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

项目摘要/摘要 急性肾损伤(AKI)显著增加发生进行性肾纤维化和慢性肾功能衰竭的风险 肾病(CKD)。巨噬细胞在AKI中扮演着复杂的角色，具有经典的激活促炎作用 巨噬细胞最初用于清除损伤后的凋亡细胞和碎片，然后交替激活 修复性巨噬细胞促进小管修复，随后巨噬细胞外流或凋亡 自适应修复事件。然而，持续的实质炎症或更严重的损伤会导致 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/再灌注损伤后修复可导致肾内纤维组织巨噬细胞异常 第10天后树突状细胞聚集。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显示巨噬细胞趋化蛋白-1的高水平表达 (Mcp1)，主要由巨噬细胞表达，并持续表达几丁质酶3样1(CHI3L1或Brp39)， 主要由内源性肾细胞引起。Mcp1的同源受体CCR2在所有骨骼上都有高表达。 而Brp39的促纤维化受体CRTH2在两个巨噬细胞上都高度表达 和肌成纤维细胞。我们发现Brp39-/-小鼠和CCR2-/-小鼠受损的肾脏表现出较少的纤维化 巨噬细胞积聚和间质纤维化程度高于野生型对照组小鼠。总之，这些发现导致了 美国假设肾损伤后肾小管修复失败促进肾小管持续表达 Brp39具有增强CRTH2+巨噬细胞和肌成纤维细胞促纤维化活性的作用，并且Brp39刺激 巨噬细胞上调Mcp1，导致CCR2依赖的促炎细胞进一步聚集， 肌成纤维细胞激活、肾脏纤维化和功能障碍。因此，靶向Brp39-CRTH2和/或Mcp1-CCR2 肾损伤后的信号通路在CKD进展的治疗中具有巨大的潜力。为了测试这一点 假设，我们建议首先定义巨噬细胞-Mcp1表达在促进异常的作用 CCR2+炎症细胞在不适应肾修复环境中的积聚和激活(目标1)；以及 然后确定持续的肾小管细胞Brp39表达在CRTH2+促纤维化激活中的重要性 巨噬细胞和肌成纤维细胞(目标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树枝状大分子 选择性靶向近端小管Brp39表达和间质巨噬细胞CCR2的纳米药物 和-CRTH2信号反应以减缓或防止CKD进展(目标3)。学习和职业生涯 本K01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，成为一名独立调查员，探索CKD和 与之相关的转化医学。

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.