Macrophage activation and polarization play a central role in atherosclerotic plaque fate. The M1/M2 activation phenotypes represent two profiles of the macrophage polarization state. During atherosclerosis regression or stabilization, macrophages switch from M1 proinflammatory phenotype to M2 anti-inflammatory reparative one. Here, we investigated whether the natural compound lupeol, a pentacyclic triterpene, induces phenotypical and functional changes in human M1 macrophages and counteracts the proinflammatory signalling triggered by 7-keto-cholesterol (7KC), a major product of oxidative stress-mediated cholesterol oxidation. Flow cytometric and immunochemical analysis showed that the treatment with lupeol of M1 monocyte-derived macrophages M_(IFN-γ/LPS) specifically stimulated these cells to upregulate the expression of the anti-inflammatory cytokines interleukin- (IL-)10 and TGF-β, and of the scavenger receptor CD36, whereas downregulated the proinflammatory cytokine IL-12 and the M1 activation marker HLA-DR. Pretreatment of macrophages with lupeol prevented the release of IL-12, IL-1β, and the upregulation of HLA-DR expression triggered by 7KC and increased the IL-10 production and CD36 expression. This treatment also prevented the impairment of endocytosis triggered by 7KC and prevented 7KC-induced foam cell formation by reducing the lipid droplet accumulation in M1-polarized THP-1 macrophages, whereas showed an additive effect in reactive oxygen species (ROS) production. Western blotting analysis of autophagy markers LC3-I/II and p62-SQSTM1 in M1-polarized THP-1 macrophages demonstrated that lupeol activated autophagy as indicated by increased LC3-II levels, and by marked inhibition of p62. These findings indicate that lupeol has a cytoprotective effect on 7KC-proinflammatory signalling by efficiently switching the macrophage polarization toward an anti-inflammatory phenotype, probably through the activation of the autophagy pathway by increasing ROS production, the reduction of cellular lipid accumulation, and an overall reduction of proinflammatory phenotype. Thus, our data demonstrating an anti-inflammatory and immunomodulatory activity of lupeol in human M1 macrophages suggest its usefulness as an adjunctive drug in the therapy of atherosclerosis.

中文翻译：

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卢贝醇抵消巨噬细胞触发的7-酮胆固醇促炎性信号：动脉粥样硬化治疗的新观点。

巨噬细胞的活化和极化在动脉粥样硬化斑块的命运中起着核心作用。M1 / M2激活表型代表巨噬细胞极化状态的两个配置文件。在动脉粥样硬化的消退或稳定过程中，巨噬细胞从M1促炎表型转变为M2抗炎修复型。在这里，我们研究了天然化合物紫杉醇（五环三萜）是否在人类M1巨噬细胞中诱导表型和功能变化，并抵消了由7-酮-胆固醇（7KC）（氧化应激介导的胆固醇氧化的主要产物）触发的促炎信号。流式细胞仪和免疫化学分析表明，用羽扇豆酚处理M1单核细胞衍生的巨噬细胞M _{（IFN- γ / LPS）}特异性刺激这些细胞上调抗炎细胞因子白介素（IL-）10和TGF- β以及清道夫受体CD36的表达，而下调促炎细胞因子IL-12和M1激活标记HLA-DR。与羽扇豆醇的巨噬细胞的预处理防止IL-12的释放，IL-1 β，以及由7KC触发的HLA-DR表达上调并增加IL-10产生和CD36表达。该处理还通过减少M1极化的THP-1巨噬细胞中的脂质滴积聚，防止了由7KC触发的内吞作用的损害，并防止了7KC诱导的泡沫细胞形成，而在活性氧（ROS）产生中表现出累加作用。在M1极化的THP-1巨噬细胞中对自噬标记LC3-I / II和p62-SQSTM1进行的蛋白质印迹分析表明，如增加的LC3-II水平和对p62的显着抑制，表明狼疮酚可激活自噬。这些发现表明，羽扇豆酚可通过有效地将巨噬细胞极化转换为抗炎表型来对7KC-促炎信号传导产生细胞保护作用，可能是通过增加ROS的产生，减少细胞脂质蓄积以及整体降低促炎表型来激活自噬途径。因此，我们的数据证明了紫杉醇在人M1巨噬细胞中的抗炎和免疫调节活性，表明其在动脉粥样硬化的治疗中作为辅助药物有用。