| Objective: The purpose of the present research is to investigate the effect of type II collagenase in degradation of rat TMJ cartilage matrix and the therapeutic effect of IL-1Ra on cartilage repair in rat TMJOA,to provide a theoretical basis for the study of the clinical treatment of TMJOA.Methods: 1. 2 months male Sprague-Dawley rats(SD) rats were used to establish rat TMJOA model by one-time TMJ cavity injection with type II collagenase, equivalent normal saline was injected into control side. The TMJs were stained with HE to observe the changes of morphology of the condylar cartilages and scored on the basis of improved system Mankin to OA; 2. Applied the former procedure to establish unilateral rat TMJOA model, reverse transcription PCR(RT-PCR) and immunohistochemical staining(IHC) were used to investigate the changes of ADAMTS-4 and ADAMTS-5 in rat TMJOA; 3. Applied the former procedure to establish bilateral rat TMJOA model, one week later, the experimental side received one-time TMJ cavity injection with IL-1Ra, and the control side received equivalent normal saline. HE, RT-PCR and IHC were all used to detect the changes of morphology of the condylar cartilages and the changes of ADAMTS-4, ADAMTS-5 expression.Results: 1. In the experimental side, the condylar cartilages showed degradation. The surface of the condylar cartilages and articular disc were gradually cracked, the number of chondrocytsreduced, the layers of the condylar cartilages disordered. In the control side, the surface of condylar cartilages and articular disc were intact and smooth, chondrocytes arranged orderly, four layers were typically recognized as fibrous layer, proliferative layer, hypertrophic and calcified cartilage layer. The score of the experimental side at 1 week: 0.67±0.58, 2 week: 1.67±0.58, 3 week: 2.67±0.58 and 4 week: 6.00±1.00. The lesions were most serious at 4 week(P<0.05). 2. In the experimental side, the positive cells of ADAMTS-4, ADAMTS-5 mainly expressed in proliferative, and hypertrophic layer, and at 4 week, they broke into the fibrous layer. The m RNA and protein expression of ADAMTS-4, ADAMTS-5 in the experimental side were higher than the control side at 4 week(P<0.05), and at 4 week higher than 2 week in the experimental side(P<0.05). The m RNA of ADAMTS-5 at 2 week and protein at 4 week in the experimental side was higher than ADAMTS-4(P<0.05). 3. The articular damages in the experimental side were relatively mild, pathological changes confined to the surface of the condylar cartilages and articular disc. While damages in the control side were serious, the surface of the condylar cartilages and articular disc cracked, the articular cartilage atrophied, chondrocyts reduced, and the layers disordered. At 2 week, the score of the experimental side:1.33±0.52, the control side:2.00±0.63, no difference was observed(P>0.05); At 4 week, the score of the experimental side:3.00±0.63, the control side:6.50±0.84, significant difference was noticed(P<0.05). The positive cells of ADAMTS-4, ADAMTS-5 mainly expressed in hypertrophic layer in the experimental side, and in fibrous layer, proliferative and hypertrophic layer in the control side. The m RNA and protein expression of ADAMTS-4, ADAMTS-5 in the experimental side were lower than the control side at 4 week(P<0.05). The m RNA of ADAMTS-5 at 2 and 4 week in the experimental side was higher than ADAMTS-4(P<0.05).Conclusions: 1. Both ADAMTS-4 and ADAMTS-5 are responsible for the changes in early stage of rat TMJOA, ADAMTS-5 plays a more important role compared with ADAMTS-4.2. IL-1Ra could promote the repair of the condylar cartilage in early stage of rat TMJOA, the possible treatment mechanism may be the inhibition of the expression of aggrecanase, compared with ADAMTS-5, the inhibition effect on ADAMTS-4 is more obviously. |
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