Innate immunity and dendritic cells in cryptosporidiosis

描述（由申请方提供）：本申请是对RFA-AI-05-042关于对B类原生动物（其中隐孢子虫属是最重要的原生动物）的天然免疫力的回应。2种，C. hominis和C.微小孢子虫与人类隐孢子虫病有关，隐孢子虫病是世界范围内发病率和死亡率的严重原因，对此没有有效的预防治疗。我们的目标是阐明免疫细胞启动抵抗隐孢子虫病的机制 以期更好地了解免疫反应的各个组成部分将导致开发有效的疫苗和佐剂来对抗人类感染。我们的中心假设是树突状细胞通过Toll样受体识别隐孢子虫，Toll样受体启动抵抗寄生虫入侵的过程。我们基于以下观察结果：1）树突状细胞通过Toll样受体感知病原体，导致过继免疫应答的启动，2）主要由树突状细胞产生的促炎细胞因子IL-12在控制隐孢子虫感染中至关重要，3）小鼠需要骨髓来源的CD 40阳性细胞来清除隐孢子虫。细小病毒感染基于这些观察结果，具体的目的是调查先天免疫应答隐孢子虫病，以确定Toll样受体信号传导的机制，导致这种反应，使用小鼠和人树突状细胞。具体的目的是：1）表征小鼠树突状细胞在先天性免疫缺陷中的作用， 抗C. 2）确定人树突状细胞在感染C. parvum或C. 3）鉴定隐孢子虫使用的Toll样受体并分离寄生虫表达的TLR活化配体。拟议的研究将为理解先天免疫识别机制和对寄生虫入侵的反应提供基础，这对未来设计疫苗和其他干预方法是必要的。

DESCRIPTION (provided by applicant): This application is in response to RFA-AI-05-042 on Innate Immunity to Category B protozoa of which Cryptosporidium spp rank among the most significant. Two species, C. hominis and C. parvum, are linked with human cryptosporidiosis, a serious cause of morbidity and mortality worldwide, and against which there is no effective therapy of prevention. Our goal is to elucidate the mechanisms by which immune cells initiate resistance against cryptosporidiosis with a view that a better understanding of the various components of the immune response will lead to development of effective vaccines and adjuvants to combat the infection in humans. Our central hypothesis is that dendritic cells recognize Cryptosporidium through Toll like receptor(s) which initiate the process of resistance against parasite invasion. We base this on the observations that: 1) dendritic cells sense pathogens through Toll-like receptors which lead to the initiation of adoptive immune responses, 2) proinflammatory cytokine IL-12, predominately produced by dendritic cells, is critical in controlling Cryptosporidium infection, and 3) bone marrow-derived CD40-positive cells are required for mice to clear C. parvum infection. Based on these observations, the specific aims are designed to investigate the innate immune response to cryptosporidiosis with a view to determining the mechanisms of Toll-like receptor signaling that lead to such responses, using both mice and human dendritic cells. The specific aims are to: 1) characterize the role of mouse dendritic cells in the innate immune response against C. parvum infection; 2) determine the nature of activation of human dendritic cells upon infection with C. parvum or C. hominis; 3) identify the Toll-like receptor used by Cryptosporidium and isolate TLR activating ligand(s) expressed by the parasite. The proposed studies will provide the basis for understanding the mechanisms of innate immune recognition and response to parasite invasion necessary for future design of vaccines and other methods of interventions.