Host cell proteins that interact with Cryptosporidium

描述（申请人提供）：小隐孢子虫是一种人畜共患病原体，可引起艾滋病患者的机会性感染之一（AIDS- oi）。由于缺乏针对隐孢子虫感染的高效治疗和这种寄生虫的自身感染潜力，免疫功能低下个体的隐孢子虫病可能会延长并危及生命。尽管全球公认隐孢子虫病对人类和动物健康的重要性，但人类和动物对隐孢子虫病的发病机制仍知之甚少。目前还不清楚宿主细胞和寄生虫在感染过程中是如何相互作用的。本项目的长期目标是阐明隐孢子虫感染过程中宿主-病原体相互作用的分子机制。我们的初步分析已经确定了人类细胞中的一些基因，这些基因受细小梭状芽孢杆菌感染的显著调节。一组值得注意的受调节基因是细胞外基质（ECM）蛋白，包括整合素、基质金属蛋白酶（MMP）和层粘连蛋白，它们可能位于宿主细胞-寄生虫界面或寄生虫周围。此外，我们还观察到细小梭菌起源的膜蛋白可以靶向寄主-寄主边界的宿主细胞膜和寄主液泡膜（PVM），这表明寄主和寄主细胞在分子水平上相互作用。基于这些观察结果，我们假设宿主细胞蛋白在感染期间积极参与与细胞内寄生虫的相互作用和通信。在这个探索性项目中，我们将通过实现以下两个特定目标来验证我们的假设：目标1)利用隐孢子虫病的体外模型确定在感染过程中可能直接与小孢子虫相互作用的宿主细胞分子；目的2)确定宿主细胞整合素相关通路在宿主-病原体相互作用中的作用。通过实现目标1，我们将确定一系列重要的宿主细胞表面蛋白，特别是那些在人类和牛细胞中共享的ECM蛋白，为未来研究它们在入侵和发育过程中与隐孢子虫的潜在相互作用奠定基础。通过实现目标2，我们将证实或反驳我们的假设，即宿主整合素相关途径确实参与了寄生虫感染的建立。小隐孢子虫是艾滋病患者中一种无法治愈的机会致病菌。对隐孢子虫病的发病机制知之甚少，特别是宿主细胞蛋白如何参与这种寄生虫的感染。本探索性项目旨在识别和研究宿主细胞细胞外基质蛋白在感染中的作用。这个项目的完成不会增加我们对疾病原因的了解，但也有可能为干预隐孢子虫病找到新的目标，艾滋病患者目前尚无治疗方法。

DESCRIPTION (provided by applicant): Cryptosporidium parvum is a zoonotic pathogen and can cause one of the opportunistic infections in AIDS patients (AIDS-OI). Because of the lack of highly effective treatment against Cryptosporidium infection and the autoinfection potential of this parasite, cryptosporidiosis in immunocompromised individuals can be prolonged and life-threatening. Despite its globally recognized importance in human and animal health, the pathogenesis of cryptosporidiosis in both humans and animals is still poorly understood. It is particularly unclear how the host cell and parasite interact physically and biochemically with each other during infection. The long-term goal of this project is to elucidate the molecular mechanisms involved in the host-pathogen interactions during the Cryptosporidium infection. Our preliminary analysis has identified a number of genes in human cells that are significantly regulated by the C. parvum infection. One noticeable group of the regulated genes are extracellular matrix (ECM) proteins, including integrin, matrix metalloproteinase (MMP) and laminin, that are likely located at the host cell-parasite interface or around the parasite. Additionally, we have also observed that C. parvum-originated membrane proteins can be targeted to the host cell membranes at the parasite-host boundary and parasitophorous vacuole membrane (PVM), suggesting that both the parasite and host cells actively interact with each other at molecular level. Based on these observations, we hypothesize that host cell proteins are actively involved in the interactions and communications with the intracellular parasite during infection. In this exploratory project, we will test our hypothesis by achieving the following two specific aims: Aim 1) Identify host cell molecules that may directly interact with C. parvum during infection using in vitro models of cryptosporidiosis; and Aim 2) Determine the role of the host cell integrin- associated pathway in the host-pathogen interactions. By achieving aim 1, we will identify a list of important host cell surface proteins, particularly those ECM proteins shared in both human and bovine cells, for future studying their potential interactions with Cryptosporidium during invasion and development. By achieving aim 2, we will confirm or refute our hypothesis that host integrin-associated pathway is indeed participated in the establishment of parasite infection. PUBLIC HEALTH RELEVANCE Cryptosporidium parvum is an untreatable opportunistic pathogen in AIDS patients. Little is known on the pathogenesis of cryptosporidiosis, particularly on how the host cell proteins contribute to the infection by this parasite. This exploratory project aims to identify and study the roles of host cell extracellular matrix proteins in infection. The completion of this project will not increase our knowledge on the cause of disease, but also has the potential to find new targets for intervening cryptosporidiosis for which no treatment is yet available in AIDS patients.