IL-12 Regulation in Leishmania Infected Dendritic Cells

描述（由申请人提供）：树突状细胞（DC）是感染病原体遇到的第一批细胞;作为哨兵，这些细胞识别入侵微生物并分泌指示适应性免疫的类别分化的信号。介导DC区分病原体的能力的机制仍然难以捉摸。使用实验利什曼原虫感染，我们将评估宿主和寄生虫因子在产生白细胞介素-12（IL-12）（驱动Thl细胞分化的关键细胞因子）中发挥的确切作用。为了模拟利什曼原虫感染过程中的初始事件，我们采用了人DC和感染性阶段寄生虫的体外系统。我们以前证明，IL-12的诱导这些细胞是利什曼原虫物种依赖性的，需要CD40 L刺激。而致命性内脏疾病（L。donovani）不能诱导IL-12，感染L.主要是与自限性皮肤病相关的物种，引发DC分泌IL-12。该提案的总体目标是确定这些不同IL-12应答的分子决定因素。具体目标1将确定利什曼原虫属的调节点。调节IL-12的产生。将采取条件性方法来确定转录或转录后调节是否在响应利什曼原虫感染的IL-12产生中起作用。具体目标2将确定利什曼原虫的因素，调节IL-12的诱导，特别是调查的影响，不同的结构修饰的寄生虫表面。利什曼原虫寄生虫引发DC产生IL-12的能力的内在差异可能影响这些寄生虫激活Thl适应性应答的能力。这些研究强调了一个事实，即由活的L。重大感染导致强大的终身免疫力。阐明所涉及的关键组分将对其他病原体感染产生影响，这些病原体感染需要持续的细胞介导的保护反应。

DESCRIPTION (provided by applicant): Dendritic cells (DC) are among the first cells encountered by infecting pathogens; acting as sentries, these cells recognize invading microorganisms and secrete signals that dictate class differentiation of adaptive immunity. The mechanisms that mediate the ability of DC to discriminate between pathogens remain elusive. Using experimental Leishmania infection we will evaluate the precise contributions that host and parasite factors play in generating interleukin-12 (IL-12), the critical cytokine driving Thl cell differentiation. To model the initial events during Leishmania infection, we employ an in vitro system of human DC and infectious stage parasites. We previously demonstrated that the induction of IL-12 by these cells is Leishmania species dependent and requires CD40L stimulation. Whereas infection by species responsible for fatal visceral disease (L. donovani) fail to induce IL-12, infection with L. major a species associated with self-limiting cutaneous disease, primes DC for IL-12 secretion. The overall goal of this proposal is to identify the molecular determinants of these disparate IL-12 responses. Specific Aim 1 will determine the point of regulation at which Leishmania spp. modulate IL-12 production. A conditional approach will be taken to determine if transcriptional or post-transcriptional regulation plays a role in the production of IL-12 in response to Leishmania infection. Specific Aim 2 will identify the Leishmania factors that regulate IL-12 induction by specifically investigating the influence of different structural modifications on the parasite surface. Intrinsic differences in the ability of Leishmania parasites to prime DC for IL-12 production likely influences the capability of these parasites to activate Thl adaptive responses. These studies are underscored by the fact that the immune mechanisms elicited by live L. major infection leads to powerful life-long immunity. Elucidation of the critical components involved will have ramifications for other pathogen infections that require sustained cell-mediated responses for protection.