title: Active leflunomide metabolite inhibits interleukin 1beta, tumour necrosis factor alpha, nitric oxide, and metalloproteinase-3 production in activated human synovial tissue cultures.
abstract: BACKGROUND
  Leflunomide is now an approved agent for the management of adult rheumatoid arthritis (RA). Its active metabolite A771726 inhibits de novo pyrimidine biosynthesis. Although considered to be an immunosuppressive agent, its mechanism of action remains obscure.
  
  
  OBJECTIVE
  Evaluation of the leflunomide active metabolite A771726 (LEF) effect on interleukin 1beta (IL1beta), tumour necrosis factor (TNFalpha), nitric oxide (NO), and stromelysin (metalloproteinase-3 (MMP-3)) production by activated human synovial tissue in culture.
  
  
  METHODS
  Synovial tissue was obtained during surgery from patients undergoing total knee replacement owing to RA or osteoarthritis (OA), cut into small pieces, and cultured in Petri dishes with test materials as previously described. IL1beta, TNFalpha, NO, and MMP-3 were measured in the culture media after 48 hours incubation with different doses of LEF by methods previously described.
  
  
  RESULTS
  LEF (0.3, 3, and 9 micro g/ml) inhibited IL1beta production in the presence of lipopolysaccharide (LPS; 3 micro g/ml) in a dose dependent manner (p<0.01) at LEF 0.3 micro g/ml. TNFalpha production in the presence of IL1beta (1 ng/ml) was also inhibited in a dose dependent manner (p<0.05 at LEF 0.3 micro g/ml). NO and MMP-3 production in the presence of LPS (3 micro g/ml) was inhibited as well (p<0.01 at LEF 1 micro g/ml and at LEF 0.3 micro g/ml, respectively). Synovial cell viability evaluated by the tetrazolium salt XTT was unaffected by the LEF concentration used. There was no qualitative difference in the response of OA and RA synovial tissue.
  
  
  CONCLUSIONS
  Leflunomide may modulate the rheumatoid articular process by inhibition of local production of IL1beta, TNFalpha, NO, and MMP-3.
authors.affiliation: Department of Rheumatology, Tel Aviv Sourasky Medical Center, Israel. oribe14@netvision.net.il
authors.forename: O
authors.initials: O
authors.lastname: Elkayam
authors.forename: I
authors.initials: I
authors.lastname: Yaron
authors.forename: I
authors.initials: I
authors.lastname: Shirazi
authors.forename: R
authors.initials: R
authors.lastname: Judovitch
authors.forename: D
authors.initials: D
authors.lastname: Caspi
authors.forename: M
authors.initials: M
authors.lastname: Yaron
mesh_terms: D000368:Aged; D000814:Aniline Compounds / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003437:Crotonates; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D006885:Hydroxybutyrates / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007375:Interleukin-1 / Q000096:biosynthesis*; D007719:Knee Joint; D008070:Lipopolysaccharides / Q000494:pharmacology; D019278:Matrix Metalloproteinase 3 / Q000096:biosynthesis*; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D009570:Nitriles; D010003:Osteoarthritis / Q000378:metabolism; D013583:Synovial Membrane / Q000187:drug effects* / Q000378:metabolism; D014052:Toluidines; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000187:drug effects
chemical_list: D000814:Aniline Compounds; D003437:Crotonates; D006885:Hydroxybutyrates; D007166:Immunosuppressive Agents; D007375:Interleukin-1; D008070:Lipopolysaccharides; D009570:Nitriles; D014052:Toluidines; D014409:Tumor Necrosis Factor-alpha; C527525:teriflunomide; D009569:Nitric Oxide; D019278:Matrix Metalloproteinase 3