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PubMed2006

Probiotics stimulate production of natural antibodies in chickens.

Commensal bacteria in the intestine play an important role in the development of immune response. These bacteria interact with cells of the gut-associated lymphoid tissues (GALT). Among cells of the GALT, B-1 cells are of note. These cells are involved in the production of natural antibodies. In the present study, we determined whether manipulation of the intestinal microbiota by administration of probiotics, which we had previously shown to enhance specific systemic antibody response, could affect the development of natural antibodies in the intestines and sera of chickens. Our findings demonstrate that when 1-day-old chicks were treated with probiotics, serum and intestinal antibodies reactive to tetanus toxoid (TT) and Clostridium perfringens alpha-toxin in addition to intestinal immunoglobulin A (IgA) reactive to bovine serum albumin (BSA) were increased in unimmunized chickens. Moreover, IgG antibodies reactive to TT were increased in the intestines of probiotic-treated chickens compared to those of untreated controls. In serum, IgG and IgM reactive to TT and alpha-toxin were increased in probiotic-treated, unimmunized chickens compared to levels in untreated controls. However, no significant difference in serum levels of IgM or IgG response to BSA was observed. These results are suggestive of the induction of natural antibodies in probiotic-treated, unimmunized chickens. Elucidating the role of these antibodies in maintenance of the chicken immune system homeostasis and immune response to pathogens requires further investigation.

Animals↗
PubMed2026

A metagenomic analysis of the gut microbiota in a mouse model of fish allergy.

BACKGROUND: Fish are among the most frequent causes of immunoglobulin E (IgE)-mediated food allergies (Type I). Currently, there is no known cure for fish allergy and individuals who are sensitized have to practice strict, lifelong avoidance of fish products in their diets. The relationship between gut microbiome and food allergies is currently a major topic of discussion; these pathologies involve the development of dysbiosis, which is a microbial imbalance resulting from immune-related mechanisms. Recent studies have provided evidence that individuals suffering from food allergies, display an intestinal microbiota with a different microbial composition compared to healthy subjects. OBJECTIVES AND METHODS: In this work, we have described for the first time the differences in microbiome composition in a mouse model of fish allergy with previous sensitization to the main allergen, beta-Parvalbumin (β-PRVB), compared to mouse individuals without allergic response. RESULTS: The metagenomic analysis has shown differences in taxonomic composition between the treatments. Regarding phyla, an increase in the relative abundance of Patescibacteria, specifically Saccharimonas genus and Candidatus_Saccharimonas group, were observed in the allergic animals (Prvb_Alum group) when compared to the other groups. In contrast, the relative abundance of the RF39 group (Bacilli), Atopobiaceae family, Erysipelotrichaceae, and the Coriobacteriaceae_UCG-002 group, was higher in the animals that did not develop an allergic response, despite being exposed to the allergen (Prvb group). Furthermore, an increase in the relative abundance of Lachnospiraceae ASF356 group was observed in the control group compared to the other treatments. This family, has been reported to be inversely associated with the progression of intestinal inflammation and anaphylactic diseases. For the first time, the gut microbiota composition of individual mice with and without fish allergies is described in detail in this work. This study may shed light on the potential contribution of gut microbiota to the onset and avoidance of food allergies.

beta-parvalbumin↗
PubMed2003

Role of intestinal flora in the development of allergy.

PURPOSE OF REVIEW: The frequency of allergic diseases is increasing worldwide. Experimental and clinical studies have linked a reduced number of early infections to this trend. The gastrointestinal system, which comprises the largest lymphoid tissue and microbial reservoir of the body, has received more attention during the last few years as a potential determiner in the development of atopic disease. RECENT FINDINGS: Alterations in intestinal microbiota have been detected both in infants suffering from allergic disease and in those later developing the disorder. Delay in the compositional development of and in gut microflora was a general finding in allergic children. In a subsequent study, perinatal administration of lactobacilli halved the later development of atopic eczema during the first 2 years of life. Specific strains of the healthy gut microbiota have been shown to induce the production of IL-10 and transforming growth factor-beta, which possess an important regulative role in the development of allergic type immune response. Probiotics also strengthen gut defence barrier mechanisms and reduce antigen load in the gut. Pattern recognition receptors in intestinal epithelial and antigen-presenting cells have been demonstrated to mediate a continuing dialogue between host and gut microbiota. SUMMARY: Despite several promising findings, the exact role of gut normal microbiota in the development of allergy remains to be elucidated. For successful interventions, more data concerning a communication between host and specific microbial species are needed.

