Inflammation, the main factor in the progression of osteoarthritis (OA), impairs the chondrogenesis of bone mesenchymal stem cells (BMSCs), which is an appealing process to target to regenerate impaired articular cartilage. This article aimed to investigate whether SP600125, a competitive ATP-specific inhibitor of the JNK pathway, could promote the chondrogenesis of BMSCs by enhancing their anti-inflammatory capacity. Chondrogenic differentiation was assessed by Alcian blue staining, immunofluorescence staining, and Western blot. The inflammation level was associated with the expression of matrix metalloproteinases (Mmp), evaluated by Western blot. Intra-articular injection of BMSCs pretreated with or without SP600125 was carried out on C57BL/6 mice after inducing OA by surgical destabilization of the medial meniscus. Safranin O-fast green (SO) and hematoxylin-eosin staining were employed to evaluate the cartilage destruction and immunohistochemical analysis was adopted to detect the expression of Col2 and Mmp-13 proteins in the mouse knee joint. We showed that SP600125 could inhibit inflammation induced by tumor necrosis factor-α (TNF-α) and promote the chondrogenesis of BMSCs. In the presence of TNF-α, the expression of aggrecan (Agc) and collagen type II alpha 1 (Col2) was significantly decreased compared with that in the control group and increased with the addition of SP600125. Moreover, the expression of Mmp-1, Mmp-3, and Mmp-13 was increased in BMSCs treated only with TNF-α and downregulated in SP600125-treated BMSCs. In vivo study showed that SP600125 could enhance protective effects of BMSCs on OA mice. Our results indicated that SP600125 rescued the chondrogenesis of BMSCs by inhibiting inflammation induced by TNF-α, which provides a theoretical basis for solving the problem of cartilage repair under inflammatory conditions.

中文翻译：

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SP600125 恢复 TNF-α 诱导的骨间充质干细胞受损的软骨形成及其在小鼠中的抗骨关节炎作用

炎症是骨关节炎 (OA) 进展的主要因素，它会损害骨间充质干细胞 (BMSCs) 的软骨形成，这是一种以再生受损关节软骨为目标的有吸引力的过程。本文旨在研究 JNK 通路的竞争性 ATP 特异性抑制剂 SP600125 是否可以通过增强 BMSCs 的抗炎能力来促进 BMSCs 的软骨形成。通过阿新蓝染色、免疫荧光染色和蛋白质印迹评估软骨形成分化。通过蛋白质印迹评估，炎症水平与基质金属蛋白酶 (Mmp) 的表达有关。在通过内侧半月板的手术去稳定诱导 OA 后，对 C57BL/6 小鼠进行了用或不用 SP600125 预处理的 BMSCs 的关节内注射。采用番红O-坚牢绿(SO)和苏木精-伊红染色评估软骨破坏情况，采用免疫组化分析检测小鼠膝关节中Col2和Mmp-13蛋白的表达。我们发现 SP600125 可以抑制肿瘤坏死因子-α (TNF-α) 诱导的炎症并促进 BMSCs 的软骨形成。在 TNF-α 存在下，与对照组相比，聚集蛋白聚糖 (Agc) 和 II 型胶原蛋白 α1 (Col2) 的表达显着降低，并随着 SP600125 的添加而增加。此外，仅用 TNF-α 处理的 BMSCs 中 Mmp-1、Mmp-3 和 Mmp-13 的表达增加，而在 SP600125 处理的 BMSCs 中表达下调。体内研究表明，SP600125 可以增强 BMSCs 对 OA 小鼠的保护作用。