor 2-dependent antioxidant genes was reduced immediately after HDM exposure, suggesting that HDM altered antioxidant responses. HDM exposure also reduced cell proliferation and induced cell death. Importantly, HDM-induced DNA damage can be prevented by the antioxidants glutathione and catalase, suggesting that HDM-induced reactive oxygen and nitrogen species can be neutralized by antioxidants. Mechanistic studies revealed that HDM-induced cellular injury is NADPH oxidase (NOX)-dependent, and apocynin, a NOX inhibitor, protected cells from double-strand breaks induced by HDM. Our results show that direct exposure of bronchial epithelial cells to HDM leads to the production of reactive oxygen and nitrogen species that damage DNA and induce cytotoxicity. Antioxidants and NOX inhibitors can prevent HDM-induced DNA damage, revealing a novel role for antioxidants and NOX inhibitors in mitigating allergic airway disease.
暴露于环境过敏原是哮喘发病的主要危险因素。过敏原具有蛋白水解活性，能够破坏气道上皮。尽管越来越多的证据表明哮喘是一种上皮疾病，但驱动哮喘的潜在机制尚未完全阐明。在本研究中，我们调查了气传过敏原对人支气管上皮细胞的直接DNA损伤潜力，并阐明了介导损伤的机制。直接暴露于屋尘螨（HDM）的人支气管上皮细胞BEAS-2B导致DNA损伤增强，这通过彗星芯片和DNA双链断裂标记物γH2AX的染色来测量。HDM刺激细胞活性氧生成，增加线粒体氧化应激，并促进亚硝化应激。值得注意的是，HDM暴露后立即降低了核因子红细胞2相关因子2依赖性抗氧化基因的表达，表明HDM改变了抗氧化反应。HDM暴露还减少了细胞增殖并诱导细胞死亡。重要的是，抗氧化剂谷胱甘肽和过氧化氢酶可以预防HDM诱导的DNA损伤，这表明HDM诱导的活性氧和氮物种可以被抗氧化剂中和。机制研究表明，HDM诱导的细胞损伤是NADPH氧化酶（NOX）依赖性的，并且NOX抑制剂夹竹桃麻素可保护细胞免受HDM诱导的双链断裂。我们的结果表明，支气管上皮细胞直接暴露于HDM会导致活性氧和氮物种的产生，从而损伤DNA并诱导细胞毒性。抗氧化剂和NOX抑制剂可以预防HDM诱导的DNA损伤，揭示了抗氧化剂和NOX抑制剂在减轻过敏性气道疾病中的新作用。
