绿脓杆菌 (P. aeruginosa) 影响呼吸道上皮细胞层功能的机制研究

Pseudomonas (P.) aeruginosa is a human opportunistic pathogen, commonly found in patients with immunodeficiency, chronic lung disease or a genetic disease cystic fibrosis. It also causes a high mortality rate in these patients by the lethal bacterial pneumonia. However, the main mechanism that P. aeruginosa uses to directly disrupt epithelial function is still unclear. To address this question, our team’s preliminary data indicate that P. aeruginosa infection increased the permeability of pig tracheal epithelia and the basal activity of the cystic fibrosis transmembrane conductance regulator (CFTR). To understand the underlying mechanisms, the first aim of this project is to investigate the effects of bacterial infection on epithelial permeability, function and morphology, as well as which signaling pathway dominantly causes these changes. The second aim is to explore which bacterial toxin plays a major role in increasing the epithelial permeability by testing several bacterial mutants, each with a toxin eliminated. In the third aim, we hypothesize that after bacterial infection, the CFTR basal activity was increased for enhancing the bacterial killing function of the epithelia. By different drugs or culture medium, CFTR function will be altered for testing the effects of these treatments on bacterial killing of the epithelial cells. Results from this study should have profound implications for discovering new drugs and therapies against bacterial infection at the early stage.

Pseudomonas aeruginosa (绿脓杆菌) 是一种易感染人类的机会性病原体，常好发于免疫功能缺乏，慢性肺部疾病或遗传性囊性纤维化疾病的患者，且易产生致死率高的细菌性肺炎。然而目前对此细菌借由何种主要机制直接影响上皮细胞功能却尚不明确。本团队的初步研究成果发现绿脓杆菌感染会增加猪气管上皮细胞的通透性和顶膜 CFTR 离子通道的基础活性。为了解其机制为何，本计划第一目标欲探讨细菌感染对上皮细胞通透性、功能和结构的影响，及经由何种信号传导机制来产生作用。第二目标是采用细菌突变株探索何种细菌毒素扮演主要角色来增加上皮细胞通透性。第三,我们推测上皮细胞受感染后，提高 CFTR 的基础活性是要增强其杀菌的功能。利用药物或不同培养液改变 CFTR 功能下，探讨其对上皮细胞的杀菌功能有何影响。本研究结果对新治疗技术和药物开发用以早期预防细菌感染具有重要的指导及应用。

Pseudomonas aeruginosa (绿脓杆菌) 是一种易感染人类的机会性病原体，常好发于免疫功能缺乏，慢性肺部疾病或遗传性囊性纤维化疾病的患者，且易产生致死率高的细菌性肺炎。然而目前对此细菌借由何种主要机制直接影响上皮细胞功能却尚不明确。本团队的初步研究成果发现绿脓杆菌感染会增加猪气管上皮细胞的通透性和顶膜 CFTR 离子通道的基础活性。为了解其机制为何，本计划第一目标研究发现虽然细菌感染 7hr 后，上皮细胞的通透性增加，但是细胞间隙和形态并无明显改变，对tight juction蛋白的mRNA表达也没有显著影响。此结果说明我们所观察到细胞通透性增加仅限离子流动的增大，应是细菌对上皮细胞早期的作用。第二目标研究中，用不同细菌突变株移除细菌特定毒素，结果发现type III毒素是增加上皮细胞通透性的主要因素。而且protein phosphatase 2A的兴奋与造成上皮细胞通透性有关。第三目标中，我们发现增加CFTR的活性24hr后，对上皮细胞的杀菌功能并没有太大影响。这些结果说明，早期细菌感染主要是以增加细胞间通透性为主要目标，可能借此能更进一步侵入上皮细胞层的下方，产生更大免疫反应。本研究结果对新治疗技术和药物开发用以早期预防细菌感染具有重要的指导及应用。