蛋氨酸限制对高脂饮食小鼠肠道氧化还原状态、炎症和菌群的影响

目的：研究饮食蛋氨酸限制对高脂饮食小鼠肠道氧化还原状态、炎症和菌群的影响。方法：将27 只SPF级雄性C57BL/6小鼠随机分为3 组，分别为正常饮食组（C：0.86%（质量分数，下同）蛋氨酸、4%猪油）、高脂饮食组（HM：0.86%蛋氨酸、20%猪油）、高脂蛋氨酸限制组（LM：0.17%蛋氨酸、20%猪油），每周测定小鼠体质量，12 周实验结束后处死小鼠，并取血液、回肠、盲肠和结肠样品，测定血浆胆固醇（total cholesterol，TC）、甘油三酯（triglyceride，TG）、高密度脂蛋白胆固醇（high-density lipoprotein cholesterol，HDL-C）、低密度脂蛋白胆固醇（low-density lipoprotein cholesterol，LDL-C）、脂多糖（lipopolysaccharide，LPS）和LPS结合蛋白（LPS-binding protein，LBP）的含量；测定回肠和结肠组织中氧化应激相关指标；用实时荧光定量聚合酶链式反应测定回肠炎症基因肿瘤坏死因子-α（tumour necrosis factor-α，TNF-α）、白介素-6（interleukin-6，IL-6）mRNA的表达水平；提取盲肠内容物DNA，用限制性末端酶切的方法分析小鼠盲肠内容物中菌群的变化；提取结肠内容物DNA，用高通量测序分析小鼠结肠内容物中菌群的变化。结果：与HM组相比，LM组小鼠体质量、血浆TC、TG和LDL-C水平显著降低（P＜0.05，P＜0.01），HDL-C水平极显著增加（P＜0.01）；回肠总抗氧化能力和还原型谷胱甘肽/氧化型谷胱甘肽（glutathione/oxidizided glutathione，GSH/GSSG）的比值显著增加（P＜0.05）；结肠GSH/GSSG比值显著增加（P＜0.05），丙二醛含量显著降低（P＜0.05）；血浆LPS和LBP水平显著降低（P＜0.05，P＜0.01）；回肠TNF-α、IL-6 mRNA的表达水平显著下调（P＜0.05）；盲肠菌群Shannon-Weiner指数与均匀度指数显著上升（P＜0.05），结肠菌群中双歧杆菌和颤螺杆菌丰度显著增加（P＜0.05）。结论：饮食蛋氨酸限制具有显著改善高脂饮食小鼠肠道组织氧化还原状态、炎症反应和菌群结构的作用。

Effect of Methionine Restriction on Gut Redox Status,Inflammation and Microbiota in High-Fat Diet-Fed Mice

Purpose: To investigate the effect of dietary methionine restriction (MR) on gut redox status, inflammation and microbiota in high-fat diet-fed mice. Methods: Twenty-seven male C57BL/6 mice were randomly and equally divided into control group (C: 0.86% methionine and 4% lard oil), high-fat diet group (HM: 0.86% methionine and 20% lard oil), high-fat diet with MR group (LM: 0.17% methionine and 20% lard oil). Body mass was recorded weekly. After 12 weeks, the mice were killed to collect blood plasma, cecum, ileum and colon. Plasma total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), lipopolysaccharide (LPS), and LPS-binding protein (LBP) contents were examined. Some indicators of oxidative stress in ileum and colon were determined. The expression of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA in ileum were determined by polymerase chain reaction (PCR). DNA was extracted from cecal contents for analysis of microbiota changes by terminal restriction fragment length polymorphism. DNA was extracted from colonic contents for analysis of microbiota changes by high throughput sequencing. Results: Compared with HM, LM significantly decreased body mass, plasma TC, TG and LDL-C, and colonic malondialdehyde (MDA) level (P < 0.05, P < 0.01). In contrast, LM significantly increased plasma HDL-C (P < 0.01), total antioxidant capacity (T-AOC) and glutathione/oxidized glutathione (GSH/GSSG) ratio in ileum (P < 0.05), and GSH/GSSG ratio and MDA level in colon (P < 0.05). Similarly, LM significantly decreased the plasma levels of LPS and LBP, the expression of TNF-α and IL-6 mRNA in ileum (P < 0.05), but significantly increased the Shannon-Weiner index and even index of cecal microbiota (P < 0.05) and the relative abundance of Bifidobacterium and Oscillospira in colonic contents (P < 0.05). Conclusion: MR can improve the intestinal redox status, inflammatory response and gut microbiota in high-fat diet-fed mice.