MOLECULAR MECHANISMS IN RENAL INTERSTITIAL FIBROSIS

描述(申请人提供)：我们研究的长期目标是解开肾纤维化的细胞和分子复杂性，以期确定可以预防甚至逆转进行性肾脏疾病的新的治疗靶点。很可能，慢性肾功能衰竭患者治疗方面的重大进展将需要针对纤维化途径中的几个关键分子的新治疗剂，类似于癌症的化疗。我们最近的研究表明，尿激酶(UPA)及其受体调节肾脏对慢性损伤的病理生理反应，有助于减轻纤维化、肾脏结构损伤和肾功能丧失的严重程度。五个特定的AIMS研究将继续调查uPA及其受体的细胞和蛋白分解作用如何调节肾纤维化形成。目的#1将通过研究uPA基因缺陷小鼠或与野生型小鼠相比巨噬细胞过度表达uPA的实验模型，确定蛋白水解酶uPA是否以及如何调节肾脏纤维化。目的#2利用骨髓移植策略产生嵌合小鼠(uPAR野生型小鼠的巨噬细胞uPAR缺失，反之亦然)，研究巨噬细胞尿激酶受体(UPAR)在肾脏炎症和纤维化中的作用。目的#3利用缺乏表达低密度脂蛋白受体相关蛋白(LRP)的巨噬细胞或成纤维细胞的基因工程小鼠，研究uPAR清道夫共受体(LRP)在肾脏纤维化反应中的作用。目的研究uPAR-LRP配体纤溶酶原激活物抑制物-1(PAL-1)在肾损伤后肾小管间质反应中的作用。目的#5将寻求确定刺激肾成纤维细胞增殖的替代(非uPAR)uPA受体。本研究旨在探讨uPA可直接或间接(通过激活纤溶酶原、潜在金属蛋白酶或肝细胞生长因子)作为一种胞外蛋白酶促进基质蛋白(如纤维蛋白原、纤维连接蛋白)的降解，从而减弱体内肾损伤的纤维化反应。进一步的假设是，uPA还通过特定的细胞受体(S)来调节肾脏损伤部位细胞的募集和功能。特别是，有人认为uPAR促进巨噬细胞募集，并与其辅助受体LRP一起，为巨噬细胞提供了一种有效的真空机制，以消除促纤维化分子，如PAL-1和蛋白酶Nexin-1。最后，另一种尚未确定的uPA受体在缺乏uPAR的情况下上调，以刺激成纤维细胞的增殖。这个受体的身份将被追查。

DESCRIPTION (provided by applicant): The long-term goal of our studies is to unravel the cellular and molecular complexities of renal fibrosis with a view to identifying new therapeutic targets that can prevent or even reverse progressive renal disease. It is likely that major advances in the treatment of patients with chronic renal failure will entail new therapeutic agents that target several key molecules in the fibrogenic pathway, akin to chemotherapy for cancer. Our recent studies suggest that urokinase (uPA) and its receptors regulate pathophysiological responses of the kidney to chronic injury, serving to attenuate the severity of fibrosis, renal structural damage and loss of renal function. Five specific aims studies will continue to investigate how the cellular and proteolytic actions of uPA and its receptors modulate renal fibrogenesis. Aim #1 will determine if and how the proteolytic enzyme uPA modulates renal fibrosis by investigating experimental models in mice with a genetic deficiency of uPA or with macrophages that over-express uPA in comparison to wild-type mice. Aim #2 will investigate the role of the macrophage urokinase receptor (uPAR) in renal inflammation and fibrogenesis using bone marrow transplantation strategies to generate chimeric mice (uPAR wild-type mice with uPAR-deficient macrophages and visa versa). Aim #3 will investigate the role of the uPAR scavenger co-receptor, lowdensity lipoprotein receptor-related protein (LRP), in the renal fibrogenic response using genetically engineered mice lacking LRP-expressing macrophages or fibroblasts. Aim #4 will investigate the role of the uPAR-LRP ligand plasminogen activator inhibitor-1 (PAl-1) in the tubulointerstitial response to renal injury. Aim #5 will seek to identify the alternative (non-uPAR) uPA receptor that stimulates kidney fibroblast proliferation. The proposed studies are designed to investigate the hypothesis that the fibrogenic response to renal injury in vivo is attenuated by uPA working as an extracellular protease to enhance degradation of matrix proteins (eg; fibrinogen, fibronectin) directly or indirectly (via activation of plasminogen, latent metalloproteinases or hepatocyte growth factor). It is further hypothesized that uPA also acts via specific cellular receptor(s) to modulate the recruitment and function of cells at the site of renal injury. In particular it is proposed that uPAR promotes macrophage recruitment and together with its co-receptor LRP, provides macrophages with an efficient vacuuming mechanism to eliminate pro-fibrotic molecules such as PAl-1 and protease nexin-1. Finally an alternative as yet unidentified uPA receptor that is up-regulated in the absence of uPAR is proposed to stimulate fibroblast proliferation. The identity of this receptor will be pursued.