ECM Remodeling in Excessive Fibroplasia

描述（由申请人提供）： 长期目标：阐明创伤修复过程中过度瘢痕形成的细胞和分子基础。本申请将集中在瘢痕疙瘩成纤维细胞胶原过度产生中纤溶酶原激活物抑制剂-1（派-1）表达改变的作用。临时纤维蛋白基质的蛋白水解降解和新形成的含胶原的瘢痕组织的重塑是损伤修复的基本特征。瘢痕疙瘩是一种病因不明的皮肤纤维化的极端形式，由伤口愈合不当引起。使用三维纤维蛋白凝胶培养系统，我们发现瘢痕疙瘩成纤维细胞由于PAI-1过表达而在纤维蛋白降解方面有缺陷。在先前的授权期间，我们在体外和体内都建立了派-1过表达是瘢痕疙瘩成纤维细胞的表型，并且是胶原积累升高的原因。降低派-1活性也消除了瘢痕疙瘩成纤维细胞中升高的胶原积累（Tuan等人，Am J Pathol 2003）。此外，我们证明，在体内，派-1随着胎鼠皮肤伤口从无瘢痕（E15）修复过渡到瘢痕形成（E18及之后）修复而增加，并且抑肽酶（一种uPA/纤溶酶抑制剂）导致E15胎鼠皮肤伤口中的瘢痕形成（Huang等人，WRR 2002）。派-1是纤溶酶原激活物（PA）/纤溶酶系统的主要抑制剂。该系统是纤维蛋白降解、细胞粘附和迁移以及金属蛋白酶（MMP）活化的中心，金属蛋白酶（MMP）活化在胶原蛋白周转中是必需的。因此，我们假设“PA 1 -1通过抑制MMP活化和/或通过调节uPA介导的细胞粘附而有助于瘢痕疙瘩成纤维细胞中胶原积累的升高”。派-1是TGF-β的下游靶标，并且瘢痕疙瘩成纤维细胞在基质收缩和胶原合成中表现出TGF-β介导的差异。因此，我们还假设“改变的TGF-β信号通路和/或派-1启动子反应元件的利用是瘢痕疙瘩成纤维细胞中派-1表达增加的原因”。已建立的证据和独特的实验模型将使我们能够通过以下具体目标来测试这些假设： 目的一：研究派-1在瘢痕疙瘩成纤维细胞中MMP和细胞粘附介导的胶原积累中的作用。 目标二：目的：探讨瘢痕疙瘩成纤维细胞中TGF-β信号通路改变和/或派-1启动子利用差异导致派-1升高的生物学机制。

DESCRIPTION (provided by applicant): Long-term goal: To elucidate the cellular and molecular basis of excess scar formation during wound repair. This application will focus on the role of altered expression of plasminogen activator inhibitor-1 (PAI-1) in collagen over-production by keloidfibroblasts. Proteolytic degradation of the provisional fibrin matrix and remodeling of the newly formed collagen-containing scar tissues are essential features in injury repair. Keloids, resulting from improper wound healing, are the extreme form of skin fibrosis with unknown etiology. Using a 3-dimensional fibrin gel culture system, we discovered that keloid fibroblasts are defective in fibrin degradation due to PAl-1 over-expression. In the previous granting period, we established, both in vitro and in vivo, that PAI-1 overexpression is phenotypic of keloid fibroblasts and is causal in the elevated collagen accumulation. Reducing PAI-1 activity also abolishes the elevated collagen accumulation in keloid fibroblasts (Tuan et al., Am J Pathol 2003). In addition, we demonstrated that, in vivo, PAI-1 increases as fetal mouse skin wounds transition from scarless (El5) to scar-forming (E18 and after) repair, and aprotinin, a uPA/plasmin inhibitor, causes scar formation in E15 fetal skin wounds (Huang et al., WRR 2002). PAI-1 is the major inhibitor of the plasminogen activator (PA)/plasmin system. This system is central to fibrin degradation, cell adhesion and migration, and metalloproteinase (MMP) activation, which is essential in collagen turnover. Thus, we hypothesize that "PAl-1 contributes to elevated collagen accumulation in keloid fibroblasts by inhibiting MMP activation and or by modulating uPA-mediated cell adhesion". PAI-1 is a down stream target of TGF-beta, and keloid fibroblasts exhibit TGF-beta-mediated differences in matrix contraction and collagen synthesis. Thus, we also hypothesize that "an altered TGF-beta signaling pathway and or utilization of PAI-1 promoter response elements are responsible for increased PAI-1 expression in keloidfibroblasts" The established evidence and the unique experimental models will allow us to test these hypotheses through the following specific aims: Aim I: To investigate the role of PAI-1 increase in MMP- and cell adhesion-mediated collagen accumulation in keloid fibroblasts. Aim II: To determine the biological mechanism of PAI-1 increase resulting from altered TGF-beta signaling events and/or difference in PAI-1 promoter utilization in keloid fibroblasts.