A new paradigm of glomerular immune cell homing

摘要 这项研究旨在探索一种全新的肾小球免疫细胞归巢范式，并揭示 生理性和肾炎性疾病的细胞和分子机制及其作用 疾病包括糖尿病肾病(DKD)和狼疮性肾炎(LN)。作为一个额外的翻译目标， 这些研究将为肾脏疾病的当前治疗方法的重新定位和新的 消炎疗法。已知循环和肾脏常驻免疫细胞优先归巢于 以及肾小球周围与其他血管床在正常和炎症状态下的比较，提示 肾小球微循环中存在保护肾脏的独特免疫调节机制 过滤。然而，其潜在的细胞和分子机制在很大程度上是未知的。这次会议的重点是 拟议的研究是致密黄斑(MD)细胞的一项新功能，该细胞位于 肾小球的血管入口，传统上被认为调节肾脏和肾小球的血流动力学。我们的 实验室最近发现，在所有类型的肾脏细胞中，MD细胞具有最高的蛋白质合成率 它们分泌多种旁分泌作用的血管生成、细胞生长和构图以及细胞外基质。 信号蛋白。初步工作确定了几个途径和基因的高度MD-浓缩 白细胞(如CxCL12、CxCl14、Ptgs2、Ptges、Anxa1、Ccn1、 MIF)，观察炎症过程中以MD为中心的肾小球密度和CD44+、CD8+T细胞的迁移 包括狼疮性肾炎在内的疾病。我们的中心假设是MD细胞驱动优先肾小球 免疫细胞通过释放旁分泌作用的促炎因子包括趋化因子和 细胞因子。该项目将使用全面的实验方法，包括新的转基因小鼠 条件性、诱导性和光遗传工具(MD-mTORgOF/10F、MD-Ai27、MD-Ai39、CCN1-基因敲除(KO)、CCN1- GFP小鼠)、肾脏和全身炎症模型(NTS、STZ-DKD、NZM.2328 LN模型)、体内MPM 成像，MD转录组分析，体外细胞培养和蛋白质组学，以及临床前治疗翻译。 其具体目的是：(1)研究MD细胞在全球的免疫调节作用和机制。 生理和肾脏炎症状态，(2)阐明CCN1的肾脏抗炎作用， (3)检测SGLT2抑制剂(SGLT2i)的抗炎作用。这些新发现的MD机制 可能是有针对性的，并将为未来抗炎治疗策略的发展提供信息。

SUMMARY This study aims to investigate a radically new paradigm of glomerular immune cell homing and to uncover the underlying cell and molecular mechanisms and their role in physiological and renal inflammatory disease conditions including diabetic kidney disease (DKD) and lupus nephritis (LN). As an additional translational aim, these studies will inform the repurposing of current treatments for kidney disease and the development of new anti-inflammatory therapies. Circulating and kidney resident immune cells are known to preferentially home in and around the glomerulus compared to other vascular beds in both normal and inflammatory states, suggesting the presence of unique immunomodulatory mechanisms in the glomerular microcirculation that protect the kidney filter. However, the underlying cell and molecular mechanisms have been largely unknown. The focus of the proposed studies is a new function of the cells of the macula densa (MD) which are strategically positioned at the glomerular vascular entrance and traditionally known to regulate renal and glomerular hemodynamics. Our laboratory recently identified that MD cells have the highest rate of protein synthesis among all kidney cell types and they secrete a variety of paracrine-acting angiogenic, cell growth and patterning, and extracellular matrix signaling proteins. Preliminary work identified the high MD-enrichment of several pathways and genes in the inflammatory response and cellular infiltration by leukocytes (e.g., Cxcl12, Cxcl14, Ptgs2, Ptges, Anxa1, Ccn1, Mif) and observed the MD-centric glomerular density and migration of CD44+ and CD8+ T cells in inflammatory diseases including lupus nephritis. Our central hypothesis is that MD cells drive the preferential glomerular homing of immune cells by the release of paracrine-acting pro-inflammatory factors including chemokines and cytokines. This project will use comprehensive experimental approaches including new transgenic mice with conditional, inducible and optogenetic tools (MD-mTORgof/lof, MD-Ai27, MD-Ai39, CCN1-knockout (KO), CCN1- GFP mice), models of renal and systemic inflammation (NTS, STZ-DKD, NZM.2328 LN models), in vivo MPM imaging, MD transcriptome analysis, in vitro cell culture and proteomics, and pre-clinical therapeutic translation. The specific aims are to (1) Examine the global immunomodulatory role and mechanisms of MD cells under physiological and renal inflammatory disease conditions, (2) Elucidate the renal anti-inflammatory role of CCN1, and (3) Test the anti-inflammatory effects of SGLT2 inhibitors (SGLT2i). These newly identified MD mechanisms may be targeted and will inform the development of future anti-inflammatory therapeutic strategies.