从miR-155/SOCS1/NF-κB信号通路研究竹节参总皂苷抑制高脂饮食诱导肥胖小鼠脂肪组织炎症的分子机制

Obesity-related metabolic diseases have been the main serious threats to human health, and so far there is no effective measure to prevent and treat these diseases. Adipose tissue inflammation is the basis for the generation of obesity-related metabolic diseases , and recent discoveries showed that“miR-155/SOCS1/NF-κB” signaling pathway played key roles in the formation of adipose tissue inflammation. Our previous studies indicated that Chikusetsu saponin could inhibit adipose tissue inflammation in high fat diet-induced obese mice，but the mechanisms are still not clear. The preliminary experiments showed that total saponins from Panax japonicus could inhibit miR-155 expression and the nuclear translocation of NF-κB in adipocytes from obese mice，suggesting that the inhibitions on adipose tissue inflammation mediated by total saponins from Panax japonicus may be correlated with their regulation on “miR-155/SOCS1/NF-κB” signaling pathway. Based on these, we will construct both high fat diet-induced obese mice model and cell model in vitro, and study the inhibitory effects of total saponins from Panax japonicus on “miR-155/SOCS1/NF-κB” signaling pathway in adipose tissue of obese mice using some techniques, such as gene overexpression and knockdown mediated by lentivirus, immunofluorescence, co-immunoprecipitation and EMSA, and further explore the molecule mechanisms of their inhibitions on adipose tissue inflammation in obese mice. Thus, this study will provide experimental basic data for the prevention and treatment of obesity-related metabolic diseases.

肥胖相关代谢性疾病已成为严重威胁人类健康的主要因素，但目前仍缺乏有效防治措施。脂肪组织炎症是肥胖相关代谢性疾病发生的基础，新近发现，miR-155/SOCS1/NF-κB信号通路在脂肪组织炎症发生中起关键作用。我们前期研究表明，竹节参皂苷可抑制高脂饮食诱导的肥胖小鼠脂肪组织炎症，但其作用机制仍未阐明；预实验结果发现，竹节参总皂苷对肥胖小鼠脂肪细胞中miR-155及NF-κB核移位有抑制作用，提示竹节参总皂苷抑制脂肪组织炎症可能与其调节“miR-155/SOCS1/NF-κB”炎症信号通路相关。基于此，我们建立高脂诱导肥胖小鼠模型及体外细胞模型，运用慢病毒介导的基因过表达及敲低、免疫荧光、免疫共沉淀、EMSA等技术，研究竹节参总皂苷对肥胖小鼠脂肪组织中“miR-155/SOCS1/NF-κB”信号通路的抑制作用，进而探讨其抑制脂肪组织炎症的分子机制，为肥胖相关代谢性疾病的防治提供实验基础。

随着人们生活水平提高，肥胖及其相关代谢性疾病的发病率日益增高，但目前仍缺乏有效临床防治措施。高脂诱导的脂肪组织炎症是肥胖等相关代谢性疾病发病的关键病理环节。竹节参系五加科人参属植物，主要活性成分为竹节参总皂苷。我们前期研究表明竹节参总皂苷具有较好抑制高脂诱导的炎症反应，其机制与抑制miR-155表达及NF-κB核移位相关；而miR-155通过下调SOCS1表达，进而促进NF-κB核移位，即miR-155/SOCS1/NF-κB通路，是高脂诱导炎症反应的主要机制，这提示竹节参总皂苷可能通过“miR-155/SOCS1/NF-κB通路”抑制高脂诱导的脂肪细胞炎症反应。基于此，本项目首先以高脂饮食喂养小鼠脂肪组织和棕榈酸(PA)诱导的3T3-L1等脂肪细胞为研究对象，从体内外研究了竹节参总皂苷对高脂诱导脂肪细胞炎症反应的影响。结果表明，在高脂喂养小鼠体内实验中，竹节参总皂苷可明显改善高脂诱导的小鼠体重、内脏脂肪指数、血糖、甘油三酯（TG）、总胆固醇（TC）、低密度脂蛋白（LDL）含量等指标；在体内外实验中，real time PCR及western blot等检测发现，高脂模型组中炎症因子（TNF-α、IL-1β等）的表达明显升高，而用竹节参总皂苷处理后，其炎症因子表达明显降低，即竹节参总皂苷可抑制高脂诱导的脂肪细胞炎症反应，进一步研究发现竹节参总皂苷的抗炎作用与其抑制脂肪组织巨噬细胞浸润及其促炎型极化有关。随后，采用real time PCR、western blot等技术检测了竹节参总皂苷对高脂诱导的脂肪细胞miR-155、SOCS1及NF-κB表达的影响。结果表明，在体内外实验中，竹节参总皂苷可显著抑制高脂诱导脂肪细胞miR-155的表达，并上调其靶基因SOCS1的表达；显著下调磷酸化的NF-κB（pNF-κBp65）及IκB（pIκB）的表达。随后，采用慢病毒介导的miR-155等基因过表达及敲低技术，在体内外实验中进一步证实了竹节参总皂苷抑制高脂诱导的脂肪细胞炎症反应与其抑制“miR-155/SOCS1/NF-κB信号通路”有关。综上所述，竹节参总皂苷可抑制高脂诱导的脂肪细胞炎症反应，其机制主要通过抑制miR-155/SOCS1/NF-κB信号通路。该项目研究成果将为临床应用竹节参总皂苷防治肥胖等相关代谢性疾病提供实验基础，因此具有重要的理论意义和临床应用价值。