PTH/PTHrP-Rezeptor-Expression im zeitlichen Verlauf einer experimentell induzierten Arthrose im Kaninchenmodell

PTH/PTHrP-receptor expression in knee joints of rabbits in experimentally induced osteoarthritis Objective: To investigate the expression of PTH1R in osteoarthritis in the rabbit knee. Methods: 12 rabbits underwent a bilateral resection of the anterior cruciate ligament of the knee. In a second group of a further 12 animals the anterior cruciate ligament was retained after surgical exploration. Post-mortem examinations of the knee were conducted after 3, 6 and 12 weeks. 4 pairs of control knees were obtained from rabbits where no intervention was conducted. All knee joints were inspected for microscopic or macroscopic changes to the articular cartilage. Immunohistochemical staining was used to determine the expression of PTH1R in the articular cartilage. Results: After resection of the anterior cruciate ligament a distinct, progressive osteoarthritis was evident as well as a substantial decrease of the PTH1R. These joints showed significantly higher degrees of osteoarthritis than those without resection of the anterior cruciate ligament (p < 0,01). There was a significant, positive correlation between the microscopic and macrospcopic degree of osteoarthritis (r = 0,857; p < 0,001). The number of PTH1R-positive cells was significantly lower 6 and 12 weeks after resection of the cruciate ligament than in the group without that ligament resection (p < 0,05 resp. p < 0,01). Joints with a high degree of osteoarthritis showed a low level of PTH1R-positive cells, and there was a significant, negative correlation between the level of PTH1R-positive cells and both the microscopic (r = - 0,601; p < 0,001) and the macroscopic (r = - 0,541; p < 0,001) degree of osteoarthritis. Conclusion: This study shows a decrease in the number of PTH1R-positive cells in the process of osteoarthritis. Because of the close association of this decrease and the microscopically and macroscopically detectable degeneration it can be assumed that PTH1R plays an important role in the pathophysiology of osteoarthritis.