Alberto Caminero

Differences of small intestinal bacteria populations in adults and children with/without celiac disease: Effect of age, gluten diet, and disease

Background: Scientific evidence has revealed microecological changes in the intestinal tract of celiac infants. The objective of this work is the study of bacterial differences in the upper small intestine in both adults (healthy, untreated celiac disease [CD], and CD treated with a gluten‐free diet) and children (healthy and untreated CD). Methods: Intestinal bacterial communities were identified by 16S rRNA gene sequencing of DNA extracted from duodenal biopsies. Results: Analysis of the sequences from adults and children showed that this niche was colonized by bacteria affiliated mainly with three phyla: Firmicutes, Proteobacteria, and Bacteroidetes. In total, 89 different genera were identified in adults and 46 in children. Bacterial richness was significantly lower in the children than in the adults. A global principal component analysis of the bacterial communities of both healthy and untreated CD patient groups (including both children and adults) revealed a strong effect of age in principal component 1—clustering all adults and children separately—and a possible effect of the disease in adults with untreated patients clustering separately. Conclusions: There are bacterial differences in the upper small intestine between untreated children CD patients and untreated CD adults due to age. There are bacterial differences in the upper small bacteria microbiota between treated and untreated CD adults due to treatment with a gluten‐free diet. (Inflamm Bowel Dis 2011;)

Monitoring of gluten-free diet compliance in celiac patients by assessment of gliadin 33-mer equivalent epitopes in feces

Background: Certain immunotoxic peptides from gluten are resistant to gastrointestinal digestion and can interact with celiac-patient factors to trigger an immunologic response. A gluten-free diet (GFD) is the only effective treatment for celiac disease (CD), and its compliance should be monitored to avoid cumulative damage. However, practical methods to monitor diet compliance and to detect the origin of an outbreak of celiac clinical symptoms are not available. Objective: We assessed the capacity to determine the gluten ingestion and monitor GFD compliance in celiac patients by the detection of gluten and gliadin 33-mer equivalent peptidic epitopes (33EPs) in human feces. Design: Fecal samples were obtained from healthy subjects, celiac patients, and subjects with other intestinal pathologies with different diet conditions. Gluten and 33EPs were analyzed by using immunochromatography and competitive ELISA with a highly sensitive antigliadin 33-mer monoclonal antibody. Results: The resistance of a significant part of 33EPs to gastrointestinal digestion was shown in vitro and in vivo. We were able to detect gluten peptides in feces of healthy individuals after consumption of a normal gluten-containing diet, after consumption of a GFD combined with controlled ingestion of a fixed amount of gluten, and after ingestion of <100 mg gluten/d. These methods also allowed us to detect GFD infringement in CD patients. Conclusions: Gluten-derived peptides could be sensitively detected in human feces in positive correlation with the amount of gluten intake. These techniques may serve to show GFD compliance or infringement and be used in clinical research in strategies to eliminate gluten immunotoxic peptides during digestion. This trial was registered at clinicaltrials.gov as NCT01478867.

Diversity of the cultivable human gut microbiome involved in gluten metabolism: isolation of microorganisms with potential interest for coeliac disease

Gluten, a common component in the human diet, is capable of triggering coeliac disease pathogenesis in genetically predisposed individuals. Although the function of human digestive proteases in gluten proteins is quite well known, the role of intestinal microbiota in the metabolism of proteins is frequently underestimated. The aim of this study was the isolation and characterisation of the human gut bacteria involved in the metabolism of gluten proteins. Twenty-two human faecal samples were cultured with gluten as the principal nitrogen source, and 144 strains belonging to 35 bacterial species that may be involved in gluten metabolism in the human gut were isolated. Interestingly, 94 strains were able to metabolise gluten, 61 strains showed an extracellular proteolytic activity against gluten proteins, and several strains showed a peptidasic activity towards the 33-mer peptide, an immunogenic peptide in patients with coeliac disease. Most of the strains were classified within the phyla Firmicutes and Actinobacteria, mainly from the genera Lactobacillus, Streptococcus, Staphylococcus, Clostridium and Bifidobacterium. In conclusion, the human intestine exhibits a large variety of bacteria capable of utilising gluten proteins and peptides as nutrients. These bacteria could have an important role in gluten metabolism and could offer promising new treatment modalities for coeliac disease.

Study of duodenal bacterial communities by 16S rRNA gene analysis in adults with active celiac disease vs non-celiac disease controls.

Several studies have suggested that abnormalities in the small‐intestinal microbiota might be involved in the development or the pathogenesis of celiac disease (CD). The objective of this study was to characterize and compare the composition of the duodenal microbiota between CD patients and non‐CD controls.

Differences in gluten metabolism among healthy volunteers, coeliac disease patients and first-degree relatives.

