High-mobility group box chromosomal protein 1 as a potential inflammatory biomarker of joint injury in Thoroughbreds.
OBJECTIVE
To investigate effects of osteochondral injury on high-mobility group box chromosomal protein 1 (HMGB-1) concentrations in synovial fluid (SF) from Thoroughbreds and to compare these results with radiographic and arthroscopic scores of severity of joint injury.


METHODS
40 clinically normal rested Thoroughbreds (group 1) and 45 Thoroughbreds with osteochondral injury as a result of racing.


METHODS
SF was obtained from the metacarpophalangeal (MCP) joints, metatarsophalangeal (MTP) joints, middle carpal joints, and radiocarpal joints. For group 2, radiographic and arthroscopic scores were determined. Concentrations of SF HMGB-1 were determined by use of an ELISA.


RESULTS
SF HMGB-1 concentrations in osteochondral-injured MCP-MTP joints were significantly higher than in normal MCP-MTP joints. Similarly, SF HMGB-1 concentrations in osteochondral-injured carpal joints were significantly higher than in normal carpal joints. Radiographic and arthroscopic scores were not correlated with SF HMGB-1 concentrations. Synovial fluid HMGB-1 concentrations > or = 11 ng/mL for MCP-MTP joints and > or = 9 ng/mL for carpal joints discriminated osteochondral-injured joints from normal joints. Horses with HMGB-1 concentrations > or = 11 ng/mL for MCP-MTP joints were twice as likely to have an osteochondral injury, and horses with HMGB-1 concentrations > or = 9 ng/mL for carpal joints were 4 times as likely to have an osteochondral injury.


CONCLUSIONS
Osteochondral injury was associated with a significant increase in SF HMGB-1 concentrations in MCP-MTP and carpal joints, compared with results for clinically normal Thoroughbreds. Analysis of SF HMGB-1 concentrations may be useful for evaluation of joint injury in horses.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA. brownmu@vetmed.ufl.edu
Murray P
MP
Brown
Troy N
TN
Trumble
Kelly A
KA
Merritt
D000818:Animals; D001182:Arthroscopy; D015415:Biomarkers; D024243:HMGB1 Protein / Q000032:analysis / Q000378:metabolism*; D006734:Horse Diseases / Q000378:metabolism*; D006736:Horses; D007596:Joints / Q000293:injuries*; D011237:Predictive Value of Tests; D013582:Synovial Fluid / Q000737:chemistry*
D015415:Biomarkers; D024243:HMGB1 Protein