Department of Pediatric Urology, Children's Hospital of Michigan, Michigan State University, 3901 Beaubien Blvd, Detroit, MI, 48201, USA.
Vattikuti Urology Institute, Henri Ford Hospital, Detroit, MI, USA.
Int Urol Nephrol. 2022 Nov;54(11):2783-2788. doi: 10.1007/s11255-022-03310-5. Epub 2022 Jul 25.
In this study we aimed to screen for the presence of biomarkers that are downregulated in children with nephrolithiasis (RS) compared to healthy controls (HC) using a proteomic approach. We hypothesized that RS and HC would display unique inhibitory protein profiles that could be used for comparative pathway analysis.
This is a prospective, controlled, pilot study of pooled urine from RS (N = 30, 24 females, mean age 12.95 ± 4.03 years) versus age- and gender-matched HC, using liquid chromatography-mass spectrometry. The criteria for protein selection were: (1) patient/control abundance ratio of < 0.5; and (2) ≤ 0.05 p-value for the Fisher's Exact Test. Results were confirmed by ELISA testing in individual samples.
67 proteins were downregulated in RS group, and 17 of those were significantly different compared to controls. Of those seventeen proteins, five (two actins, annexin A5, keratin 6B, and serpin B4) were completely absent in the urine of stone patients but were found in controls. The remaining twelve proteins were significantly less abundant in the patient's urine compared to healthy controls. Protein-protein interaction modeling of significant proteins identified syndecan-1 as the key node, a protein associated with adhesion pathways. ELISA analysis by subgroups showed statistically significant difference in the urinary excretion of osteopontin (5.1 ± 3.22 ng/mg creatinine vs 14.1 ± 9.5 ng/mg creatinine, p = 0.046) between stone patients with hypocitraturia and controls. Urinary osteopontin concentration was positively correlated with urinary citrate excretion (r = 0.417, p = 0.03).
Children with RS have a different urinary inhibitory polypeptide profile compared to HC. Decreased urinary excretion of these proteins indicates their potential inhibitory role in renal stone formation, especially of the adhesion phase. Lower concentration of urinary osteopontin in children with nephrolithiasis and hypocitraturia suggests its potential involvement in the pathogenesis of this disease. Further characterization of these proteins in a larger sample is imperative.
本研究旨在采用蛋白质组学方法筛选肾结石（RS）患儿尿液中与健康对照组（HC）相比下调的生物标志物。我们假设 RS 和 HC 会显示出独特的抑制蛋白谱，可用于比较途径分析。
这是一项前瞻性、对照、初步研究，对来自 RS（N=30，24 名女性，平均年龄 12.95±4.03 岁）的混合尿液与年龄和性别匹配的 HC 进行了比较，使用液相色谱-质谱法。蛋白质选择的标准是：（1）患者/对照丰度比<0.5；（2）Fisher 精确检验的 p 值≤0.05。结果通过个体样本的 ELISA 检测进行确认。
RS 组有 67 种蛋白下调，其中 17 种与对照组有显著差异。在这 17 种蛋白中，有 5 种（两种肌动蛋白、膜联蛋白 A5、角蛋白 6B 和丝氨酸蛋白酶抑制剂 B4）完全不存在于结石患者的尿液中，但在对照组中发现。其余 12 种蛋白在患者尿液中的丰度明显低于健康对照组。对显著蛋白的蛋白-蛋白相互作用建模确定了 syndecan-1 作为关键节点，这是一种与粘附途径相关的蛋白。亚组 ELISA 分析显示，低柠檬酸尿症结石患者与对照组相比，尿骨桥蛋白排泄有统计学显著差异（5.1±3.22ng/mg 肌酐 vs 14.1±9.5ng/mg 肌酐，p=0.046）。尿骨桥蛋白浓度与尿柠檬酸盐排泄呈正相关（r=0.417，p=0.03）。
与 HC 相比，RS 患儿的尿液抑制多肽谱不同。这些蛋白的尿液排泄减少表明它们在肾结石形成中具有潜在的抑制作用，尤其是在粘附阶段。肾结石和低柠檬酸尿症患儿尿骨桥蛋白浓度较低，提示其在该病发病机制中可能起作用。进一步在更大样本中对这些蛋白进行特征描述是必要的。
