Gut microbiota and inflammation

Systemic and local inflammation in relation to the resident microbiota of the human gastro-intestinal (GI) tract and administration of probiotics are the main themes of the present review. The dominating taxa of the human GI tract and their potential for aggravating or suppressing inflammation are described. The review focuses on human trials with probiotics and does not include in vitro studies and animal experimental models. The applications of probiotics considered are systemic immune-modulation, the metabolic syndrome, liver injury, inflammatory bowel disease, colorectal cancer and radiation-induced enteritis. When the major genomic differences between different types of probiotics are taken into account, it is to be expected that the human body can respond differently to the different species and strains of probiotics. This fact is often neglected in discussions of the outcome of clinical trials with probiotics.     

Scalp microbiota alterations in children with pediculosis

Pediculosis is a disease caused by the insect Pediculus humanus capitis that mainly occurs in childhood. A comparative study was carried out evaluating groups of schoolchildren with (group A) and without pediculosis (group B) to analyse the characteristics of the scalp microbiota. Samples were collected by swab using Stuart transport medium and incubate in Sabouraud dextrose agar with tetracycline to analyse the fungal microbiota and in blood agar to assess the bacterial microbiota. The isolates identity was confirmed by sequencing of the 16S and 18S regions of the ribosomal DNA gene for bacteria and fungi, respectively. The analysis of the 186 isolates led to the identification of 35 bacteria and 40 fungi in group A and 47 bacteria and 64 fungi in group B. The results indicate differences in bacterial and fungal species in the groups analysed. In the observed bacterial microbiota, Staphylococcus capitis occurred more frequently than Staphylococcus epidermidis in group A vs B. Among fungal isolates, Debaryomyces sp. was more frequent in group B vs A. Our findings showed scalp microbiota alterations in children with pediculosis, meriting future studies to analyse the relationship between these agents and their impact on human health.     

大肠癌患者肠道微生态变化的研究进展

正常人体肠道内定植着大量的微生物,它们在调节肠道生理功能方面具有重要的作用。饮食结构及环境变化导致的肠道菌群丰度及结构的改变,与大肠癌的发生发展密切相关。因此,探讨可能性致癌菌株与大肠癌发生的相关性,并通过添加微生态制剂调整肠道菌群结构,进而降低大肠癌发生率,具有重要的理论及临床意义。     

肠道微生物群与艾滋病疾病进展

抗病毒治疗能够降低艾滋病的发病率和死亡率，但近年来的研究发现即便在抗病毒治疗成功抑制病毒血症的情况下，肠道的免疫失调和其引发的结构性损伤引起了微生物易位，使机体产生免疫激活并形成相关炎症，导致艾滋病的疾病进展。肠道微生物群对于保持肠道黏膜屏障的功能、调节固有免疫、获得性免疫以及保持肠道的平衡状态都非常重要。因此，探讨肠道微生物群的变化与艾滋病疾病进展的关系，有很重要的理论价值和现实意义。本文着重探讨肠道微生物群与艾滋病的疾病进展相关的各项研究以及应用于艾滋病治疗的可能。     

Dietary fibre and the gut microbiota

Summary The complex human colonic microbiota plays a key role in gut health, and both the composition and metabolism of the gut microbiota are strongly diet related. Controlled dietary intake studies in obese individuals demonstrated that consumption of low‐carbohydrate diets results in low faecal butyrate concentrations together with a low abundance of the major butyrate‐producing bacteria, Roseburia spp. and Eubacterium rectale group. Resistant dietary carbohydrates, including pre‐biotics, escape digestion in the upper gastrointestinal tract and are fermented to short‐chain fatty acids (SCFAs) by bacteria in the colon. The main SCFAs formed are acetate, propionate and butyrate. Model colonic fermentor systems employed to determine which bacterial groups utilise specific substrates indicated that the bacterial composition and production of SCFAs is substrate dependent. The bacterial colonisers of specific substrates were identified using 16S rRNA sequence analysis. Sequences recovered from bran were most closely related to Roseburia spp., E. rectale and Clostridium hathewayi, while on resistant starch, sequences were most closely related to Ruminococcus bromii and Bifidobacterium adolescentis. Differing intakes of dietary carbohydrate also impact on other factors in the colon such as transit and pH. In continuous fermentor systems, a slightly acidic pH (5.5) representative of the proximal colon gave fourfold higher butyrate concentrations than at the higher pH of 6.5, which is more representative of the distal colon. Bacteroidetes dominated the fermentor at pH 6.5, while the major butyrate‐producing bacterial groups competed more effectively for carbohydrate substrates when the pH was mildly acidic (5.5). In in vitro studies in which pH values were even lower, pH 5.2, lactate and acetate accumulated. In contrast, lactate was not detected at pH 6.4 although stable isotope studies revealed that lactate was actively produced. Lactate accumulation at low pH appears to be as a result of the loss of lactate‐utilising bacteria including Eubacterium hallii. It is clear that the composition of the colonic microbiota and the balance of its metabolic products is strongly influenced by diet and, in particular, by the intake of resistant carbohydrates and dietary fibre.     

