IL-12 in Leishmania infected human dendritic cells

描述(申请人提供)：利什曼病是一种世界性疾病 在许多发展中国家造成相当大的发病率和死亡率。 利什曼原虫感染的临床表现差异很大。 从自我修复损伤到致命的内脏疾病，并被归因于 引发感染的利什曼原虫物种的差异。事实是 这些寄生虫表现出如此不同的毒力特征使得 这个群体是一个很好的模型，可以评估 而寄生虫的相关特性在产生不同的病理过程中起到了作用。 研究利什曼原虫抗性的动物模型显示保护性免疫 需要产生依赖CD40/CD40L的IL-12产生的Th1 回应。在感染期间发生的初始事件为 随后的免疫反应。模拟利什马尼亚的最初事件 感染，我们使用了一个人树突状细胞(DC)和 感染期寄生虫。我们之前已经证明了诱导 这些细胞分泌的IL-12依赖于寄生虫种类，需要CD40L 刺激。而引起内脏疾病的物种感染 (L.donovani)不会上调CD40L依赖的IL-12的产生， 感染大型乳杆菌，一种与自限性皮肤有关的物种 疾病，启动树突状细胞以增加IL-23的分泌。整体而言 这项提议的目标是确定相关的分子决定因素。 对于这些不同的IL-12反应。有两种可能性可以解释这些问题 不同之处：1)L.主要寄生虫有一些内在的激发能力 人DC用于产生IL-12，或2)一般微生物刺激用于 IL-23和L.donovani寄生虫诱导一些下调级联反应以抑制 CD40L对IL-12的刺激作用为了检验这些假设，我们的目标如下 建议：具体目标：1.鉴定人DC分泌产物 在IL-12调节中起作用的利什曼原虫。因素的归纳法 利什曼原虫诱导及其抑制或增强能力 将对IL-12的产生进行评估。具体目标2.确定切入点 利什曼原虫。调节人树突状细胞产生IL-12。 将进行研究，以确定阻断IL-12在L。 多诺瓦尼感染的DC涉及转录或翻译调节。 特指3.调控IL-12诱导的因子(S)的鉴定 利什马尼亚。利什曼原虫与宿主细胞的结合和入侵是介导性的 通过特定的宿主细胞表面受体。这些特定角色 利什曼原虫启动人DC产生IL-12的受体将是 评估过了。还将开始研究以确定寄生虫因素。 参与了这一过程。在能力上的内在差异 利什曼原虫刺激树突状细胞产生IL-12可能是部分原因 利什曼病的治愈和不可治愈形式的演变 可以作为新的抗原或化疗靶点来对抗这种疾病 毁灭性的疾病。

DESCRIPTION (provided by applicant): Leishmaniasis is a cosmopolitan disease causing substantial morbidity and mortality in much of the developing world. The clinical manifestations of Leishmania infection vary substantially ranging from self-healing lesions to fatal visceral disease and are attributed to differences in the Leishmania species initiating the infections. The fact that these parasites exhibit such different virulence characteristics makes this group an excellent model to evaluate the precise contributions that host and parasite related properties play in generating different pathologies. Animal models studying resistance to Leishmania indicate protective immunity requires the generation of CD40/CD40L-dependent IL-12 generated Th 1 responses. The initIal events that occur during an infection set the tone for a subsequent immune response. To model the initial events of Leishmania infection, we employ an in vitro system of human dendritic cells (DC) and infectious stage parasites. We previously demonstrated that the induction of IL-12 by these cells is parasite species dependent and requires CD40L stimulation. Whereas infections with species responsible for visceral disease (L. donovani) cause no upregulation of CD40L-dependent IL-12 production, infection with L. major, a species associated with self-limiting cutaneous disease, primes dendritic cells for augmented IL-23 secretion. The overall goal of this proposal is to identify the molecular determinants responsible for these disparate IL-12 responses. Two possibilities exist to explain these differences: 1) L. major parasites have some intrinsic capacity to prime human DC for IL-12 production, or 2) microbial stimulus in general primes for IL-23 and L. donovani parasites induce some down-regulatory cascade to inhibit CD40L stimulation of IL-12. To test these hypotheses, the following aims are proposed: Specific Aim 1. To identify DC secreted products induced by Leishmania that play a role in IL-12 regulation. The induction of factors induced by Leishmania parasites and their inhibitory or enhancing capacities on IL-12 production will be assessed. Specific Aim 2. To determine the point of regulation that Leishmania spp. modulate IL-12 production in human DC. Studies will be performed to determine if the block on IL-12 secretIon in L. donovani- infected DC involves transcriptional or translational regulation. Specific Aim 3. Identification of the factor(s) that regulate IL-12 induction by Leishmania. Leishmania binding to and invasion of host cells is mediated via specific host cell surface receptors. The role of these specific receptors in Leishmania priming of human DC for IL-12 production will be assessed. Studies also will be initiated to identify the parasite factors involved in this process. The intrinsic differences in the ability of Leishmania to prime dendritic cells for IL-12 production partially may account for the evolution of healing and non-healing forms of leishmanial disease and may serve as novel antigens or chemotherapeutic targets to combat this devastating disease.