CREB Programming of Alveolar Macrophage Population and Inflammatory Lung Injury

项目摘要/摘要 肺从严重炎症性损伤中恢复的能力取决于其快速动员内源性的能力 组织修复途径。巨噬细胞(Mɸ)是肺中含量最丰富的前哨免疫细胞，具有不同的 血统和功能。这些细胞的一个关键但鲜为人知的方面是它们促进 肺损伤后的修复。基础状态下，肺含有肺泡巨噬细胞(AMɸ，AMɸ)(CD11c/CD11b-/SiglecF)AS 以及间质Mɸ(IMɸ)(CD11b/CX3CR1/SiglecF-)。AM-ɸ是恢复肺功能所必需的 肺损伤后的动态平衡，但调节修复性AMɸ生成的机制仍不清楚。它是 明确需要高效、快速地动员恢复性AMɸ群体，尤其是在以下情况下 在肺部感染和损伤期间，它们的数量急剧减少。在项目2中，我们将从以下几个方面解决这个问题 关于转录因子cAMP反应元件结合(CREB)起关键作用的初步观察 在产生修复性AMɸ血统中的作用。为了支持这一概念，我们证明了髓系特异性 小鼠(CREB∆LyzM小鼠)CREB基因缺失导致未成熟AMɸ的产生 (CD11c/CD11b/SiglecFlo)，引起炎性AMɸ，从而颠覆抗炎和 成熟AMɸ的修复功能。因此，这些小鼠在基础状态下表现出明显的肺损伤证据。 由于炎性AMɸ的增加。此外，这些小鼠的肺损伤在内毒素后延长和 阿格纳尔。与对照组相比，他们的死亡率明显更高。通过研究流排序的Mɸ从Creb∆LYZM 在肺中，我们还发现了调控基因的表达变化，如PPARγ，一个重要的驱动因素 修复性AMɸ谱系规范，以及调节AMɸ代谢和免疫反应的基因。 进一步分析表明，CREB诱导了丙酮酸脱氢酶激酶4(PDK4)的表达。PDK4 进而抑制丙酮酸脱氢酶复合体(PDC)从线粒体到线粒体的移位 细胞核，从而抑制核乙酰辅酶A的产生。在没有CREB及其靶PDK4的情况下，PDC 活性显著增加，导致核乙酰辅酶A水平过高，组蛋白增加 乙酰化和AMɸ的产生，不能促进肺修复。基于这些 随着岩心产生的强大工具的可用，我们将在项目2中定义 CREB通过对ɸγ的表观遗传调控，在产生有利于分解的AM PPAR群体中的核心作用 表情。我们的具体目标是(目标1)：解决CREB在调节肺生成中的作用 肺损伤后修复的AMɸ群体，以及(目标2)：研究CREB在信号转导中的作用 通过表观遗传上调PARɸ表达产生AMγ。基于具有挑衅性的表型 CREB∆LyzM小鼠，我们相信了解修复性AMɸ是如何产生的并促进它们的生成 在损伤期间为开发肺修复策略提供了巨大的希望。

PROJECT SUMMARY/ABSTRACT The lung’s ability to recover from severe inflammatory injury depends on its capacity to rapidly mobilize intrinsic tissue repair pathways. Macrophages (Mɸ), the most abundant sentinel immune cell in lungs, have different lineages and functions. A key, but poorly understood, aspect of these cells is their intrinsic property to promote repair after lung injury. In the basal state, the lung contains alveolar Mɸ (AMɸ) (CD11c+/CD11b-/SiglecF+) as well as a population of interstitial Mɸ (IMɸ) (CD11b+/CX3CR1+/SiglecF-). AMɸ are necessary for restoring lung homeostasis after lung injury but the mechanisms regulating reparative AMɸ generation remain elusive. It is clear that a reparative AMɸ population needs to be efficiently and rapidly mobilized, in particular, in the face of sharp decrease in their number during lung infection and injury. In Project 2, we will address this question based on the seminal observation that the transcription factor cAMP Response Element Binding (CREB) plays a key role in giving rise to a reparative AMɸ lineage. In support of this concept, we show that the myeloid-specific deletion of CREB in mice (Creb∆LyzM mice) resulted in the generation of immature AMɸ (CD11c+/CD11b+/SiglecFlo), which give rise to inflammatory AMɸ, thus subverting the anti-inflammatory and reparative function of mature AMɸ. These mice thereby showed clear evidence of lung injury in the basal state due to the increase in inflammatory AMɸ. Furthermore, lung injury in these mice after LPS was prolonged and agonal. They showed significantly greater mortality than controls. By studying flow-sorted Mɸ from Creb∆LyzM lungs, we also found alterations in the expression of regulatory genes such as Pparγ , an essential driver of reparative AMɸ lineage specification, as well as genes regulating AMɸ metabolism and immune responses. Further analysis showed that CREB induced the expression of pyruvate dehydrogenase kinase 4 (PDK4). PDK4 in turn suppressed the translocation of pyruvate dehydrogenase complex (PDC) from mitochondria to the nucleus, thus inhibiting the production of nuclear acetyl-CoA. In the absence of CREB and its target PDK4, PDC activity was markedly increased which resulted in excessive nuclear acetyl-CoA levels, increased histone acetylation, and the generation of AMɸ, that were incapable of promoting lung repair. Based on these observations and with the availability of powerful tools generated by the Cores, in Project 2 we will define the central role of CREB in generating a pro-resolving AMɸ population through the epigenetic regulation of Pparγ expression. Our Specific Aims are (Aim 1): to address the role of CREB in mediating the generation of a lung reparative AMɸ population following lung injury, and (Aim 2): to investigate the role of CREB in signaling the generation of AMɸ by epigenetically upregulating Pparγ expression. Based on the provocative phenotype of Creb∆LyzM mice, we believe understanding how reparative AMɸ are generated and enhancing their generation during injury holds great promise for developing lung repair strategies.