Piperlongumine下调NLRC5抑制大肠杆菌脑膜炎形成的分子机制研究

大肠杆菌脑膜炎是新生儿中枢神经系统严重的感染性疾病，发病率和死亡率均高。细菌穿越血脑屏障（BBB）是脑膜炎发生的关键，其机制仍不清楚；抑制细菌侵袭细胞、杀灭胞内细菌是细菌性脑膜炎防治的难点。我们前期发现NLRC5能介导大肠杆菌E44侵袭人脑微血管内皮细胞（HBMEC）；Piperlongumine(PL)具有抑制E44侵袭HBMEC、降低NLRC5基因的表达、预防E44致小鼠脑膜炎发生的作用。据此提出科学假说：PL下调NLRC5抑制E44对BMEC的侵袭从而抑制细菌性脑膜炎的形成。本项目拟从体外BBB模型和基因敲除动物模型两个层面揭示NLRC5所调控的靶基因（作为细菌侵袭细胞的受体）在E44侵袭细胞中的作用，确定介导细菌侵袭细胞配体，探讨PL下调NLRC5抑制大肠杆菌脑膜炎形成的具体分子机制。本项目的实施进一步丰富了对细菌、细胞之间互作及识别的认识，为治疗细菌性脑膜炎提供新的靶点和思路。

Escherichia coli meningitis is a serious infectious disease in the central nervous system of the newborn, with high morbidity and mortality. The bacteria passing through the blood brain barrier (BBB) is the key to the occurrence of meningitis, but its mechanism is still unclear.The inhibition of bacteria invasion cells and killing intracellular bacteria have been the difficulties in the study of bacterial meningitis treatment. Our previous studies have demonstrated that NLRC5 can induce Escherichia coli E44 to invade human brain microvascular endothelial cells (HBMEC), piperlongumine (PL) can inhibit E.Coli E44 invasion of brain microvascular endothelial cells (BMECs), and can prevent the happening of the meningitis in mice caused by E44. we have also found PL can regulate the gene expression of related signaling pathways of bacterial adhesion cell , and can dramatically inhibited the gene expression of NLRC5. Knockout of NLRC5 significantly inhibits bacteria invasion HBMEC. Basing on the results above, we put forward the hypothesis that PL can suppress E44 invasion of cell by down-regulation of NLRC5 and inhibit the formation of bacterial meningitis, but some molecular mechanisms should be further elucidated. Trough this project, we intend to use in vitro model of BBB and the knock-out animal models, chromatin Immunoprecipitation (ChIP), and Next-generation sequencing technology to study the mechanism of PL reduced expression of NLRC5, to reveal the target genes of NLRC5 regulated (as a receptor when bacterial invasioncell), and to determine the mediated ligand of the bacteria.This project will help further elucidate the interaction and recognition between the bacteria and cells, and it will be potential for new targets and new approaches for treatment of bacterial meningitis .