Host cell proteins that interact with Cryptosporidium

描述（由申请人提供）：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（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延长并危及生命。尽管隐孢子虫病在人类和动物健康中的重要性得到全球公认，但其在人类和动物中的发病机制仍然知之甚少。目前还不清楚宿主细胞和寄生虫在感染过程中如何相互作用。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，这些基因受到C。细小病毒感染一组值得注意的调控基因是细胞外基质（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C.寄生虫来源的膜蛋白可以靶向于寄生虫-宿主边界处的宿主细胞膜和寄生虫液泡膜（PVM），这表明寄生虫和宿主细胞在分子水平上彼此活跃地相互作用。基于这些观察结果，我们假设宿主细胞蛋白在感染过程中积极参与与细胞内寄生虫的相互作用和通信。在这个探索性的项目中，我们将通过实现以下两个具体目标来测试我们的假设：目标1）鉴定可能直接与C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途径在宿主-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ECM蛋白在人类和牛细胞共享，为未来研究其潜在的相互作用与隐孢子虫在入侵和发展。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。公共卫生相关性微小隐孢子虫是艾滋病患者中一种无法治愈的机会致病菌。关于隐孢子虫病的发病机制，特别是宿主细胞蛋白如何参与这种寄生虫的感染，知之甚少。本探索性项目旨在鉴定和研究宿主细胞外基质蛋白在感染中的作用。该项目的完成不会增加我们对病因的了解，但也有可能找到新的靶点，用于干预艾滋病患者尚未获得治疗的隐孢子虫病。

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.