CREB Programming of Alveolar Macrophage Population and Inflammatory Lung Injury

项目总结/摘要 肺从严重炎性损伤中恢复的能力取决于其快速动员内源性炎症介质的能力。 组织修复途径。巨噬细胞（M β）是肺中最丰富的哨兵免疫细胞，具有不同的 血统和功能。这些细胞的一个关键但知之甚少的方面是它们的内在特性， 肺损伤后修复。在基础状态下，肺含有肺泡巨噬细胞（AM）（CD 11 c +/CD 11b-/SiglecF+）， 以及间质性M β（IM β）（CD 11b +/CX 3CR 1 +/SiglecF-）群体。AM是恢复肺部所必需的 肺损伤后的内稳态，但调节修复性AM β生成的机制仍然难以捉摸。是 显然，需要有效和迅速地动员一个具有修复性的反倾销人口，特别是在面临 在肺部感染和损伤期间，它们的数量急剧减少。在项目2中，我们将根据 转录因子cAMP反应元件结合（CREB）在转录过程中起着关键作用， 在产生修复性AM谱系中的作用。为了支持这一概念，我们表明，骨髓特异性 小鼠（Creb/LyzM小鼠）中CREB的缺失导致未成熟AM的产生。 （CD 11 c +/CD 11b +/SiglecFlo），其引起炎性AM炎症，从而破坏了抗炎和 成熟AM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 这是由于炎性AM的增加。此外，LPS后这些小鼠的肺损伤延长， 快死了它们的死亡率明显高于对照组。通过对Creb算法LyzM中的流排序M算法的研究， 我们还发现了调节基因表达的改变，如Pparγ，这是肺的重要驱动力。 修复性AM β谱系特化，以及调节AM β代谢和免疫应答的基因。 进一步分析表明CREB诱导丙酮酸脱氢酶激酶4（PDK 4）的表达。PDK4 反过来抑制丙酮酸脱氢酶复合物（PDC）从线粒体到线粒体的转运， 核，从而抑制核乙酰辅酶A的产生。在不存在CREB及其靶点PDK 4的情况下， 活性显著增加，导致核乙酰辅酶A水平过高，组蛋白水平增加， 乙酰化和AM β的产生，不能促进肺修复。基于这些 在项目2中，我们将根据观察结果，并利用核心生成的强大工具， CREB在通过Pparγ的表观遗传调节产生促消退AM β细胞群中的中心作用 表情我们的具体目标是（目标1）：解决CREB在介导肺生成中的作用。 目的2：研究CREB在肺损伤后修复性AM感染中的作用， 通过表观遗传学上调Pparγ表达产生AM β。基于挑衅性的表型 Creb和LyzM小鼠，我们相信了解修复性AM是如何产生的， 在肺损伤期间，这对于开发肺修复策略具有很大的希望。

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.