IL-12 Regulation in Leishmania Infected Dendritic Cells

描述（由申请人提供）：树突状细胞（DC）是感染病原体时最先遇到的细胞之一；这些细胞充当哨兵，识别入侵的微生物并分泌信号，指示适应性免疫的类别分化。介导 DC 区分病原体的能力的机制仍然难以捉摸。利用实验性利什曼原虫感染，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 Th1 细胞分化的关键细胞因子）方面所起的精确作用。为了模拟利什曼原虫感染期间的初始事件，我们采用了人类 DC 和感染期寄生虫的体外系统。我们之前证明，这些细胞对 IL-12 的诱导是利什曼原虫物种依赖性的，并且需要 CD40L 刺激。导致致命性内脏疾病的物种（杜氏乳杆菌）的感染不能诱导 IL-12，而与自限性皮肤病相关的大型乳杆菌感染则可以促使 DC 分泌 IL-12。该提案的总体目标是确定这些不同 IL-12 反应的分子决定因素。具体目标 1 将确定利什曼原虫属的监管点。调节 IL-12 的产生。将采取有条件的方法来确定转录或转录后调控是否在响应利什曼原虫感染的 IL-12 产生中发挥作用。具体目标 2 将通过专门研究不同结构修饰对寄生虫表面的影响来确定调节 IL-12 诱导的利什曼原虫因子。利什曼原虫寄生虫启动 DC 产生 IL-12 的能力的内在差异可能会影响这些寄生虫激活 Thl 适应性反应的能力。这些研究强调了这样一个事实：活的大型利斯特菌感染引发的免疫机制可带来强大的终生免疫力。阐明所涉及的关键成分将对其他需要持续细胞介导反应进行保护的病原体感染产生影响。

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.