Ion Flux Regulation of Macrophage Plasticity in Lung Injury and Repair

项目摘要/摘要 巨噬细胞(M-φ)对肺的先天免疫功能是必不可少的。巨噬细胞的能力 整合来自微生物和组织生态位的信号并极化可以促进或分解 炎症性肺损伤。项目1显示了激活的细胞外ATP(e[ATP])的基本作用--和 嘌呤能受体P2RX7(嘌呤能受体2亚型X7)与[Ca~(2+)]不敏感的协同作用 钾(K+)通道TWIK2(两孔结构域弱向内整流K+通道2) 测定巨噬细胞表型。我们发现，正则的P2RX7配体e[ATP]支配Mφ 通过控制[Ca~(2+)]内的极化和激活TWIK2 K+外流通道来诱导这种转变 变成了支持炎症的状态。我们还观察到TWIK2反应本身依赖于 E[ATP]激活P2RX7并导致钙离子内流。因此，在项目1中，我们将研究 P2RX7介导的钙内流与TWIK2介导的K+外流的调节之间的关系 决定通过激活转变为促炎性Mφ(Inf-Mφ)或修复性Mφ(Rep-Mφ)的命运 截然不同的下游信号通路。这一假设将通过解决以下具体问题来检验 目标。目标1将确定P2RX7和TWIK2激活在介导肺移位中的各自机制 巨噬细胞的极性。AIM 2将定义Mφ离子通道下游的信号通路 消炎性肺损伤。我们假设，通过确定P2RX7和TWIK2的激活和信号转导 巨噬细胞表型转换的机制，以及通过测试P2RX7在 协调TWIK2在随后的抗炎反应中的作用 在项目1中，将有可能制定更有效地解决肺部炎症的策略 通过控制巨噬细胞极化增强菌提高肺损伤耐受性 MФ的杀伤功能。

PROJECT SUMMARY/ABSTRACT Macrophages (Mφ) are essential for the innate immune function of lungs. The ability of macrophages to integrate signals from microbes and the tissue niche and to polarize can either promote or resolve inflammatory lung injury. Project 1 shows a fundamental role of the extracellular ATP (e[ATP]) activated- and [Ca2+]in-sensitive cooperation between the purinergic receptor P2RX7 (Purinergic Receptor 2 subtype X7) and potassium (K+) channel TWIK2 (Two-pore domain Weak Inwardly rectifying K+ channel 2) that is essential for determining the macrophage phenotype. We show that e[ATP], the canonical P2RX7 ligand, governs Mφ polarization through controlling [Ca2+]in and that activation of the TWIK2 K+ efflux channel induces the transition to the pro-inflammatory state. We also observed that the TWIK2 response was itself dependent on the activation of P2RX7 by e[ATP] and resultant Ca2+ influx. Thus, Project 1, we will investigate the interactions between Ca2+ influx mediated by P2RX7 and its tuning of K+ efflux mediated by TWIK2, which we hypothesize determines the transition to either pro-inflammatory Mφ (Inf-Mφ) or reparative Mφ (Rep-Mφ) fate via activation of distinct downstream signaling pathways. This hypothesis will be tested by addressing the following Specific Aims. Aim 1 will define respective mechanisms of P2RX7 and TWIK2 activation in mediating the shift in lung macrophage polarity. Aim 2 will define the signaling pathways downstream of Mφ ion channels that promote and resolve inflammatory lung injury. We posit that by identifying P2RX7 and TWIK2 activation and signaling mechanisms responsible for macrophage phenotype switching, and by testing the role of P2RX7 in coordinating the function of TWIK2 in the initial inflammatory response followed subsequent anti-inflammatory response in Project 1, it will be possible to develop strategies to more effectively resolve inflammatory lung injury and to make lung’s tolerance to injury through controlling macrophage polarization enhancing bacterial killing function of MФ.