Animals↗
PubMed2005

Lamina propria dendritic cells in the physiology and pathology of the gastrointestinal tract.

PURPOSE OF REVIEW: The mucosal immune system constantly surveys the intestinal microbiota. The outcome of this interaction is determined by the functional properties of dendritic cells, which play a key role in immune response by facilitating antigen sampling and pathogen recognition, as well as innate host defenses. RECENT FINDINGS: Recent advances have provided insight into the diverse mechanisms involved in the acquisition of intestinal antigens and led to a new appreciation of organ-specific functional subspecification of dendritic cell subsets. Dendritic cells are not a rare cell type in the intestine but populate the entire lamina propria of the gastrointestinal tract as an extensive network. Distinct dendritic cell subsets may be associated with specific immune functions in the lamina propria and Peyer's patches. Newly discovered routes of antigen acquisition, such as the formation of transepithelial dendrites, allow dendritic cells direct access to the intestinal lumen to obtain information about commensal and pathogenic microorganisms. Dendritic cells emerge as key regulators of the intestinal immune system with their ability to direct intestine-specific migration and control of T cells. SUMMARY: Dendritic cells play a major role in the complex interactions between the gut microbiota and the innate and adaptive immune system, leading to tolerance and immunity. Recent contributions have yielded important information that may aid in the development of novel therapeutic approaches to the treatment of inflammatory bowl disease and intestinal infections and to new immunization strategies.

Animals↗
PubMed2006

Comparison of fecal microflora in children with atopic eczema/dermatitis syndrome according to IgE sensitization to food.

Atopic eczema/dermatitis syndrome (AEDS) commonly often arises during early infancy. In several intervention studies a beneficial influence on AEDS course of certain intestinal bacteria, administered as 'probiotics', has been described. To evaluate the possible role of the natural intestinal microflora in children with allergic eczema/dermatitis syndrome regarding immediate type hypersensitivity to food allergens, children with food allergy (AAEDS, n = 68) have been compared with children without detectable food allergy (NAEDS, n = 25). All children (n = 93) in preschool age, mean age of 2.6 (+/-1.8) years, diagnosed with AEDS who were treated as inpatients in 2003 in a dermatological hospital were included. The correlation between fecal microflora, parasites and specific immunoglobulin E (IgE) antibodies against common food allergens was analyzed. A similar composition of intestinal microflora in children with AAEDS and NAAEDS was found. The food allergens that were most frequently detected were egg white, cow milk, casein, peanut and hazelnut. Furthermore, a significant association between IgE sensitization against important food allergens and components of the fecal microflora could not be demonstrated. With aging changes occur in the intestinal microbiota [Proteus/Klebsiella and age (rho = -0.607) and Enterococcus and age (rho = -0.428)]. In two subjects of the AAEDS group Blastocystis hominis was found. The composition of natural intestinal microflora in children with AAEDS and NAAEDS was similar. Hence, there is no evidence of a role of the intestinal microflora with regard to the development of infant (food) allergy in children with AEDS. The possible consequences for allergic diseases later in life require further investigation.

Antibody Specificity↗
PubMed2006

Fate and effect of ingested Bacillus cereus spores and vegetative cells in the intestinal tract of human-flora-associated rats.

