Mechanisms of Th2 interleukin-driven angiogenesis

描述(申请人提供)：本申请的总体目标是证明白介素19(IL-19)，一种抗炎的Th2白介素2，可以促进血管生成和改善缺血组织的灌流。IL-19是一种新发现的Th2(T调节)抗炎白介素2，在我们的工作之前，一直被认为是炎性细胞特异性的。我们仍然是唯一一个研究白介素2在血管生物学中的作用的实验室，特别是在EC和VSMC的病理生理学方面。炎症细胞因子和抗炎细胞因子都参与创面愈合和新生血管形成，但抗炎细胞因子在血管生成中的作用以及这些过程之间的相互作用尚不清楚。与我们之前的工作表明IL-19抑制血管平滑肌细胞(VSMC)迁移和增殖相反，我们最近报道了一个令人惊讶的发现，IL-19对人内皮细胞(EC)具有强大的促血管生成作用。IL-19在正常血管内皮细胞中不表达，但在人血管生成组织的毛细血管内皮细胞中表达。IL-19对EC具有促有丝分裂和趋化作用，促进细胞扩散，激活MAPK和rac1。IL-19促进主动脉环微血管形成，促进体内PECAM1阳性微血管的形成。IL-19可诱导EC血管生成基因的表达。IL-19的作用不依赖于血管内皮生长因子和碱性成纤维细胞生长因子，因为两者都不能诱导IL-19的表达，IL-19也不能诱导两者的表达。碱性成纤维细胞生长因子和血管内皮生长因子的中和不影响IL-19的活性，提示了一种新的、由Th2诱导的刺激EC激活和血管生成的途径。IL-19可使人巨噬细胞分化为M2、创伤愈合表型，并诱导巨噬细胞血管生成基因表达。IL-19的表达和功能与促炎抗血管生成细胞因子IL-12相互作用和调节。这些初步的和已发表的数据推动了这样的假设，即IL-19是一种具有多种效应细胞的新型血管生成细胞因子。IL-19是否能恢复缺血组织的血流量，主要效应细胞是内皮细胞还是M2巨噬细胞，IL-19的作用机制以及IL-19在EC和VSMC中的不同作用的分子机制和介质等问题有待进一步研究。我们将确定IL-19的缺乏是否减弱，以及IL-19的过度表达是否促进缺血组织的血管生成和恢复血流，IL-19对血管生成的调节是通过直接作用于血管细胞还是通过巨噬细胞M2极化来促进的，我们将确定和表征IL-19在体内驱动血管生成所必需的IL-19诱导因子，并检验IL-20受体亚单位的差异表达解释了IL-19在VSMC与EC相比的多效性作用的假设。这一应用潜在地改变了范式，因为它将涉及Th2白介素2作为一种新的抗炎、促血管生成的细胞因子，由炎症的常驻血管细胞表达，以促进新生血管。

DESCRIPTION (provided by applicant): The overall goal of this application is to demonstrate that Interleukin-19 (IL-19), an anti-inflammatory, Th2 interleukin, can drive angiogenesis and improve perfusion of ischemic tissue. IL-19 is a newly described Th2, (T regulatory) anti-inflammatory interleukin which until our work, had been ascribed to be inflammatory cell-specific. We remain the only laboratory to investigate a role for this Interleukin in vascular biology, particularly with respect to EC and VSMC pathophysiology. Both inflammatory and anti- inflammatory cytokines participate in wound healing and neo-vascularization, but the role of anti- inflammatory cytokines in angiogenesis and the cross-talk between these processes remain under characterized. In contrast to our previous work indicating that IL-19 suppresses vascular smooth muscle cells (VSMC) migration and proliferation, we have recently reported the surprising finding that IL-19 has potent pro-angiogenic effects on human endothelial cells (EC). IL-19 is not detected in normal EC but is expressed in EC in capillaries in human angiogenic tissue. IL-19 is mitogenic and chemotactic for EC, promotes cell spreading, and activates MAPK and Rac1. IL-19 promotes microvessel formation in aortic rings, and PECAM1-positive microvessels in vivo. IL-19 can induce angiogenic gene expression in EC. IL-19 effects are independent of VEGF and bFGF, as neither can induce IL-19 expression, and IL-19 cannot induce expression of either. Neutralization of bFGF and VEGF does not affect IL-19 activity, suggesting a novel, Th2-induced pathway to stimulate EC activation and angiogenesis. IL-19 can polarize human macrophage to the M2, "wound healing" phenotype, and induce angiogenic gene expression in macrophage. IL-19 expression and function is reciprocal to and regulates the pro- inflammatory anti-angiogenic cytokine IL-12. These preliminary and published data have driven the hypothesis that IL-19 is a novel vasculogenic cytokine with multiple effector cells. What needs to be determined is if IL-19 can restore blood flow in ischemic tissue, if the major effector cell is endothelial cells or the M2 macrophage, what soluble factors mediate IL-19 effects, and the molecular mechanisms and mediators of IL-19 differential effects in EC and VSMC. We will determine if absence of IL-19 attenuates, and if over expression of IL-19 promotes angiogenesis and restores blood flow in ischemic tissue, if IL-19 regulation of angiogenesis is facilitated by direct effects on vascular cells, or by macrophage M2 polarization, will identify and characterize IL-19 inducible factors necessary for IL-19- driven angiogenesis in vivo, and test the hypothesis that differential expression of IL-20 receptor subunits account for pleiotropic effects of IL-19 in VSMC compared with EC. This application is potentially paradigm-changing as it will implicate a Th2 interleukin as a novel anti-inflammatory, pro-vasculogenic cytokine expressed by inflamed resident vascular cells to promote neovascularization.