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.
Animals—21 purpose-bred research dogs, 3 client-owned dogs with SJ osteoarthritis, and 3 dogs without SJ osteoarthritis.
Procedures—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 and Clinical Relevance—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.
Objective—To identify proteins with differential expression between healthy dogs and dogs with stifle joint osteoarthritis secondary to cranial cruciate ligament (CCL) disease.
Sample—Serum and synovial fluid samples obtained from dogs with stifle joint osteoarthritis before (n = 10) and after (8) surgery and control dogs without osteoarthritis (9) and archived synovial membrane and articular cartilage samples obtained from dogs with stifle joint osteoarthritis (5) and dogs without arthritis (5).
Procedures—Serum and synovial fluid samples were analyzed via liquid chromatography–tandem mass spectrometry; results were compared against a nonredundant protein database. Expression of complement component 3 in archived tissue samples was determined via immunohistochemical methods.
Results—No proteins had significantly different expression between serum samples of control dogs versus those of dogs with stifle joint osteoarthritis. Eleven proteins (complement component 3 precursor, complement factor I precursor, apolipoprotein B-100 precursor, serum paraoxonase and arylesterase 1, zinc-alpha-2-glycoprotein precursor, serum amyloid A, transthyretin precursor, retinol-binding protein 4 precursor, alpha-2-macroglobulin precursor, angiotensinogen precursor, and fibronectin 1 isoform 1 preproprotein) had significantly different expression (> 2.0-fold) between synovial fluid samples obtained before surgery from dogs with stifle joint osteoarthritis versus those obtained from control dogs. Complement component 3 was strongly expressed in all (5/5) synovial membrane samples of dogs with stifle joint osteoarthritis and weakly expressed in 3 of 5 synovial membrane samples of dogs without stifle joint arthritis.
Conclusions and Clinical Relevance—Findings suggested that the complement system and proteins involved in lipid and cholesterol metabolism may have a role in stifle joint osteoarthritis, CCL disease, or both.
OBJECTIVE: To assess the relationship between histologic degeneration of cranial cruciate ligaments (CCLs) and severity of synovitis and ligament vascularity.
SAMPLE: CCL and synovium from 59 stifle joints (53 dogs). PROCEDURES: CCL and synovium specimens were obtained from stifle joints of juvenile (15 joints; 12 dogs) and adult (25 joints; 22 dogs) dogs with intact CCLs and dogs with CCL rupture (rCCL; 19 joints; 19 dogs). Vascular density and degenerative changes of the CCL core region and severity of synovitis were semiquantitatively evaluated. Relationships were analyzed by use of a random effects model to account for correlated specimens.
RESULTS: Mean ± SD modified Bonar scores (scale, 0 to 9) of adults (4.85 ± 0.44) and dogs with rCCL (5.69 ± 0.49) were significantly higher than scores of juveniles (1.13 ± 0.55). Vascularity scores (scale, 0 to 3) were significantly higher for juveniles (3.00 ± 0.24) than for adults (1.53 ± 0.27) and dogs with rCCL (0.78 ± 0.23). Synovitis scores were not significantly different among groups. There was a significant negative relationship between modified Bonar scores and vascularity scores for juveniles and adults and for adults and dogs with rCCL when controlling for age, but there was not a significant relationship between modified Bonar scores and synovitis scores. There was a significant relationship between modified Bonar scores and body weight of adults.
CONCLUSIONS AND CLINICAL RELEVANCE: Poor blood supply to the core region could be an important underlying condition for spontaneous degeneration of the CCL in at-risk dogs.