title: Concentration-dependent effects of tiludronate on equine articular cartilage explants incubated with and without interleukin-1β.
abstract: OBJECTIVE
  To determine concentration-dependent effects of tiludronate on cartilage explants incubated with or without recombinant equine interleukin-1β (rEq IL-1).
  
  
  METHODS
  Articular cartilage explants from the femorotibial joints of 3 young adult horses.
  
  
  METHODS
  Cartilage explants were incubated with 1 of 6 concentrations (0, 0.19, 1.9, 19, 190, or 1,900 mg/L) of tiludronate and with or without rEq IL-1 (0.01 ng/mL) for 96 hours. Prostaglandin E(2) (PGE(2)) concentrations in culture medium and explant digests were analyzed via PGE(2) enzyme immunoassay. Sulfated glycosaminoglycan (sGAG) concentrations in culture medium were quantified via 1,9-dimethylmethylene blue assay. Chondrocyte apoptosis in paraffin embedded explant sections was measured via terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Relative gene expression of matrix metalloproteinases (MMPs), interleukin (IL)-6, and IL-8 was determined via the comparative cycle threshold method.
  
  
  RESULTS
  rEq IL-1 increased PGE(2) concentration, sGAG release from explants, chondrocyte apoptosis, and MMP gene expression. Lower tiludronate concentrations reduced rEq IL-1-induced sGAG release and chondrocyte apoptosis, whereas the higher tiludronate concentrations increased sGAG release and chondrocyte apoptosis. At the highest tiludronate concentration evaluated, IL-8 gene expression was increased independent of whether rEq IL-1 was present.
  
  
  CONCLUSIONS
  Tiludronate had biphasic concentration-dependent effects on cartilage explants that were independent of PGE(2) secretion or MMP gene expression. Low tiludronate concentrations had some chondroprotective effects, whereas high tiludronate concentrations were detrimental to equine articular cartilage. Administration of tiludronate intra-articularly to horses may be detrimental, dependent on the dose used. In vivo studies are needed before intra-articular tiludronate administration to horses can be recommended.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA. katja.zellmer@oregonstate.edu
authors.forename: Katja F
authors.initials: KF
authors.lastname: Duesterdieck-Zellmer
authors.forename: Nellie
authors.initials: N
authors.lastname: Driscoll
authors.forename: Jesse F
authors.initials: JF
authors.lastname: Ott
mesh_terms: D000818:Animals; D017209:Apoptosis; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004164:Diphosphonates / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006025:Glycosaminoglycans / Q000378:metabolism*; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007124:Immunoenzyme Techniques / Q000662:veterinary; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D066298:In Vitro Techniques; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008751:Methylene Blue / Q000031:analogs & derivatives / Q000737:chemistry; D010003:Osteoarthritis / Q000188:drug therapy / Q000662:veterinary*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D006025:Glycosaminoglycans; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D011994:Recombinant Proteins; C013786:A73025; C058651:tiludronic acid; D020782:Matrix Metalloproteinases; D015232:Dinoprostone; D008751:Methylene Blue; C016401:1,9-dimethylmethylene blue