Center for Molecular Medicine, Department of Medicine Solna, Karolinska Institutet, And Division of Rheumatology, Karolinska University Hospital, SE-171 76, Stockholm, Sweden.
Department of Women and Child Health, Karolinska Institutet, Unit of Pediatric Rheumatology, Karolinska University Hospital, SE-171 76, Stockholm, Sweden.
Osteoarthritis Cartilage. 2020 May;28(5):698-707. doi: 10.1016/j.joca.2020.01.003. Epub 2020 Jan 23.
The alarmin HMGB1 is an endogenous molecule that is released into the extracellular space upon trauma or cell activation. Extracellular HMGB1 initiates innate immune responses and besides mediating inflammation, has osteoclast-activating features and mediates pain, all important features in OA. The aim of this study was to examine the involvement of HMGB1 in experimental OA and to explore the effect of local anti-HMGB1-therapy on disease progression.
OA was induced in mice by surgical destabilization of knee joints and HMGB1 expression and localization was assessed by immunohistochemistry. For therapy evaluation, HMGB1-neutralizing antibodies were injected intraarticularly, alone or encapsulated in an injectable hyaluronan-based delivery vehicle. Human primary chondrocytes were stimulated with rHMGB1 and analyzed by qPCR and cytometric bead-array.
HMGB1 immunostaining of mouse OA joints demonstrated intra- and pericellular expression in chondrocytes, overlapping with proteoglycan depleted areas. Intra-articular injection of anti-HMGB1 antibodies had cartilage-protective effects, comparable to treatment with a TNF inhibitor. Direct and vehicle-based delivery had similar ameliorating effects and the effect of a single, early injection could not be enhanced by repeated injections. In vitro stimulation of chondrocytes with rHMGB1 affected chondrocyte function by inducing protein expression of IL6 and IL8 and downregulating mRNA of COL2A1.
Our results suggest that the alarmin HMGB1 might be a new target for OA therapy development as we could observe an aberrant HMGB1 expression in mouse OA joints, stimulation of chondrocytes with rHMGB1 induced cytokine production and decreased matrix production and finally that HMGB1 blockade suppressed disease progression.
警报素高迁移率族蛋白 B1（HMGB1）是一种内源性分子，在创伤或细胞激活时释放到细胞外空间。细胞外 HMGB1 启动先天免疫反应，除了介导炎症外，还具有破骨细胞激活特性，并介导疼痛，这些都是 OA 的重要特征。本研究旨在研究 HMGB1 在实验性 OA 中的作用，并探讨局部抗 HMGB1 治疗对疾病进展的影响。
通过膝关节手术不稳定诱导小鼠 OA，并通过免疫组织化学评估 HMGB1 的表达和定位。为了评估治疗效果，单独或封装在可注射透明质酸基递药载体中，关节内注射 HMGB1 中和抗体。用 rHMGB1 刺激人原代软骨细胞，并用 qPCR 和细胞计数珠阵列进行分析。
HMGB1 在小鼠 OA 关节中的免疫染色显示软骨细胞内和细胞周围表达，与蛋白聚糖耗竭区重叠。关节内注射抗 HMGB1 抗体具有软骨保护作用，与 TNF 抑制剂治疗相当。直接和载体递送具有相似的改善作用，单次早期注射的效果不能通过重复注射增强。rHMGB1 刺激软骨细胞可通过诱导 IL6 和 IL8 蛋白表达和下调 COL2A1 mRNA 来影响软骨细胞功能。
我们的结果表明，警报素 HMGB1 可能成为 OA 治疗开发的新靶点，因为我们可以在小鼠 OA 关节中观察到异常的 HMGB1 表达，rHMGB1 刺激软骨细胞可诱导细胞因子产生，并减少基质产生，最后 HMGB1 阻断可抑制疾病进展。
