Biology, Immunology & therapy of Acanthamoeba Keratitis

总结 阿米巴角膜炎是一种由致病性自由生活引起的威胁视力的角膜疾病 变形虫这个研究项目的基本原理是基于以下观察：1）先天的 免疫系统在阿米巴角膜炎和多形核中性粒细胞中起重要作用 (PMN)是阿米巴角膜炎病变中突出的炎性细胞; 2）中性粒细胞是 重要的是在最初解决阿米巴感染; 3）阿米巴角膜炎的发病机制， 由浸润的嗜中性粒细胞加工的蛋白酶加剧; 4）细胞膜上的Toll样受体（TLR）， 角膜上皮启动对阿米巴感染的炎性反应。这可能是 通过在感染部位固定PMN实现; 5）角膜炎是组织损伤的结果 由阿米巴滋养体加工的因子（初级蛋白酶）介导; 6）寄生虫- 衍生的致病分子甚至在滋养体成囊或死亡后仍然存在; 7）寄生虫传播的 致病分子与角膜表面上的几种分子反应 8）寄生虫衍生的分子具有免疫原性 并可用于引发粘膜抗体的产生， 分子，从而减轻组织损伤并减少嗜中性粒细胞浸润。因此，保护和 中性粒细胞的破坏作用影响阿米巴感染和疾病过程的结果 分别第一个具体的目标将测试的假设，Toll样受体（TLR）上的 角膜上皮启动对眼部阿米巴感染的炎症反应。这可能是 通过固定最初杀死阿米巴或导致发病的中性粒细胞来实现 疾病。第二个具体目标将检验甘露糖诱导的假设- 阿米巴细胞病变蛋白（MIP-133）与角膜上皮细胞上磷脂的相互作用 并通过一种新的途径诱导细胞凋亡和花生四烯酸释放， 磷脂酶A2（PLA2）活化。第三个具体目标将测试假设，阿米巴原虫 滋养体组成型表达PLA2，其直接诱导角膜上的细胞病变效应 上皮细胞或激活磷脂并诱导花生四烯酸释放。第四个具体目标 将检验用PLA2抑制剂治疗和用MIP-133免疫将减轻 阿米巴角膜炎的发病机制。 本项目的长期目标是评估阿米巴的致病机制 角膜炎可能对设计改进的阿米巴治疗方法产生巨大影响 这些病人代表了最严重的治疗困境。

Summary Acanthamoeba keratitis is a sight-threatening corneal disease caused by pathogenic free-living amoebae. The rationale for this research project is based on the following observations: 1) The innate immune system plays an important role in Acanthamoeba keratitis and polymorphonuclear neutrophils (PMN) are the prominent inflammatory cells in Acanthamoeba keratitis lesions; 2) neutrophils are important in initial resolution of Acanthamoeba infection; 3) pathogenesis of Acanthamoeba keratitis is exacerbated by the protease elaborated by infiltrating neutrophils; 4 ) Toll-like receptors (TLRs) on the corneal epithelium initiate the inflammatory responses to Acanthamoeba infections. This may be achieved by immobilizing PMN at the site of infection; 5) keratitis is the consequence of tissue damage mediated by factors (preliminary proteases) elaborated by Acanthamoeba trophozoites; 6) parasite- derived pathogenic molecules persist even after trophozoites encyst or die; 7) parasite-borne pathogenic molecules react with several molecules on the surface of the cornea and induce the release of chemokines and cytokines by the epithelial cells; 8) parasite-derived molecules are immunogenic and can be used to elicit the production of mucosal antibodies that will neutralize the pathogenic molecules and thus, mitigate tissue damage and reduce neutrophil infiltration. Thus, the protective and destructive roles of PMNs influence the outcome of Acanthamoeba infection and disease processes respectively. The first specific aim will test the hypothesis that Toll-like receptors (TLRs) on the corneal epithelium initiate the inflammatory responses to ocular Acanthamoeba infections. This may be achieved by immobilizing PMNs that either initially kill Acanthamoeba or contribute to the pathogenesis of the disease. The second specific aim will test the hypothesis that the mannose induced- Acanthamoeba cytopathic protein (MIP-133) interacts with phospholipids on the corneal epithelial cells and induces both apoptosis and arachidonic acid release through a novel pathway involving phospholipase A2 (PLA2) activation. The Third specific aim will test the hypothesis that Acanthamoeba trophozoites constitutively express PLA2 that either directly induces cytopathic effects on the corneal epithelial cells or activates phospholipids and induces arachidonic acid release. The forth specific aim will test the hypothesis that treatment with PLA2 inhibitors and immunization with MIP-133 will mitigate the pathogenesis of Acanthamoeba keratitis. The long-range goal of this project is to evaluate the pathogenic mechanisms of Acanthamoeba keratitis that could have an enormous impact on designing improved therapies for Acanthamoeba patients that represent the most serious therapeutic dilemmas.