Encephalitozoan cuniculi-Host immunity and pathogenesis

描述（申请人提供）：微孢子虫是人类免疫缺陷（HIV）感染患者体内重要的原生动物寄生虫。最近的一项研究表明，高达40%的艾滋病相关腹泻患者正在脱落微孢子虫。这些寄生虫最近也被认为与未感染艾滋病毒的旅行者和免疫功能正常的老年人致病有关。宿主对这些病原体产生的免疫反应仍未得到充分研究。针对微孢子虫的有限研究强调了T细胞在抵抗寄生虫方面的重要性。微孢子虫是一种很容易在实验室培养的微孢子虫。T细胞缺陷小鼠，不像免疫正常的动物，不能解决感染。我们的实验室已经证明，在T细胞亚群中，CD8+细胞毒性T淋巴细胞在通过腹腔途径给药的弓形虫的保护中起主导作用。然而，在口腔感染期间，CD4和CD8+ T细胞都有助于对寄生虫的保护性免疫。由于小孢子虫是通过口服获得的，因此对肠道免疫反应的特征和保护机制的理解至关重要。我们实验室最近的研究表明，口腔结核菌感染可引起肠道内强烈而持久的上皮内淋巴细胞（IEL）反应。从感染动物中分离的IELs表现出强烈的抗原特异性细胞毒性和细胞因子反应。因此，IELs似乎在针对寄生虫的粘膜免疫反应中起重要作用。了解IEL介导的保护动力学和机制将为产生针对这些病原体的免疫治疗剂奠定基础。该建议包括三个具体目标。在第一个具体目标中，将评估IEL对cucuuli Enc感染的诱导反应。我们将分析来自Peyer’s斑块的树突状细胞（dc）在肠道内引发IEL反应中的作用。最后，研究Peyer斑块dc和IEL反应的机制。在第二个具体目标中，将分析不同IEL亚群在调节粘膜免疫对抗兔眼绦虫感染中的作用。将对IEL介导的对寄生虫的保护机制进行评估。在第三个具体目标中，将分析长期IEL对病原体的反应。我们的初步数据表明，免疫IELs在感染弓形虫的小鼠中持续存在很长时间。本研究将探讨长期抗原特异性免疫反应（记忆性免疫反应）在感染动物体内的发展和持续机制。

DESCRIPTION (Provided by applicant): Microsporidia are important protozoan parasites in human immunodeficiency (HIV) infected patients. A recent study showed up to 40% of patients with AIDS associated diarrheas were shedding microsporidia. These parasites have also been recently implicated in causing illness to non-HIV-infected travelers and immunocompetent elderly individuals. The host immune response generated against these pathogens remains understudied. The limited studies available with Enc. cuniculi, a microsporidia that can be easily cultured in the laboratory, have emphasized the importance of T cells in the protection against the parasite. T cell deficient mice, unlike the immunocompetent animals are unable to resolve the infection. Our laboratory has demonstrated that among the T cell subsets, CD8+ cytotoxic T lymphocytes play a dominant role in protection against E.cuniculi administered via intraperitoneal route. However, during an oral infection both CD4 and CD8+ T cells contribute to protective immunity against the parasites. As microsporidia are acquired orally, it is critical that the gut immune response evoked against the infection be characterized and mechanism of protection understood. Recent studies from our laboratory have shown that per oral Enc.cuniculi infection induces a strong and prolonged intraepithelial lymphocyte (IEL) response in the gut. IELs isolated from the infected animals exhibit strong antigen-specific cytotoxicity and cytokine response. Thus IELs appear to play an important role in mucosal immune response against the parasite. Understanding the kinetics and mechanism of IEL mediated protection will form a basis for generating immunotherapeutic agents against these pathogens. The proposal comprises of three specific aims. In the first specific aim the induction of IEL response to Enc. Cuniculi infection will be evaluated. Role of dendritic cells (DCs) from the Peyer's patches in priming IEL response in the gut will be assayed. Finally the mechanism by which Peyer's patch DCs and IEL response will be studied. In the second specific aim, the role of different IEL subsets in the regulation of mucosal immunity against Enc. cuniculi infection will be assayed. The mechanism of IEL mediated protection against the parasite will be evaluated. In the third specific aim long-term IEL response against the pathogen will be analyzed. Our preliminary data suggests that immune IELs in the Enc.cuniculi infected mice persist for a long period. Development and mechanism of persistence of long-term antigen specific IELs (memory IELs) in the infected animals will be evaluated.