谷胱甘肽过氧化物酶4介导铁死亡在膝骨关节炎滑膜炎发生发展中的作用

Effect of ferroptosis mediated by glutathione peroxidase 4 in the occurrence and progression of synovitis in knee osteoarthritis

背景:滑膜炎在膝骨关节炎早期进展中起主导作用,是潜在的早期治疗靶点,但滑膜炎发生机制尚不清楚。在动物模型中,全身铁含量增加和细胞内铁摄取升高可诱发和加剧骨关节炎,但滑膜炎与铁死亡的关系仍不清楚,因此探讨铁死亡在骨关节炎滑膜炎发生发展中的作用需进一步研究。目的:探讨谷胱甘肽过氧化物酶4(glutathione peroxidase4,GPX4)介导的铁死亡在膝骨关节炎滑膜炎发生发展过程中的作用。方法:入选行膝关节镜或关节置换手术的骨关节炎患者43例以及行关节镜治疗半月板损伤或韧带撕裂患者10例,根据患者术前X射线平片Kellgren-Lawrence分级分为3组:对照组(KLG 0)10例,早期膝骨关节炎组(KLG 1,2)20例和晚期膝骨关节炎组(KLG 3,4)23例。采用苏木精-伊红染色观察各组滑膜炎的严重程度,普鲁士蓝染色评估各组滑膜组织中的铁沉积情况,免疫组化法检测ACSL4、GPX4、环氧化酶2、肿瘤坏死因子α在滑膜组织中的表达,Western blot和免疫荧光分别检测ACSL4、GPX4蛋白的表达。结果与结论:①与对照组相比,骨关节炎组滑膜组织中铁含量增加,且晚期膝骨关节炎组铁沉积多于早期膝骨关节炎组;②与对照组相比,ACSL4在骨关节炎滑膜组织中高表达(P<0.01),GPX4在骨关节炎滑膜组织中低表达(P<0.01),且ACSL4表达量随着骨关节炎的进展呈现增高趋势,GPX4表达量随着骨关节炎的进展呈现降低趋势;③环氧化酶2在骨关节炎滑膜组织中的表达明显高于正常滑膜组织,其中早期骨关节炎组表达最高,与晚期骨关节炎组比较差异有显著性意义(P<0.01);④肿瘤坏死因子α在骨关节炎滑膜组织中的表达明显高于正常滑膜组织,早期骨关节炎组与晚期骨关节炎组比较差异无显著性意义(P>0.05);⑤结果表明,骨关节炎滑膜组织中有铁的沉积,铁死亡参与了膝骨关节炎滑膜炎的发生及病情进展。

BACKGROUND:Synovitis plays a leading role in the early progression of knee osteoarthritis and is a potential early therapeutic target.However,the mechanism of synovitis remains unclear.In animal models,increased systemic iron and intracellular iron uptake can induce and exacerbate osteoarthritis,but the association with ferroptosis in synovitis remains unclear.Further studies are needed to investigate the role of ferroptosis in the development and progression of synovitis in osteoarthritis.OBJECTIVE:To investigate the role of ferroptosis mediated by glutathione peroxidase 4(GPX4)in the development of synovitis in knee osteoarthritis.METHODS:The synovial tissues of 43 patients with osteoarthritis who underwent arthroscopic or joint replacement surgery and 10 patients undergoing arthroscopic treatment of meniscal injury or ligament tear were collected and divided into three groups according to the Kellgren-Lawrence grading of X-ray images:normal control group(KLG 0,n=10),early knee osteoarthritis group(KLG 1,2,n=20)and late knee osteoarthritis group(KLG 3,4,n=23).Hematoxylineosin staining was used to observe the severity of synovitis in each group,and iron deposition in the synovium in each group was evaluated by Prussian blue staining.The expressions of Acyl-CoA Synthetase Long Chain Family Member 4(ACSL4),GPX4,cyclooxygenase 2 and tumor necrosis factorαin the synovium were detected by immunohistochemical staining.Western blot and immunofluorescence were used to detect the expression of ferroptosis-related proteins ACSL4 and GPX4.RESULTS AND CONCLUSION:Compared with the normal control group,iron content in synovial tissue was increased in the knee osteoarthritis groups,and iron deposition in the late knee osteoarthritis group was higher than that in the early osteoarthritis group.ACSL4 was highly expressed in the synovial tissue of knee osteoarthritis compared with the normal control group(P<0.01),and GPX4 was lowly expressed in the synovial tissue of knee osteoarthritis(P<0.01).The expression level of ACSL4 increased with the progression of osteoarthritis,while the expression level of GPX4 decreased with the progression of osteoarthritis.The expression of cyclooxygenase 2 in the synovium of osteoarthritis was significantly higher than that in the normal synovium,and the expression was the highest in the early stage of osteoarthritis,which was significantly different from that in the advanced stage of osteoarthritis(P<0.01).The expression of tumor necrosis factorαin the synovium of osteoarthritis was significantly higher than that in the normal synovium,but there was no significant difference between early and late osteoarthritis groups(P>0.05).To conclude,the deposition of iron exists in the synovial tissue of osteoarthritis and ferroptosis is involved in the occurrence and progression of synovitis in knee osteoarthritis.