title: Hypoxia differentially affects IL-1β-stimulated MMP-1 and MMP-13 expression of fibroblast-like synoviocytes in an HIF-1α-dependent manner.
abstract: OBJECTIVE
  To further understand the expression regulation of MMP-1 and MMP-13 under physiological and pathological conditions, we investigated the combined effects of hypoxia and pro-inflammatory stimuli on the expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts.
  
  
  METHODS
  Synovial fibroblasts were cultured under either hypoxic or normoxic conditions in the presence of IL-1β stimulation. The culture supernatant was analysed for secreted levels of VEGF, MMP-1 and MMP-13. Their gene expression was quantified with real-time and semi-quantitative PCR. Another group of cells was transfected with small-interfering RNA (siRNA) specific for hypoxia-inducible factor-1 α (HIF-1α). The protein levels of HIF-1α were detected by western blot analysis.
  
  
  RESULTS
  In response to 10 ng/ml of IL-1β under normoxia, the levels of MMP-1 and MMP-13 increased compared with the levels observed under hypoxia. IL-1β stimulation under hypoxia induced a 2-fold increase in the level of MMP-1 and a 2-fold decrease in the level of MMP-13 compared with cells cultured under normoxia. A similar pattern of differential expression for MMP-1 and MMP-13 was observed with 1 and 5 ng/ml IL-1β, but not at 0.1 ng/ml. The differential expression of MMPs under the combined effect of IL-1β and hypoxia was significantly attenuated by silencing HIF-1α with siRNA.
  
  
  CONCLUSIONS
  Hypoxia in arthritic joints may differentially affect the IL-1β-stimulated expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts. This effect is dependent on HIF-1α expression. This hypoxia-mediated differential effect should be taken into consideration when testing the efficiency of therapies that target HIF-1α.
authors: Kyung Hee University, Gangdong-gu, Seoul, Korea.
authors: Yeon-Ah
authors: YA
authors: Lee
authors: Hyun M
authors: HM
authors: Choi
authors: Sang-Hoon
authors: SH
authors: Lee
authors: Seung-Jae
authors: SJ
authors: Hong
authors: Hyung-In
authors: HI
authors: Yang
authors: Myung C
authors: MC
authors: Yoo
authors: Kyoung S
authors: KS
authors: Kim
mesh_terms: D001172:Arthritis, Rheumatoid / Q000150:complications / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D005786:Gene Expression Regulation; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000494:pharmacology*; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D013583:Synovial Membrane / Q000187:drug effects* / Q000201:enzymology; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D053583:Interleukin-1beta; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1