Urinary collagen degradation products as early markers of progressive renal fibrosis.
Renal fibrogenesis is associated with increased ECM remodeling and release of collagen fragments in urine in progressive renal disease. We investigated the diagnostic value of urinary collagen degradation products in a proteinuria-driven fibrosis rat model with and without anti-fibrotic S1P-receptor modulator FTY720 treatment.



Proteinuria was induced in male Wistar rats by Adriamycin (ADR) injection (n = 16). Healthy rats served as controls (n = 12). Six weeks post-injection, all underwent renal biopsy, and FTY720-treatment started in ADR-rats (n = 8) and controls (n = 6). Others remained untreated. Rats were sacrificed after 12 weeks. Collagen type I (C1M) and III (C3M) degradation fragments were measured in blood and urine using ELISA. Kidneys were stained for various inflammatory and fibrotic markers.



Six weeks post-injection proteinuria increased (versus controls, P < 0.001) and although no accumulation of interstitial renal collagen type III (iColl3) was observed at this time, urinary C3M (uC3M) and C1M (uC1M) were significantly increased (both P < 0.001). At 12 weeks, uC3M (P < 0.001) and uC1M (P < 0.01) further increased in ADR-rats versus controls, just as fibronectin, PDGF-β receptor, hyaluronan (all P < 0.01), iColl3, PAS, myofibroblasts, macrophages and T-cells (all P < 0.05). FTY720-treatment reduced accumulation of immune cells, α-SMA+ myofibroblasts and PAS-score, but not iColl3 and uC3M. Correlation analyses indicated that uC3M and uC1M reflected and predicted tubulointerstitial fibrogenesis.



These data displayed urinary collagen breakdown products as sensitive early markers of interstitial fibrosis, preceding histological fibrotic changes, which might replace the invasive renal biopsy procedure to assess fibrosis. Anti-fibrotic FTY720 intervention reduced some fibrotic markers without affecting collagen type III metabolism.
Division of Nephrology, Department of Medicine, University Medical Center Groningen, Groningen, The Netherlands. r.s.hijmans@umcg.nl.
Ryanne S
RS
Hijmans
Nordic Bioscience, Biomarkers & Research, Herlev, Denmark.|Institute of Molecular Medicine, Cardiovascular and Renal Research, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
Daniel Guldager Kring
DG
Rasmussen
Division of Nephrology, Department of Medicine, University Medical Center Groningen, Groningen, The Netherlands.
Saleh
S
Yazdani
Division of Nephrology, Department of Medicine, University Medical Center Groningen, Groningen, The Netherlands.
Gerjan
G
Navis
Division of Pathology, Department of Pathology and Medical Biology, University Medical Center Groningen, Groningen, The Netherlands.
Harry
H
van Goor
Nordic Bioscience, Biomarkers & Research, Herlev, Denmark.
Morten Asser
MA
Karsdal
Nordic Bioscience, Biomarkers & Research, Herlev, Denmark.
Federica
F
Genovese
Division of Nephrology, Department of Medicine, University Medical Center Groningen, Groningen, The Netherlands.
Jacob
J
van den Born
D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000652:urine; D024042:Collagen Type I / Q000097:blood / Q000652:urine*; D024061:Collagen Type III / Q000097:blood / Q000652:urine*; D018450:Disease Progression; D004317:Doxorubicin; D005355:Fibrosis; D000068876:Fingolimod Hydrochloride / Q000494:pharmacology; D007668:Kidney / Q000473:pathology*; D008297:Male; D011507:Proteinuria / Q000139:chemically induced / Q000150:complications / Q000473:pathology; D059748:Proteolysis; D017208:Rats, Wistar
D015415:Biomarkers; D024042:Collagen Type I; D024061:Collagen Type III; D004317:Doxorubicin; D000068876:Fingolimod Hydrochloride
Biomarker; Chronic kidney disease; Collagen; Fibrosis; Kidney; MMP