Expression of Toll-like receptors 2 and 4 in stifle joint synovial tissues of dogs with or without osteoarthritis.
OBJECTIVE
To investigate the presence or absence of Toll-like receptor (TLR)-2 and TLR-4 in synovial tissues collected from stifle joints (SJs) of dogs with or without osteoarthritis.


METHODS
21 purpose-bred research dogs, 3 client-owned dogs with SJ osteoarthritis, and 3 dogs without SJ osteoarthritis.


METHODS
Research dogs underwent arthroscopic surgery in 1 SJ to induce osteoarthritis via cranial cruciate ligament transection (CrCLt; n = 5), femoral condylar articular cartilage groove creation (6), or release of the caudal horn of the medial meniscus (5); 5 dogs underwent sham surgery. Synovial tissue specimens were obtained from both stifle joints of each dog 12 weeks after surgery, and TLR-2 and TLR-4 gene expression were determined via real-time reverse transcription PCR assays. Expression of TLR-4 protein was determined via an immunofluorescence technique in additional specimens obtained from osteoarthritic SJs of dogs with cranial cruciate ligament insufficiency and from dogs with nonosteoarthritic SJs.


RESULTS
Synovial tissues from CrCLt-treated joints had significantly higher TLR-4 gene expression, compared with the contralateral control SJs or any other joint group. TLR-2 gene expression did not differ significantly among groups. Toll-like receptor-4 protein was detected in synovial tissues of osteoarthritic SJs but was rarely evident in nonosteoarthritic SJs.


CONCLUSIONS
Increased TLR-4 gene expression in the synovial tissue of SJs with osteoarthritis secondary to CrCLt suggests that activation of innate immunity may play a role in the pathophysiology of SJ osteoarthritis in at least a subset of dogs.
Kuroki
Keiichi
K
Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211, USA. kurokik@missouri.edu
Stoker
Aaron M
AM
Sims
Hannah J
HJ
Cook
James L
JL
D000818:Animals; D017931:DNA Primers; D004283:Dog Diseases / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D004285:Dogs; D005260:Female; D007794:Lameness, Animal / Q000235:genetics* / Q000601:surgery; D010003:Osteoarthritis / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013264:Stifle / Q000502:physiology / Q000503:physiopathology / Q000601:surgery; D051195:Toll-Like Receptor 2 / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000235:genetics*
D017931:DNA Primers; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D012313:RNA