Innate immunity and dendritic cells in cryptosporidiosis

描述(申请人提供)：本申请是对RFA-AI-05-042关于对B类原生动物的天然免疫的回应，其中隐孢子虫是最重要的原生动物之一。人类隐孢子虫病和微小隐孢子虫病这两个物种与人类隐孢子虫病有关，隐孢子虫病是全世界发病率和死亡率的严重原因，目前还没有有效的预防方法。我们的目标是阐明免疫细胞对隐孢子虫病产生抵抗的机制。 认为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(S)识别隐孢子虫，Toll样受体启动了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，导致过继免疫反应的启动；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起关键作用；3)小鼠清除微小隐孢子虫感染需要骨髓来源的CD40阳性细胞。在这些观察的基础上，利用小鼠和人树突状细胞研究隐孢子虫病的先天免疫反应，以期确定导致这种反应的Toll样受体信号转导机制。其具体目的是：1)表征小鼠树突状细胞在先天感染中的作用。 目的：研究隐孢子虫感染后的免疫应答；2)确定人树突状细胞在感染微小隐孢子虫或人隐孢子虫时的激活性质；3)鉴定隐孢子虫使用的Toll样受体，分离隐孢子虫表达的TLR激活配体(S)。拟议的研究将为理解先天免疫识别和应对寄生虫入侵的机制提供基础，这是未来设计疫苗和其他干预方法所必需的。

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.