TSLP对革兰阴性菌性角膜炎的保护作用及机制研究

Gram-negative (G-) bacterial keratitis is a common infectious ocular disease, and is a leading cause of ocular morbidity and blindness worldwide. Corneal epithelium plays an important role in the bacterial defense by sensing the presence of pathogens and providing signals that activate the innate immune system. Thymic stromal lymphopoietin (TSLP) was known as an epithelium-derived pro-inflammatory cytokine in allergic diseases. Interestingly, it has recently been reported that TSLP have protective and tolerogenic functions during G- bacterial infection. Our recent research showed the dramatically up-regulation of TSLP in corneal epithelial cells during gram-negative bacterial infection. Also we observed a much severe pseudomonas keratitis with the help of anti-TSLP, which indicates a protective role of TSLP in gram-negative bacterial keratitis. To verify this protective effect, this project will focus on the severity of bacterial keratitis by down or up regulating of TSLP. Also, we look for the target cells of TSLP signal, investigate the effect of TSLP to T cell differentiation, to explore the pathogenic mechanism of TSLP in G- bacterial keratitis. The corneal epithelium and tears of clinical G- bacterial keratitis patients are collected to verify the association of TSLP and the G- bacterial keratitis. The findings of this project will provide new insights in the pathogenesis and treatment guides of gram-negative bacterial keratitis.

革兰阴性菌（G-菌）性角膜炎是临床常见眼病，是角膜盲的常见病因。角膜上皮的屏障作用对于抵抗细菌感染十分关键。胸腺基质淋巴细胞生成素（TSLP）是由上皮分泌的细胞因子，作用于过敏反应，促进炎症进程。最近研究发现，TSLP具备抗G-菌感染的潜力。预实验发现， TSLP在G-菌感染后的角膜上皮细胞中表达上调；抑制TSLP可以加重角膜炎症反应。本课题拟通过下调或上调TSLP活性，明确TSLP在G-菌性角膜炎中的保护作用；通过鉴定TSLP作用的靶细胞和分析TSLP对T细胞分化的调控，阐明TSLP在G-菌性角膜炎中的作用机制；最后经由对G-菌性角膜炎患者临床样本的收集，揭示TSLP与G-菌性角膜炎的临床相关性。本研究有望为防治G-菌性角膜炎提供潜在的分子作用靶点。

革兰阴性菌(G-菌)性角膜炎是临床常见眼病，是角膜盲的常见病因。角膜上皮的屏障作用对于抵抗细菌感染十分关键。胸腺基质淋巴细胞生成素(TSLP)是由上皮分泌的细胞因子，作用于过敏反应，促进炎症进程。最近研究发现，TSLP具备抗G-菌感染的潜力。我们通过本次实验，在体外培养的人角膜上皮细胞和C57BL/6小鼠角膜中都发现了TSLP的表达，无论是RNA水平还是蛋白质水平均可体现。TSLP大部分表达在角膜上皮中，而TSLPR主要位于基质中，多与CD11c共表达。采用TSLP中和抗体或TSLPR siRNA下调TSLP的表达水平后，小鼠铜绿假单胞菌性角膜炎显著加重，同时细菌增殖和中性粒细胞浸润量也相应增加。TSLPR中和后明显抑制了炎症诱导的TSLP和IL-17C的表达，同时提高了IL-23和IL-17A的表达。树突状细胞敲除鼠感染铜绿假单胞菌后角膜炎程度较重，对TSLP 和IL-23的表达不产生明显影响，但可抑制IL-17A和IL-17C的表达。本课题的最终结论是：TSLP主要表达于角膜上皮细胞内，对铜绿假单胞菌性角膜炎的发病具有保护作用，通过与树突状细胞结合，调节IL-23/IL17信号通路平衡来发挥作用。这一研究结果为铜绿假单胞菌性角膜炎的治疗提供了新思路。