Insights into the Roles of Gut Microbes in Obesity

Obesity is a major public health issue as it enhances the risk of suffering several chronic diseases of increasing prevalence. Obesity results from an imbalance between energy intake and expenditure, associated with a chronic low-grade inflammation. Gut microbes are considered to contribute to body weight regulation and related disorders by influencing metabolic and immune host functions. The gut microbiota as a whole improves the host's ability to extract and store energy from the diet leading to body weight gain, while specific commensal microbes seem to exert beneficial effects on bile salt, lipoprotein, and cholesterol metabolism. The gut microbiota and some probiotics also regulate immune functions, protecting the host form infections and chronic inflammation. In contrast, dysbiosis and endotoxaemia may be inflammatory factors responsible for developing insulin resistance and body weight gain. In the light of the link between the gut microbiota, metabolism, and immunity, the use of dietary strategies to modulate microbiota composition is likely to be effective in controlling metabolic disorders. Although so far only a few preclinical and clinical trials have demonstrated the effects of specific gut microbes and prebiotics on biological markers of these disorders, the findings indicate that advances in this field could be of value in the struggle against obesity and its associated-metabolic disorders

Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects

7 pages, 1 figure, 3 tables.Diet influences the composition of the gut microbiota and host's health, particularly in patients suffering from food-related diseases. Coeliac disease (CD) is a permanent intolerance to cereal gluten proteins and the only therapy for the patients is to adhere to a life-long gluten-free diet (GFD). In the present preliminary study, the effects of a GFD on the composition and immune function of the gut microbiota were analysed in ten healthy subjects (mean age 30·3 years) over 1 month. Faecal microbiota was analysed by fluorescence in situ hybridisation (FISH) and quantitative PCR (qPCR). The ability of faecal bacteria to stimulate cytokine production by peripheral blood mononuclear cells (PBMC) was determined by ELISA. No significant differences in dietary intake were found before and after the GFD except for reductions (P = 0·001) in polysaccharides. Bifidobacterium, Clostridium lituseburense and Faecalibacterium prausnitzii proportions decreased (P = 0·007, P = 0·031 and P = 0·009, respectively) as a result of the GFD analysed by FISH. Bifidobacterium, Lactobacillus and Bifidobacterium longum counts decreased (P = 0·020, P = 0·001 and P = 0·017, respectively), while Enterobacteriaceae and Escherichia coli counts increased (P = 0·005 and P = 0·003) after the GFD assessed by qPCR. TNF-α, interferon-γ, IL-10 and IL-8 production by PBMC stimulated with faecal samples was also reduced (P = 0·021, P = 0·037, P = 0·002 and P = 0·007, respectively) after the diet. Therefore, the GFD led to reductions in beneficial gut bacteria populations and the ability of faecal samples to stimulate the host's immunity. Thus, the GFD may constitute an environmental variable to be considered in treated CD patients for its possible effects on gut health.This work was supported by grants AGL2008-01440/ALI and Consolider Fun-C-Food 20 CSD2007-00063 from the Spanish Ministry of Science and Innovation.Peer reviewe

Bifidobacterium strains suppress in vitro the pro-inflammatory milieu triggered by the large intestinal microbiota of coeliac patients

<p>Abstract</p> <p>Background</p> <p>Coeliac disease (CD) is an enteropathy characterized by an aberrant immune response to cereal-gluten proteins. Although gluten peptides and microorganisms activate similar pro-inflammatory pathways, the role the intestinal microbiota may play in this disorder is unknown. The purpose of this study was to assess whether the faecal microbiota of coeliac patients could contribute to the pro-inflammatory milieu characteristic of CD and the possible benefits of bifidobacteria.</p> <p>Methods</p> <p>The effect of faeces of 26 CD patients with active disease (mean age 5.5 years, range 2.1–12.0 years), 18 symptom-free coeliac disease (SFCD) patients (mean age 5.5 years, range 1.0–12.3 years) on a gluten-free diet for 1–2 years; and 20 healthy children (mean age 5.3 years, range 1.8–10.8 years) on induction of cytokine production and surface antigen expression in peripheral blood mononuclear cells (PBMCs) were determined. The possible regulatory roles of <it>Bifidobacterium longum </it>ES1 and <it>B. bifidum </it>ES2 co-incubated with faecal samples were also assessed <it>in vitro</it>.</p> <p>Results</p> <p>Faeces of both active CD and SFCD patients, representing an imbalanced microbiota, significantly increased TNF-α production and CD86 expression in PBMCs, while decreased IL-10 cytokine production and CD4 expression compared with control samples. Active CD-patient samples also induced significantly higher IFN-γ production compared with controls. However, <it>Bifidobacterium </it>strains suppressed the pro-inflammatory cytokine pattern induced by the large intestinal content of CD patients and increased IL-10 production. Cytokine effects induced by faecal microbiota seemed to be mediated by the NFκB pathway.</p> <p>Conclusion</p> <p>The intestinal microbiota of CD patients could contribute to the Th1 pro-inflammatory milieu characteristic of the disease, while <it>B. longum </it>ES1 and <it>B. bifidum </it>ES2 could reverse these deleterious effects. These findings hold future perspectives of interest in CD therapy.</p

