PROTEASES AND CORNEAL ULCERATION

角膜是一种独特的组织，因为它的无血管性质和对透明度的要求。因此，分子的局部合成比其他组织更重要。我们的研究表明，在角膜中发现并合成的丝氨酸蛋白酶是纤溶酶原，是纤溶酶的前体。此前，唯一已知的合成这种分子的肝外细胞是小胶质细胞。纤溶酶原可作为纤溶酶和血管生成抑制物血管抑素的前体。纤溶酶降解纤维蛋白和其他细胞外基质分子，并激活基质金属蛋白酶和生长因子。总体而言，角膜对侮辱(创伤和感染)的反应是通过局部合成来控制组织重塑的保护性分子和介体的水平。与大多数其他组织不同，角膜局部调节纤溶酶原和其他分子的水平，这些分子通常由肝脏合成并通过血管系统分配给组织。具体目的1：确定角膜是否具有合成纤溶酶原的能力，以及损伤和感染对角膜中纤溶酶原合成和血管系统纤溶酶原扩散的影响。角膜细胞在体外合成纤溶酶原的能力将与血管组织的细胞进行比较。将测试角膜合成通常由肝脏、纤维蛋白原和凝血酶原合成的其他分子的能力。体内纤溶酶原和纤维蛋白原从血管系统流入角膜，将与正常伤口和感染条件下角膜合成这些分子进行比较。具体目标2：确定在角膜中生成血管抑素样分子的机制，而不是活性酶纤溶酶的形成。将确定角膜来源的血管抑素样分子的结构和生物活性。其他非恶性细胞的细胞产生血管抑制素样活性的能力将被测试。本课程将探讨血管抑素的产生和控制的机制。几种被提议的控制纤溶酶和血管抑素产生的机制将被测试。参与血管抑制素样多肽生产的蛋白酶(S)将被确定。

The cornea is a unique tissue because of its avascular nature and its requirement for transparency. As a result, local synthesis of molecules is more important than in other tissues. Our studies have shown that the serine proteinase found in and synthesized by the cornea is plasminogen the precursor of the enzyme plasmin. Previously, the only known extrahepatic cell that synthesizes this molecule is the microglia cell. Plasminogen can serve as a precursor of plasmin and the angiostatin, an angiogenesis inhibitor. Plasmin degrades fibrin, and other extracellular matrix molecules and activates matrix metalloproteinases and growth factors. Overall hypothesis The cornea responds to insults (wounding and infection) by controlling the levels of protective molecules and mediators of tissue remodeling by local synthesis. In contrast to most other tissues, the cornea locally regulates the levels of plasminogen as well as other molecules normally synthesized by the liver and distributed through the vascular system to tissues. Specific Aim 1: To determine whether the cornea is unusual in its ability to synthesize plasminogen and to determine the effect of injury and infection on the synthesis of plasminogen in the cornea and on diffusion of plasminogen from the vascular system. The ability of the corneal cells to synthesize plasminogen in vitro will be compared to that of cells of vascularized tissues. The ability of the cornea to synthesize other molecules normally synthesized by the liver, fibrinogen and prothrombin, will be tested. The influx of plasminogen and fibrinogen from the vascular system into the cornea in vivo will be compared to the synthesis of these molecules by the cornea under normal wound and infection conditions using rabbits. Specific Aim 2: To determine in the cornea the mechanism for generation of angiostatin-like molecules in contrast to the formation of the active enzyme, plasmin. The structure and biological activity of cornea derived angiostatin-like molecules will be determined. The ability of cells of other non-malignant cells will be tested for ability to produce angiostatin-like activity. The mechanisms involved in angiostatin production and control of this process will be explored. Several proposed mechanisms for controlling plasmin vs angiostatin production will be tested. The proteinase(s) involved in the production of the angiostatin-like peptides will be identified.