何首乌活性成分二苯乙烯苷保护非酒精性脂肪肝的作用机制研究

High prevalence of nonalcoholic fatty liver disease (NAFLD) attracts worldwide attention. "Two hits" theory is the classic NAFLD pathogenesis. High-fat diet causes the formation of second hit in NAFLD by "gut - liver axis" and TLR4/NF-кB signaling pathway induced chronic low-grade inflammatory state. Our preliminary study found that 2, 3, 5, 4′-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG), the main component of Polygoni Multiflori Radix, showed significant regulatory effects on lipid accumulation in the NAFLD liver cells (first hit ). Moreover, TSG could reduce levels of inflammatory cytokines in NAFLD liver cells (second hit). We assume that these activities may be closely associated with the regulation of "gut - liver axis" and suppression of TLR4/NF-кB signal pathway. This project intends to carry out systematic studies on the regulation effects of TSG on the NAFLD "second hit" by NAFLD model rats. This research includes TSG effects on intestinal microbial balance and overgrowth, intestinal permeability change, transportation of free fatty acids, LPS endotoxin content, fetuin secretion, TLR4 activation, intervention of NF-кB transcription, releasing of TNFα and other inflammatory cytokines. Clarifying TSG impact on "gut - liver axis" and TLR4/NF-кB signal pathway for the protection of NAFLD will provide important scientific evidence in the treatment of lipid metabolism disorders by TSG related natural products and Polygoni Multiflori Radix. Furthermore, these results will benefit for the further medicinal application of TSG and Polygoni Multiflori Radix.

非酒精性脂肪肝（NAFLD）是危害性很大的疾病，"二次打击"是其发病机制。高脂饮食影响"肠-肝轴"并激活4型Toll样受体TLR4/NF-кB信号通路引起慢性低度炎症状态形成NAFLD的"二次打击"。申请人前期研究发现何首乌中活性成分二苯乙烯苷（TSG）对NAFLD脂质蓄积（第一次打击）环节有明显调节作用，并能降低肝细胞炎症因子含量（第二次打击）的作用，推测其活性可能与其对"肠-肝轴"的调节及抑制TLR4/NF-кB信号通路的激活密切相关。本项目拟利用NAFLD大鼠模型，对TSG干预NAFLD发病的二次打击机制进行系统性研究，包括TSG对肠道微生物平衡及过度繁殖、肠道通透性改变、脂肪酸的吸收转运、脂多糖内毒素含量，胎球蛋白分泌、TLR4激活、NF-кB转录、TNFα等炎症因子释放等环节的影响。阐明TSG对非酒精性脂肪肝的作用机制，为治疗脂质代谢异常疾病提供重要科学依据。

天然茋类成分二苯乙烯苷（2, 3, 5, 4′-tetrahydroxy-stilbene-2-O-β-D-glucoside, TSG）在调节机体脂质代谢领域拥有良好的活性，本研究运用离体细胞实验及整体动物实验，探究 TSG 对非酒精性脂肪肝（non-alcoholic fatty liver disease, NAFLD）脂质蓄积（第一次打击）环节的调节机理，评价 TSG 对“肠-肝轴”的调节及对 TLR4/NF-кB 信号通路的抑制作用（第二次打击），阐明 TSG 在干预脂质代谢异常疾病中的作用机制，为其进一步开发及药用提供科学依据。.研究发现二苯乙烯苷可有效调节脂质蓄积过程中关键蛋白的表达，抑制内源性脂质合成，促进甘油三酯的分解，减轻脂质在肝细胞内的蓄积；可有效改善肠道微生态，阻止肠源性内毒素易位，抑制 TLR4/NF-кB 信号通路，降低慢性低度炎症状态。即二苯乙烯苷可以在非酒精性脂肪肝发病的二次打击环节中，充分起到改善调节作用，可有效干预 NAFLD 的形成，可能成为 NAFLD 防治领域的先导化合物，为预防治疗 NAFLD 的药物开发提供主要的科学依据。