间歇性断食对老年前期肥胖大鼠肠道菌群及代谢的影响

目的 研究间歇性断食对老年前期肥胖大鼠代谢和肠道菌群的影响.方法 雌性Wistar大鼠经42周高脂高糖饲料饲养造模,根据体质量选取模型鼠进行间歇性断食干预.干预方法为每2周断食72 h,总干预时间18周.干预后进行口服葡萄糖耐量试验、血脂4项检测.收集粪便,通过Illumina高通量测序检测16S rRNA基因V4可变区,运用QIIME及LEfSe分析肠道菌群.结果 间歇性断食组体质量相对于模型对照组显著下降(P<0.01);高密度脂蛋白胆固醇和低密度脂蛋白胆固醇均显著下降(P<0.05);空腹血糖显著上升(P<0.01);葡萄糖耐量测试曲线下面积显著高于模型对照组,糖耐量减退(P<0.05);HE染色显示间歇性断食轻度减少肝脏脂肪变性.肠道菌群结果显示,断食组肠道菌群得到显著改善,具体表现为YS2、RF32、Helicobacteraceae(螺杆菌科)增加,Lactobacillus(乳杆菌属)、Roseburia(罗氏菌属)、Erysipelotrichaceae(韦荣球菌科)、Ralstonia(青枯菌属)、Bradyrhizobiaceae(慢生根瘤菌科)和RF39减少.Spearman相关性分析发现Bradyrhizobiaceae与总胆固醇、高密度脂蛋白胆固醇呈正相关;大鼠体质量与RF39呈负相关.结论 间歇性断食能改善肠道菌群,降低老年前期肥胖大鼠体质量和血脂水平,但对糖代谢有不良影响.     

肠道菌群与非酒精性脂肪性肝病

非酒精性脂肪性肝病（non-alcoholic fatty liver disease, NAFLD）在全球范围内越来越常见，造成极大的疾病负担，故对其发生、发展及防治措施进行研究变得十分迫切。近年来，肠道菌群被认为是机体的一个重要的“特殊器官”，它参与机体的代谢并与相关疾病的发生、发展相关，与NAFLD的关系亦密切，值得深入探索，以期能寻找到防治NAFLD的新措施。     

Bacterial cell wall components regulate adipokine secretion from visceral adipocytes

Recent studies suggest a relationship between intestinal microbiota and metabolic syndromes; however, the underlying mechanism remains unclear. To clarify this issue, we assessed the effects of bacterial cell wall components on adiponectin, leptin and resistin secretion from rat visceral adipocytes in vitro. We also measured the relative population of Firmicutes and Bacteroidetes in fecal microbiota and the amount of fecal mucin as an intestinal barrier function, when mice were fed a high-fat diet. In the present study, we demonstrated that bacterial cell wall components affect the secretion of adipokines, depending on the presence of antigens from gram-positive or gram-negative bacteria. Lipopolysaccharide markedly inhibited adiponectin, leptin, and resistin secretion, whereas peptidoglycan increased adiponectin secretion and decreased resistin secretion in vitro. In vivo experiments showed that the high-fat diet increased the population of Firmicutes and decreased that of Bacteroidetes. In contrast, the high-fat diet downregulated the stool output and fecal mucin content. These results demonstrate that bacterial cell wall components affect the onset of metabolic syndromes by mediating the secretion of adipokines from visceral adipose tissue. Furthermore, we believe that metabolic endotoxemia is not due to the increasing dominance of gram-negative bacteria, Bacteroidetes, but due to the depression of intestinal barrier function.     

Dysregulated hepatic bile acids collaboratively promote liver carcinogenesis

Dysregulated bile acids (BAs) are closely associated with liver diseases and attributed to altered gut microbiota. Here, we show that the intrahepatic retention of hydrophobic BAs including deoxycholate (DCA), taurocholate (TCA), taurochenodeoxycholate (TCDCA), and taurolithocholate (TLCA) were substantially increased in a streptozotocin and high fat diet (HFD) induced nonalcoholic steatohepatitis‐hepatocellular carcinoma (NASH‐HCC) mouse model. Additionally chronic HFD‐fed mice spontaneously developed liver tumors with significantly increased hepatic BA levels. Enhancing intestinal excretion of hydrophobic BAs in the NASH‐HCC model mice by a 2% cholestyramine feeding significantly prevented HCC development. The gut microbiota alterations were closely correlated with altered BA levels in liver and feces. HFD‐induced inflammation inhibited key BA transporters, resulting in sustained increases in intrahepatic BA concentrations. Our study also showed a significantly increased cell proliferation in BA treated normal human hepatic cell lines and a down‐regulated expression of tumor suppressor gene CEBPα in TCDCA treated HepG2 cell line, suggesting that several hydrophobic BAs may collaboratively promote liver carcinogenesis.     

The first thousand days – intestinal microbiology of early life: establishing a symbiosis

The development of the intestinal microbiota in the first years of life is a dynamic process significantly influenced by early‐life nutrition. Pioneer bacteria colonizing the infant intestinal tract and the gradual diversification to a stable climax ecosystem plays a crucial role in establishing host–microbe interactions essential for optimal symbiosis. This colonization process and establishment of symbiosis may profoundly influence health throughout life. Recent developments in microbiologic cultivation‐independent methods allow a detailed view of the key players and factors involved in this process and may further elucidate their roles in a healthy gut and immune maturation. Aberrant patterns may lead to identifying key microbial signatures involved in developing immunologic diseases into adulthood, such as asthma and atopic diseases. The central role of early‐life nutrition in the developmental human microbiota, immunity, and metabolism offers promising strategies for prevention and treatment of such diseases. This review provides an overview of the development of the intestinal microbiota, its bidirectional relationship with the immune system, and its role in impacting health and disease, with emphasis on allergy, in early life.     

炎症性肠病患者肠道菌群结构分析

目的应用PCR-DGGE技术对炎症性肠病患者肠道微生物菌群结构及其相似性、多样性进行研究。方法选择正常对照者9例(对照组)和炎症性肠病患者9例(实验组),采集各自粪便,提取细菌总基因组DNA,PCR扩增细菌16S rDNA基因V6—8可变区,DGGE方法检测PCR产物,对肠道菌群进行指纹图谱分析。结果正常对照组和炎症性肠病组PCR-DGGE指纹图谱分析显示,炎症性肠病细菌的多样性较正常对照组明显下降。结论PCR-DGGE技术是一种快速有效的用于分析研究人体肠道菌群结构的技术。阴道菌群的改变可能与炎症性肠病的发生、发展密切相关。