Zhu Ziheng, Wan Lei
Department of Rheumatology and Immunology, The First Affiliated Hospital of Anhui University of Chinese Medicine, Hefei, Anhui 230031, P.R. China.
Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, Anhui 230038, P.R. China.
Exp Ther Med. 2024 Jul 25;28(4):375. doi: 10.3892/etm.2024.12664. eCollection 2024 Oct.
Rheumatoid arthritis (RA) is largely caused by the inflammatory response triggered by macrophage polarization. Through epigenetic reprogramming, the inflammatory state of macrophages can be modified. Macrophage polarization is associated with the RNA epigenetic alteration N6-methyladenosine (m6A) RNA methylation. However, the specific function and underlying mechanisms of m6A methylation in the role of macrophage polarization in RA remain to be elucidated. The mRNA expression levels of m6A methylase genes and signaling pathway components associated with RA macrophages were determined in the present study using reverse-transcription quantitative PCR. Methyltransferase 14 (METTL14) protein expression levels were determined using western blot analysis, and the levels of specific cellular secretion factors were determined using ELISA and flow cytometry. The results of the present study demonstrated that elevated METTL14 expression was associated with joint tenderness, and METTL14 expression was positively correlated with both C-reactive protein and rheumatoid factor expression levels. Moreover, METTL14 exhibited potential in the prediction of visual analogue scale. Pro-inflammatory cytokines (TNF-α) and M1 macrophage markers (CD68CD86) were also positively associated with METTL14 expression. The results of the Kyoto Encyclopedia of Genes and Genomes analysis revealed that METTL14 was strongly associated with the MAPK signaling pathway. Notably, JNK and ERK2 exhibited a positive correlation with the M1 macrophage marker, CD68CD86, which was positively associated with the pro-inflammatory factor, TNF-α. JNK and ERK2 expression levels were markedly increased in the METTL14 high-expression group, compared with in the low-expression group; however, p38 and ERK1 expression levels were not significantly different between these groups. Collectively, the results of the present study demonstrated that METTL14 expression was significantly increased in the peripheral blood and synovial tissue of patients with RA, highlighting the potential association with both immunoinflammatory markers and clinical symptoms. In addition, it was suggested that METTL14 may exacerbate the downstream inflammatory response, through mediating macrophage polarization via the MAPK pathway.
类风湿关节炎（RA）很大程度上由巨噬细胞极化引发的炎症反应所致。通过表观遗传重编程，巨噬细胞的炎症状态可被改变。巨噬细胞极化与RNA表观遗传改变N6-甲基腺苷（m6A）RNA甲基化有关。然而，m6A甲基化在RA中巨噬细胞极化作用的具体功能和潜在机制仍有待阐明。在本研究中，使用逆转录定量PCR测定了与RA巨噬细胞相关的m6A甲基化酶基因和信号通路成分的mRNA表达水平。使用蛋白质印迹分析测定甲基转移酶14（METTL14）蛋白表达水平，并使用酶联免疫吸附测定（ELISA）和流式细胞术测定特定细胞分泌因子的水平。本研究结果表明，METTL14表达升高与关节压痛相关联，且METTL14表达与C反应蛋白和类风湿因子表达水平均呈正相关。此外，METTL14在预测视觉模拟评分方面具有潜力。促炎细胞因子（TNF-α）和M1巨噬细胞标志物（CD68CD86）也与METTL14表达呈正相关。京都基因与基因组百科全书分析结果显示，METTL14与丝裂原活化蛋白激酶（MAPK）信号通路密切相关。值得注意的是，JNK和ERK2与M1巨噬细胞标志物CD68CD86呈正相关，而CD68CD86与促炎因子TNF-α呈正相关。与低表达组相比，METTL14高表达组中JNK和ERK2表达水平显著升高；然而，这些组之间p38和ERK1表达水平无显著差异。总体而言，本研究结果表明，RA患者外周血和滑膜组织中METTL14表达显著增加，突出了其与免疫炎症标志物和临床症状的潜在关联。此外，研究表明METTL14可能通过MAPK途径介导巨噬细胞极化，从而加剧下游炎症反应。
