吸入糖皮质激素：降低了羧甲司坦改善熏烟大鼠气道细菌清除能力的作用？

Prevention of acute exacerbation of chronic obstructive pulmonary disease (COPD), a goal for management of stable COPD, is one of main endpoints of clinical trials which focused on evaluation of mucolytic and antioxidant agents in pharmacologic therapy for stable COPD. Till now, the regular use of mucolytics in stable COPD has been evaluated in a number of long-term studies with controversial results. It is the main reason why global initiative for chronic obstructive lung disease (GOLD) do not recommend wildspread use of mucolytics in treatment of stable COPD. In order to clarify the controversial results, we reviewed and analysed associated randomized controlled trails and our recent studies. We found that mucolytics may reduce acute exacerbations of COPD patients not receiving inhaled corticosteroids (ICS). So the various proportion of patients not receiving ICS in studies may lead to the controversial results. We speculate that mucolytics can not reduce acute exacerbations of COPD patients receiving ICS, which is due to ceiling effect or counteraction between mucolytics and ICS. In the present study, the impact and mechanisms of ICS on clearance of mucus and Haemophilus influenza load which enhanced by carbocisteine will be evaluated in vivo with rats exposed to cigarette smoke. The mechanisms of counteraction between carbosteine and ICS which may be mediated by extracellular signal-regulated kinase (ERK) pathway will be evaluated in vitro with cell culture. If the effects and mechanisms mentioned above are clarified, the value of carbocisteine in pharmacological therapy for stable COPD will be objectively evaluated. Regular use of carbocisteine, a cheaper mucolytic and antioxidant agent, will be optimized in selected COPD patients which is beneficial to management of stable COPD and reduction of COPD burden in China and other developing countries.

粘液调节/抗氧化剂治疗稳定期COPD的临床研究，常以能否减少患者急性加重次数作为评价疗效的重要指标。近年的多项研究报告显示了不同的结果，这一结果的差异影响了GOLD推荐该类药物广泛应用。申请者在分析数项较高级别循证医学研究中入选患者资料的基础上，结合申请者团队近期的研究结果，认为合用吸入性糖皮质激素可能是差异产生的重要原因。本项目拟通过实验动物研究证实这一假说。应用熏烟大鼠模型，证实吸入糖皮质激素充分抗炎的"天花板效应"可以减弱羧甲司坦改善气道黏液纤毛清除功能、减低流感嗜血杆菌细菌负荷的作用，并明确其与粘蛋白产生、细菌粘附、氧化应激的关系；应用细胞培养技术阐明上述作用是通过ERK通路实现的。这对准确评价羧甲司坦疗效和其在治疗稳定期COPD的科学定位十分有益。羧甲司坦价格低廉，如能肯定其减少COPD急性加重频次、明晰影响这一作用的因素，对指导我国稳定期COPD患者的治疗具有现实意义

粘液调节/抗氧化剂治疗稳定期COPD的临床研究，近年的多项研究报告显示了不同的结果，这一结果的差异影响了GOLD 推荐该类药物广泛应用。申请者在分析数项较高级别循证医学研究中入选患者资料的基础上，结合申请者团队的研究结果，认为合用吸入性糖皮质激素可能是差异产生的重要原因。本项目拟通过实验动物研究证实这一假说。应用熏烟大鼠模型，证实吸入糖皮质激素充分抗炎的"天花板效应"可以减弱羧甲司坦改善气道黏液纤毛清除功能、减低流感嗜血杆菌细菌负荷的作用，并明确其与粘蛋白产生、细菌粘附、氧化应激的关系；应用细胞培养技术阐明上述作用是通过ERK通路实现的。.目前已通过香烟烟雾成功诱导COPD大鼠动物模型，实验结果发现： 1.给予布地奈德雾化及羧甲司坦灌胃治疗后，经气道接种流感嗜血杆菌，进行定量培养。通过western blot、免疫组化及ELISA等方法，发现布地奈德可干扰羧甲司坦对大鼠气道清除能力的改善作用，不利于羧甲司坦发挥其气道清除功能；2.通过ELISA、免疫组化染色和BALF细胞计数、PCR等方法，证实羧甲司坦和布地奈德均可减轻烟熏大鼠的肺部炎症反应，两药各自独立或彼此联合应用的效力无统计学差异；单独应用羧甲司坦或与糖皮质激素联合应用可降低烟熏大鼠氧化应激水平，而独立应用糖皮质激素则无此效应；3.羧甲司坦通过TACE-TGF-α-EGFR-ERK通路调节有CSE诱导的人气道上皮细胞MUC5AC高表达，且羧甲司坦对TACE活性调节，与其抗氧化能力有关；4.布地奈德亦可抑制ERK信号转导通路减轻香烟所致的气道炎症。说明羧甲司坦和布地奈德的作用机制存在重叠部分，因此基础应用糖皮质激素后，由于其抑制了相同的炎症靶点，再联合羧甲司坦时未能体现其应有的作用。