Probiotics,gut microbiota and health

The human gut is a huge complex ecosystem where microbiota, nutrients, and host cells interact extensively, a process crucial for the gut homeostasis and host development with a real partnership. The various bacterial communities that make up the gut microbiota have many functions including metabolic, barrier effect, and trophic functions. Hence, any dysbiosis could have negative consequences in terms of health and many diseases have been associated to impairment of the gut microbiota. These close relationships between gut microbiota, health, and disease, have led to great interest in using probiotics (i.e. live micro-organisms), or prebiotics (i.e. non-digestible substrates) to positively modulate the gut microbiota to prevent or treat some diseases. This review focuses on probiotics, their mechanisms of action, safety, and major health benefits. Health benefits remain to be proven in some indications, and further studies on the best strain(s), dose, and algorithm of administration to be used are needed. Nevertheless, probiotic administration seems to have a great potential in terms of health that justifies more research.     

Composition and function of the human-associated microbiota

The human body is an ecosystem harboring complex site-specific microbial communities. The majority of these human-associated microbes are found in the intestinal tract, where they play important roles in energy uptake, vitamin synthesis, and epithelial and immunity development. Recent molecular studies have characterized the human-associated microbiotas in more detail than conventional culture-dependent techniques, showing a large degree of microbial diversity and differences between anatomical sites and individuals. Investigating the composition and function of microbial symbionts will facilitate better understanding of their roles in human health and disease.     

Gut microbiota interactions with anti-diabetic medications and pathogenesis of type 2 diabetes mellitus

Microorganisms including bacteria, viruses, protozoa, and fungi living in the gastrointestinal tract are collectively known as the gut microbiota. Dysbiosis is the imbalance in microbial composition on or inside the body relative to healthy state. Altered Firmicutes to Bacteroidetes ratio and decreased abundance of Akkermansia muciniphila are the predominant gut dysbiosis associated with the pathogenesis of type 2 diabetes mellitus (T2DM) and metabolic syndrome. Pathophysiological mechanisms linking gut dysbiosis, and metabolic diseases and their complications include altered metabolism of short-chain fatty acids and bile acids, interaction with gut hormones, increased gut microbial metabolite trimethylamine-N-oxide, bacterial translocation/Leaky gut syndrome, and endotoxin production such as lipopolysaccharides. The association between the gut microbiota and glycemic agents, however, is much less understood and is the growing focus of research and conversation. Recent studies suggest that the gut microbiota and anti-diabetic medications are interdependent on each other, meaning that while anti-diabetic medications alter the gut microbiota, the gut microbiota also alters the efficacy of anti-diabetic medications. With increasing evidence regarding the significance of gut microbiota, it is imperative to review the role of gut microbiota in the pathogenesis of T2DM. This review also discusses the interaction between gut microbiota and the various medications used in the treatment of T2DM.     

Association of dietary type with fecal microbiota in vegetarians and omnivores in Slovenia

Purpose

The purpose of this study was to discover differences in the human fecal microbiota composition driven by long-term omnivore versus vegan/lacto-vegetarian dietary pattern. In addition, the possible association of demographic characteristics and dietary habits such as consumption of particular foods with the fecal microbiota was examined.

Methods

This study was conducted on a Slovenian population comprising 31 vegetarian participants (11 lacto-vegetarians and 20 vegans) and 29 omnivore participants. Bacterial DNA was extracted from the frozen fecal samples by Maxwell 16 Tissue DNA Purification Kit (Promega). Relative quantification of selected bacterial groups was performed by real-time PCR. Differences in fecal microbiota composition were evaluated by PCR–DGGE fingerprinting of the V3 16S rRNA region. Participants’ demographic characteristics, dietary habits and health status information were collected through a questionnaire.

