The Correlation Study Between The Changed Expression Of AQP-1 And Chondrocytes Apoptosis In Articular Chondrocytes Of Osteoarthritis

Objective The changes of the aquaporins (AQP-1) expression may be ralated to the apoptosis. To explore the correlation between the expression of AQP-1 and chondrocyte apoptosis by studying the expression of the AQP-1 and the Caspase-3, so as to provide clues for the further study in the pathogenesis of osteoarthritis (OA).Methods Seventy two 8-week-old clean grade male SD rats, weighing 286-320g (mean, 300 g), were randomly divided into the operated group (n=24), the sham-operated group (n=24), and the control group (n=24). OA models were made by amputating the anterior cruciate ligament and medial collateral ligament, and partial excision of medial meniscus in operated group; the articular cavity was exposed only in sham-operated group; and no treatment was given in control group. The general station of the rats was observed after model was established. At 1, 2, 4, and 8 weeks, the specimens of knee joints were harvested to perform the gross and histological observations; the mRNA expressions of AQP-1 and Caspase-3 were determined by real-time quantitative PCR; and the activity of the key apoptosis enzyme caspase-3 was detected. and to do the correlation analysis between the expression of AQP-1 mRNA and the Caspase-3 mRNA and protease activity.Results Totally 6 rats died after operation, and the rats were supplied immediately; the rats survived to the end of experiment. The appearance and structure of knee articular cartilage were normal in control group and sham-operated group. While in operated group, the cartilage had a rough surface with fissure and many vegetations, and fibrosis and irregular cell arrange were seen on the surface of cartilage. There were statistically significant differences in the Mankin score between the operated group and control group at 2, 4, and 8 weeks (P<0.05). There were no significant differences in the expression of the AQP-1, Caspase-3 mRNA, and the activity of the Caspase-3 protease among 3 groups at 1 week after operation (P > 0.05); while the expressions of the AQP-1, Caspase-3, and the activity of the Caspase-3 protease in operated group were significantly higher than those in sham-operated and control group at 2, 4, and 8 weeks after operation (P < 0.05), and there was a increased trend with time. There was significantly positive correlation (r=0.817, P<0.001) between the AQP-1 mRNA expression and the Caspase-3 mRNA expression, and the regression equation was y=0.4267x~2+0.0515x (P<0.001); meanwhile, there were also significantly positive correlation (r=0.945, P<0.001) between the AQP-1 mRNA expression and the activity of caspase-3 protease, and the regression equation was y=15.423x+4.3928 (P<0.001).Conclusion The up-regulation of AQP-1 expression in osteoarthritis cartilage may be related to the chondrocyte apoptosis, and the changes of AQP-1 expression may involve in the pathogenesis of osteoarthritis.