Mast cell controls pathogen entrance by the expression of antimicrobial peptides

描述(由申请人提供)：肥大细胞的多功能性质通过它们参与先天性和获得性免疫反应清楚地展示出来。最近对肥大细胞各种功能的研究表明，这些先天免疫效应器具有杀死微生物和改变经典获得性免疫反应的双重能力。抗菌肽(AMPs)家族成员在肥大细胞和上皮损伤部位均有表达。放线菌素多肽的定位、细胞外释放的触发物以及它们改变炎症反应的能力都表明，放线菌素在肥大细胞抵抗感染的能力中发挥着重要作用。我们已经证明了小鼠肥大细胞使用放线菌素来对抗皮肤病原体引起的感染。不幸的是，对人类肥大细胞的抗菌功能知之甚少，也没有关于长春新素AMP在人类肥大细胞中的活性的研究。这项建议的主要目标是研究人类肥大细胞如何调节放线菌素的表达，以对抗皮肤病原体引起的感染。本研究提出：具体目标1：鉴定和确定人肥大细胞内毒素。A.确定调节人肥大细胞内分泌蛋白表达的信号。B.确定在人类肥大细胞中的长春花碱加工过程。具体目的2：研究人肥大细胞抑菌素的抗菌活性。A.研究Toll样受体激活在人肥大细胞抗菌活性中的作用。B.评价加工的人肥大细胞抗菌素多肽的抗菌活性。C.确定长春花素对人肥大细胞抗菌活性的贡献。具体目的3：建立动物模型，检测人肥大细胞抑菌素的抗菌活性。A.体外培养表达人或小鼠去毛滴虫的肥大细胞。B.用培养的肥大细胞重建肥大细胞缺陷小鼠。C.用细菌对小鼠进行皮内挑战。这一探索性项目将把具有独特和互补专业知识领域的研究人员聚集在一起，以加强我们对天青素AMPS在皮肤免疫中的作用的了解。这一知识有可能导致建立新的治疗目标和战略，以对抗利用皮肤作为进入门户的人类病原体的感染。我们认为，这项建议特别符合PA-06-181的目标和探索性发展赠款机制。与公共健康相关的肥大细胞通过产生抗菌肽(如β-防御素和排泄素)来自卫和控制病原体。我们已经在初步实验中表明，小鼠肥大细胞通过受体感知细菌，这种受体提醒特定的酶，准备肠道杀菌素抗菌肽来杀死入侵的病原体。这项提议试图揭开我们对人类肥大细胞中这一先天免疫途径的理解，最终目的是增强抗菌肽的活性。

DESCRIPTION (provided by applicant): The multifunctional nature of mast cells is clearly demonstrated through their involvement in both innate and adaptive immune responses. Recent insight into the various functions of mast cells has revealed that these innate immune effectors possess the dual ability to kill microbes and to modify classical adaptive immune responses. Members of the cathelicidin family of antimicrobial peptides (AMPs) are expressed in mast cells and at sites of epithelial injury. The localization of cathelicidin peptides, the trigger for their extracellular release, and their capacity to modify inflammatory responses all suggest that cathelicidins play an important role in the capacity of mast cells to fight infection. We have demonstrated that mouse mast cells use cathelicidin to fight infections caused by skin pathogens. Unfortunately, very little is known on human mast cell antimicrobial function and no studies describing cathelicidin AMP activity in human mast cells are available. The major goal of this proposal is to investigate how human mast cells regulate cathelicidin expression to fight infections caused by skin pathogens. This investigation proposes to: Specific Aim 1: Identify and define human mast cell cathelicidin. a. Identify signals that regulate expression of human mast cell cathelicidin. b. Define cathelicidin processing in human mast cells. Specific Aim 2: Investigate the antimicrobial activity of human mast cell cathelicidin. a. Investigate the role of Toll-like receptor activation in human mast cell antimicrobial activity. b. Evaluate the antimicrobial activity of processed human mast cell cathelicidin peptides. c. Ascertain the contribution of cathelicidin to human mast cell antimicrobial activity. Specific Aim 3: Establish an animal model to test the antimicrobial activity of human mast cell cathelicidin. a. Generate extracorporeal cultures of mast cells that express human or mouse cathelicidin. b. Reconstitute mast cell-deficient mice with cultured mast cells. c. Challenge mice intradermally with bacteria. This exploratory project will bring together investigators with unique and complementary areas of expertise in order to enhance our understanding of the role of cathelicidin AMPs in skin immunity. This knowledge has the potential to lead to the establishment of new therapeutic targets and strategies to combat infections by human pathogens that use the skin as a portal of entry. We believe that this proposal is particularly responsive to the goals of PA-06-181 and the exploratory developmental grant mechanism. PUBLIC HEALTH RELEVANCE Mast cells defend themselves and keep pathogens under control through their ability to produce antimicrobial peptides such as beta-defensins and cathelicidins. We have shown in preliminary experiments that mouse mast cells sense bacteria through receptors, which alert specific enzymes that prepare cathelicidin antimicrobial peptides to kill invading pathogens. This proposal seeks to unravel our understanding of this innate immune pathway in human mast cells with the ultimate goal of enhancing antimicrobial peptide activity.