Macrophages as modulators of repair after neonatal stroke

描述(申请人提供)：成人或新生儿中风后有自我修复的潜力，但内源性神经再生是短暂和无效的。我们的目标是加强新生儿中风后的修复。血管生成通过形成“神经血管生态位”来促进成人中风后的神经发生。脑巨噬细胞通过对脑微环境的影响以及对血管生成和神经发生的直接作用，调节卒中后的修复和功能恢复。Galectin-3(Galectin-3，Gal-3)最近被认为与血管生成有关。推测Gal-3能够为神经血管生态位的形成提供“对接点”，并介导血管内皮生长因子诱导的血管生成，这使得该分子成为促进修复的一个有吸引力的靶点，但它在新生儿卒中后修复中的作用尚不清楚。我们假设，小胶质细胞/巨噬细胞通过增强Gal-3依赖的血管生成，对新生儿卒中后的长期康复起关键作用。利用我们建立的新生大鼠和小鼠大脑中动脉短暂性闭塞模型，我们将确定血管生成和神经生成是否依赖于脑巨噬细胞产生的Gal-3。在目标1中，我们将确定小胶质细胞耗竭对新生儿卒中后血管生成和神经血管生态位形成的影响。我们将用生物发光法监测活体动物的轴突生长。在目标2中，我们将研究增强或干扰Gal-3信号对活体大鼠内皮细胞激活的影响，方法是通过超声增强靶向�vss 3整合素的特定分子探针。在TLR2启动子下，将进一步研究携带Luc/GFP双重报告基因的新生缺血型Gal-3基因敲除小鼠的修复。在目标3中，我们将利用超声和VEGFR2的特异性探针来描绘Gal-3或VEGFR2抑制后的神经血管生态位形成。在受损的Gal-3基因敲除小鼠中，将确定血管内皮生长因子介导的血管生成。新生儿卒中后小胶质细胞耗竭和Gal-3操作的功能后果将被确定。了解调节修复的机制是成功实现板凳到床转换以加强受损新生儿大脑修复的重要第一步。

DESCRIPTION (provided by applicant): There is a potential for self-repair after adult or neonatal stroke, but endogenous neurogenesis is short- lived and ineffective. Our goal is to enhance the repair after neonatal stroke. Angiogenesis facilitates neurogenesis after adult stroke through the formation of a "neurovascular niche." Brain macrophages can modulate repair and functional recovery after stroke through effects on the brain microenvironment and direct effects on angiogenesis and neurogenesis. Galectin-3 (Gal-3) has recently been implicated in the process of angiogenesis. The postulated ability of Gal-3 to provide a "docking point" for the formation of a neurovascular niche and to mediate VEGF-induced angiogenesis makes this molecule an attractive target for enhancing repair, but its effect on repair after neonatal stroke is not known. We hypothesize that microglia/macrophages critically affect long-term recovery after neonatal stroke, in part through enhanced Gal-3-dependent angiogenesis. Using our established models of transient middle cerebral artery occlusion in neonatal rats and mice, we wil determine whether angiogenesis and neurogenesis depend on Gal-3 produced in brain macrophages. In Aim 1, we will determine the effects of microglial depletion on angiogenesis and neurovascular niche formation after neonatal stroke. We will monitor axonal outgrowth in living animals by bioluminescence. In Aim 2, we will investigate the effects of enhanced or disrupted Gal-3 signaling on endothelial activation in living rats by ultrasound enhanced with specific molecular probes to target �vss3 integrin. Repair will be further studied in neonatal ischemic Gal-3 knockout mice bearing the dual luc/gfp reporter under the TLR2 promoter. In Aim 3, we will delineate neurovascular niche formation folowing Gal-3 or VEGFR2 inhibition in injured living rats by using ultrasound and specific probes for VEGFR2. VEGF-mediated angiogenesis will be determined in injured Gal-3 knockout mice. Functional consequences of microglial depletion and Gal-3 manipulations after neonatal stroke will be determined. Understanding the mechanisms regulating repair is an important first step on the way to successful bench-to-bed translation to enhance repair in injured newborn brains.