Saran Anita M, Yuan Huaping, Takeuchi Emiko, McLaughlin Margaret, Salant David J
Renal Section and Department of Medicine, Evans Biomedical Research Center, Boston University Medical Center, Boston, Massachusetts, USA.
Kidney Int. 2003 Dec;64(6):2072-8. doi: 10.1046/j.1523-1755.2003.00305.x.
The onset of proteinuria in passive Heymann nephritis, (PHN), a rat model of human membranous nephropathy (MN), is complement-dependent and is associated with altered podocyte slit diaphragm integrity and dissociation of nephrin from the actin cytoskeleton. These studies examined if complement is responsible for these podocyte changes.
PHN was induced with sheep anti-Fx1A. Controls were injected with normal sheep globulin. A third group was injected with anti-Fx1A and depleted of complement with cobra venom factor. Four days later, proteinuria was measured, slit diaphragm integrity was examined by electron microscopy, nephrin distribution was studied by immunofluorescence, and the glomerular content of nephrin and its association with actin were assessed by sequential extraction of isolated glomeruli and Western blotting.
Four days after immunization, seven out of eight PHN rats were proteinuric, whereas none of the complement depleted group had proteinuria despite similar levels of antibody deposition. Complement depletion preserved slit diaphragm morphology. Immunofluorescence microscopy with an antibody to the extracellular domain of nephrin showed a normal staining pattern in the rats depleted of complement and a shift to a more dispersed and clustered pattern in the PHN group. Western blot analysis of the glomerular extracts showed a significant reduction in the total amount of nephrin and in the fraction of actin-associated nephrin in the PHN group, whereas the amounts in the complement-depleted rats were similar to normal controls.
The onset of proteinuria in the PHN model of MN is coincident with complement-dependent alterations in the association of nephrin with the actin cytoskeleton and loss of podocyte slit diaphragm integrity.
被动型海曼肾炎（PHN）是人类膜性肾病（MN）的大鼠模型，蛋白尿的出现依赖补体，且与足细胞裂孔隔膜完整性改变及nephrin从肌动蛋白细胞骨架解离有关。这些研究探讨了补体是否是导致这些足细胞变化的原因。
用羊抗Fx1A诱导PHN。对照组注射正常羊球蛋白。第三组注射抗Fx1A并用眼镜蛇毒因子清除补体。4天后，测量蛋白尿，通过电子显微镜检查裂孔隔膜完整性，通过免疫荧光研究nephrin分布，通过对分离的肾小球进行顺序提取和蛋白质印迹法评估肾小球中nephrin的含量及其与肌动蛋白的关联。
免疫后4天，8只PHN大鼠中有7只出现蛋白尿，而补体清除组尽管抗体沉积水平相似但均无蛋白尿。补体清除保留了裂孔隔膜形态。用抗nephrin细胞外结构域的抗体进行免疫荧光显微镜检查显示，补体清除的大鼠染色模式正常，而PHN组则转变为更分散和聚集的模式。肾小球提取物的蛋白质印迹分析显示PHN组中nephrin总量及与肌动蛋白相关的nephrin部分显著减少，而补体清除的大鼠中的含量与正常对照组相似。
MN的PHN模型中蛋白尿的出现与nephrin与肌动蛋白细胞骨架关联的补体依赖性改变及足细胞裂孔隔膜完整性丧失同时发生。
