Autophagy and ocular toxoplasmosis

描述（申请人提供）：刚地弓形虫是世界上视网膜脉络膜炎最常见的原因。尽管使用抗生素，眼弓形虫病仍会复发，并且仍然是视力丧失的重要原因，特别是在先天性感染的儿童以及老年人和免疫抑制者中。不幸的是，我们对眼弓形虫病保护机制的理解是不完整的。巨噬细胞、小胶质细胞和T细胞是眼弓形虫病细胞浸润的主要组成部分。这些细胞之间相互作用的一个重要事件是刺激巨噬细胞/小胶质细胞上表达的CD40。我们发现了一种新的模式，免疫系统通过CD40杀死弓形虫。CD40诱导巨噬细胞和视网膜小胶质细胞的弓形虫活性。这依赖于自噬，这是一个针对寄生虫溶酶体降解的过程。这一发现可能是眼弓形虫病的关键，因为这种疾病的体内控制需要CD40。因此，研究cd40诱导的自噬调控可能会为根除弓形虫和治疗眼弓形虫病找到新的分子靶点，从而有望防止该病的复发。本应用的目的是了解巨噬细胞和视网膜小胶质细胞中的CD40信号如何控制眼弓形虫病，以及弓形虫如何破坏这些信号。本研究的中心假设是，CD40通过蛋白激酶激活和诱导自噬介导眼睛对弓形虫病的抗性。相比之下，弓形虫和由寄生虫触发的细胞因子使用一种策略来破坏自噬激活所需的信号，从而使寄生虫逃避根除。这一假设将通过免疫化学研究以及阻断特定囊泡运输分子的遗传方法进行验证。在第一个特定目标中，我们将确定CD40诱导的自噬和蛋白激酶激活是否介导对眼弓形虫病的抗性。在第二个目标中，我们将确定细胞因子阻止最佳自噬诱导的细胞内事件，并测试抑制这些事件是否可以改善对眼弓形虫病的控制。这项工作可能会导致基于调节自噬和/或CD40信号的新策略来根除弓形虫和治疗眼弓形虫病。公共卫生相关性：眼睛弓形虫病是一种复发性疾病，是视力丧失的主要原因。目前可用的治疗方案并不能预防这种疾病的复发。我们计划进行研究，希望能找到一些分子，用来增强免疫系统控制眼弓形虫病的能力。

DESCRIPTION (provided by applicant): Toxoplasma gondii is the most common cause of retinochoroiditis in the world. Ocular toxoplasmosis relapses despite the use of antibiotics and remains an important cause of loss of visual acuity especially in children with congenital infection as well as the elderly and the immunosuppressed. Unfortunately, our understanding of the mechanisms of protection against ocular toxoplasmosis is fragmentary. Macrophages, microglia and T cells are the major components of the cell infiltrates in ocular toxoplasmosis. An important event in the interaction between these cells is the stimulation of CD40 expressed on macrophages/microglia. We identified a new paradigm by which the immune system through CD40 kills T. gondii. CD40 induces toxoplasmacidal activity in macrophages and retinal microglia. This is dependent on autophagy, a process that targets the parasite to lysosomal degradation. This finding is likely key to ocular toxoplasmosis because in vivo control of this disease requires CD40. Thus, studying the regulation of CD40-induced autophagy will likely identify new molecular targets for eradication of T. gondii and for therapy of ocular toxoplasmosis that will hopefully prevent relapse of this disease. The objective of this application is to understand how CD40 signaling in macrophages and retinal microglia controls ocular toxoplasmosis and how T. gondii subverts these signals. The central hypothesis for the proposed research is that, CD40 mediates resistance against toxoplasmosis in the eye through protein kinase activation and induction of autophagy. In contrast, T. gondii and cytokines triggered by the parasite use a strategy to impair the signaling needed for optimal activation of autophagy allowing the parasite to evade eradication. This hypothesis will be tested using immunochemical studies as well as genetic approaches that block specific vesicular trafficking molecules. In the first specific aim we will determine if autophagy and protein kinase activation induced by CD40 mediate resistance to ocular toxoplasmosis. In the second aim, we will identify the intracellular events by which cytokines prevent optimal induction of autophagy and test whether inhibition of these events improves control of ocular toxoplasmosis. The proposed work may lead to new strategies to eradicate T. gondii and treat ocular toxoplasmosis based on modulation autophagy and/or CD40 signaling. PUBLIC HEALTH RELEVANCE: Toxoplasmosis of the eye is a relapsing disease and a major cause of visual loss. Currently available therapeutic regimens do not prevent relapse of this disease. We plan studies that will hopefully identify molecules that can be used to boost the ability of the immune system to control ocular toxoplasmosis.