Novel Anti-fibrotic Therapy for Diabetic Nephropathy

描述（由申请人提供）：糖尿病肾病（DN）是世界上终末期肾病（ESRD）最常见的原因，影响约15-25%的I型糖尿病患者和30-40%的II型糖尿病患者。DN的发展被认为是多种代谢和血流动力学因素之间的累积相互作用的结果，这些因素激活细胞内信号传导途径，触发细胞因子和生长因子的产生，导致肾脏疾病进展为肾小球硬化和间质硬化。在DN中驱动纤维化的两种最重要的生长因子是转化生长因子-b（TGF β）和结缔组织生长因子（CTGF），其由TGF β诱导。已经提出了抑制TGF β和CTGF活性的治疗策略来阻止DN的进展。该提议将开发一种新的嵌合Fc融合蛋白，其被设计为抑制TGF β和CTGF的促纤维化活性。CCN 3/HGF是一种异二聚体融合蛋白，由CTGF拮抗剂CCN 3和肝细胞生长因子（HGF）的α链片段组成，两者均融合到IgG的Fc部分的N末端。在哺乳动物细胞表达过程中，通过使用Fc链中的“钮入孔”突变来加强蛋白质的异源二聚化。Fc融合蛋白的设计预计将增强稳定性并改善药代动力学，如临床使用中的其他Fc融合蛋白所示。CCN 3/HGF显示在参与DN纤维化发病机制的各种类型的肾细胞（包括成纤维细胞、肾上皮小管细胞和系膜细胞）中阻断TGF β和CTGF诱导的促纤维化反应。该项目的目标是推进CCN 3/HGF的临床前开发。将开发产生高水平CCN 3/HGF的稳定CHO细胞系。融合蛋白的抗纤维化活性将使用不同的肾细胞类型在体外证实。将在DN的eNOS-/-/leprdb/db双敲除小鼠模型中评估CCN 3/HGF的治疗功效。这些研究的结果将为在未来的工作中提交IND铺平道路。CCN 3/HGF独特的双重作用机制将为DN患者提供一种新的治疗选择，可能上级目前相对有限和无效的治疗方法。

DESCRIPTION (provided by applicant): Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD) in the world and affects about 15-25% of type I diabetes patients and 30-40% of patients with type II diabetes. The development of DN is thought to result from the cumulative interactions among multiple metabolic and hemodynamic factors which activate intracellular signaling pathways that trigger the production of cytokines and growth factors leading to renal disease that progresses to glomerulosclerosis and interstitial sclerosis. Two of the most important growth factors driving fibrosis in DN are transforming growth factor-b (TGFb) and connective tissue growth factor (CTGF), which is induced by TGFb. Therapeutic strategies to inhibit the activity of TGFb and CTGF have been proposed to halt the progression of DN. This proposal will develop a novel chimeric Fc fusion protein designed to inhibit the pro-fibrotic activities of both TGFb and CTGF. CCN3/HGF is a heterodimeric fusion protein consisting of the CTGF antagonist, CCN3, and the alpha chain fragment of hepatocyte growth factor (HGF) both fused to the N-terminus if the Fc portion of IgG. Heterodimerization of the protein during mammalian cell expression is enforced by the use of the "knobs into holes" mutations in the Fc chains. The design of the Fc fusion protein is predicted to enhance stability and improve pharmacokinetics as shown for other Fc fusion proteins in clinical use. CCN3/HGF was shown to block TGFb and CTGF-induced pro-fibrotic responses in vitro in various types of kidney cells involved in the pathogenesis of DN fibrosis including fibroblasts, renal epithelial tubule cells, and mesangial cells. The goal of this project is to advance the preclinical development of CCN3/HGF. Stable CHO cell lines producing high levels of CCN3/HGF will be developed. The anti-fibrotic activity of the fusion protein will be confirmed in vitro using differnt kidney cell types. Therapeutic efficacy of CCN3/HGF will be evaluated in the eNOS-/-/leprdb/db double-knockout mouse model of DN. The results of these studies will pave the way for submission of an IND in future work. The unique dual mechanism of action of CCN3/HGF will provide a new therapeutic option potentially superior to the relatively limited and ineffective current treatments for DN patients.