Trpm2 Regulation of Phagocyte Bactericidal Activity and Resolution of Lung Injury

项目摘要 肺泡巨噬细胞(AM-Ф)对细菌的杀灭效率是决定肺功能的重要因素 解决炎症性肺损伤的能力，确实可能是发展对肺的耐受性所必需的 继发感染所致的损伤。然而，细菌杀灭的分子机制还不是很清楚。 明白了。支撑项目1的关键观测显示了 吞噬体膜相关阳离子--ROS敏感的瞬时受体电位-2，TRPM2 通道，调节M-Ф的杀菌活性。TRPM2对控制吞噬小体的pH是必不可少的 阻断TRPM2介导的酸化阻止了细菌的杀灭，而且增强了 炎症性肺损伤。因此，在项目1中，我们将检验与吞噬小体相关的中心假设 M-Ф中的TRPM2通过调节吞噬促进炎性肺损伤的消退 酸化，因此是激活细菌杀灭的中心机制。这一假设将是 通过解决以下特定目标(SA)进行测试。SA#1将决定吞噬小体的作用 氧化酶NOX2和/或NOX4在调节吞噬小体中诱导的膜TRPM2激活 MФ的酸化特性，从而产生杀菌能力强的MФ。SA#2将定义关键的 TRPM2调节M-Ф的负反馈机制也可能通过抑制来酸化吞噬小体 NOX2/NOX4介导ROS的产生，从而促进M-Ф的杀菌作用。SA#3将 确定TRPM2调节的吞噬体酸化在减轻炎性肺损伤中的作用 在吞噬细胞中特异性缺失TRPM2的转基因模型及其作用增强 吞噬体酸化在提高对继发感染损伤耐受性中的作用我们假设，通过 确定负责MФ吞噬体内TRPM2激活的中央信号机制，它将 有可能制定更有效地解决炎症性肺损伤的策略，并使肺的 通过增强M-Ф的杀菌功能来耐受伤害。

Project Summary The efficiency of bacterial killing by alveolar macrophages (AMФ) is an essential determinant of the lung's ability to resolve inflammatory lung injury, and indeed may be required for the development of tolerance to lung injury induced by secondary infection. However, the molecular mechanisms of bacterial killing are not well understood. The crucial observation underpinning Project 1 shows a fundamental host-defense function of the ROS-sensitive transient receptor potential melastatin-2, TRPM2, a phagosomal membrane-associated cation channel, in regulating bactericidal activity of MФ. TRPM2 was essential for controlling the pH of phagosomes and blocking of the TRPM2-mediated acidification prevented bacterial killing and, moreover, enhanced inflammatory lung injury. Thus, in Project 1 we will test the central hypothesis that phagosome-associated TRPM2 in MФ promotes the resolution of inflammatory lung injury by regulating phagosomal acidification, and thereby is a central mechanism for activating bacterial killing. This hypothesis will be tested by addressing the following Specific Aims (SA). SA #1 will determine the role of phagosomal membrane TRPM2 activation induced by the oxidases NOX2 and/or NOX4 in regulating the phagosomal acidification property of MФ, and thus in generating bactericidal-competent MФ. SA #2 will define the crucial TRPM2-regulated negative feedback mechanism in MФ that may also acidify phagosomes through dampening NOX2/NOX4-mediated ROS production, and thus the promote bacteria killing function of MФ. SA #3 will determine the role of TRPM2 regulated phagosomal acidification in resolving inflammatory lung injury using genetically modified models with specific deletion of TRPM2 in phagocytic cells, and the role enhanced phagosomal acidification in promoting the tolerance to injury induced by secondary infection. We posit that by identifying the central signaling mechanisms responsible for TRPM2 activation in the MФ phagosomes, it will be possible to develop strategies to more effectively resolve inflammatory lung injury and to make lung's tolerance to injury through enhancing bacterial killing function of MФ.