IL-12 Regulation in Leishmania Infected Dendritic Cells

描述(申请人提供)：树突状细胞(DC)是感染病原体的第一批细胞之一；作为哨兵，这些细胞识别入侵的微生物并分泌信号，决定适应性免疫的类别分化。树突状细胞区分病原体能力的调节机制仍不清楚。利用实验性利什曼原虫感染，我们将评估宿主和寄生虫因素在产生白介素12(IL-12)方面所起的确切作用，白介素12是驱动Th1细胞分化的关键细胞因子。为了模拟利什曼原虫感染期间的初始事件，我们使用了人类DC和感染期寄生虫的体外系统。我们先前证明这些细胞对IL-12的诱导依赖于利什曼原虫的种类，并且需要CD40L的刺激。而引起致命性内脏疾病的物种(L.donovani)的感染不能诱导IL-12，而与自限性皮肤病相关的主要L.m a物种的感染则为IL-12的分泌启动DC。这项提案的总体目标是确定这些不同的IL-12反应的分子决定因素。具体目标1将确定利什曼原虫的调节点。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反应利什曼原虫感染的IL-12的产生中发挥作用。具体目标2将通过具体研究不同结构修饰对寄生虫表面的影响来鉴定调节IL-12诱导的利什曼因子。利什曼原虫启动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Th1适应性反应的能力。这些研究强调了这样一个事实，即主要活菌感染引发的免疫机制会导致强大的终身免疫。对所涉及的关键成分的阐明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反应来保护。

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.