Hasan Arif Ul, Ohmori Koji, Hashimoto Takeshi, Kamitori Kazuyo, Yamaguchi Fuminori, Noma Takahisa, Igarashi Junsuke, Tsuboi Kazuhito, Tokuda Masaaki, Nishiyama Akira, Kohno Masakazu
Department of Cardiorenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, 1750-1, Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan; Department of Pharmacology, Faculty of Medicine, Kagawa University, 1750-1, Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
Department of Cardiorenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, 1750-1, Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
Biochem Biophys Res Commun. 2017 Apr 22;486(1):76-82. doi: 10.1016/j.bbrc.2017.03.001. Epub 2017 Mar 3.
How nutritional excess leads to inflammatory responses in metabolic syndrome is not well characterized. Here, we evaluated the effects of ω-3 polyunsaturated fatty acid specific G-protein coupled receptor 120 (GPR120) activation on inflammatory pathways in adipocytes, and the influence of this process on macrophage migration. Using 3T3-L1 adipocytes, we found that agonizing GPR120 using its synthetic ligand, GSK137647, attenuated both basal and lipopolysaccharide-induced production of interleukin-6 (IL-6) and C-C motif chemokine ligand 2 (CCL2). Moreover, the intervention reduced the phosphorylation of nuclear factor kappa B inhibitor alpha (IκBα) and nuclear translocation of nuclear factor kappa-B p65 subunit (p65). Furthermore, the silencing of GPR120 itself reduced IL-6 and CCL2 mRNA expression. Inhibition of protein kinase C (PKC) augmented the down-regulatory effect of GSK137647 on IL-6 and CCL2 mRNA. Using a luciferase assay to measure promoter activity of the IL-6 gene in mouse embryonic fibroblasts, we demonstrated that exogenous transfection of GPR120 alone reduced the promoter activity, which was augmented by GSK137647. Inhibition of PKC further reduced the promoter activity. Nevertheless, RAW 264.7 macrophages grown in conditioned medium collected from GSK137647-treated adipocytes attenuated the expressions of matrix metalloproteinases-9 and -3, and tissue inhibitor of metalloproteinase-1. Conditioned medium also inhibited the lipopolysaccharide-induced migration of these macrophages. Taken together, these findings provide critical evidence that although GPR120 is associated with a PKC-mediated pro-inflammatory pathway, the direct inhibitory effects of GPR120 on the nuclear factor kappa B pathway are anti-inflammatory. Moreover, GPR120 activity can attenuate the adipocyte-mediated enhanced production of extracellular matrix-modulating factors in macrophages and can reduce their migration by a paracrine mechanism.
营养过剩如何导致代谢综合征中的炎症反应尚未得到充分阐明。在此，我们评估了ω-3多不饱和脂肪酸特异性G蛋白偶联受体120（GPR120）激活对脂肪细胞炎症信号通路的影响，以及该过程对巨噬细胞迁移的影响。使用3T3-L1脂肪细胞，我们发现用其合成配体GSK137647激动GPR120可减弱基础状态和脂多糖诱导的白细胞介素-6（IL-6）和C-C基序趋化因子配体2（CCL2）的产生。此外，该干预降低了核因子κB抑制因子α（IκBα）的磷酸化以及核因子κB p65亚基（p65）的核转位。此外，GPR120自身的沉默降低了IL-6和CCL2 mRNA的表达。蛋白激酶C（PKC）的抑制增强了GSK137647对IL-6和CCL2 mRNA的下调作用。使用荧光素酶测定法测量小鼠胚胎成纤维细胞中IL-6基因的启动子活性，我们证明单独外源性转染GPR120可降低启动子活性，而GSK137647可增强该活性。PKC的抑制进一步降低了启动子活性。然而，在从GSK137647处理的脂肪细胞收集的条件培养基中生长的RAW 264.7巨噬细胞减弱了基质金属蛋白酶-9和-3以及金属蛋白酶组织抑制剂-1的表达。条件培养基也抑制了脂多糖诱导的这些巨噬细胞的迁移。综上所述，这些发现提供了关键证据，即尽管GPR120与PKC介导的促炎途径相关，但GPR120对核因子κB途径的直接抑制作用具有抗炎性。此外，GPR120活性可减弱脂肪细胞介导的巨噬细胞中细胞外基质调节因子的增强产生，并可通过旁分泌机制减少其迁移。
