Characterizing osteochondrosis in the dog: potential roles for matrix metalloproteinases and mechanical load in pathogenesis and disease progression

SummaryObjectiveTo address possible roles of matrix metalloproteinases (MMPs) and mechanical stress in the pathogenesis of osteochondrosis (OC).MethodsNaturally-occurring canine OC lesions (n=50) were immunohistochemically analyzed for MMP-1, -3, and -13, and normal canine articular cartilage explants (n=6) cultured under 0-, 2-, or 4-MPa compressive loads (0.1Hz, 20min every 8h up to 12 days) were compared to OC samples (n=4) biochemically and molecularly.ResultsMMP-1 and -3 immunoreactivities were readily detected in both OC samples and control tissues obtained from age-matched dogs (n=11) whereas MMP-13 was only detectable in OC samples. MMP-13 gene expression as determined by real-time reverse transcription polymerase chain reaction was elevated in OC samples and cartilage explants cultured without mechanical stimuli (0MPa groups) compared to normal cartilage (day 0 controls). Glycosaminoglycan content (per weight) in cartilage explants cultured under no load was significantly (P