OmpA在肺炎克雷伯菌入侵血脑屏障致细菌性脑膜炎中的作用机制研究

细菌性脑膜炎是一种严重的中枢神经系统疾病，具有较高的发病率和致残率。我们分析临床资料发现：肺炎克雷伯菌占脑脊液分离革兰阴性菌第二位，且部分患者是由血流感染肺炎克雷伯菌后细菌经血脑屏障进入脑脊液而继发脑膜炎。这种现象可能与病原菌利用外膜蛋白黏附于人脑内皮细胞并侵入血脑屏障有关，其中OmpA蛋白作为革兰阴性菌主要的外膜蛋白，可辅助病原菌黏附于细胞表面。我们的前期研究显示，血流感染入侵脑脊液组分离的肺炎克雷伯菌ompA基因表达量显著高于仅血流感染组，提示OmpA蛋白在病原菌黏附及入侵血脑屏障中具有重要的作用。本课题以OmpA为研究靶点，利用基因敲除回补技术分别构建基因敲除和回补菌株，通过体外感染人脑内皮细胞及构建体内小鼠感染模型等方法明确OmpA蛋白在肺炎克雷伯菌入侵血脑屏障致脑膜炎中的重要作用及机制。本研究成果将为临床预防并治疗肺炎克雷伯菌脑膜炎提供潜在靶点和理论依据。

Bacterial meningitis is a serious central nervous system (CNS) disease with high morbidity and disability rate. Our analysis of clinical data revealed that Klebsiella pneumoniae (K. pneumoniae) ranked second in Gram-negative bacteria isolated from cerebrospinal fluid (CSF). And K. pneumoniae in some patients with bloodstream infections can be secondary to meningitis from blood through blood-brain barrier (BBB). This phenomenon may be related to pathogens using outer membrane proteins (OMPs) to adhere to human brain microvascular endothelial cells (HBMEC) and invade BBB. Among them, OmpA protein is the main OMP of Gram-negative bacteria, which can help pathogens adhere to cell surface. Our previous studies showed that the expression of ompA gene of K. pneumoniae isolated from both bloodstream and CSF group was significantly higher than that bloodstream alone group, suggesting that OmpA protein played an important role in pathogen adhesion and invasion of the BBB. In this project, the outer membrane protein OmpA is used as the research target. Gene knockout and complement technology are used to construct gene knockout and complement strains, respectively. The establishment of in vitro infection of human endothelial cells and in vivo mouse infection model clarify the important role and mechanism of OmpA protein caused by K. pneumoniae meningitis. The research results will provide potential targets and theoretical basis for clinical prevention and treatment of K. pneumoniae meningitis.