The fate and effect of Bacillus cereus F4433/73R in the intestine of human-flora-associated rats was studied using bacteriological culturing techniques and PCR-denaturing gradient gel electrophoresis in combination with cell assays and immunoassays for detection of enterotoxins. In faecal samples from animals receiving vegetative cells, only few B. cereus cells were detected. Spores survived the gastric barrier well, and were in some cases detected up to 2 weeks after ingestion. Selective growing revealed no major changes in the intestinal flora during passage of B. cereus. However, denaturing gradient gel electrophoresis analysis with universal 16S rRNA gene primers revealed significant changes in the intestinal microbiota of animals dosed with spores. Vero cell assays and a commercial kit (BCET-RPLA) did not reveal any enterotoxin production from B. cereus F4433/73R in the intestinal tract.

Animals↗
PubMed2025

Effects of Sodium-Glucose Cotransporter-2 Inhibitors on Modulating Protein-Bound Uremic Toxins and Gut Microbiota in Predialysis CKD Patients: Matched Case-Control Study.

KEY POINTS: A reduction of indoxyl sulfate, p-cresyl sulfate, and several short-chain fatty acids was seen in sodium-glucose cotransporter-2 inhibitor-treated CKD patients. Variations in gut microbiota composition are correlated with levels of gut-derived uremic toxins in sodium-glucose cotransporter-2 inhibitor-treated CKD patients. BACKGROUND: The intricate interplay between CKD and intestinal microbiota has gained increasing attention, with gut dysbiosis being implicated in uremic toxin accumulation and CKD progression. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are now transforming CKD management but pose uncertain effects on shaping gut microbiota. This study aimed to elucidate the effect of SGLT2i on perturbations of gut microbial composition and metabolic responses in patients with CKD. METHODS: Analysis of fecal microbiota and targeted profiling of serum short-chain fatty acids and gut-derived uremic toxins were conducted in a matched case-control study, including 60 patients with CKD (treated: n=30; untreated: n=30) and 30 non-CKD controls. RESULTS: Gut microbial composition differed significantly among the three study groups. Patients with CKD receiving SGLT2i exhibited distinctive taxonomic profiles, such as enrichment of Bacteroides stercoris and Bacteroides coprocola. Surveys of metabolomic profiles revealed a reduction of two uremic solutes, indoxyl sulfate and p-cresyl sulfate (pCS), and several short-chain fatty acids (formic, acetic, propionic, valeric, and 2-methylbutanoic acid) in SGLT2i-treated CKD patients. Co-occurrence analysis demonstrated a set of intestinal microbes that is positively or negatively correlated with the levels of pCS, and the abundance of these pCS-associated intestinal microorganisms was correlated with the levels of indoxyl sulfate and isovaleric acids in the same and opposite direction, respectively. Further functional prediction indicated attenuated pathways related to protein and carbohydrate metabolism. CONCLUSIONS: Treatment with SGLT2i in patients with CKD is associated with distinct gut microbial composition and metabolite profiles, suggesting potential modulation of gut dysbiosis and metabolic pathways. Further studies are warranted to elucidate the clinical implications of these findings in CKD management.

CKD↗
PubMed2006

Protection mechanism of probiotic combination against human pathogens: in vitro adhesion to human intestinal mucus.

In this study we evaluated the ability of commercial strains (L. rhamnosus GG, L. rhamnosus LC705, and P. freudenreichii ssp. shermanii JS) in combination with B. breve 99 or B. lactis Bb12 to inhibit, displace and compete with model pathogens in order to test their influence on the adhesion of selected pathogens to immobilized human intestinal mucus. Our results demonstrate that specific probiotic combinations are able to enhance the inhibition percentages of pathogens adhesion to intestinal mucus when compared to individual strains. This suggests that combinations of probiotic strains are useful and more effective in inhibition of pathogen adhesion than individual strains. Such combinations should be assessed in clinical studies in subjects where the intestinal microbiota aberrancies have been identified.

Antibiosis↗
PubMed2026

Multi-Omic Insights Into Mediterranean Diet-Associated Microbiota.

