Cao Qian, Zhou Xiangping, Zou Fei, He Rong, He Liena, Chen Jiajun, Li Yue, Cao Ting, Li Yumeng, Lan Xiaopeng, Liu Shuangquan
Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hunan Province Clinical Research Center for Accurate Diagnosis and Treatment of High-incidence Sexually Transmitted Diseases, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hunan, 421001, China.
J Leukoc Biol. 2025 Jul 3. doi: 10.1093/jleuko/qiaf099.
During Treponema pallidum(T.pallidum) infection, m6A modification negatively regulates inflammatory responses in macrophages. However, whether m6A modification participates in the regulation of macrophage M2 polarization during T.pallidum infection remains unclear. Using THP-1-derived macrophages as a model, this study investigated the mechanism by which T.pallidum lipoprotein TpF1 promotes macrophage M2 polarization, and analyzed the effect of TpF1 on m6A modification in macrophages and the regulatory role of methyltransferase METTL14. Results showed that upon TpF1 stimulation, expression of M2 macrophage markers CD206 and PPARγ was significantly increased, and levels of anti-inflammatory factors TGF-β and CCL18 were upregulated at both mRNA and protein levels. In contrast, expression of M1 marker CD80 and pro-inflammatory factors IL-1β and TNF-α was significantly decreased at both mRNA and protein levels, indicating that TpF1 promotes macrophage polarization toward the M2 phenotype. Meanwhile, TpF1 upregulated global m6A levels in macrophages, accompanied by increased expression of m6A methyltransferase METTL14 and reader protein YTHDF2. Knocking down METTL14 with siRNA inhibited TpF1-induced elevation of global m6A levels and macrophage M2 polarization. Mechanistically, TpF1 promoted macrophage M2 polarization by activating the NF-κB pathway, as demonstrated by the inhibitory effect of NF-κB-specific inhibitors on M2 polarization. Further studies revealed that METTL14 knockdown significantly suppressed TpF1-induced NF-κB activation. These findings indicate that T.pallidum lipoprotein TpF1 promotes macrophage M2 polarization via METTL14-mediated regulation of the NF-κB signaling pathway, offering new insights into the immune evasion mechanisms of Treponema pallidum.
在梅毒螺旋体感染期间,m6A修饰对巨噬细胞中的炎症反应起负调控作用。然而,m6A修饰是否参与梅毒螺旋体感染期间巨噬细胞M2极化的调控仍不清楚。本研究以THP-1来源的巨噬细胞为模型,探究梅毒螺旋体脂蛋白TpF1促进巨噬细胞M2极化的机制,并分析TpF1对巨噬细胞中m6A修饰的影响以及甲基转移酶METTL14的调控作用。结果显示,在TpF1刺激下,M2巨噬细胞标志物CD206和PPARγ的表达显著增加,抗炎因子TGF-β和CCL18在mRNA和蛋白水平均上调。相反,M1标志物CD80以及促炎因子IL-1β和TNF-α在mRNA和蛋白水平均显著降低,表明TpF1促进巨噬细胞向M2表型极化。同时,TpF1上调巨噬细胞中的整体m6A水平,伴随m6A甲基转移酶METTL14和阅读蛋白YTHDF2表达增加。用siRNA敲低METTL14可抑制TpF1诱导的整体m6A水平升高和巨噬细胞M2极化。机制上,TpF1通过激活NF-κB途径促进巨噬细胞M2极化,NF-κB特异性抑制剂对M2极化的抑制作用证明了这一点。进一步研究表明,敲低METTL14可显著抑制TpF1诱导的NF-κB激活。这些发现表明,梅毒螺旋体脂蛋白TpF1通过METTL14介导的NF-κB信号通路调控促进巨噬细胞M2极化,为梅毒螺旋体的免疫逃逸机制提供了新见解。
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