Results

Vegetarian diet was associated with higher ratio (% of group-specific DNA in relation to all bacterial DNA) of Bacteroides–Prevotella, Bacteroides thetaiotaomicron, Clostridium clostridioforme and Faecalibacterium prausnitzii, but with lower ratio (%) of Clostridium cluster XIVa. Real-time PCR also showed a higher concentration and ratio of Enterobacteriaceae (16S rDNA copies/g and %) in female participants (p < 0.05 and p < 0.01) and decrease in Bifidobacterium with age (p < 0.01). DGGE analysis of the 16S rRNA V3 region showed that relative quantity of DGGE bands from certain bacterial groups was lower (Bifidobacterium, Streptococus, Collinsella and Lachnospiraceae) or higher (Subdoligranulum) among vegetarians, indicating the association of dietary type with bacterial community composition. Sequencing of selected DGGE bands revealed the presence of common representatives of fecal microbiota: Bacteroides, Eubacterium, Faecalibacterium, Ruminococcaceae, Bifidobacterium and Lachnospiraceae. Up to 4 % of variance in microbial community analyzed by DGGE could be explained by the vegetarian type of diet.

Conclusions

Long-term vegetarian diet contributed to quantity and associated bacterial community shifts in fecal microbiota composition. Consumption of foods of animal origin (eggs, red meat, white meat, milk, yoghurt, other dairy products, fish and seafood) and vegetarian type of diet explained the largest share of variance in microbial community structure. Fecal microbiota composition was also associated with participants’ age, gender and body mass.     

1型糖尿病儿童肠道菌群谱分析研究

目的 通过16SrRNA基因测序方法探索1型糖尿病(T1DM)儿童肠道菌群结构变化的特征,并比较T1DM儿童与健康儿童间肠道菌群的差异,为临床应用益生菌进行TIDM早期干预提供理论基础和实验依据。方法 选取2018年10月-2019年10月在昆明市儿童医院内分泌遗传代谢科住院并初诊为T1DM的5~14岁儿童18例,同时选取19例性别、年龄相近的健康儿童为研究对象,收集两组儿童粪便标本后进行16SrRNA基因测序实验,并采用QIIME 2分析流程进行生物信息学分析,比较两组间肠道菌群的差异。结果 1)利用QIIME2软件将相似度100%的序列聚类分析后共获得3 248个Feature数;2)经物种鉴定及注释,绝大部分菌群都分类到属级和种级;3)Alpha多样性分析说明本次研究测序深度充分,并且T1DM儿童肠道菌群的丰富度及多样性较健康儿童降低 (P<0.05);4)Beta多样性分析中,PCoA图说明T1DM儿童和健康儿童间肠道菌群结构存在明显差异;5)肠道菌群组成差异分析中,在门水平上,T1DM儿童放线菌门、拟杆菌门和蓝细菌门丰度显著增高,而变形菌门、杆菌门的丰度降低(P<0.05);在属水平上,T1DM儿童粪杆菌属、双歧杆菌属和拟杆菌属的丰度较健康儿童增高,而埃希氏杆菌属-志贺氏杆菌、肠球菌属、Blautia菌属丰度降低(P<0.05)。结论 T1DM儿童存在肠道菌群生态失衡,并且菌群物种的丰富度及多样性降低。此外,T1DM儿童与健康儿童肠道菌群结构分布存在明显差异。     

1型糖尿病儿童肠道菌群谱分析研究

目的 通过16SrRNA基因测序方法探索1型糖尿病(T1DM)儿童肠道菌群结构变化的特征,并比较T1DM儿童与健康儿童间肠道菌群的差异,为临床应用益生菌进行TIDM早期干预提供理论基础和实验依据。方法 选取2018年10月-2019年10月在昆明市儿童医院内分泌遗传代谢科住院并初诊为T1DM的5~14岁儿童18例,同时选取19例性别、年龄相近的健康儿童为研究对象,收集两组儿童粪便标本后进行16SrRNA基因测序实验,并采用QIIME 2分析流程进行生物信息学分析,比较两组间肠道菌群的差异。结果 1)利用QIIME2软件将相似度100%的序列聚类分析后共获得3 248个Feature数;2)经物种鉴定及注释,绝大部分菌群都分类到属级和种级;3)Alpha多样性分析说明本次研究测序深度充分,并且T1DM儿童肠道菌群的丰富度及多样性较健康儿童降低 (P<0.05);4)Beta多样性分析中,PCoA图说明T1DM儿童和健康儿童间肠道菌群结构存在明显差异;5)肠道菌群组成差异分析中,在门水平上,T1DM儿童放线菌门、拟杆菌门和蓝细菌门丰度显著增高,而变形菌门、杆菌门的丰度降低(P<0.05);在属水平上,T1DM儿童粪杆菌属、双歧杆菌属和拟杆菌属的丰度较健康儿童增高,而埃希氏杆菌属-志贺氏杆菌、肠球菌属、Blautia菌属丰度降低(P<0.05)。结论 T1DM儿童存在肠道菌群生态失衡,并且菌群物种的丰富度及多样性降低。此外,T1DM儿童与健康儿童肠道菌群结构分布存在明显差异。     