Microorganismos para mejorar el estado de salud de individuos con trastornos relacionados con la ingesta de gluten

La presente invención aporta microorganismos para el tratamientode alergias alimentarias, más concretamente la enfermedad celiaca, así como métodos para su sección. Sus mecanismos de acción incluyen: (i) la regulación de la respuesta inmunológica innata y adaptativa; (ii) la reducción de la concentración de epítopos tóxicos en la luz intestinal; (iii) el fortalecimiento de la función barrera defensiva frente a bacterias y antígenos perjudiciales, y (iv) el aporte de actividades enzimáticas que favorecen la digestión.Peer reviewedConsejo Superior de Investigaciones Científicas (España)T3 Traducción de patente europe

Role of Intestinal Bacteria in Gliadin-Induced Changes in Intestinal Mucosa: Study in Germ-Free Rats

10 pages, 6 figures.[Background and Aims]: Celiac disease (CD) is a chronic inflammatory disorder of the small intestine that is induced by dietary wheat gluten proteins (gliadins) in genetically predisposed individuals. The overgrowth of potentially pathogenic bacteria and infections has been suggested to contribute to CD pathogenesis. We aimed to study the effects of gliadin and various intestinal bacterial strains on mucosal barrier integrity, gliadin translocation, and cytokine production.[Methodology/Principal Findings]: Changes in gut mucosa were assessed in the intestinal loops of inbred Wistar-AVN rats that were reared under germ-free conditions in the presence of various intestinal bacteria (enterobacteria and bifidobacteria isolated from CD patients and healthy children, respectively) and CD-triggering agents (gliadin and IFN-γ) by histology, scanning electron microscopy, immunofluorescence, and a rat cytokine antibody array. Adhesion of the bacterial strains to the IEC-6 rat cell line was evaluated in vitro. Gliadin fragments alone or together with the proinflammatory cytokine interferon (IFN)-γ significantly decreased the number of goblet cells in the small intestine; this effect was more pronounced in the presence of Escherichia coli CBL2 and Shigella CBD8. Shigella CBD8 and IFN-γ induced the highest mucin secretion and greatest impairment in tight junctions and, consequently, translocation of gliadin fragments into the lamina propria. Shigella CBD8 and E. coli CBL2 strongly adhered to IEC-6 epithelial cells. The number of goblet cells in small intestine increased by the simultaneous incubation of Bifidobacterium bifidum IATA-ES2 with gliadin, IFN-γ and enterobacteria. B. bifidum IATA-ES2 also enhanced the production of chemotactic factors and inhibitors of metalloproteinases, which can contribute to gut mucosal protection.[Conclusions]: Our results suggest that the composition of the intestinal microbiota affects the permeability of the intestinal mucosa and, consequently, could be involved in the early stages of CD pathogenesis.This work was supported by grants 310/07/0414, 303/08/0367, P304/10/P406 of the Grant Agency of the Czech Republic; IAA500200801, IAA500200710, KJB50020094 of the Academy of Sciences; AV CR-C.S.I.C. 09/10, Project 2B06155 of the Ministry of Education; and Institutional Research Concept AVOZ50200510. This work was also supported by grants 2006CZ0030 and 2008CZ0023 from Consejo Superior de Investigaciones Científicas (CSIC, Spain) and AGL2008-01440/ALI and Consolider Fun-C-Food CSD2007-00063 from the Spanish Ministry of Science and Innovation. The scholarship to G. De Palma from Junta de Ampliación de Estudios - Consejo Superior de Investigaciones Científicas (JAE-CSIC; Spain) is fully acknowledged.Peer reviewe

Intestinal dysbiosis and reduced immunoglobulin-coated bacteria associated with coeliac disease in children

<p>Abstract</p> <p>Background</p> <p>Coeliac disease is a chronic intestinal inflammatory disorder due to an aberrant immune response to dietary gluten proteins in genetically predisposed individuals. Mucosal immune response through IgA secretion constitutes a first line of defence responsible for neutralizing noxious antigens and pathogens. The aim of this study was the characterization of the relationships between immunoglobulin-coated bacteria and bacterial composition of faeces of coeliac disease (CD) patients, untreated and treated with a gluten-free diet (GFD) and healthy controls.</p> <p>Results</p> <p>IgA-coated faecal bacterial levels were significantly lower in both untreated and treated CD patients than in healthy controls. IgG and IgM-coated bacterial levels were also significantly lower in treated CD patients than in untreated CD patients and controls. Gram-positive to Gram-negative bacteria ratio was significantly reduced in both CD patients compared to controls. <it>Bifidobacterium</it>, <it>Clostridium histolyticum</it>, <it>C. lituseburense </it>and <it>Faecalibacterium prausnitzii </it>group proportions were less abundant (<it>P </it>< 0.050) in untreated CD patients than in healthy controls. <it>Bacteroides-Prevotella </it>group proportions were more abundant (<it>P </it>< 0.050) in untreated CD patients than in controls. Levels of IgA coating the <it>Bacteroides-Prevotella </it>group were significantly reduced (<it>P </it>< 0.050) in both CD patients in comparison with healthy controls.</p> <p>Conclusions</p> <p>In CD patients, reduced IgA-coated bacteria is associated with intestinal dysbiosis, which altogether provide new insights into the possible relationships between the gut microbiota and the host defences in this disorder.</p

SHP-2 Phosphatase Prevents Colonic Inflammation by Controlling Secretory Cell Differentiation and Maintaining Host-Microbiota Homeostasis.

Polymorphisms in the PTPN11 gene encoding for the tyrosine phosphatase SHP-2 were described in patients with ulcerative colitis. We have recently demonstrated that mice with an intestinal epithelial cell-specific deletion of SHP-2 (SHP-2(IEC-KO) ) develop severe colitis 1 month after birth. However, the mechanisms by which SHP-2 deletion induces colonic inflammation remain to be elucidated. We generated SHP-2(IEC-KO) mice lacking Myd88 exclusively in the intestinal epithelium. The colonic phenotype was histologically analyzed and cell differentiation was determined by electron microscopy and lysozyme or Alcian blue staining. Microbiota composition was analyzed by 16S sequencing. Results show that innate defense genes including those specific to Paneth cells were strongly up-regulated in SHP-2-deficient colons. Expansion of intermediate cells (common progenitors of the Goblet and Paneth cell lineages) was found in the colon of SHP-2(IEC-KO) mice whereas Goblet cell number was clearly diminished. These alterations in Goblet/intermediate cell ratio were noticed 2 weeks after birth, before the onset of inflammation and were associated with significant alterations in microbiota composition. Indeed, an increase in Enterobacteriaceae and a decrease in Firmicutes were observed in the colon of these mice, indicating that dysbiosis also occurred prior to inflammation. Importantly, loss of epithelial Myd88 expression inhibited colitis development in SHP-2(IEC-KO) mice, rescued Goblet/intermediate cell ratio, and prevented NFκB hyperactivation and inflammation. These data indicate that SHP-2 is functionally important for the maintenance of appropriate barrier function and host-microbiota homeostasis in the large intestine. J. Cell. Physiol. 231: 2529-2540, 2016. © 2016 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc

