PATHOPHYSIOLOGY OF BILIARY CRYPTOSPORIDIOSIS

描述(改编自申请者摘要)：长期目标为 更好地理解胆管细胞(上皮细胞)的作用 胆管)在健康和疾病中，目前的提议集中在 胆管上皮细胞与微小隐孢子虫的相互作用 在艾滋病的发展中起重要作用的一种新的病原体--胆管病。vbl.使用 作者建立的胆道隐孢子虫病体外模型 已发现微小弧菌在直接感染时激活核因子-kB系统 胆管细胞；发现微小弧菌只在旁观者中诱导细胞凋亡 未感染的胆管细胞通过Fas/FasL依赖机制； 微小隐孢子虫诱导FasL表达并刺激细胞膜FasL裂解 直接感染胆管细胞。他们还发现，虽然艾滋病毒-1可以 不感染胆管细胞，重组具有生物活性的HIV-1Tat蛋白 增强Fas介导的和微小葡萄球菌相关的细胞凋亡 胆管细胞。基于这些初步数据，作者提出了这部小说 中心假说：微小弧菌可导致患者胆道疾病 通过两个相互依赖和互补的机制感染艾滋病：(1)微小隐孢子虫 通过激活核因子-kB抑制感染胆管细胞的凋亡 允许有机体寄生受感染细胞的生存途径 微小隐孢子虫通过以下途径促进未感染胆管细胞的凋亡 Fas/FasL促凋亡通路的激活及其协同作用 HIV依赖的可溶性因子，如TAT。他们将采用互补性 生物化学、分子和形态学方法解决三个具体问题 目的：(1)微小弧菌通过直接寄生/宿主细胞激活NFkB系统 膜相互作用和触发细胞生存信号允许微生物 (2)微小隐孢子虫激活核转录因子诱导 FasL在直接感染的胆管细胞中的表达及对膜的刺激作用 FasL裂解；(3)FasL表达上调，细胞膜增多 微小隐孢子虫感染的胆管细胞中FasL裂解与HIV-1的协同作用 Tat蛋白，通过Fas/FasL诱导旁观者未感染细胞凋亡 依赖机制。这些实验的结果将澄清分子 微小隐孢子虫对胆管上皮细胞的细胞病变机制。 该计划的创新方面包括新颖的方法和概念 关于微小隐孢子虫与胆管细胞的相互作用。所产生的信息可能 为开发新的治疗策略提供理论框架 治疗微小隐孢子虫引起的艾滋病-胆管病。

DESCRIPTION (Adapted from the Applicant's Abstract): With the long-term goal of better understanding the role of cholangiocytes (epithelial cells that line bile ducts) in health and disease, the current proposal focuses on the interactions between biliary epithelia and Cryptosporidium parvum (C. parvum), an emerging pathogen important in the development of AIDS-cholangiopathy. Using an in vitro model of biliary cryptosporidiosis established by the authors, they have found that C. parvum activates the NF-kB system in directly infected cholangiocytes; discovered that C. parvum induces apoptosis only in bystander uninfected cholangiocytes via a Fas/FasL dependent mechanism; and demonstrated that C. parvum induces FasL expression and stimulates membrane FasL cleavage in directly infected cholangiocytes. They have also found that while HIV- 1 can not infect cholangiocytes, recombinant biologically active HIV- 1 TAT protein enhances both Fas-mediated and C. parvum-associated apoptosis in cholangiocytes. Based on these preliminary data, the authors propose the novel central hypothesis that C. parvum induces biliary tract disease in patients with AIDS by two interdependent and complementary mechanisms: (i) C. parvum inhibits apoptosis in infected cholangiocytes by activation of the NF-kB survival pathway allowing the organism to parasitize the infected cell to propagate; (ii) C. parvum promotes apoptosis in uninfected cholangiocytes via activation of the Fas/FasL pro-apoptotic pathway and the synergistic effects of HIV-dependent soluble factors such as TAT. They will employ complementary biochemical, molecular and morphologic approaches to address three specific aims: (1) C. parvum activates the NFkB system via direct parasite/host cell membrane interactions and triggers cell survival signals allowing for microbial propagation; (2) C. parvum activates nuclear transcription factors to induce FasL expression in directly infected cholangiocytes and stimulates membrane FasL cleavage; and (3) upregulation of FasL expression and increase of membrane FasL cleavage in C. parvum infected cholangiocytes, synergistically with HIV-1 TAT protein, causes apoptosis in bystander uninfected cells via a Fas/FasL dependent mechanism. Results of these experiments will clarify the molecular mechanisms by which C. parvum is cytopathic for biliary epithelial cells. Innovative aspects of the program include novel methodologies and concepts regarding C. parvum-cholangiocyte interaction. The information generated could provide a theoretical framework for development of novel therapeutic strategies for C. parvum induced AIDS-cholangiopathy.