Mechanisms of flagellin-induced protection against microbial keratitis

微生物性角膜炎是视力丧失的常见原因。角膜对炎症非常敏感- 介导的损害，因此具有强大的先天防御。然而，当上皮屏障功能被破坏时， 被破坏的机会性细菌和真菌病原体可以进入上皮细胞层， 在角膜中定植导致感染在最初的授权期间，鞭毛蛋白，Toll样蛋白的配体， 受体5（TLR 5），用于加强角膜先天免疫，并使其对广谱的 引起角膜炎的病原体，包括绿脓杆菌、白色念珠菌和曲霉菌 烟熏。这种高度可诱导和强大的先天粘膜保护可以归因于鞭毛蛋白诱导的 上皮细胞中的基因组重编程，反过来，与专业免疫细胞相互作用， 炎症和根除入侵的病原体。本申请中的假设是鞭毛蛋白通过 TLR 5刺激保护性角膜先天粘膜免疫，包括上皮细胞，浸润的PMN， 和活化的树突状细胞，共同赋予对微生物角膜炎的强大抵抗力。三个具体 我们的目标是验证这一假设：1）确定鞭毛蛋白诱导的重编程是如何调节的 在角膜上皮细胞和角膜中。这可以通过使用染色质来评估。 用于基因特异性染色质修饰免疫沉淀分析和组蛋白脱乙酰酶抑制剂， 使用siRNA和敲除小鼠来描绘激活转录因子-3的作用， 在调节角膜中的先天性免疫应答中，由fg诱导的因子。2)以确定如何 上皮细胞参与并协调鞭毛蛋白诱导的针对微生物的粘膜天然免疫防御 角膜炎。上皮细胞的作用及其与树突状细胞在先天防御中的相互作用将被确定 通过使用各种转基因和基因敲除小鼠、骨髓重建和细胞去除。3)到 确定鞭毛蛋白如何诱导角膜对非鞭毛病原体的保护。治疗 鞭毛蛋白的潜力及其作用机制将通过使用真菌感染的小鼠模型来表征。 角膜炎（念珠菌和曲霉菌作为病原体，感染后局部应用鞭毛蛋白）和双重 TLR敲除小鼠。这项研究的结果将有助于阐明角膜先天免疫及其 诱导，并可能导致新的预防/治疗方式的发展， 治疗微生物性角膜炎。

Microbial keratitis is a common cause of vision loss. The cornea is exquisitely sensitive to inflammation- mediated damage and therefore has strong innate defenses. However, when the epithelial barrier function is breached, opportunistic bacterial and fungal pathogens can gain access to the epithelial cell layers and colonize in the cornea, leading to infection. During the initial grant period, flagellin, the ligand of Toll-like receptor 5 (TLR5), was used to fortify corneal innate immunity and render resistance to a broad spectrum of keratitis causing pathogens, including Pseudomonas aeruginosa, Candida albicans and Aspergillus fumigates. This highly inducible and robust innate mucosal protection can be attributed to flagellin-induced genomic reprogramming in the epithelium which, in turn, interacts with professional immune cells to control inflammation and to eradicate invading pathogens. The hypothesis in this application is that flagellin, through TLR5, stimulates protective corneal innate mucosal immunity that involves epithelial cells, infiltrated PMNs, and activated dendritic cells, collectively conferring robust resistance to microbial keratitis. Three specific aims are proposed to test this hypothesis: 1) To determine how flagellin-induced reprogramming is regulated in corneal epithelial cells and in the cornea. This can be assessed by using the chromatin immunoprecipitation assay and histone deacetylase inhibitors for gene-specific chromatin modification and by using siRNA and knockout mice for delineating the role of activating transcription factor-3, a transcription factor induced by fg, in regulating the innate immune response in the cornea. 2) To determine how the epithelium participates in and coordinates flagellin-induced mucosal innate immune defense against microbial keratitis. The role of the epithelium and its interaction with dendritic cells in innate defense will be determined by using various transgenic and knockout mice, bone marrow reconstitution, and cell depletion. 3) To determine how flagellin induces protection against non-flagellated pathogens in the cornea. The therapeutic potential of flagellin and its mechanisms of action will be characterized by using mouse models of fungal keratitis (Candida and Aspergillus as pathogens and post-infection topical flagellin application) and double TLR knockout mice. The results of the proposed study should shed light on corneal innate immunity and its induction, and may lead to the development of new prophylactic/therapeutic modalities for preventing and treating microbial keratitis.