Email updates

Keep up to date with the latest news and content from BMC Medicine and BioMed Central.

Journal App

google play app store
Open Access Research article

Urinary soluble urokinase receptor levels are elevated and pathogenic in patients with primary focal segmental glomerulosclerosis

Jing Huang1234, Gang Liu1234, Yi-miao Zhang1234, Zhao Cui1234, Fang Wang1234, Xiao-jing Liu1234, Rong Chu1234 and Ming-hui Zhao12345*

Author Affiliations

1 Renal Division, Peking University First Hospital, Beijing, PR China

2 Institute of Nephrology, Peking University, Beijing, PR China

3 Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, PR China

4 Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing, PR China

5 Peking-Tsinghua Center for Life Sciences, Beijing, PR China

For all author emails, please log on.

BMC Medicine 2014, 12:81  doi:10.1186/1741-7015-12-81

Published: 20 May 2014

Abstract

Background

Focal segmental glomerulosclerosis (FSGS) is a major cause of end-stage renal disease. Recent studies have proposed that plasma soluble urokinase receptor (suPAR) might be a causative circulating factor but this proposal has caused controversy. This study aimed to measure urinary suPAR levels in patients with primary FSGS and its significance in the pathogenesis of FSGS.

Methods

Sixty-two patients with primary FSGS, diagnosed between January 2006 and January 2012, with complete clinical and pathologic data were enrolled, together with disease and normal controls. Urinary suPAR levels were measured using commercial ELISA kits and were corrected by urinary creatinine (Cr). The associations between urinary suPAR levels and clinical data at presentation and during follow up were analyzed. Conditionally immortalized human podocytes were used to study the effect of urinary suPAR on activating β3 integrin detected by AP5 staining.

Results

The urinary suPAR level of patients with primary FSGS (500.56, IQR 262.78 to 1,059.44 pg/μmol Cr) was significantly higher than that of patients with minimal change disease (307.86, IQR 216.54 to 480.18 pg/μmol Cr, P = 0.033), membranous nephropathy (250.23, IQR 170.37 to 357.59 pg/μmol Cr, P <0.001), secondary FSGS (220.45, IQR 149.38 to 335.54 pg/μmol Cr, P <0.001) and normal subjects (183.59, IQR 103.92 to 228.78 pg/μmol Cr, P <0.001). The urinary suPAR level of patients with cellular variant was significantly higher than that of patients with tip variant. The urinary suPAR level in the patients with primary FSGS was positively correlated with 24-hour urine protein (r = 0.287, P = 0.024). During follow up, the urinary suPAR level of patients with complete remission decreased significantly (661.19, IQR 224.32 to 1,115.29 pg/μmol Cr versus 217.68, IQR 121.77 to 415.55 pg/μmol Cr, P = 0.017). The AP5 signal was strongly induced along the cell membrane when human differentiated podocytes were incubated with the urine of patients with FSGS at presentation, and the signal could be reduced by a blocking antibody specific to uPAR.

Conclusions

Urinary suPAR was specifically elevated in patients with primary FSGS and was associated with disease severity. The elevated urinary suPAR could activate β3 integrin on human podocytes.

Please see related article http://www.biomedcentral.com/1741-7015/12/82 webcite.

Keywords:
Focal segmental glomerulosclerosis; Urinary soluble urokinase receptor; Podocyte