title: Pro-inflammatory IL-1beta and/or TNF-alpha up-regulate matrix metalloproteases-1 and -3 mRNA in chondrocyte subpopulations potentially pathogenic in osteoarthritis: in situ hybridization studies on a single cell level.
abstract: OBJECTIVE
  In osteoarthritis chondrocytes, matrix metalloproteases (MMPs) and their inhibitors are induced by interleukin (IL)-1beta or tumor necrosis factor (TNF)-alpha and balanced by inhibitors, but their messenger RNA (mRNA) expression has not been studied in individual cells.
  
  
  METHODS
  Normal articular chondrocytes (10 donors; age 50 ± 6 years, mean ± SEM) were stimulated in a monolayer for 24 h with IL-1beta, TNF-alpha, or transforming growth factor (TGF)-beta1 (10 ng/mL each), alone or in combination. mRNA expression for MMP-1, MMP-3 and tissue inhibitor of metalloproteinase (TIMP)-1 was studied by in situ hybridization ((35) S-cRNA) and quantitative reverse transcription polymerase chain reaction (RT-PCR) (n ≥ 3 each).
  
  
  RESULTS
  Whereas < 5% chondrocytes constitutively expressed MMP-1, a higher percentage expressed MMP-3 and TIMP-1 (31.1 ± 1.8%; 36.7 ± 2.8%, respectively). Upon stimulation with IL-1beta, TNF-alpha or IL-1beta/TNF-alpha, the percentage of cells positive for MMP-1, MMP-3 and TIMP-1 rose significantly (IL-1beta: 31.5%, 54.5% and 60.2%, respectively; TNF-alpha: 35.4%, 56.6%, 50.9%; IL-1beta/TNF-alpha: 38.8%, 45.2%, 52.1%). In bulk population (RT-PCR), mRNA for MMP-1 and MMP-3 was also induced by IL-1beta (11.9-fold, 1.2-fold, respectively), TNF-alpha (4.8-fold, 1.0-fold) or IL-1beta/TNF-alpha (14.7-fold, 1.4-fold), an effect attenuated by TGF-beta1. TIMP-1 mRNA, in contrast, was down-regulated by IL-1beta, TNF-alpha or IL-1beta/TNF-alpha, an effect again partially reverted by TGF-beta1. Finally, collagen type II mRNA was down-regulated by IL-1beta, TNF-alpha or IL-1beta/TNF-alpha (by 90%, 50% and 98%, respectively) and that of collagen type I was up-regulated (5.7-fold, 3.0-fold, 3.7-fold).
  
  
  CONCLUSIONS
  Up-regulation of MMP-1/MMP-3 by IL-1beta and/or TNF-alpha in a fraction of chondrocytes in vitro suggests that a subpopulation of catabolic cells may also exist in osteoarthritis. These cells may undergo considerable dedifferentiation, as indicated by a decreased collagen-II/collagen-I ratio.
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Jena, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Kunisch
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Jena, Germany.
authors.forename: Raimund W
authors.initials: RW
authors.lastname: Kinne
authors.affiliation: Arthritis Research Unit, Department of Molecular & Experimental Medicine, The Scripps Research Institute (TSRI), La Jolla, California, USA.
authors.forename: Rayya J
authors.initials: RJ
authors.lastname: Alsalameh
authors.affiliation: Department of Medicine 3, University Hospital Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Saifeddin
authors.initials: S
authors.lastname: Alsalameh
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D000090602:Collagen Type I, alpha 1 Chain; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D053583:Interleukin-1beta / Q000494:pharmacology*; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D010003:Osteoarthritis / Q000201:enzymology* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: C499177:COL2A1 protein, human; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D024043:Collagen Type II; D053583:Interleukin-1beta; D012333:RNA, Messenger; C560822:TIMP1 protein, human; D019715:Tissue Inhibitor of Metalloproteinase-1; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; C511768:MMP3 protein, human; D019278:Matrix Metalloproteinase 3; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1
keywords: IL-1beta; MMP; TGF-beta1; TIMP; TNF-alpha; chondrocyte subpopulations; in situ hybridization