title: Serum markers of the extracellular matrix remodeling reflect antifibrotic therapy in bile-duct ligated rats.
abstract: BACKGROUND
  Progression of liver fibrosis is characterized by synthesis and degradation of extracellular matrix (ECM). Matrix-metalloproteinases (MMP) cleave collagen fibers at a specific site and thereby generate soluble fragments of ECM (neo-epitopes). The levels of these neo-epitopes might reflect the stage of liver fibrosis and may allow monitoring of anti-fibrotic therapies. Here we analyzed these neo-epitopes as read-out for a liver directed therapy with statins.
  
  
  METHODS
  Bile duct ligation (BDL) was performed on wild type rats, which received atorvastatin (15 mg/kg(*)d) for 1 week starting at 1, 2, 3, 4 and 5 weeks after BDL (T1-T5), while controls remained untreated. Hepatic fibrosis was analyzed by immunohistochemistry and hepatic hydroxyproline content. TGFβ levels were measured by RT-PCR. Proteolytic activity of MMP-2 was examined by zymography. Levels of degradation MMP driven type I, III, IV and VI collagen degradation (C1M, C3M, C4M, and C6M) and type III and IV collagen formation (PRO-C3 and P4NP7S) markers were assessed by specific ELISAs in serum probes.
  
  
  RESULTS
  Serum markers of ECM neo-epitopes reflected significantly the deposition of ECM in the liver and were able to distinguish between early (T1-T3) and severe fibrosis (T4-T5). Statin treatment resulted in reduction of neo-epitope markers, especially when therapy was started in the stage of severe fibrosis (T4-T5). Furthermore, these markers correlated with hepatic expression of profibrotic cytokines TGFβ1 and TGFβ2. Formation markers of type III and IV collagen (PRO-C3 and P4NP7S) and degradation markers C4M and C6M correlated significantly with hepatic MMP-2 activity in rats with severe fibrosis.
  
  
  CONCLUSIONS
  Determination of ECM remodeling turnover markers in serum allowed a distinction between mild and severe fibrosis. With respect to statin therapy, the markers may serve as read-out for efficacy of anti-fibrotic treatment.
authors.affiliation: Department of Internal Medicine I, University of Bonn Bonn, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Schierwagen
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Leeming
authors.forename: Sabine
authors.initials: S
authors.lastname: Klein
authors.forename: Michaela
authors.initials: M
authors.lastname: Granzow
authors.forename: Mette J
authors.initials: MJ
authors.lastname: Nielsen
authors.forename: Tilman
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: Aleksander
authors.initials: A
authors.lastname: Krag
authors.forename: Morten A
authors.initials: MA
authors.lastname: Karsdal
authors.forename: Jonel
authors.initials: J
authors.lastname: Trebicka
keywords: ECM (extracellular matrix); antifibrotic; fibrosis; markers; remodeling; statins
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