Jin Xiaoyu, Wang Xunhao, Xu Siyu, Xu Nuo, Wang Ziwei, Hu Chunqing, Liu Wei, Zhang Zhaofeng, Liu Xiyu, Fan Jingjing, Jiang Ruiyang, Wu Rui, Lv Zhongyang, Shi Dongquan
Division of Sports Medicine and Adult Reconstructive Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, 321 Zhongshan Road, Nanjing 210008, Jiangsu, China.
Suzhou Medical College of Soochow University, Suzhou 215031, Jiangsu, China.
J Orthop Translat. 2025 Jul 29;54:101-114. doi: 10.1016/j.jot.2025.07.003. eCollection 2025 Sep.
Osteoarthritis (OA) is the most common degenerative joint disease, characterized by cartilage deterioration, which is closely associated with chondrocyte ferroptosis. The aim of this study was to investigate the role and mechanism of previously unexplored gene, growth factor independence 1 () in chondrocyte ferroptosis, in order to provide a new therapeutic target for OA.
The expression of ferroptotic hallmarks and Gfi1 were analyzed in human and mice OA cartilages and tert-butyl hydroperoxide (TBHP)-induced primary chondrocytes. Small interfering RNA or overexpression plasmids were used to knock down or overexpress to explore its role in chondrocyte ferroptosis and metabolism. Then, the role of Gfi1 in destabilization of medial meniscus (DMM) surgery-induced mice OA model was investigated with or without the intra-articular injection of adeno-associated virus-overexpressing (AAV-). Furthermore, RNA sequencing analysis was performed to reveal the key downstream pathway of Gfi1 exerting its role in chondrocyte ferroptosis.
The expression of Gfi1 was significantly decreased, while 4-HNE, a typical lipid peroxidation product, was significantly increased both in damaged human and DMM surgery-induced mice OA cartilages. Consistently, Gfi1 was remarkably downregulated in TBHP-induced ferroptotic chondrocytes. Moreover, knockdown aggravated chondrocyte ferroptosis by elevated levels of ferroptotic hallmarks, including total ROS, lipid ROS and Fe accumulation. The upregulation of ferroptotic driver (Cox2, Acsl4) and catabolic marker (Mmp13) and downregulation of ferroptotic suppressors (Gpx4, Fth1, Slc7a11) and anabolic marker (Col II) were also observed in TBHP-induced chondrocytes by knockdown. On the contrary, overexpression showed anti-ferroptotic effect in TBHP-induced chondrocytes. Intra-articular injection of AAV- evidently alleviated cartilage degeneration by resisting ferroptosis and preserving the anabolism-catabolism homeostasis in OA cartilages. Comprehensive evaluation of subchondral bone sclerosis, osteophyte formation, synovitis and behavior performance further validated that overexpression ameliorated OA progression. Mechanistically, MAPK signaling pathway was identified as the key downstream mediator of Gfi1 exerting anti-ferroptotic role in OA.
Gfi1 is downregulated in OA and its overexpression ameliorates OA progression by inhibiting chondrocyte ferroptosis via inactivation of MAPK signaling pathway.
This study identifies Gfi1 as a novel therapeutic anti-ferroptotic target for cartilage degeneration, providing more clues for optimizing OA treatment strategies in clinical practice.
骨关节炎（OA）是最常见的退行性关节疾病，其特征为软骨退变，这与软骨细胞铁死亡密切相关。本研究旨在探讨此前未被探索的基因生长因子独立性1（Gfi1）在软骨细胞铁死亡中的作用及机制，以为OA提供新的治疗靶点。
分析人及小鼠OA软骨组织和叔丁基过氧化氢（TBHP）诱导的原代软骨细胞中铁死亡标志物和Gfi1的表达。使用小干扰RNA或过表达质粒敲低或过表达Gfi1，以探究其在软骨细胞铁死亡及代谢中的作用。然后，通过关节腔内注射过表达Gfi1的腺相关病毒（AAV-Gfi1），研究Gfi1在半月板不稳定（DMM）手术诱导的小鼠OA模型中的作用。此外，进行RNA测序分析以揭示Gfi1在软骨细胞铁死亡中发挥作用的关键下游途径。
在受损的人OA软骨组织及DMM手术诱导的小鼠OA软骨组织中，Gfi1的表达显著降低，而典型的脂质过氧化产物4-羟基壬烯醛（4-HNE）显著增加。同样，在TBHP诱导的铁死亡软骨细胞中，Gfi1明显下调。此外，敲低Gfi1通过提高包括总活性氧（ROS）、脂质ROS和铁积累等铁死亡标志物的水平加重软骨细胞铁死亡。在TBHP诱导的软骨细胞中，敲低Gfi1还观察到铁死亡驱动因子（Cox2、Acsl4）和分解代谢标志物（Mmp13）上调，以及铁死亡抑制因子（Gpx4、Fth1、Slc7a11）和合成代谢标志物（Col II）下调。相反，过表达Gfi1在TBHP诱导的软骨细胞中显示出抗铁死亡作用。关节腔内注射AAV-Gfi1通过抵抗铁死亡和维持OA软骨组织中的合成代谢-分解代谢平衡，明显减轻软骨退变。对软骨下骨硬化、骨赘形成、滑膜炎和行为表现的综合评估进一步证实，过表达Gfi1改善了OA的进展。机制上，丝裂原活化蛋白激酶（MAPK）信号通路被确定为Gfi1在OA中发挥抗铁死亡作用的关键下游介质。
Gfi1在OA中表达下调，其过表达通过使MAPK信号通路失活抑制软骨细胞铁死亡，从而改善OA进展。
本研究确定Gfi1为软骨退变的新型抗铁死亡治疗靶点，为临床实践中优化OA治疗策略提供了更多线索。
