Packialakshmi Balamurugan, Limerick Emily, Ackerman Hans C, Lin Xionghao, Nekhai Sergei, Oliver James D, Stewart Ian J, Knepper Mark A, Fitzhugh Courtney, Zhou Xiaoming
Department of Medicine, Uniformed Services University of Health Sciences, Bethesda, MD, United States.
Cellular and Molecular Therapeutic Branch, National Heart Lung and Blood Institute, Bethesda, MD, United States.
Front Physiol. 2024 Feb 15;15:1300667. doi: 10.3389/fphys.2024.1300667. eCollection 2024.
Sickle cell nephropathy (SCN) is a leading cause of morbidity and mortality in sickle cell disease (SCD). Early intervention is crucial for mitigating its effects. However, current diagnostic methods rely on generic tests and may not detect SCN until irreversible renal damage occurs. Therefore, specific biomarkers for early diagnosis of SCN are needed. Urinary exosomes, membrane-bound vesicles secreted by renal podocytes and epithelial cells, contain both common and cell type-specific membrane and cytosolic proteins, reflecting the physiologic and pathophysiologic states of the kidney. Using proteomics, we analyzed the proteomes of urinary exosomes from humanized SCD mice at 2 months (without albuminuria) and 4 months (with albuminuria) of age. Excretion of 164 proteins were significantly increased and 176 proteins was significantly decreased in the exosomes when mice developed albuminuria. Based on the relevance to SCD, chronic kidney disease and Western blot confirmation in mice, we analyzed protein abundance of heparanase, cathepsin C, α2-macroglobulin and sarcoplasmic endoplasmic Ca ATPase-3 (SERCA3) in the urinary exosomes and urine of 18 SCD subjects without albuminuria and 12 subjects with albuminuria using Western blot analyses. Both male and female subjects increased or tended to increase the excretion of these proteins in their urinary exosomes upon developing albuminuria, but female subjects demonstrated stronger correlations between the excretion of these proteins and urine albumin creatinine ratio (UACR) compared to male subjects. In contrast, exosomal excretion of Tamm-Horsfall protein, β-actin and SHP-1 was independent of albuminuria. These findings provide a foundation for a time-course study to determine whether increases in the levels of these proteins precede the onset of albuminuria in patients, which will help determine the potential of these proteins as biomarkers for early detection of SCN.
镰状细胞肾病（SCN）是镰状细胞病（SCD）发病和死亡的主要原因。早期干预对于减轻其影响至关重要。然而，目前的诊断方法依赖于通用检测，可能直到发生不可逆的肾损伤才检测到SCN。因此，需要用于SCN早期诊断的特异性生物标志物。尿外泌体是肾足细胞和上皮细胞分泌的膜结合囊泡，包含常见的和细胞类型特异性的膜蛋白和胞质蛋白，反映肾脏的生理和病理生理状态。我们使用蛋白质组学分析了2月龄（无蛋白尿）和4月龄（有蛋白尿）的人源化SCD小鼠尿外泌体的蛋白质组。当小鼠出现蛋白尿时，外泌体中164种蛋白质的排泄量显著增加，176种蛋白质显著减少。基于与SCD、慢性肾病的相关性以及在小鼠中的蛋白质印迹证实，我们使用蛋白质印迹分析了18名无蛋白尿的SCD受试者和12名有蛋白尿的受试者尿外泌体和尿液中乙酰肝素酶、组织蛋白酶C、α2-巨球蛋白和肌浆内质网Ca ATP酶-3（SERCA3）的蛋白质丰度。男性和女性受试者在出现蛋白尿时，其尿外泌体中这些蛋白质的排泄量均增加或有增加趋势，但与男性受试者相比，女性受试者中这些蛋白质的排泄量与尿白蛋白肌酐比值（UACR）之间的相关性更强。相比之下，Tamm-Horsfall蛋白、β-肌动蛋白和SHP-1的外泌体排泄与蛋白尿无关。这些发现为一项时间进程研究奠定了基础，以确定这些蛋白质水平的升高是否先于患者蛋白尿的发作，这将有助于确定这些蛋白质作为SCN早期检测生物标志物的潜力。
