Mitochondria could be a potential key mediator linking the intestinal microbiota to depression

The intestinal microbiota has been reported to affect depression, a common mental condition with severe health-related consequences. However, what mediates the effect of the intestinal microbiota on depression has not been well elucidated. We summarize the roles of the mitochondria in eliciting beneficial effects on the gut microbiota to ameliorate symptoms of depression. It is well known that mitochondria play a key role in depression. An important pathogenic factor, namely inflammatory response, may adversely impact mitochondrial functionality to maintain cellular homeostasis. Dysfunction of mitochondria not only affects neuronal function but also reduces neuron cell numbers. We posit that the intestinal microbiota could affect neuronal mitochondrial function through short-chain fatty acids such as butyrate. Brain inflammatory processes could also be affected through the modulation of gut permeability and blood lipopolysaccharide levels. Aberrant mitochondria functionality coupled to adverse cellular homeostasis could be a key mediator for the effect of the intestinal microbiota on the progression of depression.     

Measuring the subgingival microbiota in periodontitis patients: Comparison of the surface layer and the underlying layers

Periodontitis is a major cause of tooth loss in adults that initially results from dental plaque. Subgingival plaque pathogenesis is affected by both community composition and plaque structures, although limited data are available concerning the latter. To bridge this knowledge gap, subgingival plaques were obtained using filter paper (the fourth layer) and curette (the first-third layers) sequentially and the phylogenetic differences between the first–third layers and the fourth layer were characterized by sequencing the V3–V4 regions of 16S rRNA. A total of 11 phyla, 148 genera, and 308 species were obtained by bioinformatic analysis, and no significant differences between the operational taxonomic unit numbers were observed for these groups. In both groups, the most abundant species were Porphyromonas gingivalis and Fusobacterium nucleatum. Actinomyces naeslundii, Streptococcus intermedius, and Prevotella intermedia possessed relatively high proportions in the first–third layers; while in the fourth layer, both traditional pathogens (Treponema denticola and Campylobacter rectus) and novel pathobionts (Eubacterium saphenum, Filifactor alocis, Treponema sp. HOT238) were prominent. Network analysis showed that either of them exhibited a scale-free property and was constructed by two negatively correlated components (the pathogen component and the nonpathogen component), while the synergy in the nonpathogen component was lower in the first–third layers than that in the fourth layer. After merging these two parts into a whole plaque group, the negative/positive correlation ratio increased. With potential connections, the first–third layers and the fourth layer showed characteristic key nodes in bacterial networks.     

分娩方式对北京地区持续母乳喂养的34周龄婴儿肠道菌群影响

[目的] 比较持续母乳喂养条件下不同分娩方式的34周龄婴儿肠道菌群差异,探讨分娩方式对较大婴儿肠道菌群发育的影响。[方法] 在北京地区招募健康足月分娩母乳喂养婴儿,在34周仍然参与随访的持续母乳喂养婴儿共21例,其中剖宫产婴儿16例、阴道分娩婴儿5例,进行肠道菌群的16S rRNA检测。[结果] 两组共21个粪便样本中,共注释到6个门,分别为：疣微菌门、变形菌门、梭杆菌门、厚壁菌门、放线菌门和拟杆菌门;两组共21个样本中共有57个OTU注释到属水平,其中,26个属水平OTU被注释到厚壁菌门,18个属水平OTU被注释到变形菌门,6个属水平OTU被注释到放线菌门,5个属水平OTU被注释到拟杆菌门,梭杆菌门、疣微菌门各有1个属水平OTU被注释。其中变形菌门在阴道分娩组（44.17%）肠道菌群中的含量高于剖宫产组（16.10%）;而放线菌门在阴道分娩婴儿（0.00%）肠道菌群中的含量低于剖宫产婴儿（0.09%）。阴道分娩组与剖宫产组相比,共有7个菌属的丰度发生了显著降低（P<0.05）,分别为副杆菌属、葡萄球菌属、嗜血杆菌属、乳杆菌属、肠球菌属、双歧杆菌属及一注释到科水平的毛螺旋菌科OTU。[结论] 分娩方式对持续母乳喂养的婴儿肠道菌群结构存在影响,且这种影响在出生后34周仍然存在。     

The role of biogeography in shaping diversity of the intestinal microbiota in house mice

The microbial communities inhabiting the mammalian intestinal tract play an important role in diverse aspects of host biology. However, little is known regarding the forces shaping variation in these communities and their influence on host fitness. To shed light on the contributions of host genetics, transmission and geography to diversity in microbial communities between individuals, we performed a survey of intestinal microbial communities in a panel of 121 house mice derived from eight locations across Western Europe using pyrosequencing of the bacterial 16S rRNA gene. The host factors studied included population structure estimated by microsatellite loci and mitochondrial DNA, genetic distance and geography. To determine whether host tissue (mucosa)‐associated communities display properties distinct from those of the lumen, both the caecal mucosa and contents were examined. We identified Bacteroides, Robinsoniella and Helicobacter as the most abundant genera in both the caecal content and mucosa‐associated communities of wild house mice. Overall, we found geography to be the most significant factor explaining patterns of diversity in the intestinal microbiota, with a comparatively weaker influence of host population structure and genetic distance. Furthermore, the influence of host genetic distance was limited to the mucosa communities, consistent with this environment being more intimately coupled to the host.     

