title: Antifibrotic, nephroprotective potential of ACE inhibitor vs AT1 antagonist in a murine model of renal fibrosis.
abstract: BACKGROUND
  Several studies have shown antifibrotic effects of angiotensin converting enzyme (ACE) inhibitors as well as of angiotensin receptor 1 (AT1) antagonists, however, prospective trials with clinical end points comparing these effects do not exist. COL4A3-/- mice develop a non-hypertensive progressive renal fibrosis. We used this animal model to compare the potential of ACE inhibitor vs AT1 antagonist to prevent renal fibrosis irrespective of blood pressure-dependent involvement by the renin system.
  
  
  METHODS
  COL4A3-/- mice were treated with placebo, ramipril or candesartan. Blood pressure, proteinuria, serum urea and lifespan were monitored. Renal matrix was characterized by immuno-histochemistry, light and electron microscopy. Further biochemical analysis was provided using cDNA microarray and western blot techniques.
  
  
  RESULTS
  Untreated mice died of renal failure after 71+/-6 days. Ramipril and candesartan both delayed onset and reduced the extent of proteinuria. Both had minor effects on blood pressure and postponed onset of uraemia. Ramipril increased lifespan by 111% to 150+/-21 days (P<0.01), whereas candesartan resulted in only a 38% prolongation to 98+/-16 days (P<0.01). Ramipril reduced glomerular and tubulo-interstitial fibrosis and numbers of activated fibroblasts to a greater extent than candesartan. Microarray and western blot analysis revealed a higher antifibrotic potential of ramipril in terms of downregulation of TGFbeta, connective tissue growth factor, metalloproteinases and extracellular matrix proteins.
  
  
  CONCLUSIONS
  The results indicate an antifibrotic, nephroprotective effect of ACE inhibitors and AT1 antagonists in an animal model of progressive renal fibrosis. The greater antifibrotic effect of ramipril at the maximal therapeutic doses employed may not be explained by different antiproteinuric or blood pressure lowering properties, but by-in contrast to candesartan-its ability to hinder the proinflammatory, profibrotic activation of the angiotensin receptor 2.
authors.affiliation: Medical Faculty University of Cologne, Department of Internal Medicine I, Cologne General Hospital, Merheim Medical Center, Cologne, Germany. oliver.gross@uni-koeln.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Gross
authors.forename: Eckhard
authors.initials: E
authors.lastname: Schulze-Lohoff
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Koepke
authors.forename: Bogdan
authors.initials: B
authors.lastname: Beirowski
authors.forename: Klaus
authors.initials: K
authors.lastname: Addicks
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.forename: Neil
authors.initials: N
authors.lastname: Smyth
authors.forename: Manfred
authors.initials: M
authors.lastname: Weber
mesh_terms: D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D000818:Animals; D001562:Benzimidazoles / Q000627:therapeutic use*; D001713:Biphenyl Compounds; D004195:Disease Models, Animal; D005355:Fibrosis / Q000517:prevention & control; D006977:Hypertension, Renal / Q000517:prevention & control*; D007668:Kidney / Q000187:drug effects* / Q000473:pathology*; D051379:Mice; D017257:Ramipril / Q000627:therapeutic use*; D013777:Tetrazoles / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D000806:Angiotensin-Converting Enzyme Inhibitors; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D013777:Tetrazoles; D017257:Ramipril; C081643:candesartan