title: Activation of receptor for advanced glycation end products in osteoarthritis leads to increased stimulation of chondrocytes and synoviocytes.
abstract: OBJECTIVE
  The major risk factor for osteoarthritis (OA) is aging, but the mechanisms underlying this risk are only partly understood. Age-related accumulation of advanced glycation end products (AGEs) could be one of these mechanisms. We undertook this study to investigate the role of the receptor for AGEs (RAGE) in mediating the cellular effects of AGEs on chondrocytes and fibroblast-like synoviocytes (FLS).
  
  
  METHODS
  AGE levels in human cartilage were determined by fluorescence, browning, and pentosidine levels. Chondrocyte activation by AGEs was assessed as the release of proteoglycans and the synthesis of matrix metalloproteinase 1 (MMP-1) and type II collagen messenger RNA (mRNA). The activation of FLS by AGEs was measured by MMP-1 production and invasion through matrix proteins.
  
  
  RESULTS
  Patients with focal degeneration of cartilage showed increased AGE levels in their healthy cartilage compared with the levels in healthy cartilage from donors without cartilage degeneration (P < 0.01 for both fluorescence and browning; P not significant for pentosidine content). Stimulation of bovine chondrocytes with glycated albumin increased the release of proteoglycans by 110% (P < 0.001) and the production of MMP-1 mRNA by 200% (P = 0.028). In addition, OA FLS produced 240% more MMP-1 when stimulated with glycated albumin (P < 0.001). Glycated matrix or albumin increased the catabolic activity of OA FLS, which was assessed as invasive behavior, by 150% and 140% (P = 0.001 and P = 0.010), respectively. Effects of stimulation with AGEs were blocked by a neutralizing antibody against RAGE, but not by an isotype control.
  
  
  CONCLUSIONS
  This study shows that AGEs trigger RAGE on chondrocytes and FLS, leading to increased catabolic activity and therefore to cartilage degradation. AGEs, via RAGE, could therefore contribute to the development and/or progression of OA.
authors.affiliation: TNO Quality of Life/TNO Pharma, and Leiden University Medical Center, 2301 CE Leiden, The Netherlands.
authors.forename: Marjan M C
authors.initials: MM
authors.lastname: Steenvoorden
authors.forename: Tom W J
authors.initials: TW
authors.lastname: Huizinga
authors.forename: Nicole
authors.initials: N
authors.lastname: Verzijl
authors.forename: Ruud A
authors.initials: RA
authors.lastname: Bank
authors.forename: H Karel
authors.initials: HK
authors.lastname: Ronday
authors.forename: Hilco A F
authors.initials: HA
authors.lastname: Luning
authors.forename: Floris P J G
authors.initials: FP
authors.lastname: Lafeber
authors.forename: René E M
authors.initials: RE
authors.lastname: Toes
authors.forename: Jeroen
authors.initials: J
authors.lastname: DeGroot
mesh_terms: D002102:Cadaver; D019902:Chondrocytes / Q000276:immunology*; D005347:Fibroblasts / Q000276:immunology*; D017127:Glycation End Products, Advanced / Q000502:physiology*; D006801:Humans; D010003:Osteoarthritis / Q000276:immunology*; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000502:physiology*; D013583:Synovial Membrane / Q000166:cytology*
chemical_list: D017127:Glycation End Products, Advanced; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic