肠源性内毒素血症在大鼠代谢综合征相关疾病发生发展中的作用及其机制

Role of intestinal endotoxemia in development of metabolic syndrome-related diseases in rats

目的:探讨肠源性内毒素血症(IETM)在代谢综合征(MS)相关疾病发生发展中的作用及可能的分子机制。方法:将64只大鼠随机分为8组,分别是3月正常对照组(3C)、3月高糖高脂组(3H)、6月正常对照组(6C)、6月高糖高脂组(6H)、9月正常对照组(9C)、9月高糖高脂组(9H)、12月正常对照组(12C)和12月高糖高脂组(12H)。测定血浆脂多糖(LPS)、游离脂肪酸(FFA)、肿瘤坏死因子α(TNF-α)、C反应蛋白(CRP)、巨噬细胞趋化蛋白-1(MCP-1)、空腹血糖(FPG)和空腹胰岛素(FINS),并计算胰岛素抵抗指数(HOMA-IR)。免疫组化方法观察脂肪组织、肝组织和胰腺组织CD68表达水平;Western blotting测定肝组织、胰腺组织中JNK1、p-JNK1、NF-κB p65、IκB、GRP78蛋白表达水平。结果:与正常对照组相比,各阶段高糖高脂组的大鼠血清LPS、TNF-α、CRP、MCP-1、FPG、FINS和HOMA-IR的水平都升高,其差异有统计学意义;免疫组化结果显示各阶段高糖高脂组大鼠的脂肪组织、肝组织和胰腺组织CD68表达水平明显升高,且随时间推移加重;各阶段高糖高脂组的大鼠肝组织p-JNK1、NF-κBp65表达显著高于正常组,而IκB表达显著低于正常组;高糖高脂组的大鼠胰腺组织p-JNK1和NF-κB p65的表达于第6个月开始升高,第9个月、第12个月达到高峰,而IκB的表达也于第6个月开始降低。结论:IETM可能在MS相关的代谢性疾病中发挥着重要的作用,NF-κBJNK和GRP78信号可能参与了上述过程。

AIM：To investigate the effect of intestinal endotoxemia（IETM） on the development of metabolic syndrome（MS）-related diseases and its molecular mechanisms.METHODS;Sixty-four rats were randomly divided into 8 groups,which were normal groups of 3 months（3C）,6 months（6C）,9 months（9C） and 12 months（12C）,and high-sucrose and high -fat groups of 3 months（3H）,6 months（6H）,9 months（9H） and 12 months（12H）.The levels of lipopolysaccharide（LPS）,tumor necrosis factorα（TNF -α）,C-reactive protein（CRP）,monocyte chemotactic protein-1（MCP-1 ）,fasting plasma glucose（FPG） and fasting plasma insulin（FINS） in the serum were measured. The insulin resistance index（HOMA -IR） was also calculated.The protein expression of CD68 in the tissues of fat,liver and pancreas was detected by the method of immunohistochemistry.The expression of JNK1,p-JNKl,NF -κB p65,IκB and GRP78 in the liver and pancreas was analyzed by Western blotting.RESULTS：The levels of LPS,FFA,TNF -α, CRP,MCP-1,FPG,FINS and HOMA-IR in high-sucrose and high-fat groups of every phase were higher than those in normal groups.The results of immunohistochemislry showed that the expression of CD68（representing the infiltration of mononuclear cells） in the tissues of fat,liver and pancreas in high-sucrose and high -fat groups gradually increased from the 3rd month to the 12th month.Compared with normal groups,the expression of p -JNK1,NF -κB p65 and GRP78 in the liver were increased from the 3rd month to the 12th month,but the expression of IkB in the liver was reduced.The expression of p -JNK1 and NF -κB p65 in the pancreatic tissues was increased from the 6th month to the 12th month,but the expression of IkB reduced.However,the expression of GRP78 in pancreatic tissues was increased from the 3rd month to the 12th month.CONCLUSION;Intestinal endotoxemia may play an important role in the development of MS-related diseases.LPS-mediated JNK1,NF -κB and GRP78 expression may be involved in the signal transduction pathways of MS development induced by intestinal endotoxemia.