This study aimed to evaluate the gut microbiota and mycobiota composition, depending on the Mediterranean diet (MD) adherence, using metataxonomics. Combining metagenomics and metatranscriptomics, we also investigate the gene expression level in the bacterial community. Two groups of healthy subjects greatly differing in adherence were selected. Significant differences in microbiota composition were observed between individuals with high adherence (HAMD; mean 10.5 +/- 0.9 points) and low adherence (LAMD; 5.23 +/- 83 points). Notably, the olive oil, vegetable, and fruit consumption presented an important discriminant power between groups. Saccharomyces, Penicillium, and Candida were the most abundant genera. Mycobiota richness was higher in LAMD than in HAMD. Aspergillus was identified as a biomarker for LAMD, whereas Yarrowia, a potential probiotic, was a biomarker for HAMD. Metatranscriptomics indicated that Bacillota was the most metabolically active phylum in the gut microbiota. The low-abundant genus, Methanobrevibacter, showed high transcriptional activity, contributing to the crucial methanogenesis process. Gene expression analyses further highlighted functional differences. Overall, HAMD microbiota presented increased metabolic activity, protein synthesis, and cellular mobility. Overexpression of flagellin and urease genes may enhance immune response in HAMD. Further metatranscriptomic studies are necessary to deepen our understanding of intestinal microbiota transcriptional programs and their interactions with the diet and human health.

Humans↗
PubMed2005

Human gut microbiota does not ferment erythritol.

Erythritol, a naturally occurring polyol, is gaining attention as a bulk sweetener for human nutrition. Industrially, it is produced from glucose by fermentation. From various studies it is known to be non-cariogenic. Moreover, it is rapidly absorbed in the small intestine and quantitatively excreted in the urine. Only about 10 % enters the colon. Earlier in vitro experiments showed that erythritol remained unfermented for a fermentation period of 12 h. In order to investigate whether fresh human intestinal microbiota is able to adapt its enzyme activities to erythritol, a 24 h lasting fermentation was carried out under well-standardised in vitro conditions. For comparison maltitol, lactulose and blank (faecal inoculum only) were incubated as well. Fermentation patterns were established by following total gas production, hydrogen accumulation, changes in pH value, SCFA production and substrate degradation. Taking all fermentation parameters into account, erythritol turned out to be completely resistant to bacterial attack within 24 h, thus excluding an adaptation within that period. Since under in vivo conditions more easily fermentable substrates enter the colon continuously, it seems very unlikely that erythritol will be fermented in vivo.

Erythritol↗
PubMed1998

Evaluation of fructooligosaccharide supplementation of oral electrolyte solutions for treatment of diarrhea: recovery of the intestinal bacteria.

Although oral electrolyte solutions (OES) replenish salts and water lost during diarrhea, present formulations do not address disturbances of the normal intestinal microbiota. Therefore, we evaluated the efficacy of an OES with and without fructooligosaccharide (FOS) for treatment of pigs with acute secretory diarrhea induced by cholera toxin. Before, during, and after diarrhea, bacteriologic evaluation was made of contents collected from the mid small intestine, cecum, and distal colon and mucosa scraped from the mid small intestine. Diarrhea caused significant declines in total bacterial counts of contents from all three regions, with less of an impact on bacteria associated with the mucosa. Although total bacterial counts recovered within 24 hr, regardless of treatment, densities of Enterobacteriaceae were higher in pigs treated with OES whereas those receiving FOS had more lactobacilli. Our results show that secretory diarrhea disturbs the normal densities and relative species abundance of the microbiota, with the influences more pronounced for contents relative to the mucosa, and that adding FOS to OES accelerates the recovery of bacteria perceived as beneficial while potentially slowing the recovery of pathogenic forms.

Animals↗
PubMed2006

Molecular monitoring of the fecal microbiota of healthy human subjects during administration of lactulose and Saccharomyces boulardii.

