Sun Chongkai, Xu Yuan, Peng Ziyue, Zhou Xuyou, Wang Zixuan, Wan Haoyang, Yu Bin
Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Guangdong Provincial Key Laboratory of Bone and Cartilage Regenerative Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China.
J Cell Mol Med. 2025 Sep;29(17):e70683. doi: 10.1111/jcmm.70683.
Staphylococcus aureus (S. aureus) has been identified as a hindrance to osteoblast differentiation, thereby contributing significantly to the development of osteomyelitis. Consequently, exploring pharmaceutical interventions targeting osteoblast differentiation mediated by S. aureus may present a novel approach for treating osteomyelitis. It has been reported that N6-methyladenosine (m6A) methylation is highly associated with infection. Moreover, studies continue to validate that short-chain fatty acids play an important role in transcriptional modification and have been considered as a potential treatment for S. aureus infection. Our research aimed to examine the impact and underlying mechanism of butyrate, a short-chain fatty acid, in reducing the inhibitory influence exerted by S. aureus on osteoblast differentiation. The concentration of butyrate beneficial to MC3T3-E1 cell viability was screened by Cell Counting Kit-8 (CCK8) assay. Reverse transcription-quantitative PCR (RT-qPCR), Western blotting, and alkaline phosphatase (ALP)staining were used to verify the osteogenic indexes and the expression levels of m6A methylation-related proteins in MC3T3-E1 cells infected with S. aureus at different time points. Besides, the same methods were used to verify the effects of butyrate stimulation and METTL3 knockdown on the osteogenic ability of MC3T3-E1 cells. H&E staining, Goldner staining, and immunohistochemical staining were used to verify the effect of butyrate on mice with endo-plant associated S. aureus osteomyelitis. The potential mechanisms of METTL3 and autophagy in MC3T3-E1 cells were studied by Western blotting. In vitro experiments, we found that butyrate significantly enhanced the expression of osteogenic-related genes down-regulated by infection in MC3T3-E1 cells induced by S. aureus, including RUNX2, OCN, and ALP. In addition, METTL3, an important m6A methyltransferase, was significantly up-regulated in S. aureus-infected MC3T3-E1 cells, but its expression could be down-regulated by butyrate. Inhibiting the expression of METTL3 by siRNA could effectively rescue the osteogenic markers down-regulated by S. aureus infection in MC3T3-E1 cells, which was similar to the results of butyrate treatment. In vivo experiments had shown that butyrate could alleviate inflammation and osteogenic activity in implant-associated osteomyelitis. The construction of bone marrow METTL3 low-expression mice using siRNA also showed similar effects on osteogenic activity. Additionally, Western blotting confirmed that knocking down METTL3 rescued the autophagy imbalance caused by S. aureus infection in MC3T3-E1 cells. In general, our research demonstrated that butyrate effectively alleviated the hindrance of osteoblast activity induced by S. aureus infection by suppressing the expression of METTL3, suggesting that butyrate may be a novel treatment for S. aureus osteomyelitis.
金黄色葡萄球菌已被确定为成骨细胞分化的障碍,从而在骨髓炎的发展中起重要作用。因此,探索针对金黄色葡萄球菌介导的成骨细胞分化的药物干预措施可能为治疗骨髓炎提供一种新方法。据报道,N6-甲基腺苷(m6A)甲基化与感染高度相关。此外,研究不断证实短链脂肪酸在转录修饰中起重要作用,并被认为是治疗金黄色葡萄球菌感染的潜在方法。我们的研究旨在探讨短链脂肪酸丁酸盐在减轻金黄色葡萄球菌对成骨细胞分化的抑制作用方面的影响及其潜在机制。通过细胞计数试剂盒-8(CCK8)检测筛选出对MC3T3-E1细胞活力有益的丁酸盐浓度。采用逆转录定量PCR(RT-qPCR)、蛋白质印迹法和碱性磷酸酶(ALP)染色来验证不同时间点感染金黄色葡萄球菌的MC3T3-E1细胞中的成骨指标和m6A甲基化相关蛋白的表达水平。此外,采用相同方法验证丁酸盐刺激和METTL3基因敲低对MC3T3-E1细胞成骨能力的影响。采用苏木精-伊红(H&E)染色、Goldner染色和免疫组织化学染色来验证丁酸盐对内置物相关金黄色葡萄球菌骨髓炎小鼠的作用。通过蛋白质印迹法研究METTL3和自噬在MC3T3-E1细胞中的潜在机制。在体外实验中,我们发现丁酸盐显著增强了金黄色葡萄球菌诱导的MC3T3-E1细胞中因感染而下调的成骨相关基因的表达,包括RUNX2、OCN和ALP。此外,重要的m6A甲基转移酶METTL3在感染金黄色葡萄球菌的MC3T3-E1细胞中显著上调,但其表达可被丁酸盐下调。用小干扰RNA(siRNA)抑制METTL3的表达可有效挽救金黄色葡萄球菌感染的MC3T3-E1细胞中下调的成骨标志物,这与丁酸盐处理的结果相似。体内实验表明,丁酸盐可减轻植入物相关骨髓炎中的炎症和成骨活性。使用siRNA构建骨髓METTL3低表达小鼠也对成骨活性显示出类似的作用。此外,蛋白质印迹法证实敲低METTL3可挽救金黄色葡萄球菌感染在MC3T3-E1细胞中引起的自噬失衡。总体而言,我们的研究表明,丁酸盐通过抑制METTL3的表达有效减轻了金黄色葡萄球菌感染诱导的成骨细胞活性障碍,表明丁酸盐可能是治疗金黄色葡萄球菌骨髓炎的一种新方法。
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