Nrf2/Trx/NF-κB信号通路在大气细颗粒物致慢性阻塞性肺病的机制研究

Air pollution is quite serious in China nowadays especially due to fine particulate matter in the atmosphere (PM2.5). Epidemiological studies give evidence to prove that PM2.5 is associated with the increasing of prevalence and mortality on chronic obstructive pulmonary disease (COPD). However, the mechanisms are not fully understood. Our previous research found that PM2.5 exposure triggered oxidative stress in human pulmonary epithelial (BEAS-2B) cells and increased expressions of nuclear factor-E2-related factor-2 (Nrf2) and thioredoxin (Trx). Meanwhile, nuclear factor-kappa B (NF-κB) and inflammatory cytokine interleukin-8 (IL-8) were activated by PM2.5. These observations indicated that PM2.5 may induce inflammatory response through the Nrf2/Trx/NF-κB signaling pathway in BEAS-2B cells. In this project, COPD models induced by PM2.5 in rats would be established to determine whether PM2.5 facilitates COPD development. The correlation among lung function, pathological changes of lung tissue and levels of inflammatory cytokines in rats were analyzed. In vitro, experimental technologies such as overexpression of Nrf2, Transwell co-culture system and disturbed nuclear translocation of Trx would be used to explore the molecular mechanisms of Nrf2/Trx/NF-κB signaling pathway on PM2.5-induced COPD. The research would provide an innovative way and strategy for early intervention, diagnosis and therapy in COPD, which has great public health significance.

我国大气颗粒物污染严重，细颗粒物（PM2.5）危害尤为突出，研究显示PM2.5与暴露人群慢性阻塞性肺疾病(COPD)的患病率和死亡率密切相关，但其诱发COPD的机制不清。课题组前期发现PM2.5可引起人正常肺上皮细胞（BEAS-2B）发生氧化应激，抗氧化调控基因Nrf2、Trx表达上调，伴有转录因子NF-κB和炎性因子IL-8的上调，提示PM2.5可能经Nrf2/Trx/NF-κB参与诱发BEAS-2B的炎症反应。本课题拟建立PM2.5诱导的大鼠COPD模型，分析大鼠肺功能、肺组织病理变化、COPD相关炎症因子的关系，探索PM2.5在COPD中的早期作用规律；体外细胞实验利用Nrf2过表达、干扰Trx入核、Transwell共培养等技术，探讨Nrf2/Trx/NF-κB通路在PM2.5致COPD的作用机制。该研究将为COPD的早期干预、早期诊断和治疗提供新思路，具有重要的公共卫生学意义。

慢性阻塞性肺病(COPD)是以持续性气流受限为特征的疾病，与气道和肺组织对有害颗粒及气体的异常慢性炎症反应有关。我国大气颗粒物污染严重，细颗粒物（PM2.5）危害尤为突出，已有的研究提示PM2.5可能与COPD的发生发展密切相关。本研究通过建立PM2.5诱发的COPD动物模型，分析不同染毒时间小鼠肺功能、肺组织病理变化及COPD相关炎症因子的变化，以探索PM2.5在COPD发生中的早期作用规律；体外实验利用共培养系统构建PM2.5诱导的COPD细胞模型，通过应用Nrf2激动剂t-BHQ以及Trx入核抑制剂cHCEU干扰Trx入核的方法，检测氧化应激及炎症反应等相关指标的表达，从而探讨Nrf2/Trx/NF-κB信号通路在PM2.5致COPD中的分子机制。研究结果：① 从病理学、功能学、影像学以及相应生物学指标等方面证实PM2.5可以诱发小鼠发生COPD；② PM2.5直接刺激和间接刺激BEAS-2B细胞均可引起细胞发生氧化应激和炎症反应；③ 在PM2.5刺激的BEAS-2B细胞模型中应用t-BHQ，上调Trx等抗氧化基因表达，缓解氧化应激，同时利用cHCEU抑制Trx入核以拮抗NF-κB的转录活性，从而缓解PM2.5诱发的炎性反应。提示PM2.5可以引起氧化损伤，由于抗氧化通路Nrf2/Trx应激性上调表达，且氧化应激促使还原型Trx发生核转移而增强胞核中NF-κB的DNA结合能力，促进炎症因子等释放增加，最终导致COPD的发生。该研究为COPD的早期干预、早期诊断和治疗提供了新思路，具有重要的公共卫生学意义。