title: Endogenous MMP-9 and not MMP-2 promotes rheumatoid synovial fibroblast survival, inflammation and cartilage degradation.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of endogenous matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) on the invasive characteristics of RA synovial fibroblasts.
  
  
  METHODS
  Synovial fibroblasts isolated from patients with RA or OA were treated with MMP small interfering RNA (siRNA), inhibitors and recombinant proteins or TNF-α, with or without cartilage explants. Cell viability and proliferation were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and 5-bromo-2-deoxyuridine (BrdU) proliferation assays, respectively; apoptosis by an in situ cell death detection kit; migration and invasion by CytoSelect invasion assay, scratch migration and collagen gel assays; cartilage degradation by 1,9-dimethylmethylene blue assay; and inflammatory mediators and MMPs by ELISA, western blot and zymography.
  
  
  RESULTS
  MMP-2 was expressed by both OA and RA synovial fibroblasts, whereas only RA synovial fibroblasts expressed MMP-9. Suppressing MMP-2 or MMP-9 reduced RA synovial fibroblast proliferation equally. However, MMP-9 siRNA had greater effects compared with MMP-2 siRNA on promoting apoptosis and suppressing RA synovial fibroblast viability, migration and invasion. Suppression/inhibition of MMP-9 also decreased the production of IL-1β, IL-6, IL-8 and TNF-α, inactivated nuclear factor κB (NF-κB), extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) and suppressed RA synovial fibroblast-mediated cartilage degradation. In contrast, suppression/inhibition of MMP-2 stimulated TNF-α and IL-17 secretion and activated NF-κB, while recombinant MMP-2 (rMMP-2) inactivated NF-κB and suppressed RA synovial fibroblast-mediated cartilage degradation. Results using specific inhibitors and rMMPs provided supportive evidence for the siRNA results.
  
  
  CONCLUSIONS
  Endogenous MMP-2 or MMP-9 contribute to RA synovial fibroblast survival, proliferation, migration and invasion, with MMP-9 having more potent effects. Additionally, MMP-9 stimulates RA synovial fibroblast-mediated inflammation and degradation of cartilage, whereas MMP-2 inhibits these parameters. Overall, our data indicate that MMP-9 derived from RA synovial fibroblasts may directly contribute to joint destruction in RA.
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea. meilang.xue@sydney.edu.au.
authors: Meilang
authors: M
authors: Xue
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Kelly
authors: K
authors: McKelvey
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Kaitlin
authors: K
authors: Shen
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Nikita
authors: N
authors: Minhas
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Lyn
authors: L
authors: March
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Sang-Youel
authors: SY
authors: Park
authors: Sutton Research Laboratory, Department of Rheumatology, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia and Bio-Safety Research Institute, Chonbuk National University, College of Veterinary Medicine, Jeonju, South Korea.
authors: Christopher J
authors: CJ
authors: Jackson
mesh_terms: D000368:Aged; D017209:Apoptosis / Q000502:physiology; D001172:Arthritis, Rheumatoid / Q000201:enzymology / Q000473:pathology*; D002358:Cartilage, Articular / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D005347:Fibroblasts / Q000201:enzymology / Q000473:pathology / Q000502:physiology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000502:physiology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000201:enzymology / Q000473:pathology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D013583:Synovial Membrane / Q000201:enzymology / Q000473:pathology*
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D034741:RNA, Small Interfering; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9
keywords: cartilage degradation; inflammation; invasion; matrix metalloproteinase 2 and 9; migration; proliferation; rheumatoid arthritis; survival; synovial fibroblasts