Regulation of macrophage maturation in ischemia: Topography and composition of the ischemic vascular niche and regulation by Notch signaling.

缺血引起炎症反应，旨在恢复灌注和促进愈合，但通常会加重损伤。巨噬细胞对功能性动脉响应缺血的生长是必不可少的，但显示出从破坏到营养或修复作用的多种功能。巨噬细胞分化和功能在缺血期间如何调节仍然是未知的。在后肢缺血的小鼠模型中，我们最近表明血管通过Notch信号传导控制巨噬细胞从募集的单核细胞分化和成熟，这反过来促进动脉生成和缺血组织恢复。巨噬细胞成熟由血管内皮细胞中表达的Notch配体Dll 1控制，并且需要通过Rbpj的巨噬细胞经典Notch信号传导，其同时抑制炎性巨噬细胞命运。此外，Notch活化的作用足以从离体单核细胞产生成熟巨噬细胞，其显示稳定的抗炎表型，即使在用促炎刺激物刺激时。在这里，我们建议研究的地形和组成的缺血生态位和分子事件调节缺血巨噬细胞分化的Notch信号。我们将确定控制巨噬细胞成熟的血管结构域，并将专门确定介导缺血中巨噬细胞成熟的Notch受体。我们将进一步确定缺血性巨噬细胞成熟所必需的生长因子背景。我们将采用遗传报告基因研究和条件删除策略，在小鼠模型的后肢缺血，以及在体外研究与巨噬细胞培养物建立在规定的条件下，以解决这些问题。利用这些发现，我们将尝试，在一个翻译研究，以产生人巨噬细胞离体治疗潜力。

Ischemia causes an inflammatory response that is intended to restore perfusion and promote healing but often aggravates damage. Macrophages are essential for growth of functional arteries in response to ischemia yet show diverse functions ranging from destructive to trophic or reparative actions. How macrophage differentiation and function is regulated during ischemia remains largely unknown. In a mouse model of hind limb ischemia we have recently shown that blood vessels control macrophage differentiation and maturation from recruited monocytes via Notch signaling, which in turn promotes arteriogenesis and ischemic tissue recovery. Macrophage maturation is controlled by Notch ligand Dll1 expressed in vascular endothelial cells and requires macrophage canonical Notch signaling via Rbpj, which simultaneously suppresses an inflammatory macrophage fate. Furthermore, the effects of Notch activation are sufficient to generate mature macrophages from monocytes ex vivo that display a stable anti-inflammatory phenotype, even when stimulated with pro-inflammatory stimuli. We here propose to study the topography and composition of the ischemic niche and the molecular events regulating ischemic macrophage differentiation by Notch signaling. We will identify the vascular domain controlling macrophage maturation and will specifically identify the Notch receptors mediating macrophage maturation in ischemia. We will further define the growth factor context essential for ischemic macrophage maturation. We will employ genetic reporter studies and conditional deletion strategies in mouse models of hind limb ischemia as well as in vitro studies with macrophage cultures established under defined conditions to address these questions. Using these findings we will try, in a translational study, to generate human macrophages ex vivo with therapeutic potential.