title: Metzincins and related genes in experimental renal ageing: towards a unifying fibrosis classifier across species.
abstract: BACKGROUND
  We have previously described a transcriptomic classifier consisting of metzincins and related genes (MARGS) discriminating kidneys and other organs with or without fibrosis from human biopsies. We now apply our MARGS-based algorithm to a rat model of age-associated interstitial renal fibrosis.
  
  
  METHODS
  Untreated Fisher 344 rats (n = 76) were sacrificed between 2 to 104 weeks of age. For gene expression studies, we used single colour (Cy3) Agilent Whole Rat Genome 4 × 44k microarrays; 4-5 animals of each sex were profiled at each of the following ages: 2, 5, 6, 8, 15, 21, 78 and 104 weeks. Intensity data were subjected to variance stabilization (www.Partek.com). Data were analysed with ANOVA and other statistical methods.
  
  
  RESULTS
  Sixty MARGS were differentially expressed across age groups. More MARGS were differentially expressed in older males than in older females. Principal component analysis showed gene expression induced segregation of age groups by sex from 6 to 104 weeks of age. The expression level of MMP7 correlated best with fibrosis grade. Severity of fibrosis was determined in 20 animals at 78 and 104 weeks of age. Expression values of 15 of 19 genes of the original classifier present on the Agilent array, in conjunction with linear discriminant analysis, was sufficient to correctly classify these 20 samples into non-fibrosis and fibrosis. Overrepresentation of MMP2 protein and CD44 protein in fibrosis was confirmed by immunofluorescence.
  
  
  CONCLUSIONS
  Based on these results and our previous work, the MARGS classifier represents a cross-organ and cross-species classifier of fibrosis irrespective of aetiology. This finding provides evidence for a common pathway leading to fibrosis and will help to design a PCR-based clinical test.
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Marti
authors.affiliation: Division of Systems Biology, National Center for Toxicological Research, FDA, Jefferson, AR, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Fuscoe
authors.affiliation: Division of Systems Biology, National Center for Toxicological Research, FDA, Jefferson, AR, USA.
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Kwekel
authors.affiliation: Institute of Anatomy, University of Bern, Bern, Switzerland.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Anagnostopoulou
authors.affiliation: Spheromics, Kontiolahti, Finland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Scherer
mesh_terms: D000375:Aging / Q000235:genetics* / Q000473:pathology*; D000465:Algorithms; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005355:Fibrosis; D020869:Gene Expression Profiling / Q000379:methods*; D007668:Kidney / Q000473:pathology* / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism; D046228:Microarray Analysis; D016133:Polymerase Chain Reaction; D025341:Principal Component Analysis; D051381:Rats; D011916:Rats, Inbred F344; D059467:Transcriptome / Q000502:physiology*
chemical_list: D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2
keywords: CD44; ageing; classifier; fibrosis; matrix metalloproteinases; metzincins