Kounoue Noriyuki, Oguchi Hideyo, Hashiguchi Akinori, Honda Kazuho, Kang Dedong, Mikami Tetuo, Tochigi Naobumi, Kawamura Takeshi, Itabashi Yoshihiro, Yonekura Takashi, Sakurabayashi Kei, Sakai Ken
Department of Nephrology, Toho University Faculty of Medicine, Tokyo, Japan.
Department of Nephrology, Toho University Graduate School of Medicine, Tokyo, Japan.
Kidney Med. 2024 Jul 20;6(9):100876. doi: 10.1016/j.xkme.2024.100876. eCollection 2024 Sep.
Membranous nephropathy (MN) recurs in some kidney allograft patients, and recurrence increases graft failure rates. We present a unique case of recurrent MN in first and second allografts showing glomerular capillary wall-positivity for complement receptor 1 (CR1) consistent with immunoglobulin G (IgG). A man in his late 20s developed MN and started hemodialysis. MN recurred and caused graft loss after the first transplantation and recurred again soon after the second transplantation. The IgG subclass staining was almost consistently negative for IgG4 and phospholipase A2 receptor (PLA2R)-staining was negative. Recurrent MN of unknown etiology was considered. Mass spectrometry demonstrated that CR1 had increased in the transplanted kidney biopsies. Immunohistochemistry and immunofluorescence studies demonstrated CR1 colocalized with IgG along glomerular capillaries in this case, whereas CR1 was localized in podocytes with no colocalization of IgG in a control case of PLA2R-associated MN. Correlative light and immunoelectron microscopy showed localization of CR1 at the interface between electron-dense deposits and podocytes. Collectively, this case demonstrated a unique enhancement and localization of CR1. MN with enhancement of CR1 has not been reported to date. CR1 may be a candidate causative antigen in this case of recurrent MN, although further study is needed to investigate the pathogenesis of CR1.
膜性肾病（MN）在一些肾移植受者中会复发，复发会增加移植肾失功的发生率。我们报告了一例独特的复发性MN病例，该病例在首次和第二次移植肾中均出现复发，其肾小球毛细血管壁上补体受体1（CR1）呈阳性，与免疫球蛋白G（IgG）一致。一名20多岁的男性患MN并开始接受血液透析。首次移植后MN复发并导致移植肾失功，第二次移植后不久再次复发。IgG亚类染色几乎始终为IgG4阴性，磷脂酶A2受体（PLA2R）染色为阴性。考虑为病因不明的复发性MN。质谱分析显示移植肾活检组织中CR1增加。免疫组织化学和免疫荧光研究表明，在该病例中CR1与IgG沿肾小球毛细血管共定位，而在PLA2R相关性MN的对照病例中，CR1定位于足细胞，无IgG共定位。相关的光学和免疫电子显微镜检查显示CR1定位于电子致密沉积物与足细胞之间的界面。总体而言，该病例显示了CR1独特的增强和定位。迄今为止，尚未报道过CR1增强的MN。在该复发性MN病例中，CR1可能是候选致病抗原，尽管需要进一步研究以探讨CR1的发病机制。
