木犀草素通过蛋白激酶C途径抑制肥胖相关的巨噬细胞极化

Luteolin Inhibits Obesity-Associated Adipose Tissue Macrophage Polarization through Protein Kinase C(PKC) Pathway

目的:木犀草素(luteolin,LU)是富含于多种植物源食品中的天然黄酮类化合物,实验旨在探讨其对肥胖相关的巨噬细胞极化的影响及机制。方法:将5周龄雄性小鼠分为3组分别给予低脂饮食(low-fat diet,LFD)、高脂饮食(high-fat diet,HFD)和添加0.01%木犀草素的高脂饮食(HFD+0.01%LU),喂养12周后利用免疫组织化学染色检测附睾脂肪组织中巨噬细胞,并利用实时定量荧光聚合酶链式反应分别检测促炎性M1巨噬细胞和抗炎性M2巨噬细胞的标记基因表达情况;体外实验研究木犀草素对脂多糖(lipopolysaccharides,LPS)诱导的巨噬细胞系RAW264.7极化的影响,利用蛋白激酶C激活剂佛波酯进行干预后,检测促炎性细胞因子、M1和M2标记基因的mRNA表达情况。结果:木犀草素降低了高脂饮食诱导的脂肪组织巨噬细胞聚集和M1型巨噬细胞标记基因CD11c与Nos2 mRNA的表达;体外木犀草素也抑制了LPS诱导巨噬细胞炎性因子和M1型巨噬细胞标记基因的表达,上调M2型巨噬细胞标记基因的表达,且这些作用依赖于蛋白激酶C途径。结论:木犀草素能够抑制肥胖相关的巨噬细胞极化,并且通过蛋白激酶C途径抑制LPS诱导RAW264.7巨噬细胞炎性因子的表达与极化。

Objective: Luteolin is a natural flavonoid abundant in many edible plants. The aim of this study is to explore the effect of luteolin(LU) on obesity-associated adipose tissue macrophage(ATM) polarization and its underlying mechanisms. Methods: Five-week-old C57BL/6 mice were fed with low-fat diet(LFD), high-fat diet(HFD), or HFD with 0.0l% luteolin(HFD+0.0l% LU) for 12 weeks, respectively. Macrophage infiltration and polarization were detected by immunohistochemical staining or real-time PCR in epididymal adipose tissue. The in vitro effect of luteolin on RAW264.7 macrophage inflammation and polarization in lipopolysaccharide(LPS) and/or PMA-stimulated conditions was also explored. The expression levels of proinflammatory cytokines and M1/M2 marker genes were detected by real-time PCR. Results: Dietary luteolin reduced HFD-induced ATM infiltration and mRNA levels of M1 macrophage marker genes. In LPSstimulated conditions, luteolin inhibited the expression of proinflammatory cytokines and M1 marker genes in RAW264.7 macrophages. In contrast, the expression of M2 marker genes was enhanced by luteolin. However, these effects of luteolin were aborted by protein kinase C(PKC) activator phorbol myristate acetate(PMA). Conclusion: Luteolin can inhibit obesityassociated ATM and RAW264.7 macrophage polarization in LPS stimulated-conditions through protein kinase C pathway.