Fu Weicong, Fang Yinfei, Wang Tianbao, Lu Qinglin, Wu Junqi, Yang Qining
Department of Orthopedics, Affiliated Jinhua Hospital, Zhejiang University School of Medicine: Jinhua Municipal Central Hospital, No.365, Renmin East Road, Wucheng District, Jinhua City, 321000, Zhejiang Province, China.
Department of Clinical Laboratory, Affiliated Jinhua Hospital, Zhejiang University School of Medicine: Jinhua Municipal Central Hospital Hospital, Jinhua, 321000, Zhejiang, China.
Inflammation. 2024 Sep 18. doi: 10.1007/s10753-024-02145-9.
Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by pain, swelling, stiffness, and impaired function. Attenuating inflammation is a crucial objective in RA management. Diet and nutrition are believed to influence RA symptomatology, with a low-protein diet being one potential nutritional strategy, although its underlying mechanisms remain to be fully elucidated. In this research, serum derived from arthritic transgenic K/BxN mice was administered to naive mice to establish a K/BxN rheumatoid arthritis model. Physiological assessments and histological staining were performed to evaluate joint pathology. (Enzyme-linked immunosorbent assay) ELISA was used to measure inflammatory cytokines. Flow cytometry and immunofluorescence were applied to characterize macrophage phenotypes. Transcriptomic analysis elucidated molecular pathways under the effect of a low-protein diet and verified by immunoblotting. Mitochondrial reactive oxygen species (ROS) was detected by Mito-SOX. Protein expression was silenced through the application of siRNA transfection. Our results indicate that a low-protein diet significantly alleviates disease symptoms and decreases pro-inflammatory cytokine levels in synovial fluid. Furthermore, this dietary intervention inhibits M1 macrophage polarization while promoting a shift towards the M2 phenotype. Transcriptomic analysis revealed that the beneficial effects of the low-protein diet in alleviating rheumatoid arthritis are closely linked to the NRF2 pathway. In vitro, low protein treatment can promote the activity of NRF2 via inhibiting the ubiquitin mediated proteolysis and activate the NRF2/SIRT3/SOD2 pathway to inhibit the production of ROS, which will further inhibit the M1 macrophage polarization. NRF2 knockdown can abolish the effects of low-protein treatment, indicating that the inhibition of M1 polarization and the anti-inflammatory response induced by low-protein treatment are dependent on NRF2. In summary, our findings propose that low-protein diet can inhibit synovial macrophage M1 polarization via activating NRF2/SIRT3/SOD2 pathway to reduce mitochondrial ROS production. This mechanism effectively decreases synovial inflammation and alleviates RA symptoms.
类风湿性关节炎（RA）是一种慢性炎症性疾病，其特征为疼痛、肿胀、僵硬和功能受损。减轻炎症是类风湿性关节炎管理的关键目标。饮食和营养被认为会影响类风湿性关节炎的症状，低蛋白饮食是一种潜在的营养策略，尽管其潜在机制仍有待充分阐明。在本研究中，将来自关节炎转基因K/BxN小鼠的血清给予未接触过病原体的小鼠，以建立K/BxN类风湿性关节炎模型。进行生理评估和组织学染色以评估关节病理。采用酶联免疫吸附测定（ELISA）法检测炎性细胞因子。运用流式细胞术和免疫荧光法对巨噬细胞表型进行表征。转录组分析阐明了低蛋白饮食作用下的分子途径，并通过免疫印迹法进行验证。采用Mito-SOX检测线粒体活性氧（ROS）。通过应用小干扰RNA（siRNA）转染使蛋白表达沉默。我们的结果表明，低蛋白饮食可显著减轻疾病症状，并降低滑液中促炎细胞因子水平。此外，这种饮食干预可抑制M1巨噬细胞极化，同时促进向M2表型转变。转录组分析显示，低蛋白饮食在减轻类风湿性关节炎方面的有益作用与核因子E2相关因子2（NRF2）途径密切相关。在体外，低蛋白处理可通过抑制泛素介导的蛋白水解作用来促进NRF2的活性，并激活NRF2/沉默信息调节因子2相关酶3（SIRT3）/超氧化物歧化酶2（SOD2）途径以抑制ROS的产生，这将进一步抑制M1巨噬细胞极化。敲低NRF2可消除低蛋白处理的作用，表明低蛋白处理诱导的M1极化抑制和抗炎反应依赖于NRF2。总之，我们的研究结果表明，低蛋白饮食可通过激活NRF2/SIRT3/SOD2途径来抑制滑膜巨噬细胞M1极化，从而减少线粒体ROS的产生。这一机制可有效减轻滑膜炎症并缓解类风湿性关节炎症状。
