Department of Nephrology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Department of Nephrology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan,
Nephron. 2019;141(3):177-187. doi: 10.1159/000495217. Epub 2018 Dec 12.
BACKGROUND/AIMS: Extracellular vesicles (EVs), including exosomes, are present in various bodily fluids, including urine. We and others previously reported that cells expressing fibroblast-specific protein 1 (FSP1) accumulate within damaged glomeruli, and that urinary FSP1, as well as urinary soluble CD163, could potentially serve as a biomarker of ongoing glomerular injury.
To test that idea, we collected urine samples from 37 patients with glomerular disease; purified the urinary EVs; characterized them using Nanosight, western blotting, and immunoelectron microscopy; and determined FSP1 and soluble CD163 levels using enzyme-linked immunosorbent assays.
Deemed to be mainly exosomes based on their size distribution, the EVs in urine contained FSP1, and a portion of the FSP1-positive vesicles was also positive for podocalyxin. FSP1 levels in urinary EVs were (1) positively correlated with rates of biopsy-proven cellular crescent formation (r = 0.562, p < 0.001) and total crescent formation (r = 0.448, p = 0.005) among total glomeruli; (2) significantly higher in patients with cellular crescents affecting 20% or more of their glomeruli than in those with fewer affected glomeruli (p = 0.003); and (3) significantly decreased after glucocorticoid and immunosuppressant therapy (p < 0.05). A positive correlation between FSP1 levels in urinary EVs and urinary soluble CD163 levels was confirmed (r = 0.367, p < 0.05).
These data suggest that a portion of urinary FSP1 is secreted as EVs originating from podocytes, and that FSP1 levels reflect active and ongoing glomerular injury and disease activity, such as cellular crescent formation.
背景/目的：细胞外囊泡（EVs），包括外泌体，存在于各种体液中，包括尿液。我们和其他人之前曾报道过，表达成纤维细胞特异性蛋白 1（FSP1）的细胞在受损的肾小球内积聚，尿 FSP1 和尿可溶性 CD163 可能作为持续肾小球损伤的生物标志物。
为了验证这一观点，我们收集了 37 例肾小球疾病患者的尿液样本；纯化尿液中的 EVs；使用纳米示踪法、western blot 和免疫电子显微镜对其进行表征；并使用酶联免疫吸附试验测定 FSP1 和可溶性 CD163 水平。
根据其大小分布，认为这些 EV 主要是外泌体，尿液中的 EV 含有 FSP1，部分 FSP1 阳性囊泡也为足细胞蛋白聚糖阳性。尿 EV 中的 FSP1 水平：1）与活检证实的细胞新月体形成率（r = 0.562，p < 0.001）和总新月体形成率（r = 0.448，p = 0.005）呈正相关；2）在影响 20%或更多肾小球的细胞新月体患者中明显高于影响较少肾小球的患者（p = 0.003）；3）在糖皮质激素和免疫抑制剂治疗后明显降低（p < 0.05）。尿 EV 中 FSP1 水平与尿可溶性 CD163 水平呈正相关（r = 0.367，p < 0.05）。
这些数据表明，尿 FSP1 的一部分作为起源于足细胞的 EV 分泌，FSP1 水平反映了活跃和持续的肾小球损伤以及疾病活动，如细胞新月体形成。
