According to the 'hygiene hypothesis', the intestinal microbes would not only regulate local immune status, but also affect systematic immune homeostasis, which may play an important role in the pathogenesis of allergic diseases. This review will mainly focus on investigating the intricate relationships among intestinal microbes, immune system and allergic diseases. Multiple factors affecting gut microorganisms may influence the immune homeostasis directly and later become risk factors of allergic diseases. This point of view may pave the way for the design of new interventions to the diseases.
Humans ; Hypersensitivity ; microbiology ; Intestines ; microbiology

Humans ; Intestines ; microbiology ; Liver Diseases ; Microbiota

Humans ; Intestines ; immunology ; microbiology ; Liver Diseases ; immunology ; microbiology

OBJECTIVEIn this review, to illustrate the resistance mechanism for pathogen insult, we discussed the role of the intestinal microbiome in promoting resistance to local gastrointestinal tract infections and to respiratory tract infections.

DATA SOURCESThe review was based on data obtained from the published research articles.

STUDY SELECTIONA total of 49 original articles were selected in accordance with our main objective to illustrate the resistance mechanism(s) by which commensal microbiota can contribute to host defense against local and systemic infections.

RESULTSDiverse microorganisms colonize human environmentally exposed surfaces such as skin, respiratory tract, and gastrointestinal tract. Co-evolution has resulted in these microbes with extensive and diverse impacts on multiple aspects of host biological functions. During the last decade, high-throughput sequencing technology developed has been applied to study commensal microbiota and their impact on host biological functions. By using pathogen recognition receptors pathway and nucleotide binding oligomerization domain-like receptors pathway, the commensal microbiome promotes resistance to local and systemic infections, respectively. To protect against the local infections, the microbiome functions contain the following: the competing for sites of colonization, direct production of inhibition molecules or depletion of nutrients needed for pathogens, and priming immune defenses against pathogen insult. At the same time, with the purpose to maintain homeostasis, the commensal bacteria can program systemic signals toward not only local tissue but also distal tissue to modify their function for infections accordingly.

CONCLUSIONSCommensal bacteria play an essential role in protecting against infections, shaping and regulating immune responses, and maintaining host immune homeostasis.

Disease Resistance ; Humans ; Infection ; microbiology ; Intestines ; microbiology ; Symbiosis ; physiology

BackgroundIncreasing evidence has supported the link of intestinal Fusobacterium nucleatum infection to colorectal cancer (CRC). However, the value of F. nucleatum as a biomarker in CRC detection has not been fully defined. In order to reduce the random error and bias of individual research, this meta-analysis aimed to evaluate the diagnostic performance of intestinal F. nucleatum in CRC patients and provide evidence-based data to clinical practice.

MethodsAn article search was performed from PubMed, Embase, Cochrane Library, and Web of Science databases up to December 2017, using the following key words: "Fusobacterium nucleatum", "Fusobacterium spp.", "Fn", "colorectal cancer(s)", "colorectal carcinoma(s)", "colorectal neoplasm(s)", and "colorectal tumor(s)". Articles on relationships between F. nucleatum and CRC were selected according to the preestablished inclusion and exclusion criteria. This meta-analysis was performed using STATA 12.0 software, which included mapping of forest plots, heterogeneity tests, meta-regression, subgroup analysis, sensitivity analysis, and publication bias. The sensitivity, specificity, positive likelihood ratio (LR), negative LR, diagnostic odds ratio (DOR), and their corresponding 95% confidence interval (CI) of each eligible study were summarized.

ResultsFinally, data for 1198 participants (629 CRC and 569 healthy controls) in 10 controlled studies from seven articles were included. The summary receiver operator characteristic curve was mapped. The diagnostic performance of intestinal F. nucleatum infection on CRC was as follows: the area under the curve: 0.86 (95% CI: 0.83-0.89), the pooled sensitivity: 0.81 (95% CI: 0.64-0.91), specificity: 0.77 (95% CI: 0.59-0.89), and DOR: 14.00 (95% CI: 9.00-22.00).

ConclusionIntestinal F. nucleatum is a valuable marker for CRC diagnosis.

