| Background Knee osteoarthritis（KOA）is a chronic and progressive bone and joint disease which is caused by many factors and finally affects all joint tissues.In China,the overall incidence of symptomatic KOA is 8.1%.Both clinical and basic studies have confirmed that passive exercise can improve knee function and delay the progression of KOA,while vitamin D is related to the regulation of immune response and inflammatory response in vivo.In this study,the concentration of interleukin-1β（IL-1β）in synovial fluid and the expression of matrix metalloproteinase 13（MMP 13）in articular cartilage tissue of KOA rats were observed after passive exercise combined with vitamin D2intervention,and its effects on inflammatory reaction and cartilage matrix degradation were discussed.Objective To investigate the effects of passive exercise combined with vitamin D2 on inflammatory reaction and cartilage matrix degradation in KOA rats,and compare and analyze passive exercise combined with vitamin D2 versus passive exercise alone and vitamin D2 alone.Methods 1.After the KOA rat model was prepared by intra-articular injection of papain,50female SD rats were divided into the model group and different doses of vitamin D2groups by random block method（4×10~5U/kg,5×10~5U/kg,6×10~5U/kg and 7×10~5U/kg,respectively）,with 10 rats in each group.After verifying that the modeling was successful,the corresponding intervention measures were given respectively.After the intervention,observe the general condition of the rats,calculate the swelling rate of the right knee joint,ELISA was used to detect the concentration of IL-1βin synovial fluid.Tissue sections were prepared for HE staining,toluidine blue staining and modified safranin O-fast green staining,and Mankin‘s score was performed on the slices,immunohistochemistry was used to detect the expression of MMP 13 in articular cartilage.Through analysis and comparison,determine the best intervention dose of vitamin D2.2.According to the optimal intervention dose of vitamin D2,another 50 female SD rats were randomly divided into blank group,model group,exercise group（passive exercise group）,combined group（passive exercise combined with vitamin D2 group）and VD2 group（vitamin D2 group）,with 10 rats in each group.Corresponding intervention measures were given after successful modeling.After the intervention,observe the general condition of the rats,calculate the swelling rate of the right knee joint,ELISA was used to detect the concentration of IL-1βin synovial fluid.Tissue sections were prepared for HE staining,toluidine blue staining and modified safranin O-fast green staining,and Mankin‘s score was performed on the slices,immunohistochemistry was used to detect the expression of MMP 13 in articular cartilage.Results 1.After modeling,the general observation showed that the color of articular cartilage on the modeling side was dark and the transparency was poor,observation under fluorescence microscope showed that chondrocytes decreased,cartilage stratification was unclear,cartilage layer became thinner,matrix staining was shallow and uneven,and tidal line was unclear,which indicated that cartilage was damaged and KOA model was successfully established.The chondrocytes,matrix coloring and thickness of cartilage layer in saline side were not significantly different from those in the blank side,which indicated that saline did not cause damage to cartilage.2.After modeling,the right knee joint of rats swelled,and the swelling rate（%）was5.93±3.99;After the different doses of vitamin D2 intervention,chondrocytes increased,matrix staining deepened,cartilage layer thickened,Mankin‘s score,the concentration of IL-1βin synovial fluid and the expression level of MMP 13 in cartilage tissue decreased compared with the model group（P<0.05）.Among them,the thickness of cartilage layer in vitamin D2 group with 6×10~5U/kg dose is more obvious than that in other vitamin D2 groups,and the Mankin‘s score,IL-1βconcentration in synovial fluid and MMP 13expression level in cartilage tissue are lower than those in other vitamin D2 groups,which indicates that the intervention effect of vitamin D2 group with 6×10~5U/kg dose is better.3.When passive exercise combined with with the best dose of vitamin D2 intervention,the swelling rate（%）of the right knee joint of rats after modeling was 6.05±3.26;In exercise group,combined group and VD2 group,chondrocytes increased,matrix staining deepened and cartilage layer thickened.Compared with model group,Mankin‘s score,the concentration of IL-1βin synovial fluid and the expression level of MMP 13 in cartilage tissue decreased（P<0.05）.4.Compared with exercise group and combined group,the number of chondrocytes,the staining of matrix and the thickening of cartilage layer in VD2 group were increased significantly.There was no significant difference in Mankin‘s score among exercise group,joint group and VD2 group（P>0.05）.The concentration of IL-1βin the synovial fluid of the combined group was lower than that of the exercise group and the VD2group（P<0.05）.The expression level of MMP 13 in cartilage tissue of combined group and exercise group was lower than that of VD2group（P<0.05）,but there was no significant difference between exercise group and combined group（P>0.05）.Conclusion Passive exercise,vitamin D2 and passive exercise combined with vitamin D2 can reduce the concentration of IL-1βin articular fluid and the expression level of MMP 13 in cartilage tissue of KOA rats,reduce the inflammatory reaction in joints,reduce the degradation of cartilage matrix,thus promoting the repair of articular cartilage and delaying the progress of KOA.The anti-inflammatory effect of passive exercise combined with vitamin D2 is enhanced,but its inhibitory effect on cartilage matrix degradation is equivalent to that of passive exercise alone and vitamin D2 alone. |
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