Abstract：
BACKGROUND: Insufficient occlusal support (IOS) frequently causes subchondral bone absorption in temporomandibular joint osteoarthritis, and the underlying mechanism requires further investigation.
METHODS: An IOS model was established by abrading rat molars. Micro-computed tomography was used to evaluate subchondral bone changes. Osteoclastogenesis of synovium-derived macrophages (SDMs) was confirmed by TRAP staining. Cartilage-specific TNFα depletion was achieved by intra-articular injection of adeno-associated virus carrying shRNA against murine TNFα under control of collagen type II. In vitro, chondrocytes were mechanically compressed and conditioned medium (CM) was collected to detect its ability to induce osteoclastogenesis of SDMs.
RESULTS: Synovial osteoclastogenesis and condyle resorption were observed following IOS. TNFα level was elevated in hypertrophic chondrocytes after IOS. Synovial Wnt5a level increased, but Wnt3a level decreased after IOS. Depletion of TNFα in chondrocytes alleviated the synovial osteoclastogenesis and condyle bone resorption. In vitro compression of chondrocytes potentiated TNFα expression and secretion. The CM promoted osteoclastogenesis of SDMs, which were partially prohibited by TNFα neutralizing antibody. Furthermore, inhibition of Wnt3a facilitated osteoclastogenesis, whereas inhibition of Wnt5a partially suppressed osteoclastogenesis, of SDMs cultured in CM.
CONCLUSIONS: Chondrocyte-secreted TNFα induced by IOS is a critical regulator of synovial osteoclastogenesis and subsequent condylar resorption, partially through non-canonical Wnt5a pathway.
METHODS: An IOS model was established by abrading rat molars. Micro-computed tomography was used to evaluate subchondral bone changes. Osteoclastogenesis of synovium-derived macrophages (SDMs) was confirmed by TRAP staining. Cartilage-specific TNFα depletion was achieved by intra-articular injection of adeno-associated virus carrying shRNA against murine TNFα under control of collagen type II. In vitro, chondrocytes were mechanically compressed and conditioned medium (CM) was collected to detect its ability to induce osteoclastogenesis of SDMs.
RESULTS: Synovial osteoclastogenesis and condyle resorption were observed following IOS. TNFα level was elevated in hypertrophic chondrocytes after IOS. Synovial Wnt5a level increased, but Wnt3a level decreased after IOS. Depletion of TNFα in chondrocytes alleviated the synovial osteoclastogenesis and condyle bone resorption. In vitro compression of chondrocytes potentiated TNFα expression and secretion. The CM promoted osteoclastogenesis of SDMs, which were partially prohibited by TNFα neutralizing antibody. Furthermore, inhibition of Wnt3a facilitated osteoclastogenesis, whereas inhibition of Wnt5a partially suppressed osteoclastogenesis, of SDMs cultured in CM.
CONCLUSIONS: Chondrocyte-secreted TNFα induced by IOS is a critical regulator of synovial osteoclastogenesis and subsequent condylar resorption, partially through non-canonical Wnt5a pathway.
摘要：
背景：咬合支持（IOS）不足通常会导致颞下颌关节骨关节炎的软骨下骨吸收，潜在的机制需要进一步调查。
方法：通过磨牙磨牙建立IOS模型。显微计算机断层扫描用于评估软骨下骨的变化。滑膜来源的巨噬细胞(SDM)的破骨细胞生成通过TRAP染色证实。在II型胶原蛋白的控制下，通过关节内注射携带针对鼠TNFα的shRNA的腺相关病毒来实现软骨特异性TNFα的消耗。体外，机械压缩软骨细胞并收集条件培养基(CM)以检测其诱导SDMs破骨细胞生成的能力。
结果:在IOS后观察到滑膜破骨细胞生成和髁再吸收。IOS后肥大软骨细胞中TNFα水平升高。滑膜Wnt5a水平升高,但IOS后Wnt3a水平下降。软骨细胞中TNFα的消耗减轻了滑膜破骨细胞生成和髁骨吸收。软骨细胞的体外压缩增强了TNFα的表达和分泌。CM促进SDM的破骨细胞生成，部分被TNFα中和抗体所抑制。此外，抑制Wnt3a促进破骨细胞生成，而抑制Wnt5a部分抑制破骨细胞生成，在CM中培养的SDM。
结论：IOS诱导的软骨细胞分泌的TNFα是滑膜破骨细胞生成和随后的髁再吸收的关键调节因子，部分通过非规范的Wnt5a途径。
方法：通过磨牙磨牙建立IOS模型。显微计算机断层扫描用于评估软骨下骨的变化。滑膜来源的巨噬细胞(SDM)的破骨细胞生成通过TRAP染色证实。在II型胶原蛋白的控制下，通过关节内注射携带针对鼠TNFα的shRNA的腺相关病毒来实现软骨特异性TNFα的消耗。体外，机械压缩软骨细胞并收集条件培养基(CM)以检测其诱导SDMs破骨细胞生成的能力。
结果:在IOS后观察到滑膜破骨细胞生成和髁再吸收。IOS后肥大软骨细胞中TNFα水平升高。滑膜Wnt5a水平升高,但IOS后Wnt3a水平下降。软骨细胞中TNFα的消耗减轻了滑膜破骨细胞生成和髁骨吸收。软骨细胞的体外压缩增强了TNFα的表达和分泌。CM促进SDM的破骨细胞生成，部分被TNFα中和抗体所抑制。此外，抑制Wnt3a促进破骨细胞生成，而抑制Wnt5a部分抑制破骨细胞生成，在CM中培养的SDM。
结论：IOS诱导的软骨细胞分泌的TNFα是滑膜破骨细胞生成和随后的髁再吸收的关键调节因子，部分通过非规范的Wnt5a途径。
