Neonatal Fc Receptor (FcRn) Trafficking of Immune Complexes to the Lysosome as a Driver of Glomerulonephritis

新生儿 Fc 受体 (FcRn) 将免疫复合物运输到溶酶体作为肾小球肾炎的驱动因素

基本信息

批准号：
10535435
负责人：
JUDITH T., BLAINE
金额：
$ 40.55万
依托单位：
UNIVERSITY OF COLORADO DENVER
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-01 至 2024-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10535435
关键词：
Aftercare Albumins Animal Model Antigen-Antibody Complex Apoptosis Apoptotic Biochemical Biological Response Modifiers CD8B1 gene Cathepsins Cathepsins B Cell Death Cell Membrane Permeability Cells Cessation of life Cytosol Degradation Pathway Dendritic Cells Deposition Disease Disease Progression Disease model End stage renal failure Endothelial Cells Enzymes Extravasation FOXP3 gene Fc Receptor Functional disorder Glomerulonephritis Goals Health Histologic Histology Human Imaging Techniques Immune Immune Targeting Immunoglobulin G Immunological Models Induction of Apoptosis Kidney Kidney Diseases Kidney Failure Knock-out Knockout Mice Location Lupus Nephritis Lysosomes Macrophage Mediating Mediator Membranous Glomerulonephritis Methods Mitochondria Modeling Morbidity - disease rate Mus Nephritis Outer Mitochondrial Membrane Pathway interactions Patients Permeability Play Proteinuria Proteolytic Processing Research Role Serum Severity of illness Signal Transduction Sorting Structure T-Lymphocyte Testing Up-Regulation Work cell type cytochrome c glomerular filtration glomerulosclerosis human model improved in vivo in vivo Model insight interest mitochondrial membrane monomer mortality mouse model neonatal Fc receptor nephrotoxicity neutrophil novel podocyte preservation prevent response targeted treatment trafficking transcriptome sequencing

项目摘要

Abstract/Project Summary Immune mediated kidney diseases cause substantial morbidity and often lead to progressive renal failure. Immune complexes (ICs) have been found in podocytes in a variety of immune mediated kidney diseases but it is not known how podocytes handle immune complexes and whether trafficking of immune complexes in podocytes exacerbates glomerulonephritis. The neonatal Fc receptor (FcRn) correctly sorts and traffics ICs in a variety of cells including podocytes. FcRn is also required to traffic immune complexes to the lysosome in dendritic cells for proteolytic processing and presentation on MHC II. In preliminary studies, we have found that podocyte specific knockout of FcRn protects in two models of immune mediated nephritis but that this protection is not conferred by an immune mediated mechanism. While there is no difference in any of the immune parameters examined, we have found that there is significantly less apoptotic cell death and upregulation of apoptotic pathways in FcRn knockout (KO) podocytes treated with immune complexes and significantly decreased apoptosis in the glomeruli of podocyte specific FcRn KO mice after induction of nephrotoxic serum nephritis (NTS). In addition, we have found significantly less lysosomal activation and less upregulation of lysosomal enzymes in FcRn KO podocytes treated with immune complexes. Since FcRn is required to traffic immune complexes to the lysosome, we hypothesize that in immune mediated nephritis, FcRn directed trafficking of ICs to the lysosome results in lysosomal dysfunction, upregulation of the intrinsic apoptotic pathway and podocyte death. To test this hypothesis we will directly examine lysosomal structure and function in WT and FcRn KO podocytes after an immune challenge using both advanced imaging techniques and biochemical methods. We will also examine whether FcRn mediated trafficking of immune complexes to the lysosome results in increased lysosomal permeability and leakage of lysosomal cathepsins into the cytosol causing degradation of mitochondrial membrane integrity, leakage of cytochrome c and upregulation of intrinsic apoptotic pathways. We will test whether podocyte specific knockout of FcRn results in decreased lysosomal activation and improved lysosomal function in podocytes in vivo after induction of immune mediated kidney disease (NTS) and whether this in turn results in less apoptotic cell death, an increased number of viable podocytes and less severe disease as assessed by functional and histologic parameters. Since upregulation of lysosomal cathepsins correlates with more severe lupus nephritis in patients, we will also examine whether podocyte specific knockout of FcRn ameliorates lupus nephritis in a spontaneous mouse model of this disease. Taken together, the proposed work will provide novel insights into FcRn mediated trafficking of immune complexes in podocytes and may allow for the creation of targeted therapies to slow or prevent progression of immune mediated glomerulonephritis.

摘要/项目摘要免疫介导的肾脏疾病导致大量发病，并常常导致进行性肾衰竭。在多种免疫介导的肾脏疾病的足细胞中都发现了免疫复合物 (IC)，但它目前尚不清楚足细胞如何处理免疫复合物以及免疫复合物的运输是否在足细胞会加剧肾小球肾炎。新生儿 Fc 受体 (FcRn) 能够正确分类和运输 IC 多种细胞，包括足细胞。 FcRn 还需要将免疫复合物运输至溶酶体树突状细胞用于蛋白水解加工和 MHC II 呈递。在初步研究中，我们发现足细胞特异性敲除 FcRn 可在两种免疫介导的肾炎模型中提供保护，但这种保护作用不是由免疫介导机制赋予的。虽然任何免疫方面都没有差异检查参数后，我们发现凋亡细胞死亡和上调明显减少用免疫复合物处理的 FcRn 敲除 (KO) 足细胞中的凋亡途径，显着肾毒性血清诱导后足细胞特异性 FcRn KO 小鼠肾小球细胞凋亡减少肾炎（NTS）。此外，我们发现溶酶体激活显着减少，上调也减少用免疫复合物处理的 FcRn KO 足细胞中的溶酶体酶。由于 FcRn 需要流量溶酶体的免疫复合物，我们假设在免疫介导的肾炎中，FcRn 定向运输 IC 进入溶酶体会导致溶酶体功能障碍、内在凋亡途径的上调和足细胞死亡。为了检验这一假设，我们将直接检查 WT 中的溶酶体结构和功能，使用先进成像技术和生化技术进行免疫攻击后的 FcRn KO 足细胞方法。我们还将检查 FcRn 是否介导免疫复合物向溶酶体的运输溶酶体通透性增加和溶酶体组织蛋白酶渗漏到细胞质中导致降解线粒体膜完整性、细胞色素 c 渗漏和内在凋亡途径的上调。我们将测试足细胞特异性敲除 FcRn 是否会导致溶酶体激活减少并改善诱导免疫介导的肾病（NTS）后体内足细胞的溶酶体功能以及是否这反过来又会导致细胞凋亡减少、存活足细胞数量增加以及疾病严重程度减轻通过功能和组织学参数评估。由于溶酶体组织蛋白酶的上调与对于更严重的狼疮性肾炎患者，我们也会检查足细胞是否特异性敲除FcRn 改善狼疮性肾炎的自发性小鼠模型。综上所述，拟议的工作将为足细胞中 FcRn 介导的免疫复合物运输提供新的见解，并可能允许创建靶向疗法来减缓或预防免疫介导的肾小球肾炎的进展。