【作者】 金文；

【导师】 肖培根； 胡卓伟；

【作者基本信息】 中国协和医科大学 ， 生药学， 2007， 博士

【摘要】 代谢综合征是一种伴随中心性肥胖、高血压、血糖异常和血脂紊乱等多症候群的综合征，目前已成为全球性健康问题。胰岛素抵抗是代谢综合征的主要发病机制之一，低度慢性炎症反应在胰岛素抵抗的发生和发展过程中起重要作用。模式识别受体Toll样受体(TLR)是介导先天免疫和获得免疫的桥梁，可通过识别内外源致病原，启动先天免疫，决定获得性免疫的发展方向。因此，我们试图通过给予免疫调节剂1α，25-VitD3(VitD3)或外源性TLR激动剂，降低慢性炎症反应，治疗以胰岛素抵抗为主要病理基础的代谢综合征。结果表明，预先给予VitD3的动物发展为胰岛素抵抗的比例显著降低，VitD3和TLR2激动剂PGN可通过上调TLR2表达，活化核转录因子STAT3，显著增加胰腺外周淋巴结、脾脏、肝脏、肌肉和脂肪组织中CD4~+CD25~+Treg的数目和功能，抑制IL-6和IL-18等炎性因子产生；通过上调肝脏PPARα表达，降低血清中总胆固醇和低密度脂蛋白胆固醇的水平，改善肥胖所致脂质代谢紊乱；通过减少肥胖引起的胰腺间质脂肪细胞、成纤维细胞和巨噬细胞浸润，上调葡萄糖转运体-2表达，增加胰岛β细胞数目，改善MSG大鼠胰岛β细胞胰岛素抵抗；通过上调肝脏的胰岛素受体底物-1表达，降低血糖水平和脂肪细胞大小，提高肌肉、脂肪组织对胰岛素的敏感性，有效地改善MSG大鼠的胰岛素抵抗症状。此外，采用抗原呈递细胞系筛选到具有免疫调节作用的发酵多糖并组方为CFX，我们发现预先给予CFX的大鼠发展为胰岛素抵抗的比例显著降低，CFX增加脂肪组织CD4~+CD25~+Treg的数目，活化核转录因子STAT3，有效地改善MSG肥胖大鼠脂代谢紊乱、提高胰岛素敏感性，但其作用机制还有待进一步研究。本研究从免疫调节的角度，针对代谢综合征的病理基础胰岛素抵抗的起因——炎症，使用免疫调节剂VitD3、TLR2激动剂和具免疫调节作用的发酵多糖，研究了改变机体局部和系统的免疫反应可以有效地提高胰岛素敏感性，为防治代谢综合征提供了理论依据，具有潜在应用价值。更多还原

【Abstract】 Modern lifestyle, with abundant nutrient supply and reduced physical activity,has resulted in dramatic increase in the rates of obesity-associated diseasesconditions, including hyperglycemia, hyperinsulin, dyslipidiaemia and type 2diabetes, which is named after metabolic syndrome (MS). The underlyingcause of metabolic syndrome is a chronic inflammatory response characterizedby enhancement of Th1 immune response that may be responsible forpathogenesis of insulin resistance. Pattern recognition receptors the Toll-likereceptors (TLRs) link the innate immunity and adaptive immunity, TLRs areprimary sensors of both innate and adaptive immune systems and play a pivotalrole in response against structurally conserved components of pathogens. Wewonder if shift of Th1/Th2 balance toward to regulatory T (Treg) cells or Th2responses improves insulin sensitivity in MSG obese rats. The insulinsensitivity was determined by body weight, the insulin sensitivity index, oralglucose tolerance test, insulin tolerance test, and hyperinsulinemic-euglycemicclamp. The expression and activity of TLRs and their signal pathways wereconfirmed by PCR or western blot. We found that 1α, 25-VitD3 (VitD3), animmunomodulator, significantly blocked the maturation induced by highconcentration of glucose or TLR4 agonist and promoted the macrophagestimulated by palmitate to M2 polarization in vitro. We also found theincidence of insulin resistance decreased by pretreatment with VitD3. VitD3improved the insulin sensitivity by activating insulin signaling and attenuatingthe inflammation status in system and local immune microenvironments.Furthermore, a TLR2 agonist peptidoglycan (PGN), markedly improved theinsulin sensitivity because PGN stimulated TLR2 leading to a Th2 immuneresponse. We also found VitD3 and PGN increased the Treg cell number inspleen, lymph node and insulin target tissue-adipose tissue, liver and muscle tissue, leading to polarization of T cell development toward Treg direction viaupregulating the TLR2 in spleen. VitD3 and PGN stimulated immunesuppression responses via phosphorylation of STAT3, upregulation of TGFβand reduced the activation of NF-κB. VitD3 and PGN ameliorated thedyslipidiaemia via upregulation of PPARα, improved the function of pancreaseβcells via upregulating GLUT2 and reducing macrophage infiltration. Inaddition, we reported that the mixture of polysaccharides CFX stimulatesimmaturation of dendritic cells (DCs) and the immaturated DCs promote Tregcell development in DC-based functional screening system. We found theaccident of insulin resistance decreased by pretreatment with CFX, CFXobservably improved the dyslipidiaemia and the insulin sensitivity byactivating the STAT3 in liver and elevating of Treg in adipose tissue. Takentogether, we conclude that the insulin sensitivity can be improved byimmunomodulator through regulation in immune microenviroment.更多还原