Shen Tian, Lei Tao, Chen Lin, Zhu Bing-Bing, Xu Bi-Lin, Zhang Cui-Ping, Wang Hong-Ping
Department of Endocrinology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Front Physiol. 2021 Sep 8;12:669202. doi: 10.3389/fphys.2021.669202. eCollection 2021.
Non-alcoholic fatty liver disease (NAFLD)is accompanied by typical inflammatory damage and cell death. As a pro-inflammatory form of cell death, pyroptosis participates in important pathological processes involved in NAFLD. Regulatory roles of both CCCTC-binding factor (CTCF) and dipeptidyl peptidase-4 (DPP4) have been reported in NAFLD, but it is still unclear whether the mechanism of action of gardenoside, a potential therapeutic for NAFLD, can be driven these proteins. In this study, the direct interaction between CTCF and DPP4 was first confirmed by a dual-luciferase reporter assay system. Then, a cell model of NAFLD was established by induction with palmitic acid (PA) and lipopolysaccharide (LPS). A mouse NAFLD model was established, and the effect of gardenoside on both the cell and mouse models of NAFLD was also investigated. Increased lipid accumulation, NLRP3 inflammasome activation, and hepatocyte pyroptosis were recorded in NAFLD and . Gardenoside treatment effectively reduced the lipid accumulation, increased cell viability, reduced reactive oxygen species (ROS) generation, and attenuated pyroptosis and apoptosis in NAFLD in the and models. Alterations in these biological processes were evidenced by the decreased expression levels of several pro-pyroptotic markers including the NLR family, pyrin domain-containing 3 (NLRP3), apoptosis-related speckle-like protein (ASC), caspase-1 p20, Gasdermin D N-terminal domain (GSDMD-N), and IL-1β, along with simultaneously decreased CTCF and DPP4 levels. Importantly, CTCF silencing or DPP4 silencing exhibited effects similar to gardenoside treatment, while CTCF overexpression counteracted this trend, which indicated that CTCF might be a target responsible for gardenoside-induced alleviation of NAFLD, such therapeutic effects might be achieved through controlling the expression of the direct target of CTCF (DPP4) and several downstream molecules. In general, the current study provides a promising strategy for NAFLD treatment.
非酒精性脂肪性肝病（NAFLD）伴有典型的炎症损伤和细胞死亡。作为一种促炎性细胞死亡形式，焦亡参与了NAFLD的重要病理过程。CCCTC结合因子（CTCF）和二肽基肽酶4（DPP4）在NAFLD中的调节作用已有报道，但仍不清楚NAFLD的潜在治疗药物栀子苷的作用机制是否受这些蛋白质驱动。在本研究中，首先通过双荧光素酶报告基因检测系统证实了CTCF与DPP4之间的直接相互作用。然后，用棕榈酸（PA）和脂多糖（LPS）诱导建立NAFLD细胞模型。建立了小鼠NAFLD模型，并研究了栀子苷对NAFLD细胞模型和小鼠模型的影响。在NAFLD细胞和小鼠模型中均记录到脂质蓄积增加、NLRP3炎性小体激活和肝细胞焦亡。栀子苷治疗有效减少了脂质蓄积，提高了细胞活力，减少了活性氧（ROS）生成，并减轻了NAFLD细胞和小鼠模型中的焦亡和凋亡。包括NLR家族含pyrin结构域3（NLRP3）、凋亡相关斑点样蛋白（ASC）、半胱天冬酶-1 p20、Gasdermin D N端结构域（GSDMD-N）和白细胞介素-1β在内的几种促焦亡标志物的表达水平降低，同时CTCF和DPP4水平降低，证明了这些生物学过程的改变。重要的是，CTCF沉默或DPP4沉默表现出与栀子苷治疗相似的效果，而CTCF过表达则抵消了这一趋势，这表明CTCF可能是栀子苷诱导减轻NAFLD的靶点，这种治疗效果可能是通过控制CTCF的直接靶点（DPP4）和几个下游分子的表达来实现的。总体而言，本研究为NAFLD治疗提供了一种有前景的策略。