Immune Development and Intestinal Microbiota in Celiac Disease

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. The etiology of this disorder is complex, involving both environmental and genetic factors. The major genetic risk factor for CD is represented by HLA-DQ genes, which account for approximately 40% of the genetic risk; however, only a small percentage of carriers develop the disease. Gluten is the main environmental factor responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Epidemiological and clinical data suggest that environmental factors other than gluten might play a role in disease development, including early feeding practices (e.g., breast milk versus formula and duration of breastfeeding), infections, and alterations in the intestinal microbiota composition. Herein, we review what is known about the influence of dietary factors, exposure to infectious agents, and intestinal microbiota composition, particularly in early life, on the risk of developing CD, as well as the possible dietary strategies to induce or increase gluten tolerance

Increased prevalence of pathogenic bacteria in the gut microbiota of infants at risk of developing celiac disease: The PROFICEL study

8 páginas, 1 figura, 2 tablasCeliac disease (CD) is an immune-mediated enteropathy involving genetic and environmental factors, whose interaction influences disease risk. The intestinal microbiota, including viruses and bacteria, could play a role in the pathological process leading to gluten intolerance. In this study, we investigated the prevalence of pathogens in the intestinal microbiota of infants at familial risk of developing CD. We included 127 full-term newborns with at least one first-degree relative with CD. Infants were classified according to milk-feeding practice (breastfeeding or formula feeding) and HLA-DQ genotype (low, intermediate or high genetic risk). The prevalence of pathogenic bacteria and viruses was assessed in the faeces of the infants at 7 days, 1 month and 4 months of age. The prevalence of Clostridium perfringens was higher in formula-fed infants than in breast-fed over the study period, and that of C. difficile at 4 months. Among breastfed infants, a higher prevalence of enterotoxigenic E. coli (ETEC) was found in infants with the highest genetic risk compared either to those with a low or intermediate risk. Among formula-fed infants, a higher prevalence of ETEC was also found in infants with a high genetic risk compared to those of intermediate risk. Our results show that specific factors, such as formula feeding and the HLA-DQ2 genotype, previously linked to a higher risk of developing CD, influence the presence of pathogenic bacteria differently in the intestinal microbiota in early life. Further studies are warranted to establish whether these associations are related to CD onset later in life.This work was supported by grants AGL2011-25169, AGL2014-52101-P and AGL2007-66126-C03-03/ALI (YS and FP) from the Spanish Ministry of Economy and Competitiveness (MINECO). The scholarship to MO from CSIC (JAEpre) and the contract to ABP from the European Union's Seventh Framework Program under the grant agreement no 613979 (MyNewGut) are also fully acknowledged.Peer reviewe

Influence of Milk-Feeding Type and Genetic Risk of Developing Coeliac Disease on Intestinal Microbiota of Infants: The PROFICEL Study

Interactions between environmental factors and predisposing genes could be involved in the development of coeliac disease (CD). This study has assessed whether milk-feeding type and HLA-genotype influence the intestinal microbiota composition of infants with a family history of CD. The study included 164 healthy newborns, with at least one first-degree relative with CD, classified according to their HLA-DQ genotype by PCR-SSP DQB1 and DQA1 typing. Faecal microbiota was analysed by quantitative PCR at 7 days, and at 1 and 4 months of age. Significant interactions between milk-feeding type and HLA-DQ genotype on bacterial numbers were not detected by applying a linear mixed-model analysis for repeated measures. In the whole population, breast-feeding promoted colonization of C. leptum group, B. longum and B. breve, while formula-feeding promoted that of Bacteroides fragilis group, C. coccoides-E. rectale group, E. coli and B. lactis. Moreover, increased numbers of B. fragilis group and Staphylococcus spp., and reduced numbers of Bifidobacterium spp. and B. longum were detected in infants with increased genetic risk of developing CD. Analyses within subgroups of either breast-fed or formula-fed infants indicated that in both cases increased risk of CD was associated with lower numbers of B. longum and/or Bifidobacterium spp. In addition, in breast-fed infants the increased genetic risk of developing CD was associated with increased C. leptum group numbers, while in formula-fed infants it was associated with increased Staphylococcus and B. fragilis group numbers. Overall, milk-feeding type in conjunction with HLA-DQ genotype play a role in establishing infants' gut microbiota; moreover, breast-feeding reduced the genotype-related differences in microbiota composition, which could partly explain the protective role attributed to breast milk in this disorder