A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2
A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2
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DOI：
10.1681/asn.2022010070
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发表时间：
2022-08-29
影响因子：
13.6
通讯作者：
Yan, Kunimasa
中科院分区：
文献类型：
--
作者：
Hada, Ichiro;Shimizu, Akira;Yan, Kunimasa
背景原发性肾病综合征（INS）足细胞损伤的原因尚不清楚。虽然最近的证据指出B细胞和自身免疫的作用，但缺乏由自身免疫介导的动物模型限制了进一步的研究。我们的目的是建立一个模拟人INS的小鼠模型，通过免疫小鼠与Crb 2，一个跨膜蛋白表达在足细胞足突。方法用重组小鼠Crb 2胞外段免疫C3 H/HeN小鼠。检测血清抗Crb 2抗体、尿蛋白/肌酐比值和肾组织学改变。对于信号传导研究，将表达Crb 2的小鼠足细胞系与抗Crb 2抗体孵育。结果首次免疫后4周，血清抗Crb 2自身抗体和尿蛋白均明显升高。蛋白尿在9-13周达到肾病范围，并持续至29周。最初的肾脏组织学类似于人类的微小病变疾病，免疫荧光染色显示肾小球中有精细的点状IgG染色，与足细胞足突处的Crb 2共定位。18周后，一部分小鼠出现了类似FSGS的特征。在免疫小鼠的肾小球和Crb 2表达足细胞与抗Crb 2抗体孵育，磷酸化ezrin，连接Crb 2的细胞骨架，增加，伴随着改变Crb 2的本地化和肌动蛋白分布。结论抗Crb 2自身抗体在小鼠足细胞损伤中起重要作用。Crb 2免疫可能是研究人INS免疫发病机制的有用模型，并且可能支持针对足细胞蛋白的自身免疫在INS中的作用。
Background The cause of podocyte injury in idiopathic nephrotic syndrome (INS) remains unknown. Although recent evidence points to the role of B cells and autoimmunity, the lack of animal models mediated by autoimmunity limits further research. We aimed to establish a mouse model mimicking human INS by immunizing mice with Crb2, a transmembrane protein expressed at the podocyte foot process. Methods C3H/HeN mice were immunized with the recombinant extracellular domain of mouse Crb2. Serum anti-Crb2 antibody, urine protein-to-creatinine ratio, and kidney histology were studied. For signaling studies, a Crb2-expressing mouse podocyte line was incubated with anti-Crb2 antibody. Results Serum anti-Crb2 autoantibodies and significant proteinuria were detected 4 weeks after the first immunization. The proteinuria reached nephrotic range at 9-13 weeks and persisted up to 29 weeks. Initial kidney histology resembled minimal change disease in humans, and immunofluorescence staining showed delicate punctate IgG staining in the glomerulus, which colocalized with Crb2 at the podocyte foot process. A subset of mice developed features resembling FSGS after 18 weeks. In glomeruli of immunized mice and in Crb2-expressing podocytes incubated with anti-Crb2 antibody, phosphorylation of ezrin, which connects Crb2 to the cytoskeleton, increased, accompanied by altered Crb2 localization and actin distribution. Conclusion The results highlight the causative role of anti-Crb2 autoantibody in podocyte injury in mice. Crb2 immunization could be a useful model to study the immunologic pathogenesis of human INS, and may support the role of autoimmunity against podocyte proteins in INS.