Oral cavity and gut are important parts of the human digestive tract. The structure and pathogenesis of oral and gut microbial communities have been extensively investigated. The interaction and pathogenic effects of oral and gut microbiota have also been widely explored. This review aimed to integrate data from literature and discuss the structures and functions of microbial communities in the oral cavity and gut. The mutual colonization and pathogenesis of oral and gut microbes and the relationship between these phenomena and involved systemic diseases are also described.
Gastrointestinal Tract ; microbiology ; Humans ; Microbiota ; Mouth ; microbiology

Gastrointestinal Microbiome ; physiology ; Gastrointestinal Tract ; microbiology ; Humans ; Intestinal Diseases ; microbiology

Gastrointestinal Microbiome ; Gastrointestinal Tract ; microbiology ; Humans ; Hypersensitivity ; microbiology

Early in 1962, after an extensive review including 312 cases of bacteremia in burn patients, we were surprised to find that there was about 30% of bacteremia in the patients who had no detectable microorganisms from repeated wound cultures, but blood cultures were usually positive for gut flora. From that time on the idea of gut-origin infection emerged. In following twenty years, a series of experiments were carried on in Wistar rats with 30% TBSA full-thickness burn. The results showed that the fluorescein labeled enteric microbes (Pseudomonas aeruginosa, Bacteroid fragilis and Candida albicans) could translocate through the stress injured intestinal wall and were recovered in visceral organs. The radioisotope 125I labeled endotoxin began to ascend in concentration in portal vein since 15 minutes postburn. Radioautography of liver sections demonstrated the labeled endotoxin granules. With the creation of minute mesenteric lymph fistulas, the clearance of endotoxin and TNFalpha was found to be significantly high in lymph fluid exited from the intestine. All above evidences indicated that the gut is a potential route of endogenous infection, and it also explained how did the patients manifest sepsis early after burn injury without a definite infectious focus. Now the concepts of gut-origin infection are commonly accepted, the measures like early enteral feeding for the protection of intestinal barrier has been established.
Bacteremia ; etiology ; Bacterial Translocation ; Burns ; microbiology ; Gastrointestinal Tract ; microbiology ; Humans

Microorganism distributes in the organs of human body which connect with external environment, especially those organs in the gastrointestinal tracts, and it also plays a fundamental role in the physiopathology of the host's body. Because the microorganism is very small and has a great variety, it is difficult to reveal the significance of microorganism in the human physiopathology comprehensively and deeply. With the development of molecular biology, genomics, bioinformatics and other disciplines, the microbiome research will be more possible and easier. There are two key contents of microecology. One of these is to identify and quantify the diversity of microorganism, and the other is to reveal activity and the physiopathological function of microorganism in the host. Microbiome research methods, therefore, can be summarized as the traditional detection methods, construction of gene library, the genetic fingerprint analysis and molecular hybridization techniques and so on.
Computational Biology ; Gastrointestinal Microbiome ; Gastrointestinal Tract ; microbiology ; Humans

The rapidly evolving aging society in China is associated with increased incidences of osteoporosis and fractures, which have become common health problems that threaten the quality of life of the elderly. Gut microbiota colonizing in the human intestinal tract form a mutual symbiotic relationship with the host and play an important role in the metabolism and immune regulation of the host. In recent years increasing studies have demonstrated that gut microbiota not only affect the digestive system but also contribute to the disease conditions involving the immune system, and have a close relationship with the occurrence and progression of osteoporosis. This review summarizes the progress and hotspots in recent researches of the associations among gut microbiota, the immune system, osteoporosis.
Aged ; Aging ; China ; Gastrointestinal Microbiome ; Gastrointestinal Tract ; microbiology ; Humans ; Microbiota ; Osteoporosis ; microbiology ; Quality of Life

Animals ; Gastrointestinal Microbiome ; Gastrointestinal Tract ; microbiology ; Humans ; Obesity ; microbiology ; pathology ; therapy

