Targeting macrophage persistence to prevent the AKI-to-CKD transition

项目概要/摘要 急性肾损伤（阿基）显著增加了发生进行性肾纤维化和慢性肾纤维化的风险。 肾病（CKD）。巨噬细胞在阿基中起着复杂的作用， 巨噬细胞最初用于清除损伤后的凋亡细胞和碎片， 修复性巨噬细胞促进肾小管修复，随后巨噬细胞的排出或凋亡， 适应性修复事件。然而，持续的实质炎症或更严重的损伤导致 适应不良的肾脏修复我们最近的出版物和初步数据表明，未能实现管状 单侧缺血/再灌注损伤（U-IRI）后的修复导致异常的肾内促纤维化巨噬细胞， 树突细胞积聚超过第10天。潜在巨噬细胞归巢和促纤维化的表达 未修复肾脏的激活信号揭示巨噬细胞趋化蛋白-1的高水平表达 （Mcp 1），主要由巨噬细胞，沿着几丁质酶3样1（Chi 3l 1或Brp 39）的持续表达， 主要是内源性肾细胞。Mcp 1的同源受体Ccr 2在所有骨组织中高度表达， 而Brp 39的促纤维化受体Crth 2在两种巨噬细胞上都高度表达， 和肌成纤维细胞。我们发现Brp 39-/-小鼠和Ccr 2-/-小鼠的损伤肾脏表现出较少的促纤维化， 巨噬细胞积聚和间质纤维化。总之，这些发现导致了 我们假设肾损伤后肾小管修复失败促进肾小管细胞持续表达 Brp 39刺激的Crth 2+巨噬细胞和肌成纤维细胞促纤维化活化增加， 巨噬细胞上调Mcp 1，导致进一步的Ccr 2依赖性促炎细胞积累， 肌成纤维细胞活化、肾纤维化和功能障碍。因此，靶向Brp 39-Crth 2和/或Mcp 1-Ccr 2 肾损伤后的信号传导通路对于CKD进展的治疗具有巨大的潜力。为了验证这一 假设，我们建议首先确定巨噬细胞Mcp 1表达在促进异常 Ccr 2+炎性细胞在适应不良的肾修复环境中的积累和活化（目的1）;以及 然后确定持续的肾小管细胞-Brp 39表达在Crth 2+的促纤维化激活中的重要性。 巨噬细胞和肌成纤维细胞（Aim 2）。最后，为了将我们对这两个信号的理解 在临床相关疗法的开发中，我们将设计和测试两种不同的基于树枝状聚合物的 选择性靶向近端小管-Brp 39表达和间质巨噬细胞-Ccr 2的纳米药物 和-Crth 2信号传导应答以减缓或预防CKD进展（Aim 3）。学习和事业 本K 01建议书中的开发/培训活动旨在为徐乐源博士提供技术和 科学专业知识和经验，成为探索CKD主题的独立研究者， 相关的转化医学。

Project Summary/Abstract Acute kidney injury (AKI) significantly increases the risk of developing progressive kidney fibrosis and chronic kidney disease (CKD). Macrophages play complex roles in AKI, with classically activated proinflammatory macrophages initially serving for clearance of apoptotic cells and debris after injury, and alternatively activated reparative macrophages promoting tubule repair followed by either egress or apoptosis of the macrophages in the event of adaptive repair. However, persistent parenchymal inflammation or more severe injury leads to maladaptive kidney repair. Our recent publication and preliminary data has shown that failure to achieve tubular repair after unilateral ischemia/reperfusion injury (U-IRI) leads to abnormal intrarenal profibrotic macrophage and dendritic cell accumulation beyond day 10. The expression of potential macrophage homing and profibrotic activation signals in unrepaired kidneys reveals high-level expression of macrophage chemoattractant protein-1 (Mcp1), predominantly by macrophages, along with sustained expression of chitinase 3-like 1 (Chi3l1 or Brp39), predominantly by endogenous renal cells. The cognate receptor for Mcp1, Ccr2, is highly expressed on all bone marrow-derived cells; while the profibrotic receptor for Brp39, Crth2, is highly expressed on both macrophages and myofibroblasts. We found that injured kidneys from Brp39-/- mice and Ccr2-/- mice exhibit less profibrotic macrophage accumulation and interstitial fibrosis than wild-type control mice. Together, these findings have led us to hypothesize that failed tubule repair following kidney injury promotes sustained tubular cell expression of Brp39, with increased Crth2+ macrophage and myofibroblast profibrotic activation, and that the Brp39-stimulated macrophages upregulate Mcp1, leading to further Ccr2-dependent proinflammatory cell accumulation, myofibroblast activation, renal fibrosis and dysfunction. Thus, targeting the Brp39-Crth2 and/or Mcp1-Ccr2 signaling pathways after kidney injury holds great potential for the treatment of CKD progression. To test this hypothesis, we propose to first define the role of macrophage-Mcp1 expression in promoting abnormal accumulation and activation of Ccr2+ inflammatory cells in the setting of maladaptive kidney repair (Aim 1); and then determine the importance of sustained tubular cell-Brp39 expression in the profibrotic activation of Crth2+ macrophages and myofibroblasts (Aim 2). Lastly, in order to translate our understanding of these two signaling into the development of clinically relevant therapeutics, we will engineer and test two distinct dendrimer-based nanomedicines for selective targeting of proximal tubule-Brp39 expression and of interstitial macrophage-Ccr2 and -Crth2 signaling responses to slow or prevent CKD progression (Aim 3). The studies and career development/training activities in this K01 proposal are designed to equip Dr. Leyuan Xu with the technical and scientific expertise and the experience to become an independent investigator exploring the topics of CKD and its related translational medicine.