学龄儿童肥胖与肠道菌群多样性及菌属丰度的关联研究

目的分析学龄肥胖儿童和正常体重儿童肠道菌群多样性差异, 识别肥胖儿童肠道特征菌属, 为后续相关机制研究和学龄儿童肥胖的防治提供依据。方法基于2016年在上海市嘉定区某小学建立的研究队列人群, 将2016-2018年3年均处肥胖状态的儿童共63名纳入肥胖组, 其中男生43名, 女生20名。在3年均为正常体重的儿童中, 根据年龄、性别和所在班级, 将其与肥胖组儿童进行1∶1匹配, 共选择63名纳入对照组。采用问卷收集儿童基本信息、饮食状况、母乳喂养等情况, 收集两组儿童的粪便样本并进行16S rDNA测序。对质量优化后的测序序列按照97%相似性进行可操作分类单元聚类及物种注释。分析肥胖组和对照组儿童肠道菌群多样性及菌属丰度差异。计算肠道菌群的Ace、Chao1、Shannon、Simpson 4种α多样性指数, 并利用主坐标分析, 在非加权Unifrac距离和加权Unifrac距离的基础上表示β多样性。使用相似性分析(ANOSIM)比较两组β多样性的差异。利用STAMP软件挑选出两组儿童共有菌属中的差异细菌, 并利用广义线性模型(GLM)分析肥胖与α多样性以及显著差异菌属的关联。结果肥胖组...     

肠道微生态对放射治疗的影响与相关机制

微生态是由定植于人类上皮屏障的共生菌和其他微生物组成的。共生的微生态对人类的生存和健康发挥着重要作用。微生态还参与了肿瘤的发生、发展和扩散过程。新近研究有力证实了微生态尤其是肠道微生态在抗肿瘤反应中和毒性反应的调节中发挥重要作用。肠道微生态影响着治疗所致的免疫原性细胞死亡诱导的免疫反应。本文中我们将聚焦于肠道微生态对放射治疗所致的机体免疫反应及毒性反应的调节作用及具体机制。     

Influencing health through intestinal microbiota modulation and probiotics

Science has progressed fast in providing answers to probiotic health benefits to the consumers. This symposium also proves that progress is fast. However, several challenges still need to be solved and more effective strains and strain combinations discovered. This will pave the way from good probiotics to specific products for clearly identified target populations. The intestinal microbiota and its interaction(s) with probiotics challenges researchers to turn to the next new page to discover new approaches and treatment modalities that utilize probiotics as means of providing good nutrition with clear health benefits to all consumers.     

Interactions between the microbiota and the intestinal mucosa

The intestinal microflora can be considered as a postnatally aquired organ composed of a large diversity of bacterial cells that can perform different functions for the host. This organ is highly exposed to environmental influences and thus modulated in its composition and functions by external factors, such as nutrition. Specific components of the intestinal microflora, including lactobacilli and bifidobacteria, have been associated with beneficial effects on the host, such as promotion of gut maturation and integrity, antagonisms against pathogens and immune modulation. In addition, the microflora seem to play a significant role in the maintenance of intestinal immune homeostasis and prevention of inflammation. At the present time, the contribution of intestinal epithlial cell in the first line of defence against pathogenic bacteria and microbial antigens has been recognized, in contrast, the interactions of intestinal epithelial cells with commensal bacteria are less understood. The present work summarizes the increasing scientific attention for mechanisms of the innate immune response of the host to different components of the autochthonous microflora and suggests a potential role for selected probiotic bacteria in the regulation of intestinal inflammation.