Calorie restriction (CR) is a dietary regimen that reduces calorie intake without incurring malnutrition or a reduction in essential nutrients. It has long been recognized as a natural strategy for promoting health, extending longevity, and prevents the development of metabolic and age-related diseases. In the present review, we focus on the general effect of CR on gut microbiota composition and global metabolism. We also propose mechanisms for its beneficial effect. Results showed that probiotic and butyrate-producing microbes increased their relative abundance, whereas proinflammatory strains exhibited suppressed relative abundance following CR. Analyses of the gut microbial and host metabolisms revealed that most host microbial co-metabolites were changed due to CR. Examples of dramatic CR-induced changes in host metabolism included a decrease in the rate of lipid biosynthesis and an increase in the rates of fatty acid catabolism, β-oxidation, glycogenolysis, and gluconeogenesis. The observed phenotypes and the further verification of the direct link between gut microbiota and metabolome may benefit patients that are at risk for developing metabolic disease. Thus, improved gut microbiota composition and metabolome are potential biomarkers for determining the effectiveness of dietary interventions for age-related and metabolic diseases.
Animals ; Bacteroides ; Bacteroidetes ; Caloric Restriction ; Gastrointestinal Microbiome ; Gastrointestinal Tract ; microbiology ; Humans ; Metabolic Diseases ; microbiology ; Metabolome

With the widely application of the metagenomics, the relationship between microbiota and disease has become a hot research topic. Understanding the potential association between upper gastrointestinal cancer or precancerous lesions and microbiota may play an important role in the early detection, clinical diagnosis and treatment, and prognostic evaluation of upper gastrointestinal cancer. Therefore, a literature retrieval was conducted by using PubMed, Embase and wanfang databases to summarize the latest research progress in the microbiota of upper gastrointestinal cancer, including oral, esophageal, gastric cancer and precancerous lesions. Lower microbial diversity or richness in esophageal cancer and precancerous lesions and specific prognostic biomarkers for esophageal cancer were found. Lactobacillus richness showed an increase trend during the process from gastritis to gastric cancer. This paper summarizes the progress in the research of potential biological etiology of upper gastrointestinal cancer from the perspective of metagenomics in order to provide evidence on the, prevention and control of upper gastrointestinal cancer.
Esophageal Neoplasms/microbiology* ; Gastrointestinal Microbiome ; Gastrointestinal Neoplasms/microbiology* ; Gastrointestinal Tract/microbiology* ; Humans ; Lactobacillus ; Metagenomics/trends* ; Microbiota ; Precancerous Conditions/microbiology* ; Prognosis ; Research/trends* ; Risk Factors ; Stomach Neoplasms/microbiology*

Human gut microbiota play an essential role in both healthy and diseased states of humans. In the past decade, the interactions between microorganisms and tumors have attracted much attention in the efforts to understand various features of the complex microbial communities, as well as the possible mechanisms through which the microbiota are involved in cancer prevention, carcinogenesis, and anti-cancer therapy. A large number of studies have indicated that microbial dysbiosis contributes to cancer susceptibility via multiple pathways. Further studies have suggested that the microbiota and their associated metabolites are not only closely related to carcinogenesis by inducing inflammation and immune dysregulation, which lead to genetic instability, but also interfere with the pharmacodynamics of anticancer agents. In this article, we mainly reviewed the influence of gut microbiota on cancers in the gastrointestinal (GI) tract (including esophageal, gastric, colorectal, liver, and pancreatic cancers) and the regulation of microbiota by diet, prebiotics, probiotics, synbiotics, antibiotics, or the Traditional Chinese Medicine. We also proposed some new strategies in the prevention and treatment of GI cancers that could be explored in the future. We hope that this review could provide a comprehensive overview of the studies on the interactions between the gut microbiota and GI cancers, which are likely to yield translational opportunities to reduce cancer morbidity and mortality by improving prevention, diagnosis, and treatment.
Anti-Bacterial Agents ; therapeutic use ; Gastrointestinal Microbiome ; drug effects ; Gastrointestinal Neoplasms ; microbiology ; prevention & control ; Gastrointestinal Tract ; microbiology ; Humans