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其参与先天性和适应性免疫应答而清楚地证明。最近对肥大细胞的各种功能的了解揭示了这些先天性免疫效应物具有杀死微生物和改变经典适应性免疫应答的双重能力。抗菌肽（AMP）的凯萨林菌素家族成员在肥大细胞和上皮损伤部位表达。Cathelicidin肽的定位、其细胞外释放的触发剂以及其改变炎症反应的能力都表明Cathelicidin在肥大细胞抗感染的能力中起重要作用。我们已经证明，小鼠肥大细胞使用cathelicidin来对抗皮肤病原体引起的感染。不幸的是，对人肥大细胞的抗微生物功能知之甚少，也没有描述人肥大细胞中凯萨林菌素AMP活性的研究。该提案的主要目标是研究人类肥大细胞如何调节cathelicidin表达以对抗皮肤病原体引起的感染。本研究的主要目的是：1.鉴定和定义人肥大细胞cathelicidin。a.鉴定调节人肥大细胞凯萨林菌素表达的信号。B.定义人类肥大细胞中的凯萨林菌素加工过程。具体目的2：研究人肥大细胞凯萨林菌素的抗菌活性。a.研究Toll样受体活化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凯萨林菌素肽的抗微生物活性。C.确定抗菌肽对人肥大细胞抗菌活性的贡献。具体目的3：建立一种检测人肥大细胞抗菌肽抗菌活性的动物模型。a.产生表达人或小鼠凯萨林菌素的肥大细胞的体外培养物。B.用培养的肥大细胞重建肥大细胞缺陷小鼠。C.用细菌皮内攻击小鼠。这个探索性项目将汇集具有独特和互补专业知识领域的研究人员，以提高我们对cathelicidin AMP在皮肤免疫中作用的理解。这些知识有可能导致建立新的治疗靶点和策略，以对抗使用皮肤作为入口的人类病原体的感染。我们认为，这一提议特别符合PA-06-181和探索性发展赠款机制的目标。肥大细胞通过产生抗菌肽（如β-防御素和cathelicidins）的能力来保护自己并控制病原体。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，这些受体提醒制备凯萨林菌素抗菌肽的特定酶杀死入侵的病原体。该提案旨在解开我们对人类肥大细胞中这种先天免疫途径的理解，最终目标是增强抗菌肽活性。

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.