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，以期确定可预防甚至逆转进行性肾病的新治疗靶点。慢性肾衰竭患者治疗的重大进展可能需要靶向纤维化途径中几个关键分子的新治疗药物，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，有助于减轻纤维化的严重程度，肾结构损伤和肾功能丧失。五个特定目的的研究将继续研究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将通过研究与野生型小鼠相比具有uPA遗传缺陷或具有过表达uPA的巨噬细胞的小鼠的实验模型来确定蛋白水解酶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）在肾脏炎症和纤维化中的作用，使用骨髓移植策略产生嵌合小鼠（uPAR野生型小鼠与uPAR缺陷型巨噬细胞，反之亦然）。目的#3将使用缺乏低密度脂蛋白受体相关蛋白（LRP）表达巨噬细胞或成纤维细胞的基因工程小鼠研究uPAR清除剂辅助受体（LRP）在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（PA 1 -1）在对肾损伤的肾小管间质反应中的作用。目的#5将寻求鉴定刺激肾成纤维细胞增殖的替代（非uPAR）uPA受体。拟定研究旨在研究以下假设：uPA作为细胞外蛋白酶直接或间接（通过激活纤溶酶原、潜伏性金属蛋白酶或肝细胞生长因子）增强基质蛋白（例如纤维蛋白原、纤连蛋白）降解，从而减弱体内肾损伤的纤维化反应。进一步假设uPA还通过特异性细胞受体调节肾损伤部位细胞的募集和功能。特别地，提出uPAR促进巨噬细胞募集，并且与其共受体LRP一起为巨噬细胞提供有效的真空机制以消除促纤维化分子如PA 1 -1和蛋白酶连接蛋白-1。最后，提出了一种替代的尚未鉴定的uPA受体，其在uPAR不存在下上调以刺激成纤维细胞增殖。该受体的身份将被追求。

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.