Diet is a major factor in maintaining a healthy human gastrointestinal tract, and this has triggered the development of functional foods containing a probiotic and/or prebiotic component intended to improve the host's health via modulation of the intestinal microbiota. In this study, a long-term placebo-controlled crossover feeding study in which each subject received several treatments was performed to monitor the effect of a prebiotic substrate (i.e., lactulose), a probiotic organism (i.e., Saccharomyces boulardii), and their synbiotic combination on the fecal microbiota of three groups of 10 healthy human subjects differing in prebiotic dose and/or intake of placebo versus synbiotic. For this purpose, denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene amplicons was used to detect possible changes in the overall bacterial composition using the universal V(3) primer and to detect possible changes at the subpopulation level using group-specific primers targeting the Bacteroides fragilis subgroup, the genus Bifidobacterium, the Clostridium lituseburense group (cluster XI), and the Clostridium coccoides-Eubacterium rectale group (cluster XIVa). Although these populations remained fairly stable based on DGGE profiling, one pronounced change was observed in the universal fingerprint profiles after lactulose ingestion. Band position analysis and band sequencing revealed that a band appearing or intensifying following lactulose administration could be assigned to the species Bifidobacterium adolescentis. Subsequent analysis with real-time PCR (RT-PCR) indicated a statistically significant increase (P < 0.05) in total bifidobacteria in one of the three subject groups after lactulose administration, whereas a similar but nonsignificant trend was observed in the other two groups. Combined RT-PCR results from two subject groups indicated a borderline significant increase (P = 0.074) of B. adolescentis following lactulose intake. The probiotic yeast S. boulardii did not display any detectable universal changes in the DGGE profiles, nor did it influence the bifidobacterial levels. This study highlighted the capacity of an integrated approach consisting of DGGE analysis and RT-PCR to monitor and quantify pronounced changes in the fecal microbiota of healthy subjects upon functional food administration.

Adult↗
PubMed2003

CD4+ CD25+ regulatory T lymphocytes inhibit microbially induced colon cancer in Rag2-deficient mice.

Inflammatory bowel diseases, including ulcerative colitis and Crohn's disease, increase the risk of colorectal cancer in humans. It has been recently shown in humans and animal models that intestinal microbiota and host immunity are integral in the progression of large bowel diseases. Lymphocytes are widely believed to prevent bacterially induced inflammation in the bowel, and lymphocytes are also critical in protecting against primary tumors of intestinal epithelia in mice. Taken together, this raises the possibility that lymphocytes may inhibit colon carcinogenesis by reducing bacterially driven inflammation. To examine the role of bacteria, lymphocytes, and inflammatory bowel disease in the development of colon cancer, 129/SvEv Rag-2-deficient and congenic wild-type mice were orally inoculated with a widespread enteric mouse bacterial pathogen, Helicobacter hepaticus, or sham-dosed with media only. H. hepaticus-infected Rag2-/-, but not sham-dosed Rag2-/- mice, rapidly developed colitis and large bowel carcinoma. This demonstrated a link between microbially driven inflammation and cancer in the lower bowel and suggested that innate immune dysregulation may have an important role in inflammatory bowel disease and progression to cancer. H. hepaticus-infected wild-type mice did not develop inflammation or carcinoma showing that lymphocytes were required to prevent bacterially induced cancer at this site. Adoptive transfer with CD4+ CD45RBlo CD25+ regulatory T cells into Rag-deficient hosts significantly inhibited H. hepaticus-induced inflammation and development of cancer. These results suggested that the ability of CD4+ T cells to protect against intestinal cancer was correlated with their ability to reduce bacterially induced inflammatory bowel disease. Further, regulatory T cells may act directly on the innate immune system to reduce or prevent disease. These roles for T cells in protection against colon carcinoma may have implications for new modes of prevention and treatment of cancer in humans.

Adoptive Transfer↗
PubMed1999

Protective nutrients and bacterial colonization in the immature human gut.

