FBH1在咖啡酸改善肠道菌群紊乱-炎症反应中的作用及分子机制研究

The intestinal microbiota plays a fundamental role in health and in the progression of diseases such as ulcerative colitis (UC). Caffeic acid (CaA) possesses various pharmacological effects, such as anti-inflammatory activities. However, the effect of CaA on enteric dysbacteriosis- inflammatory response in UC is still unclear. Our previous study had shown that CaA could attenuate the dextran sulphate sodium (DSS)-induced UC symptoms in C57BL/6 mice. In addition, CaA could significantly inhibit the upregulation of IL-1β and NFκB in parallel with the downregulation of FBH1. Toll-like receptors (TLRs) mediate recognition of microbial molecules to eliminate pathogens. The disorder of intestinal microbiota may trigger inflammation through excessive activation of TLRs/IL-1 pathways. The ubiquitin proteasome system is an important contributor to UC pathogenesis. The ubiquitin proteasome system could negatively regulate TLRs signaling to inhibit inflammation. F-box DNA helicase 1 (FBH1) could interact with SKP1 and form an SCF (SKP1/Cullin/F-box) complex together with Cullin and ROC1. In addition, the SCF complex containing FBH1 as an F-box protein displays ubiquitin ligase activity. These suggest that FBH1 may play a key role in the amelioration of enteric dysbacteriosis- inflammatory response by CaA in UC. However, the underlying molecular mechanism is still unclear. To explore the effects of CaA on the enteric dysbacteriosis and inflammatory response, chronic UC will be induced in mice by administering 2% DSS (36-50 kDa) dissolved in drinking water. The role of FBH1 and related molecular mechanism will be further explored in animal study as well as primary cells in vitro. The results will help provide insights into the biological activities of phytochemicals, and provide new clues to nutrition support and screening the potential target for UC prevention and cure.

肠道菌群紊乱是溃疡性结肠炎（UC）的重要病因。咖啡酸（CaA）具有抗炎活性，但其对UC肠道菌群紊乱-炎症反应的的影响尚不清楚。前期研究表明，CaA能显著缓解葡聚糖硫酸钠（DSS）诱导的UC，CaA还能显著抑制结肠中IL-1β、NFκB的上调以及FBH1的下调。泛素-蛋白酶体途径能介导TLRs/IL-1信号通路的负调控，进而抑制肠道菌群紊乱引起过度的炎症反应。而FBH1是具有E3泛素连接酶活性的SCF蛋白复合体的重要组成部分，提示FBH1可能在CaA改善肠道菌群紊乱-炎症反应中具有重要作用，但其分子机制有待深入研究。本研究拟构建DSS诱导的慢性小鼠UC模型，系统评价CaA对肠道菌群紊乱、炎症反应的影响，从整体和原代细胞水平上着重阐述FBH1在其中的作用及分子机制。研究结果将以全新的视角审视植物化学物的生物活性，也为UC早期预防及治疗的靶点筛选及其营养支持疗法提供重要参考。

本研究拟探讨咖啡酸（CaA）、绿原酸(ChA)、丹酚酸B（Sal B）对小鼠溃疡性结肠炎（UC）的影响，评价肠道菌群在其中的作用。构建DSS诱导的急性或慢性UC模型，评价CaA、ChA、SalB对UC小鼠体重、疾病活动指数（DAI）、结肠长度及组织形态、血清炎症因子及短链脂肪酸（SCFA）水平、免疫细胞浸润及NFκB信号通路的影响；采用16S rRNA测序明确CaA及其衍生物对肠道菌群稳态的作用，评估阿克曼菌（Akkermansia）对UC的影响。研究结果表明：1. CaA、ChA、Sal B能显著缓解DSS导致的小鼠体重下降、DAI增加、结肠缩短、2. CaA、ChA、Sal B能显著减轻UC小鼠结肠结构破坏以及T细胞（CD3+）、巨噬细胞（F4/80+）、中性粒细胞（CD177+）浸润；3. CaA、ChA能显著抑制UC小鼠NFκB信号通路的激活，抑制TNFα、IFNγ、IL-6等炎症因子分泌；4. SalB能显著增加UC小鼠血清乙酸、丙酸、戊酸含量；5. CaA、ChA、Sal B能显著增加UC小鼠肠道菌群α多样性、重塑肠道菌群结构；6. CaA、ChA能显著增加UC小鼠肠道菌群中Akkermansia的丰度；7. 灭活的Akkermansia菌及其外膜蛋白Amuc_1100能显著增加UC小鼠结肠长度、减轻结肠病理损伤；8. 灭活的Akkermansia菌及其外膜蛋白Amuc_1100能显著减少脾脏中CD8+ T细胞的比例以及结肠中CD8+ T细胞浸润进而缓解炎症。研究结果为深入探讨咖啡酸及其衍生物抗炎活性机制、寻找结肠炎膳食干预靶标提供新的思路。