Department of Pediatrics, Yoshida Hospital, Yoshida 32-14, Tsubame City, 959-0242 Niigata, Japan.
Diabetologia. 2012 Nov;55(11):2913-9. doi: 10.1007/s00125-012-2661-7. Epub 2012 Aug 2.
AIMS/OBJECTIVE: Nephropathy, a major complication of diabetes, is the leading cause of end-stage renal disease. Recent studies have demonstrated that podocyte injury is involved in the onset of and progression to renal insufficiency. Here, we describe a novel, highly sensitive ELISA for detecting urinary podocalyxin, a glycoconjugate on the podocyte apical surface that indicates podocyte injury, particularly in the early phase of diabetic nephropathy.
Urine samples from patients with glomerular diseases (n = 142) and type 2 diabetes (n = 71) were used to quantify urinary podocalyxin by ELISA. Urine samples were obtained from 69 healthy controls for whom laboratory data were within normal values. Podocalyxin was detected in urine by immunofluorescence, immunoelectron microscopy and western blotting.
Morphologically, urinary podocalyxin was present as a vesicular structure; western blotting showed it as a positive band at 165-170 kDa. Levels of urinary podocalyxin were elevated in patients with various glomerular diseases and patients with diabetes. In patients with diabetes, urinary podocalyxin was higher than the cut-off value in 53.8% patients at the normoalbuminuric stage, 64.7% at the microalbuminuric stage and 66.7% at the macroalbuminuric stage. Positive correlations were observed between urinary podocalyxin levels and HbA(1c), urinary β(2) microglobulin, α(1) microglobulin and urinary N-acetyl-β-D-glucosaminidase, although urinary podocalyxin levels were not correlated with other laboratory markers such as blood pressure, lipid level, serum creatinine, estimated GFR or proteinuria.
CONCLUSIONS/INTERPRETATION: Urinary podocalyxin may be a useful biomarker for detecting early podocyte injury in patients with diabetes.
肾病是糖尿病的一种主要并发症，也是导致终末期肾病的主要原因。最近的研究表明，足细胞损伤与肾功能不全的发生和进展有关。在这里，我们描述了一种新的、高度敏感的 ELISA 方法，用于检测尿足细胞蛋白，这是一种位于足细胞表面的糖缀合物，表明足细胞损伤，特别是在糖尿病肾病的早期阶段。
使用 ELISA 定量检测肾小球疾病患者（n=142）和 2 型糖尿病患者（n=71）的尿足细胞蛋白。对 69 名健康对照者的尿液样本进行检测，这些对照者的实验室数据均在正常值范围内。通过免疫荧光、免疫电子显微镜和 Western blot 检测尿液中的足细胞蛋白。
形态学上，尿足细胞蛋白呈囊泡状结构；Western blot 显示其在 165-170 kDa 处有阳性条带。各种肾小球疾病患者和糖尿病患者的尿足细胞蛋白水平升高。在糖尿病患者中，53.8%的正常白蛋白尿期、64.7%的微量白蛋白尿期和 66.7%的大量白蛋白尿期患者的尿足细胞蛋白高于截断值。尿足细胞蛋白水平与 HbA(1c)、尿β(2)微球蛋白、α(1)微球蛋白和尿 N-乙酰-β-D-氨基葡萄糖苷酶呈正相关，尽管尿足细胞蛋白水平与其他实验室标志物如血压、血脂水平、血清肌酐、估计肾小球滤过率或蛋白尿无相关性。
尿足细胞蛋白可能是检测糖尿病患者早期足细胞损伤的有用生物标志物。
