title: Pro-inflammatory stimulation of meniscus cells increases production of matrix metalloproteinases and additional catabolic factors involved in osteoarthritis pathogenesis.
abstract: OBJECTIVE
  Meniscus injury increases the risk of osteoarthritis; however, the biologic mechanism remains unknown. We hypothesized that pro-inflammatory stimulation of meniscus would increase production of matrix-degrading enzymes, cytokines and chemokines which cause joint tissue destruction and could contribute to osteoarthritis development.
  
  
  METHODS
  Meniscus and cartilage tissue from healthy tissue donors and total knee arthroplasties (TKAs) was cultured. Primary cell cultures were stimulated with pro-inflammatory factors [IL-1β, IL-6, or fibronectin fragments (FnF)] and cellular responses were analyzed by real-time PCR, protein arrays and immunoblots. To determine if NF-κB was required for MMP production, meniscus cultures were treated with inflammatory factors with and without the NF-κB inhibitor, hypoestoxide.
  
  
  RESULTS
  Normal and osteoarthritic meniscus cells increased their MMP secretion in response to stimulation, but specific patterns emerged that were unique to each stimulus with the greatest number of MMPs expressed in response to FnF. Meniscus collagen and connective tissue growth factor (CTGF) gene expression was reduced. Expression of cytokines (IL-1α, IL-1β, IL-6), chemokines (IL-8, CXCL1, CXCL2, CSF1) and components of the NF-κB and tumor necrosis factor (TNF) family were significantly increased. Cytokine and chemokine protein production was also increased by stimulation. When primary cell cultures were treated with hypoestoxide in conjunction with pro-inflammatory stimulation, p65 activation was reduced as were MMP-1 and MMP-3 production.
  
  
  CONCLUSIONS
  Pro-inflammatory stimulation of meniscus cells increased matrix metalloproteinase production and catabolic gene expression. The meniscus could have an active biologic role in osteoarthritis development following joint injury through increased production of cytokines, chemokines, and matrix-degrading enzymes.
authors: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. Electronic address: ausstone@wakehealth.edu.
authors: A V
authors: AV
authors: Stone
authors: Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. Electronic address: rloeser@wakehealth.edu.
authors: R F
authors: RF
authors: Loeser
authors: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. Electronic address: kvanderm@wakehealth.edu.
authors: K S
authors: KS
authors: Vanderman
authors: Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. Electronic address: dllong@wakehealth.edu.
authors: D L
authors: DL
authors: Long
authors: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
authors: S C
authors: SC
authors: Clark
authors: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. Electronic address: ferguson@wakehealth.edu.
authors: C M
authors: CM
authors: Ferguson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics; D017077:Culture Media, Conditioned; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D004224:Diterpenes / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology*; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D008592:Menisci, Tibial / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology; D040081:Protein Array Analysis / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000502:physiology
chemical_list: D018925:Chemokines; D017077:Culture Media, Conditioned; D016207:Cytokines; D004224:Diterpenes; D018836:Inflammation Mediators; D016328:NF-kappa B; C432343:hypoestoxide; D020782:Matrix Metalloproteinases
keywords: Cytokine; MMP; Matrix metalloproteinase; Meniscus; Osteoarthritis