Colonic Neoplasms ; microbiology ; Colorectal Neoplasms ; microbiology ; Fusobacterium nucleatum ; physiology ; Humans ; Intestines ; microbiology ; pathology

With the development of intestinal flora, short chain fatty acid(SCFA), produced by the intestinal microbiota, has been found to be important for the host. It also plays an important role in the part of the occurrence and development of some diseases. The relationship between SCFA produced by intestinal microbiota and the host body has become the research focus in recent years. The physiological function and clinical application of SCFA were reviewed in this article.
Fatty Acids, Volatile ; biosynthesis ; physiology ; Humans ; Intestines ; microbiology ; Microbiota

Bariatric surgery is the most effective treatment for obesity and its comorbidities, but mechanisms of bariatric surgery remain unknown. In addition to volume restriction and malabsorption, gut hormones, bile acids, adipokines, intestinal microbiome and central nervous system may be the potential mechanisms.
Bariatric Surgery ; Gastrointestinal Hormones ; Humans ; Intestines ; microbiology ; Microbiota ; Obesity

IS901 RFLP analysis of 36 Mycobacterium avium subsp. avium (MAA) isolates from 15 pheasants (Phasianus colchicus) and two goshawks (Accipiter gentilis) from four pheasant farms was performed. Using this method, six different IS901 RFLP types (E, F, G, M, Q, and V) were identified. The distribution of IS901 RFLP profiles was tightly linked to individual flocks. Matching IS901 RFLP profiles observed in the present study indicate MAA transmission between pheasants and goshawks in the same locality. In two flocks, different pheasants within a flock as well as in various organs of five individual pheasants were found to have two distinct IS901 RFLP profiles.
Animals ; Bone Marrow/microbiology ; *Galliformes ; Intestines/microbiology ; Liver/microbiology ; Mycobacterium avium/*genetics ; *Polymorphism, Genetic ; *Polymorphism, Restriction Fragment Length ; Poultry Diseases/*microbiology ; Spleen/microbiology ; Tuberculosis, Avian/*microbiology

The increasing incidence rate of allergic diseases has attracted global attention, and these diseases greatly threaten children′s health. The common pathogenesis of allergic diseases is the specific IgE- or cell-mediated immune response to common inhalant or food allergens. Epidemiological investigation, analysis of fecal flora, and clinical studies all suggest that the development and progression of allergic diseases are closely related to the early disturbance of intestinal flora. Probiotics can regulate intestinal immune response, increase the barrier function of epithelial cells, inhibit the adhesion and colonization of pathogenic bacteria, and thus restore or reconstruct normal intestinal flora. With the increasing understanding of allergic diseases, the effect of probiotics in the prevention and treatment of such diseases will be taken more and more seriously.
Child ; Humans ; Hypersensitivity ; drug therapy ; immunology ; microbiology ; prevention & control ; Intestines ; immunology ; microbiology ; Probiotics ; administration & dosage

The study aims to screen the ability of the bacteria to metabolize ononin and assess the effect of ononin on the intestinal bacteria. Fresh human fecal sample was obtained from a healthy volunteer, diluted serially in sterile water and sixty-nine different bacterial colonies were picked out ultimately. UPLC-Q-TOF/MS with automated data analysis software (MetaboLynx) was applied to fast analysis of ononin metabolites. Furthermore, an E(max) precision microplate reader was employed to determine the growth situation of Enterococcous sp., Enterobacter sp., Lactobacilli sp., and Bifidobacteria sp. Results indicated that hydrogenation, demethylation, hydroxylation and deglycosylation were the major metabolic pathways of ononin by human intestinal bacteria in vitro. Ononin can inhibit the growth of pathogen such as Enterococcus sp., Enterobacter sp. and can promote the growth of probiotics such as Bifidobacteria sp. and Lactobacilli sp. This study suggested that intestinal bacteria have the metabolic effects of ononin and the biotransformation was completed by different bacteria. And ononin can affect the balance of intestinal flora and the degree of influence varies depending on the bacterial species and the concentration of ononin.
Bacteria ; metabolism ; Biotransformation ; Feces ; microbiology ; Glucosides ; metabolism ; Humans ; Intestines ; microbiology ; Isoflavones ; metabolism ; Metabolic Networks and Pathways