Department of Medicine, Systemic Autoimmune Diseases Unit, Hospital Universitari Vall D'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain.
Department of Medicine, Systemic Autoimmune Diseases Unit, Hospital Universitari Vall D'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain Department of Renal Pathology, Hospital Universitari Vall D'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Nephrol Dial Transplant. 2015 Sep;30(9):1488-96. doi: 10.1093/ndt/gfv128. Epub 2015 Jun 3.
Despite overall improvement in prognosis, 10-30% of patients with lupus nephritis (LN) will develop end-stage renal disease. To date, renal biopsy is still the 'gold standard' test used to predict renal outcome. However, due to its invasive nature, new non-invasive biomarkers are required. Urinary exosomes, microvesicles released by every epithelial cell facing the urinary space, represent an ideal source of markers for renal dysfunction and injury. Here, we sought to evaluate miR-29c expression levels in urinary exosomes as a novel biomarker of renal fibrosis in LN.
Urinary exosomes were isolated from 32 samples of patients with biopsy-proven LN, 15 non-lupus chronic kidney diseases and 20 healthy controls. Electronic microscopy and western blot were used to characterize the exosomes. Expression levels of miR-29c were detected by RT-PCR quantitative and correlated with clinical and histological parameters along with the expression levels of Smad2/3, TGF-β and MMP2/9. For comparison, miRNA expression was also evaluated in the urinary pellet.
MiR-29c levels in urinary exosomes showed a negatively strong correlation with the histological chronicity index (r = -0.898, P = 0.001) and glomerular sclerosis (r = -0.555, P = 0.007). No correlation with eGFR and creatinine levels was found. MiR-29c expression levels could predict the degree of chronicity in patients with LN with an area under the curve (AUC) of 0.946 (P < 0.001) and with high sensitivity and specificity (94% and 82%). Smad3 and MMP2 expression in urinary exosomes correlated negatively with miR-29c expression (r = -0.737 and -0.856, respectively). In the urinary pellet, no miR-29c expression was detected; however, upregulation of Smad3 and MMP2 was observed (3.54- and 5.85-fold increase).
Overall, miR-29c correlated with the degree of renal chronicity but not with renal function, suggesting it could be used as a novel non-invasive marker of early progression to fibrosis in patients with LN.
尽管狼疮肾炎 (LN) 患者的总体预后有所改善，但仍有 10-30%的患者会发展为终末期肾病。迄今为止，肾活检仍然是用于预测肾脏结局的“金标准”检测。然而，由于其具有侵袭性，因此需要新的非侵入性生物标志物。尿液外泌体是由所有面向尿腔的上皮细胞释放的微囊泡，是肾功能和损伤的理想标志物来源。在这里，我们试图评估尿液外泌体中 miR-29c 的表达水平作为 LN 肾纤维化的新型生物标志物。
从 32 例经活检证实的 LN 患者、15 例非狼疮性慢性肾脏病患者和 20 例健康对照者的尿液中分离尿液外泌体。电子显微镜和 Western blot 用于鉴定外泌体。通过 RT-PCR 定量检测 miR-29c 的表达水平，并与临床和组织学参数以及 Smad2/3、TGF-β和 MMP2/9 的表达水平相关联。为了进行比较，还评估了尿沉渣中的 miRNA 表达。
尿液外泌体中的 miR-29c 水平与组织学慢性指数（r = -0.898，P = 0.001）和肾小球硬化（r = -0.555，P = 0.007）呈负强相关。与 eGFR 和肌酐水平无相关性。miR-29c 表达水平可预测 LN 患者的慢性程度，曲线下面积（AUC）为 0.946（P < 0.001），且具有高灵敏度和特异性（94%和 82%）。尿液外泌体中 Smad3 和 MMP2 的表达与 miR-29c 的表达呈负相关（r = -0.737 和 -0.856）。在尿沉渣中，未检测到 miR-29c 的表达；然而，观察到 Smad3 和 MMP2 的上调（分别增加 3.54 倍和 5.85 倍）。
总体而言，miR-29c 与肾脏慢性程度相关，但与肾功能无关，表明其可作为 LN 患者纤维化早期进展的新型非侵入性标志物。
