Analysis of the stress signaling pathway using synovial cells from human temporomandibular joint and application to a gene therapy.

机械应力被认为在调节骨代谢中起着至关重要的作用。过大的机械负荷直接或间接损伤关节组织，被认为是影响颞下颌关节紊乱病(TMDs)发生和发展的因素之一。然而，TMD的确切病理生理学机制尚未阐明。在本研究中，我们特别关注滑膜细胞，并试图揭示滑膜细胞承受过高的机械应力对关节破坏和修复的机制。我们从人TMJ中建立了一种滑膜衬里细胞株，命名为SGA2细胞。SGA2细胞表达成纤维细胞标志物Vimentin和Prolyl 4-羟基酶，还表达层粘连蛋白和热休克蛋白27，这些都是B细胞的标志物。提示SGA2细胞来源于滑膜衬里的B细胞。但部分细胞表达巨噬细胞标志CD68，提示它们来源于中间型滑膜衬里细胞，同时表达A型和B型细胞标志。机械牵张增加滑膜细胞RANKL、MMPs(MMP3、MMP13)和炎性介质(IL1β、TNFα、iNOS)的表达。这些结果表明，滑膜细胞承受过高的机械应力，促进破骨细胞分化，降解骨基质，产生多种炎症介质。在适宜的培养条件下，SGA2细胞可分化为成骨细胞、软骨细胞和脂肪细胞。这些结果提示，成人颞下颌关节滑膜中含有可向成骨、成软骨或成脂方向分化的间充质干细胞，这种滑膜来源的间充质干细胞可能有助于关节炎关节的再生。

Mechanical stress is thought to play a crucial role in the regulation of bone metabolism. Excessive mechanical loading has been reported to damage articular tissues directly or indirectly, and it is considered to be one of the factors affecting to onset and progression of temporomandibular joint disorders (TMDs). However, the exact pathophysiology of TMD has not been elucidated. In this study, we particularly focused on synovial cells and attempted to reveal the mechanism of joint destruction and repair by synovial cells loaded excessive mechanical stress. We have established a synovial lining cell strain, designated SGA2 cells, from human TMJ. SGA2 cells expressed the fibroblastic markers vimentin and prolyl 4-hydroxylase ; they also expressed laminin and heat shock protein 27, all of which are markers of type B cells. These results suggested that SGA2 cells derived from synovial lining type B cells. However, some cells expressed the macrophage marker CD 68, suggesting that they were derived from intermediate type synovial lining cells, expressing both type A and type B cell markers. Mechanical stretch enhanced the expression of RANKL, MMPs (MMP-3, MMP-13) and inflammatory mediators (IL-1beta, TNF-alpha, iNOS) in synovial cells. These results suggested that synovial cells loaded excessive mechanical stress promoted osteoclast differentiation, degraded bone matrix and produced several inflammatory mediators. Under appropriate culture conditions, SGA2 cells differentiated into the osteoblast, chondrocyte and adipocyte. These results suggested that the synovial membrane of adult human temporomandibular joint contains MSCs with the capacity to differentiate along osteogenic, chondrogenic or adipogenic lineages, and that this synovial membrane-derived MSCs are likely to contribute to joint regeneration in arthritis.