Isolation and identification of gastrointestinal microbiota from the short-nosed fruit bat Cynopterus brachyotis brachyotis

Studies on the microbial ecology of gut microbiota in bats are limited and such information is necessary in determining the ecological significance of these hosts. Short-nosed fruit bats (Cynopterus brachyotis brachyotis) are good candidates for microbiota studies given their close association with humans in urban areas. Thus, this study explores the gut microbiota of this species from Peninsular Malaysia by means of biochemical tests and 16S rRNA gene sequences analysis. The estimation of viable bacteria present in the stomach and intestine of C. b. brachyotis ranged from 3.06 × 10¹⁰ to 1.36 × 10¹⁵ CFU/ml for stomach fluid and 1.92 × 10¹⁰ to 6.10 × 10¹⁵ CFU/ml for intestinal fluid. A total of 34 isolates from the stomach and intestine of seven C. b. brachyotis were retrieved. A total of 16 species of bacteria from eight genera (Bacillus, Enterobacter, Enterococcus, Escherichia, Klebsiella, Pantoea, Pseudomonas and Serratia) were identified, Enterobacteriaceae being the most prevalent, contributing 12 out of 16 species isolated. Most isolates from the Family Enterobacteriaceae have been reported as pathogens to humans and wildlife. With the possibility of human wildlife transmission, the findings of this study focus on the importance of bats as reservoirs of potential bacterial pathogens.     

Voluntary Running Exercise Alters Microbiota Composition and Increases n-Butyrate Concentration in the Rat Cecum

The effects of voluntary wheel-running exercise on cecal microbiota and short-chain fatty acid production were investigated in rats. The microbiota composition was notably different between the exercised and sedentary rats. Furthermore, the exercised rats showed a significantly higher n-butyrate concentration than the sedentary rats. This alteration of the cecal microbial environment may contribute to the beneficial effect of exercise on gastrointestinal disorders.     

肠道微生物群落与炎症性肠病关系研究进展

目的炎症性肠病（IBD）包括克罗恩病（CD）和溃疡性结肠炎（UC）,以持续性肠道非特异性炎症为特征,通常反复发作、迁延不愈,临床上仍无特效性的治疗手段。IBD确切的发病机制尚不清楚,涉及免疫、环境及遗传等因素,这些因素共同诱导肠道炎症、黏膜损伤和修复。肠道微生物群落及其代谢产物、宿主基因易感性及肠道黏膜免疫三方面共同参与了IBD的发病机制。本文从消化道微生态角度出发,对目前IBD相关的肠道微生物群落研究现状、宿主-微生物间免疫应答及益生菌治疗等内容进行探讨。     

哺乳期过度喂养对幼鼠肥胖和肠道菌群结构的影响

目的 研究哺乳期过度喂养对幼鼠肠道细菌组成的影响以及肠道细菌与哺乳期过度喂养导致的幼年肥胖的相关性.方法 将正常出生体重的4日龄雄性ICR仔鼠分为正常喂养组(NF组,每8只由1只母鼠喂养)和哺乳期过度喂养组(OF组,每4只由1只母鼠喂养),哺乳至3周龄时,对仔鼠进行口服糖耐量试验(OGTT),称量体重、各种器官和脂肪组织的重量,用基于细菌16S rRNA基因的变性梯度凝胶电泳(DGGE)和实时定量PCR分析仔鼠的粪便细菌组成,对细菌类群数量与表型数据进行相关分析.结果 OF组仔鼠从10日龄起体重显著高于NF组,3周龄时附睾和肾周脂肪垫重量显著高于NF组,两组仔鼠的空腹血糖以及OGTT血糖曲线下面积比较差异无统计学意义.对DGGE图谱的主成分分析表明两组仔鼠的菌群结构比较差异有统计学意义.定量PCR显示,OF组仔鼠粪便中产生内毒素的肠杆菌科细菌和产生破坏肠屏障功能的H2S的硫酸盐还原菌的数量显著高于NF组,而双歧杆菌、乳杆菌和丁酸盐产生菌的数量在两组仔鼠之间差异无统计学意义.粪便硫酸盐还原菌的数量与内脏脂肪的重量显著正相关.结论 哺乳期过度喂养增加了肠道中肠杆菌科细菌和硫酸盐还原菌的数量,这些细菌的增加与仔鼠幼年期肥胖相关.