Department of Endocrinology & Metabolism, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, Guangdong, China; Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, Guangdong, China.
Department of Endocrinology & Metabolism, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, Guangdong, China.
Biomed Pharmacother. 2021 Aug;140:111778. doi: 10.1016/j.biopha.2021.111778. Epub 2021 May 29.
Liraglutide has been demonstrated to alleviate hepatic steatosis in clinical practice, but the underlying mechanism remains unclear. Our previous study indicated that the HIF-2α/PPARα pathway was involved in hepatic lipid accumulation induced by hypoxia.We aimed to investigate whether liraglutide could alleviate lipid-induced hepatic steatosis via the HIF-2α/PPARα pathway. Whole-body HIF-2α heterozygous knockout (HIF-2α) mice and littermate wild-type (WT) mice were successfully established. Male mice challenged with a high-fat diet were treated with liraglutide (0.6 mg/kg/d) or normal saline by intraperitoneal injection for 4 weeks. We observed that, compared with WT mice, many indicators of HIF-2α mice improved, including GTT, ITT, fasting blood glucose, body weight, liver weight, and lipid profile in serum or liver lipid deposition, and the expression level of PPARα, mitochondrial function genes, and fatty acid oxidation genes were upregulated, while those of HIF-2α and lipogenesis genes were downregulated significantly. After liraglutide treatment in WT mice, we found that significant improvements were observed in the fat mass, GTT, ITT, fasting blood glucose, body weight, liver weight, lipid profile in serum or liver lipid deposition; the β-oxidation genes were upregulated and the lipogenesis genes were downregulated; and the abundance of intestinal Akkermansia muciniphila increased significantly. However, the effects of liraglutide on WT mice were not observed in HIF-2α mice. In addition, in the HepG2 steatotic hepatocyte model, liraglutide alleviated lipid deposits by repressing lipid synthesis and enhancing fatty acid β-oxidation, which were substantially suppressed by the HIF-2α modulators. Therefore, the HIF-2α/PPARα pathway is essential for liraglutide-alleviated lipid-induced hepatic steatosis.
利拉鲁肽已被证明可在临床实践中缓解肝脂肪变性,但潜在机制尚不清楚。我们之前的研究表明,HIF-2α/PPARα通路参与了缺氧诱导的肝脂质积累。我们旨在研究利拉鲁肽是否可以通过 HIF-2α/PPARα通路缓解脂质诱导的肝脂肪变性。成功建立了全身 HIF-2α 杂合敲除(HIF-2α)小鼠和同窝野生型(WT)小鼠。用高脂肪饮食挑战雄性小鼠,并通过腹腔注射给予利拉鲁肽(0.6mg/kg/d)或生理盐水治疗 4 周。与 WT 小鼠相比,我们观察到 HIF-2α 小鼠的许多指标得到了改善,包括 GTT、ITT、空腹血糖、体重、肝重和血清或肝脂质沉积中的血脂谱,以及 PPARα、线粒体功能基因和脂肪酸氧化基因的表达水平上调,而 HIF-2α 和脂生成基因的表达水平显著下调。在 WT 小鼠中给予利拉鲁肽治疗后,我们发现脂肪量、GTT、ITT、空腹血糖、体重、肝重、血清或肝脂质沉积中的血脂谱均有明显改善;β-氧化基因上调,脂生成基因下调;肠道阿克曼氏菌黏蛋白的丰度显著增加。然而,在 HIF-2α 小鼠中,利拉鲁肽对 WT 小鼠的作用并未观察到。此外,在 HepG2 脂肪变性肝细胞模型中,利拉鲁肽通过抑制脂质合成和增强脂肪酸β-氧化来减轻脂质沉积,这些作用被 HIF-2α 调节剂显著抑制。因此,HIF-2α/PPARα 通路是利拉鲁肽缓解脂质诱导的肝脂肪变性所必需的。