慢性阻塞性肺疾病发病中粘蛋白MUC5B的作用机制及羧甲司坦干预研究

Airway mucus hypersecretion is one of the characteristics of chronic obstructive pulmonary disease (COPD). The MUC5B, a major category of mucin detected in sputum, is associated with airway defensive responses (reported by Nature in 2014). We have previously proved that carbocisteine, a mucolytic drug, markedly reduced the rate of COPD acute exacerbations (Lancet 2008) and, in COPD models, alleviated oxidative stress and inflammatory-induced injury, which have been shown to activate MAPK and Nrf-2 signaling pathways and up-regulate MUC5B expression. This has led us to postulate if the regulation of MUC5B expression was triggered by the MAPK and Nrf-2 signaling pathways in COPD. We hypothesized that tobacco smoke up-regulated MUC5B expression via activation of MAPK and Nrf-2 signaling pathways, which could be abrogated by the administration of carbocisteine. In this study, we will use various experimental methods such as MUC5B gene knockout COPD mice model，luciferase reporter plasmid transfected cell model ,EMSA, PCR and siRNA gene silence，to explore the mechanisms of MUC5B in COPD and the therapeutic effects of carbocisteine, thus offering scientific rationales for confirming the new target and roles of mucolytics, for instance carbocisteine, in the prevention and treatment of COPD.

气道粘液高分泌是慢性阻塞性肺疾病（COPD）主要临床特征之一，2014年《Nature》发现痰液中粘蛋白5B（MUC5B）与气道防御功能密切相关。我们已证实粘液溶解剂羧甲司坦能显著减少COPD急性加重（Lancet2008），且明显减轻COPD模型动物的氧化应激和炎性损伤。氧化应激和炎性损伤可活化MAPK和Nrf-2信号通路，也可上调MUC5B表达。但MUC5B在COPD发病中的调控是否由MAPK和Nrf-2通路引起？我们提出假说：香烟烟雾通过活化MAPK和Nrf-2启动子上调MUC5B是COPD发病重要机制之一，而羧甲司坦可干预此过程。本项目将构建MUC5B基因敲除小鼠COPD模型及多种荧光报告质粒转染细胞模型，通过免疫荧光双染色、EMSA、PCR、siRNA基因沉默等方法，阐明COPD发病中MUC5B作用机制及羧甲司坦干预作用，为确立羧甲司坦等祛痰药物防治COPD的新靶点提供科学依据。

气道粘液高分泌是慢性阻塞性肺疾病（COPD）主要临床特征之一，2014 年 《Nature》发现痰液中粘蛋白 5B（MUC5B）与气道防御功能密切相关。我们已证实粘液溶解 剂羧甲司坦能显著减少 COPD 急性加重（Lancet2008），且明显减轻 COPD 模型动物的氧化应 激和炎性损伤。氧化应激和炎性损伤可活化 MAPK 和 Nrf-2 信号通路，也可上调 MUC5B 表达。 但 MUC5B在COPD 发病中的调控是否由 MAPK 和 Nrf-2 通路引起？我们提出假说：香烟烟雾通 过活化 MAPK 和 Nrf-2 启动子上调 MUC5B 是 COPD 发病重要机制之一，而羧甲司坦可干预此过程。本项目已通过构建 MUC5B 基因敲除小鼠 COPD 模型及多种细胞模型，阐明MUC5B在COPD发病中起到重要的保护作用,羧甲司坦可通过减轻炎症，降低过多的MUC5AC或MUC5B来保护COPD模型小鼠的肺功能及改善肺气肿，这种作用可能通过Erk或者NF-κB通路实现。