TNF-like weak inducer of apoptosis (TWEAK) signaling: a novel therapeutic target

描述（由申请人提供）：虽然浸润性巨噬细胞和肾小球细胞在狼疮性肾炎（LN）（SLE最常见和最危险的临床表现之一）的发病机制中至关重要，但它们的相互作用仍不完全清楚。了解巨噬细胞和常驻肾细胞的相对贡献及其相互作用，将有助于我们了解LN的发病机制，并为更有针对性的治疗提供机会。TNF-受体超家族成员与其同源配体的异常相互作用被认为在狼疮发病机制中起核心作用。抑制这些配体/受体对中的几个已经在人类狼疮的临床试验中显示出希望。TWEAK是TNF-配体超家族的分泌型细胞因子成员。TWEAK与其受体Fn 14结合，并刺激巨噬细胞、成纤维细胞、滑膜细胞和内皮细胞分泌趋化因子、细胞因子和其他促炎介质。我们的初步研究结果表明，TWEAK/Fn 14信号是必不可少的LN的发病机制：1。尿TWEAK水平在人LN中增加，并且与疾病活动性相关; 2. TWEAK受体Fn 14在体外由鼠和人系膜细胞（MC）和足细胞表达，在体内在狼疮肾中表达。用TWEAK处理足细胞导致关键致病性细胞因子（包括MCP-1、RANTES、VCAM-1和IP-10）的表达增加。肾脏中MCP-1的增加导致炎症细胞的募集和局部炎症过程的放大; 3.向B6小鼠注射TWEAK增加MCP-1表达，促进T细胞和巨噬细胞向肾脏的趋化性，并刺激肾小球细胞增殖; 4.初步研究显示抗TWEAK抗体在SLE的慢性移植物抗宿主鼠模型中减少蛋白尿的有益作用。我们的假设是，阻断TWEAK-Fn 14信号传导将有利于治疗小鼠LN，并且巨噬细胞和驻留肾细胞的TWEAK激活是这种细胞因子对狼疮炎性肾病的贡献的核心。我们提出这项建议的具体目的如下：研究TWEAK-Fn 14信号传导在LN发病机制中的直接参与，并通过a）表征具有Fn 14缺陷的狼疮易感MRL-1 pr/lpr（MRL-1 pr）小鼠;和B）向狼疮易感小鼠施用抗TWEAK单克隆抗体（mAb）来确定其治疗潜力; II.表征巨噬细胞中TWEAK活化对LN发病机制的相对贡献; III.确定TWEAK信号在驻留肾细胞，特别是足细胞中的作用，在LN的发展中，包括蛋白尿和肾小球硬化。 公共卫生相关性：TNF蛋白家族的细胞因子成员，对几种不同的细胞类型（包括小鼠和人肾细胞）具有许多促炎作用。由TWEAK诱导的一些炎症介质在受狼疮影响的肾脏中观察到的炎症中是重要的。 我们的目标是研究TWEAK与狼疮中不同细胞类型受体结合的重要性，并探索抗TWEAK抗体是否有助于治疗肾脏炎症。

DESCRIPTION (provided by applicant): While both infiltrating macrophages and glomerular cells are crucial in the pathogenesis of lupus nephritis (LN), one of the most common and dangerous clinical manifestations of SLE, their interactions remain incompletely understood. Appreciating the relative contribution of macrophages and resident kidney cells, and their interactions, would help us to understand the pathogenesis of LN and could provide an opportunity for more targeted therapies. Abnormal interaction of TNF-receptor superfamily members and their cognate ligands are believed to play a central role in lupus pathogenesis. Inhibition of several of these ligand/receptor pairs has already shown promise in clinical trials in human lupus. TWEAK is a secreted cytokine member of the TNF-ligand superfamily. TWEAK binds to its receptor, Fn14, and stimulates macrophages, fibroblasts, synoviocytes, and endothelial cells to secrete chemokines, cytokines, and other proinflammatory mediators. Our preliminary results suggest that TWEAK/Fn14 signaling is essential in the pathogenesis of LN: 1. Urinary TWEAK levels are increased in human LN, and correlate with disease activity; 2. The TWEAK receptor, Fn14, is expressed by murine and human mesangial cells (MC) and podocytes in vitro, and in lupus kidneys in vivo. Treatment of podocytes with TWEAK leads to increased expression of key pathogenic cytokines, including MCP-1, RANTES, VCAM-1, and IP-10. Increased MCP-1 in the kidney leads to recruitment of inflammatory cells and amplification of the local inflammatory process; 3. Injection of TWEAK to B6 mice increases MCP-1 expression, promotes chemotaxis of T cells and macrophages into the kidney, and stimulates glomerular cell proliferation; 4. Preliminary studies show a beneficial effect of anti-TWEAK antibodies in reducing proteinuria in the chronic graft versus host murine model of SLE. Our hypotheses are that blocking TWEAK-Fn14 signaling will be beneficial in treatment of murine LN, and that TWEAK activation of both macrophages and resident kidney cells is central in the contribution of this cytokine to inflammatory renal disease in lupus. Our Specific Aims for this proposal are as follows: I. Investigate the direct involvement of TWEAK-Fn14 signaling in the pathogenesis of LN and determine its therapeutic potential by a) characterizing lupus prone MRL-lpr/lpr (MRL-lpr) mice with Fn14 deficiency; and b) administering an anti- TWEAK monoclonal antibody (mAb) to lupus prone mice; II. Characterize the relative contribution of TWEAK activation in macrophages to the pathogenesis of LN; III. Determine the effect of TWEAK signaling in resident kidney cells, and particularly podocytes, in the development of LN, including albuminuria and glomerulosclerosis. PUBLIC HEALTH RELEVANCE: A cytokine member of the TNF family of proteins, has many pro-inflammatory effects on several different cell types including mouse and human kidney cells. Some of the inflammatory mediators induced by TWEAK are important in the inflammation observed in kidneys affected by lupus. Our goals for this proposal are to investigate the importance of TWEAK binding to its receptor on different cell types in lupus, and to explore whether an anti-TWEAK antibody may be helpful in treating kidney inflammation.