Elucidation of condylar cartilage resorption mechanism in TMJ-osteoarthritis and search of a new regulatory factor

髁突软骨吸收性骨关节炎（TMJ- osteoarthritis， OA）伴运动障碍和功能障碍是目前牙科领域治疗难度较大的疾病之一。人们认为，骨关节炎发病的关键因素是在髁突上增加过多的机械负荷，另一方面，推测软骨破坏是由未知的新因素与机械负荷协同作用引起的。因为有OA在正常生理状态下进展的情况。下颌髁突由表层、软骨层、软骨下骨和骨等几个不同的区域组成，每一层都有不同的功能，对颌骨运动产生的各种机械刺激作出反应，表层具有润滑功能以减少摩擦，软骨层下的骨坚硬地支撑着上述组织。为了阐明各层代谢异常的诱导机制，进一步阐明髁突软骨破坏的机制是十分重要的。我们证实了1118年髁突软骨表面区具有边界润滑功能的浅带蛋白的表达，并阐明了其表达水平受细胞因子和机械负荷大小的选择性调节。在本研究中，我们特别关注了下一层（软骨下骨），研究了过度机械负荷损伤的软骨下骨对髁突软骨代谢的影响。将200克金属物体作为高强度冲击载荷落在下颌髁上，特别是在软骨下骨中发现IL -1β的免疫组织学表达。接下来，为了研究成骨细胞和软骨细胞之间的相互作用，我们使用共培养系统将成骨细胞单层与软骨细胞一起培养在海藻酸珠中。与机械应力加载成骨细胞共培养后，软骨细胞中MMP-1、3和13 mRNA表达量增加，II型、X型胶原和DNA mRNA表达量减少，蛋白多糖合成量减少。由此可见，外源对下颌髁突头的侵袭诱导软骨下骨IL -1 β的形成。本研究结果提示软骨下成骨细胞与关节软骨细胞之间的物理相互作用可能是骨性关节炎病理改变中软骨降解的原因。少

The TMJ- osteoarthritis (OA) of the condylar cartilage absorption with movement disorder and dysfunction is one of the disease that are difficult for treatment in dental field Excessive mechanical loading to be added to the condyle as the muse is thought about with key factor of onset of OA On the other hand, it is speculated that the cartilage destruction is induced by an unknown new factor in synergy with a mechanical loading, bemuse there is the case that OA progress in a normal physiological condition. Mandibular condyle is composed of several different zone, as superficial zone from surface, cartilaginous layer, subchondral bone and bone, each layer has a different function and respond to various mechanical irritation by jaw movement Superfical zone has a lubrication function to decrease the friction, and a bone underlying in the cartilaginous layer supports the above tissues rigidly. In order to elucidate an inducing mechanism of metabolic abnormality in each layer it is importan … More t for clarifying the mechanisms of condylar cartilage destruction. We confirmed the expression of superficial zone protein which had boundary lubrication function in superficial zone of condylar cartilage in 1118 year and clarified the expression level was regulated selectively by cytokine and the magnitude of mechanical loading. In this study, we particularly focused on the downward layer (subchondral bone), and investigated the influences of subchondral bone damaged with excessive mechanical loading on the metabolisim of condylar cartilage. As a result of a 200 grams metal object was dropped to the mandibular condyle as a high magnitude impact loading, in particular, the expression of IL -1β was found in subchondral bone immunohistologically. Next, to investigate interactions between osteoblasts and chondrocytes, we used a co-culture system to culture osteoblasts monolayer together with chondrocytes in alginate beads. The mRNA expression of MMP-1, 3 and 13 in the chondrocytes by co-culture with mechanical stress-loaded osteoblasts showed increased, and the mRNA expression type II, X collagen and DNA, proteoglycan syntheses were decreased- From these results, the aggression to mandibular condyle head from the outside induce IL -1 β from subchondral bone. The results from the present study suggest that physical interactions between subchondral osteoblasts and articular chondrocytes could be responsible for the cartilage degradation in pathological changes of proceeding OA. Less