Macrophages are indispensable regulators of inflammatory responses. Macrophage polarisation and their secreted inflammatory factors have an association with the outcome of inflammation. Luteolin, a flavonoid abundant in plants, has anti-inflammatory activity, but whether luteolin can manipulate M1/M2 polarisation of bone marrow-derived macrophages (BMDMs) to suppress inflammation is still unclear. This study aimed to observe the effects of luteolin on the polarity of BMDMs derived from C57BL/6 mice and the expression of inflammatory factors, to explore the mechanism by which luteolin regulates the BMDM polarity. M1-polarised BMDMs were induced by lipopolysaccharide (LPS) + interferon (IFN)-γ and M2-polarisation were stimulated with interleukin (IL)-4. BMDM morphology and phagocytosis were observed by laser confocal microscopy; levels of BMDM differentiation and cluster of differentiation (CD)11c or CD206 on the membrane surface were assessed by flow cytometry (FCM); mRNA and protein levels of M1/M2-type inflammatory factors were performed by qPCR and ELISA, respectively; and the expression of p-STAT1 and p-STAT6 protein pathways was detected by Western-blotting. The isolated mouse bone marrow cells were successfully differentiated into BMDMs, LPS + IFN-γ induced BMDM M1-phenotype polarisation, and IL-4 induced M2-phenotype polarisation. After M1-polarised BMDMs were treated with luteolin, the phagocytosis of M1-polarized BMDMs was reduced, and the M1-type pro-inflammatory factors including IL-6, tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), and CD86 were downregulated while the M2-type anti-inflammatory factors including IL-10, IL-13, found in inflammatory zone (FIZZ)1, Arginase (Arg)1 and CD206 were upregulated. Additionally, the expression of M1-type surface marker CD11c decreased. Nevertheless, the M2-type marker CD206 increased; and the levels of inflammatory signalling proteins phosphorylated signal transducer and activator of transcription (p-STAT)1 and p-STAT6 were attenuated and enhanced, respectively. Our study suggests that luteolin may transform BMDM polarity through p-STAT1/6 to regulate the expression of inflammatory mediators, thereby inhibiting inflammation. Naturally occurring luteolin holds promise as an anti-inflammatory and immunomodulatory agent.

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木犀草素改变骨髓来源巨噬细胞的极性以调节细胞因子风暴

巨噬细胞是炎症反应不可或缺的调节剂。巨噬细胞极化及其分泌的炎症因子与炎症结果有关。木犀草素是一种在植物中含量丰富的黄酮类化合物，具有抗炎活性，但木犀草素是否可以操纵骨髓源性巨噬细胞 (BMDM) 的 M1/M2 极化来抑制炎症仍不清楚。本研究旨在观察木犀草素对C57BL/6小鼠BMDMs极性及炎症因子表达的影响，探讨木犀草素调控BMDM极性的机制。M1 极化的 BMDM 由脂多糖 (LPS) + 干扰素 (IFN)-γ 诱导，M2 极化由白细胞介素 (IL)-4 刺激。激光共聚焦显微镜观察BMDM形态和吞噬作用；通过流式细胞术 (FCM) 评估膜表面 BMDM 分化和分化簇 (CD)11c 或 CD206 的水平；分别通过qPCR和ELISA检测M1/M2型炎症因子的mRNA和蛋白水平；Western-blot检测p-STAT1和p-STAT6蛋白通路的表达。分离的小鼠骨髓细胞成功分化为 BMDM、LPS + IFN-γ 诱导的 BMDM M1 表型极化和 IL-4 诱导的 M2 表型极化。木犀草素处理 M1 极化 BMDMs 后，M1 极化 BMDMs 的吞噬作用降低，M1 型促炎因子包括 IL-6、肿瘤坏死因子 (TNF)-α、诱导型一氧化氮合酶 (iNOS)和 CD86 下调，而 M2 型抗炎因子包括 IL-10、IL-13、在炎症区 (FIZZ)1 中发现，精氨酸酶 (Arg)1 和 CD206 上调。此外，M1 型表面标志物 CD11c 的表达降低。尽管如此，M2 型标记物 CD206 增加了；炎症信号蛋白磷酸化信号转导和转录激活因子 (p-STAT)1 和 p-STAT6 的水平分别减弱和增强。我们的研究表明，木犀草素可能通过 p-STAT1/6 改变 BMDM 极性来调节炎症介质的表达，从而抑制炎症。天然存在的木犀草素有望作为抗炎和免疫调节剂。炎症信号蛋白磷酸化信号转导和转录激活因子 (p-STAT)1 和 p-STAT6 的水平分别减弱和增强。我们的研究表明，木犀草素可能通过 p-STAT1/6 改变 BMDM 极性来调节炎症介质的表达，从而抑制炎症。天然存在的木犀草素有望作为抗炎和免疫调节剂。炎症信号蛋白磷酸化信号转导和转录激活因子 (p-STAT)1 和 p-STAT6 的水平分别减弱和增强。我们的研究表明，木犀草素可能通过 p-STAT1/6 改变 BMDM 极性来调节炎症介质的表达，从而抑制炎症。天然存在的木犀草素有望作为抗炎和免疫调节剂。