MOLECULAR MECHANISMS IN RENAL INTERSTITIAL FIBROSIS

描述（由申请人提供）：我们研究的长期目标是揭示肾纤维化的细胞和分子复杂性，以期发现新的治疗靶点，可以预防甚至逆转进行性肾脏疾病。慢性肾衰竭患者治疗的重大进展可能需要新的治疗药物，这些药物针对纤维形成途径中的几个关键分子，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。五个特定目标的研究将继续研究uPA及其受体的细胞和蛋白水解作用如何调节肾纤维化。目的1将通过研究uPA基因缺陷小鼠或与野生型小鼠相比过度表达uPA的巨噬细胞的实验模型，确定蛋白水解酶uPA是否以及如何调节肾纤维化。目的2将研究巨噬细胞尿激酶受体（uPAR）在肾脏炎症和纤维形成中的作用，使用骨髓移植策略产生嵌合小鼠（uPAR野生型小鼠具有uPAR缺失的巨噬细胞，反之亦然）。Aim #3将研究uPAR清除剂共受体低密度脂蛋白受体相关蛋白（LRP）在缺乏表达LRP的巨噬细胞或成纤维细胞的基因工程小鼠肾纤维化反应中的作用。目的4将研究uPAR-LRP配体纤溶酶原激活物抑制剂-1 （PAl-1）在肾损伤小管间质反应中的作用。Aim #5将寻找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作为细胞外蛋白酶直接或间接（通过激活纤溶酶原、潜在金属蛋白酶或肝细胞生长因子）增强基质蛋白（如纤维蛋白原、纤维连接蛋白）降解，从而减弱体内肾损伤的纤维化反应的假设。进一步的假设是，uPA也通过特定的细胞受体来调节肾损伤部位细胞的募集和功能。特别提出uPAR促进巨噬细胞募集，并与其共受体LRP一起，为巨噬细胞提供有效的抽真空机制，以消除PAl-1和蛋白酶连接蛋白-1等促纤维化分子。最后，一种尚未确定的uPA受体在缺乏uPAR的情况下被上调，以刺激成纤维细胞增殖。这个受体的身份将被追究。

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.