title: Influence of extracellular matrix on the expression of inflammatory cytokines, proteases, and apoptosis-related genes induced by hydrostatic pressure in three-dimensionally cultured chondrocytes.
abstract: BACKGROUND
  The purpose of this study was to investigate the influence of hydrostatic pressure (HP) on the gene expression of cartilage matrix, cytokines, and apoptosis-associated factors in chondrocytes in which the cartilage was in extracellular matrix (ECM)-rich or ECM-poor condition.
  
  
  METHODS
  Chondrocytes were isolated from rabbit joints and cultured in alginate beads. Immediately after embedding (0W group) or after 2 weeks culture (2W group), the amounts of glycosaminoglycan (GAG) in the alginate beads were quantified. Both groups were exposed to continuous HP of 10 or 50 MPa for 12 h. The expression of inflammatory cytokines, proteases, and apoptosis-related factors were examined by reverse transcription-polymerase chain reaction (RT-PCR). The expression of proteoglycan core protein (PG) and collagen type II were quantified by real-time RT-PCR.
  
  
  RESULTS
  All of the GAG components in alginate beads markedly increased in the 2W group. The expression of PG and collagen type II increased after exposure to 10 MPa in both groups. In the 0W group, these levels decreased after exposure to 50 MPa of HP. The expression of interleukins IL-6 and IL-8 increased after exposure to HP in the 0W group. HP at 50 MPa induced mRNA expression of ADAMTS-5 in the 0W group but not in the 2W group. The expression of Fas increased after exposure to HP in the 0W group.
  
  
  CONCLUSIONS
  These findings suggested that nonphysiological, excessive HP on chondrocytes with the ECM in poor condition reduced matrix gene expression and increased expression of the genes associated with apoptosis and catabolism of the cartilage matrix. These results might therefore be associated with the pathogenesis of osteoarthritis.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Taisuke
authors.initials: T
authors.lastname: Kunitomo
authors.forename: Kenji A
authors.initials: KA
authors.lastname: Takahashi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.forename: Kei
authors.initials: K
authors.lastname: Sakao
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Honjo
authors.forename: Masazumi
authors.initials: M
authors.lastname: Saito
authors.forename: Atsuo
authors.initials: A
authors.lastname: Inoue
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tonomura
authors.forename: Toru
authors.initials: T
authors.lastname: Morihara
authors.forename: Osam
authors.initials: O
authors.lastname: Mazda
authors.forename: Jiro
authors.initials: J
authors.lastname: Imanishi
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002358:Cartilage, Articular / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006874:Hydrostatic Pressure; D011817:Rabbits
chemical_list: D016207:Cytokines