title: Comparison of the response to experimentally induced short-term inflammation in the temporomandibular and metacarpophalangeal joints of horses.
abstract: OBJECTIVE
  To investigate the relationship between inflammatory responses of the temporomandibular joint (TMJ) and the metacarpophalangeal (MCP) joint in clinically normal horses.
  
  
  METHODS
  7 mature horses.
  
  
  METHODS
  In each horse, 1 TMJ and 1 MCP joint were injected with lipopolysaccharide (LPS; 0.0025 μg). The contralateral TMJ and MCP joint were injected with saline (0.9% NaCl) solution. Synovial fluid samples were collected from all 4 joints over 24 hours after injection. Concentrations of interleukin-6, tumor necrosis factor-α, transforming growth factor-β, and total protein were measured via immunoassay. Horses were assessed for clinical signs of joint inflammation at each time point.
  
  
  RESULTS
  Concentrations of interleukin-6 were not significantly different between LPS-injected MCP joints and TMJs at any time point. Transforming growth factor-β concentrations were significantly increased in MCP joints, compared with concentrations in TMJs, at 12 and 24 hours after injection. Tumor necrosis factor-α concentrations were significantly higher in LPS-injected TMJs than in LPS-injected MCP joints at 1 and 6 hours after injection. Total protein concentration did not differ significantly between LPS-injected MCP joints and TMJs. Injection of LPS induced clinical inflammation at all time points; additionally, 2 MCP joints (but no TMJs) had an inflammatory response to injection of saline solution.
  
  
  CONCLUSIONS
  The inflammatory response to LPS appeared to be attenuated more quickly in TMJs than in MCP joints of horses. The difference in response suggested that a lack of clinical osteoarthritis in the TMJ of horses could be attributable to a difference in cytokine response.
authors: Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada. james.carmalt@usask.ca
authors: James L
authors: JL
authors: Carmalt
authors: Chris D
authors: CD
authors: Bell
authors: Dane M
authors: DM
authors: Tatarniuk
authors: Sarabjeet S
authors: SS
authors: Suri
authors: Baljit
authors: B
authors: Singh
authors: Cheryl
authors: C
authors: Waldner
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism*; D005260:Female; D006734:Horse Diseases / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism*; D006736:Horses; D007270:Injections, Intra-Articular / Q000662:veterinary; D015850:Interleukin-6 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008662:Metacarpophalangeal Joint / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D010003:Osteoarthritis / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D011506:Proteins / Q000032:analysis; D011897:Random Allocation; D013582:Synovial Fluid / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D013704:Temporomandibular Joint / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D008070:Lipopolysaccharides; D011506:Proteins; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha