PDF(Pubmed)
Abstract：
OBJECTIVE: Abnormal autophagic function and activated inflammasomes are typical features in the liver of patients with non-alcoholic steatohepatitis (NASH). Here, we explored whether gemigliptin, a dipeptidyl peptidase 4 (DPP4) inhibitor for treatment of type 2 diabetes, can induce autophagy and regulate inflammasome activation as a potential NASH treatment independent of its anti-diabetic effect.
METHODS: Expression analysis was performed using human liver samples obtained from 18 subjects who underwent hepatectomy. We explored the function and mechanism of gemigliptin using a methionine- and choline-deficient diet (MCD)-induced NASH mouse model and HepG2 cells cultured in MCD-mimicking medium.
RESULTS: Autophagy was suppressed by marked decreases in the expression of ULK1 and LC3II/LC3I ratio in human NAFLD/NASH patients, a NASH mouse model, and HepG2 cells cultured with MCD-mimicking media. Surprisingly, we found that the expression of p-AMPK decreased in liver tissues from patients with steatosis but was restored in NASH patients. The expression of p-AMPK in the NASH mouse model was similar to that of the control group. Hence, these results indicate that autophagy was reduced in NASH via an AMPK-independent pathway. However, gemigliptin treatment attenuated lipid accumulation, inflammation, and fibrosis in the liver of MCD diet-fed mice with restoration of ULK1 expression and autophagy induction. In vitro, gemigliptin alleviated inflammasome activation through induction of ULK1-dependent autophagy. Furthermore, gemigliptin treatment upregulated ULK1 expression and activated AMPK even after siRNA-mediated knockdown of AMPKα1/2 and ULK1, respectively.
CONCLUSIONS: Collectively, these results suggest that gemigliptin ameliorated NASH via AMPK-independent, ULK1-mediated effects on autophagy.
METHODS: Expression analysis was performed using human liver samples obtained from 18 subjects who underwent hepatectomy. We explored the function and mechanism of gemigliptin using a methionine- and choline-deficient diet (MCD)-induced NASH mouse model and HepG2 cells cultured in MCD-mimicking medium.
RESULTS: Autophagy was suppressed by marked decreases in the expression of ULK1 and LC3II/LC3I ratio in human NAFLD/NASH patients, a NASH mouse model, and HepG2 cells cultured with MCD-mimicking media. Surprisingly, we found that the expression of p-AMPK decreased in liver tissues from patients with steatosis but was restored in NASH patients. The expression of p-AMPK in the NASH mouse model was similar to that of the control group. Hence, these results indicate that autophagy was reduced in NASH via an AMPK-independent pathway. However, gemigliptin treatment attenuated lipid accumulation, inflammation, and fibrosis in the liver of MCD diet-fed mice with restoration of ULK1 expression and autophagy induction. In vitro, gemigliptin alleviated inflammasome activation through induction of ULK1-dependent autophagy. Furthermore, gemigliptin treatment upregulated ULK1 expression and activated AMPK even after siRNA-mediated knockdown of AMPKα1/2 and ULK1, respectively.
CONCLUSIONS: Collectively, these results suggest that gemigliptin ameliorated NASH via AMPK-independent, ULK1-mediated effects on autophagy.
摘要：
目的：非酒精性脂肪性肝炎（NASH）患者肝脏的典型特征是自噬功能异常和炎症体激活。这里,我们探索了吉格列汀，用于治疗2型糖尿病的二肽基肽酶4（DPP4）抑制剂，可以诱导自噬和调节炎症小体激活，作为一种潜在的NASH治疗，独立于其抗糖尿病作用。
方法:使用从18名接受肝切除术的受试者获得的人肝脏样品进行表达分析。我们使用甲硫氨酸和胆碱缺乏饮食（MCD）诱导的NASH小鼠模型和在MCD模拟培养基中培养的HepG2细胞探索了吉格列汀的功能和机制。
结果：人NAFLD/NASH患者ULK1和LC3II/LC3I比例表达显著降低，NASH小鼠模型，和用MCD模拟培养基培养的HepG2细胞。令人惊讶的是,我们发现p-AMPK在脂肪变性患者肝组织中的表达降低,但在NASH患者中恢复.NASH小鼠模型中p-AMPK的表达与对照组相似。因此，这些结果表明,在NASH中,自噬通过不依赖AMPK的途径减少.然而,吉格列汀治疗减轻脂质积累，炎症,MCD饮食喂养的小鼠肝脏中的纤维化和ULK1表达的恢复和自噬诱导。体外，吉格列汀通过诱导ULK1依赖性自噬减轻炎性体活化。此外，甚至在siRNA介导的AMPKα1/2和ULK1敲低后，吉格列汀处理上调ULK1表达并激活AMPK。
结论：总的来说，这些结果表明，吉格列汀通过AMPK非依赖性改善NASH，ULK1介导的自噬效应。
方法:使用从18名接受肝切除术的受试者获得的人肝脏样品进行表达分析。我们使用甲硫氨酸和胆碱缺乏饮食（MCD）诱导的NASH小鼠模型和在MCD模拟培养基中培养的HepG2细胞探索了吉格列汀的功能和机制。
结果：人NAFLD/NASH患者ULK1和LC3II/LC3I比例表达显著降低，NASH小鼠模型，和用MCD模拟培养基培养的HepG2细胞。令人惊讶的是,我们发现p-AMPK在脂肪变性患者肝组织中的表达降低,但在NASH患者中恢复.NASH小鼠模型中p-AMPK的表达与对照组相似。因此，这些结果表明,在NASH中,自噬通过不依赖AMPK的途径减少.然而,吉格列汀治疗减轻脂质积累，炎症,MCD饮食喂养的小鼠肝脏中的纤维化和ULK1表达的恢复和自噬诱导。体外，吉格列汀通过诱导ULK1依赖性自噬减轻炎性体活化。此外，甚至在siRNA介导的AMPKα1/2和ULK1敲低后，吉格列汀处理上调ULK1表达并激活AMPK。
结论：总的来说，这些结果表明，吉格列汀通过AMPK非依赖性改善NASH，ULK1介导的自噬效应。
