高脂饮食诱导肥胖小鼠白色脂肪组织中IL-33的表达及意义

Expression and significance of IL-33 in white adipose tissues of obese mice induced by high fat diet

目的:探讨细胞因子IL-33在高脂饮食诱导的肥胖小鼠体内不同类型白色脂肪组织的表达情况。方法:3T3-L1前脂肪细胞诱导分化10 d, ELISA检测细胞培养上清中IL-33的含量;Western blot和RT-PCR检测细胞中IL-33的表达。6~8周的C57BL/6雄性小鼠随机分为两组,高脂组给予60%高脂饲料饲养10周,对照组用普通饲料,10周后,检测小鼠血清葡萄糖和血脂;ELISA检测血清中IL-33的含量;Western blot和RT-PCR检测不同类型白色脂肪组织中IL-33的表达。结果:3T3-L1前脂肪细胞诱导分化为成熟脂肪细胞后,细胞培养上清中IL-33含量无显著变化,细胞中IL-33的蛋白含量上调,IL-33 mRNA下调。在小鼠实验中,与对照组相比,高脂组小鼠体重显著升高,脂肪组织增重;高脂小鼠的空腹血糖、血清总胆固醇、高密度脂蛋白和IL-33浓度均显著升高,但血清甘油三酯和低密度脂蛋白无显著变化;高脂小鼠皮下脂肪组织中IL-33的蛋白含量增高,内脏脂肪组织中IL-33的蛋白水平降低,但IL-33 mRNA的表达与其蛋白水平正好相反。结论:高脂饮食诱导的肥胖小鼠皮下和内脏脂肪组织中IL-33有不同的表达,且与基因水平呈负相关,提示IL-33在不同白色脂肪组织发挥着不同的调节作用。

Objective:To investigate the expression of the cytokine IL-33 in different white adipose tissues of obese mice induced by high fat diet.Methods:3 T3-L1 preadipocytes were induced for 10 days and the content of IL-33 in the supernatant was determined by ELISA analysis.Western blot and RT-PCR were applied to detect the expression of IL-33.6~8 weeks C57 BL/6 male mice were randomly divided into two groups: high fat diet group(HFD) and normal diet group(ND).HFD mice were fed with 60% high-fat and ND mice were fed with ordinary feed for 10 weeks respectively.After 10 weeks, the serum glucose and blood liqid of all mice were detected.ELISA was measure the level of IL-33 in serum.Expression of IL-33 in different adipose tissues was detected by western blot and RT-PCR.Results: The content of IL-33 remained consistent in the supernatant of differentiated 3 T3-L1 cells, where as the protein expression of IL-33 in the cells was elevated and the mRNA of IL-33 was down-regulated.In vivo, compared with ND,the body weight rose obviously and adipose tissues got heavier in HFD.Fasting glucose, total cholesterol of serum(TC),high density lipoprotein(HDL) and the concentration of IL-33 were significantly increased in obese mice.However, there were no significant differences in serum triglycerides(TG) and low density lipoprotein(LDL).Additionally, the level of IL-33 in subcutaneous adipose tissue of obese mice was increased and decreased in visceral adipose tissue, while the expression of IL-33 mRNA was opposite to it.Conclusion: IL-33 has differential expression in subcutaneous and visceral adipose tissue with negative correlation of gene level in obese mice induced by high fat diet, which indicates that IL-33 plays a different role in various white adipose tissue.