Podocyte membrane vesicles in urine originate from tip vesiculation of podocyte microvilli
Podocyte membrane vesicles in urine originate from tip vesiculation of podocyte microvilli
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DOI：
10.1016/j.humpath.2010.02.004
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发表时间：
2010-09-01
期刊：
影响因子：
3.3
通讯作者：
Kihara, Itaru
中科院分区：
文献类型：
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作者：
Hara, Masanori;Yanagihara, Toshio;Kihara, Itaru
足细胞损伤参与肾小球疾病的发生和发展。我们以前的研究表明，足细胞的顶端细胞膜脱落到尿沉渣中，尿足糖萼蛋白是一个有用的足细胞损伤的生物标志物。在这项研究中，我们研究了尿足糖萼蛋白的来源。对126例健康儿童和77例肾小球疾病患者的尿液和肾脏标本进行免疫组化分析。免疫荧光研究表明，尿podocalyxin脱落的颗粒状结构进入尿沉淀物和上清液。大量的足糖萼蛋白脱落到患者的尿沉淀物（17.2 +/- 3.2 ng/mg肌酐）和上清液（172.6 +/- 24.6 ng/mg肌酐）中，而健康对照组的尿足糖萼蛋白含量较低（沉淀物，0.5 +/- 0.1 ng/mg肌酐;上清液，24.3 +/- 3.5 ng/mg肌酐）。电子和免疫电子显微镜检查显示，沉淀物（125.6 +/- 8.8 nm）和上清液（121.2 +/- 6.4 nm）中的足细胞微绒毛大小与活检标本（123.6 +/- 8.9 nm）中的足细胞微绒毛相似，将其与更小的尿液外泌体（直径30-80 nm）区分开来。尿podocalyxin阳性囊泡在免疫荧光显微镜检查中对外泌体标记物CD 24和CD 63均呈阴性。podocalyxin阳性囊泡也测试阴性的细胞骨架标志物，和电子显微镜检查发现微绒毛的尖端囊泡。我们的结论是，人尿顶细胞膜囊泡似乎不是来自足细胞外泌体，而是来自肾小球足细胞微绒毛的尖端囊泡化。(C)2010年爱思唯尔公司All rights reserved.
Podocyte injury is involved in both the onset and progression of glomerular diseases. Our previous studies revealed that apical cell membranes of podocyte are shed into urine sediment and that urinary podocalyxin is a useful biomarker of podocyte injury. In this study, we examined the origin of urinary podocalyxin. Urine samples and kidney specimens from healthy children (n = 126) and patients with glomerular diseases (n = 77) were analyzed by immunohistologic methods. Immunofluorescence studies demonstrated that urinary podocalyxin was shed as granular structures into both the urine sediment and supernatant. Large amounts of podocalyxin were shed into both the urine sediment (17.2 +/- 3.2 ng/mg creatinine) and the supernatant (172.6 +/- 24.6 ng/mg creatinine) of patients, compared with the small amounts of urinary podocalyxin in healthy controls (sediment, 0.5 +/- 0.1 ng/mg creatinine; supernatant, 24.3 +/- 3.5 ng/mg creatinine). Electron and immunoelectron microscopic examinations showed that podocalyxin-positive vesicles in the sediment (125.6 +/- 8.8 nm) and the supernatant (121.2 +/- 6.4 nm) were similar in size to podocyte microvilli in biopsy specimens (123.6 +/- 8.9 nm), differentiating them from the much smaller urine exosomes (30-80 nm in diameter). Urine podocalyxin-positive vesicles tested negative in immunofluorescence microscopy on both exosomal markers CD24 and CD63. Podocalyxin-positive vesicles also tested negative for cytoskeletal markers, and electron microscopic examination revealed tip vesiculation of microvilli. We conclude that human urinary apical cell membrane vesicles appear to originate not from podocyte exosomes but from tip vesiculation of glomerular podocyte microvilli. (C) 2010 Elsevier Inc. All rights reserved.