The normal human microflora is a complex ecosystem that is in part dependent on enteric nutrients for establishing colonization. The gut microbiota are important to the host with regard to metabolic functions and resistance to bacterial infections. At birth, bacterial colonization of a previously germ-free human gut begins. Diet and environmental conditions can influence this ecosystem. A breast-fed, full-term infant has a preferred intestine microbiota in which bifidobacteria predominate over potentially harmful bacteria, whereas in formula-fed infants, coliforms, enterococci, and bacteroides predominate. The pattern of bacterial colonization in the premature neonatal gut is different from that in the healthy, full-term infant gut. Those infants requiring intensive care acquire intestinal organisms slowly, and the establishment of bifidobacterial flora is retarded. A delayed bacterial colonization of the gut with a limited number of bacterial species tends to be virulent. Bacterial overgrowth is one of the major factors that promote bacterial translocation. The aberrant colonization of the premature infant may contribute to the development of necrotizing enterocolitis. Breast-feeding protects infants against infection. Oligo-saccharides and glycoconjugates, natural components in human milk, may prevent intestinal attachment of enteropathogens by acting as receptor homologues. Probiotics and prebiotics modulate the composition of the human intestinal microflora to the benefit of the host. These beneficial effects may result in the suppression of harmful microorganisms, the stimulation of bifidobacterial growth, or both. In the future, control and manipulation of the bacterial colonization in the neonatal gut may be a new approach to the prevention and treatment of intestinal infectious diseases of various etiologies.

Bacteria↗
PubMedDate not supplied

[The antibacterial properties of the intestinal microflora of healthy calves].

Antibacterial properties of bacteria of genera Escherichia, Enterococcus, Bacillus, Lactobacillus, Bifidobacterium isolated from different parts of gastro-intestinal tract of the healthy milk-fed and weanling calves were studied against test-bacteria, microorganisms of the Escherichia genus with and without pathogenic factors as well as the genera Klebsiella, Enterobacter, Proteus, Salmonella, Staphylococcus representatives that had been isolated from healthy and sick calves. Certain tolerance was determined between the groups of bacteria under study and only some strains of lactobacteria and bifidobacteria showed selective antibacterial action on pathogenic and conditionally pathogenic microorganisms, thus stabilizing intestinal microbiota in the gastro-enteric tract of calves.

Animals↗
PubMed2022

Identification of shared bacterial strains in the vaginal microbiota of related and unrelated reproductive-age mothers and daughters using genome-resolved metagenomics.

It has been suggested that the human microbiome might be vertically transmitted from mother to offspring and that early colonizers may play a critical role in development of the immune system. Studies have shown limited support for the vertical transmission of the intestinal microbiota but the derivation of the vaginal microbiota remains largely unknown. Although the vaginal microbiota of children and reproductive age women differ in composition, the vaginal microbiota could be vertically transmitted. To determine whether there was any support for this hypothesis, we examined the vaginal microbiota of daughter-mother pairs from the Baltimore metropolitan area (ages 14-27, 32-51; n = 39). We assessed whether the daughter's microbiota was similar in composition to their mother's using metataxonomics. Permutation tests revealed that while some pairs did have similar vaginal microbiota, the degree of similarity did not exceed that expected by chance. Genome-resolved metagenomics was used to identify shared bacterial strains in a subset of the families (n = 22). We found a small number of bacterial strains that were shared between mother-daughter pairs but identified more shared strains between individuals from different families, indicating that vaginal bacteria may display biogeographic patterns. Earlier-in-life studies are needed to demonstrate vertical transmission of the vaginal microbiota.

Child↗
PubMed2002

How host-microbial interactions shape the nutrient environment of the mammalian intestine.

Humans and other mammals are colonized by a vast, complex, and dynamic consortium of microorganisms. One evolutionary driving force for maintaining this metabolically active microbial society is to salvage energy from nutrients, particularly carbohydrates, that are otherwise nondigestible by the host. Much of our understanding of the molecular mechanisms by which members of the intestinal microbiota degrade complex polysaccharides comes from studies of Bacteroides thetaiotaomicron, a prominent and genetically manipulatable component of the normal human and mouse gut. Colonization of germ-free mice with B. thetaiotaomicron has shown how this anaerobe modifies many aspects of intestinal cellular differentiation/gene expression to benefit both host and microbe. These and other studies underscore the importance of understanding precisely how nutrient metabolism serves to establish and sustain symbiotic relationships between mammals and their bacterial partners.

Animals↗