Coeliac disease (CD) is an immune-mediated enteropathy resulting from exposure to gluten in genetically predisposed individuals. Gluten proteins are partially digested by human proteases generating immunogenic peptides that cause inflammation in patients carrying HLA-DQ2 and DQ8 genes. Although intestinal dysbiosis has been associated with patients with CD, bacterial metabolism of gluten has not been studied in depth thus far. The aim of this study was to analyse the metabolic activity of intestinal bacteria associated with gluten intake in healthy individuals, CD patients and first-degree relatives of CD patients. Faecal samples belonging to twenty-two untreated CD patients, twenty treated CD patients, sixteen healthy volunteers on normal diet, eleven healthy volunteers on gluten-free diet (GFD), seventy-one relatives of CD patients on normal diet and sixty-nine relatives on GFD were tested for several proteolytic activities, cultivable bacteria involved in gluten metabolism, SCFA and the amount of gluten in faeces. We detected faecal peptidasic activity against the gluten-derived peptide 33-mer. CD patients showed differences in faecal glutenasic activity (FGA), faecal tryptic activity (FTA), SCFA and faecal gluten content with respect to healthy volunteers. Alterations in specific bacterial groups metabolising gluten such as Clostridium or Lactobacillus were reported in CD patients. Relatives showed similar parameters to CD patients (SCFA) and healthy volunteers (FTA and FGA). Our data support the fact that commensal microbial activity is an important factor in the metabolism of gluten proteins and that this activity is altered in CD patients.

Coeliac disease screening in first-degree relatives on the basis of biopsy and genetic risk.

Background Serological markers of coeliac disease (CD) lack diagnostic value to identify mild histopathological lesions mainly in adults at risk of CD. Aims The aim of this study was to evaluate the usefulness of human leukocyte antigen (HLA)-DQ2/8 genotyping, followed by duodenal biopsy for the detection of CD in adult first-degree relatives (FDRs) of patients with CD. Materials and methods Ninety-two adult DQ2/8 positive FDRs were consecutively included. A duodenal biopsy was offered irrespective of the serology result or associated symptoms. The clinical features, associated autoimmune diseases and biochemical parameters were recorded. Results Sixty-seven FDRs (mean age 34 years) underwent a duodenal biopsy. Histopathological alterations were found in 32 (48%) and showed the following stages: 12 Marsh I (18%), one Marsh II (1.5%), four Marsh IIIA (6%), five Marsh IIIB (7.5%) and 10 Marsh IIIC (15%). Positive serological markers were present in 17/67 (25%), with only one showing Marsh I and the remainder presenting some degree of duodenal atrophy (Marsh III). In addition, 33/67 (54%) had gastrointestinal symptoms, with dyspepsia being the most prevalent. The distribution of symptoms, anaemia and autoimmune disease was independent of the duodenal histopathological stage. Serology-based screening would diagnose 50% of the cases showing any degree of CD spectrum and miss 6% of the cases with mucosal atrophy. Conclusion Adult FDRs of patients with CD can benefit from a screening strategy on the basis of HLA-DQ genotyping, followed by a duodenal biopsy. Gastrointestinal symptoms and lymphocytic enteritis are common findings that may benefit from a gluten-free diet.

Age-related differences in celiac disease: Specific characteristics of adult presentation.

Celiac disease may appear both in early childhood and in elderly subjects. Current knowledge of the disease has revealed some differences associated to the age of presentation. Furthermore, monitoring and prognosis of celiac subjects can vary depending on the pediatric or adult stage. The main objective of this review is to provide guidance for the adult diagnostic and follow-up processes, which must be tailored specifically for adults and be different from pediatric patients.

Gluten Metabolism in Humans: Involvement of the Gut Microbiota

Abstract Gluten proteins are the major storage proteins that are deposited in the starchy endosperm cells of developing wheat grain. These proteins have the capacity to form a viscoelastic network, and thus wheat is used in numerous processed foods. Therefore, a large amount of gluten protein is ingested by humans. However, because of their high proline and glutamine content, gluten peptides are relatively resistant to complete digestion by human digestive proteases because those enzymes are deficient in prolyl endopeptidasic activity. The incomplete digestion of gluten proteins generates high molecular weight oligopeptides that remain in the lumen of the small intestine; some of these are capable of triggering the inflammatory process associated with celiac disease (CD). Nevertheless, there are several reasons why gut microbiota should be taken into account when considering the metabolism of proteins in the human intestine. For example, there are bacteria in the oral cavity that have the ability to hydrolyze gluten peptides, and there are bacteria in the large intestine with the ability to digest gliadin peptides. These bacteria could generate different digestion processes for gluten proteins in CD patients and in healthy people. Therefore, this review examines gluten metabolism throughout the gastrointestinal tract, and the role of the gut microbiota in this process.Gluten proteins are the major storage proteins that are deposited in the starchy endosperm cells of developing wheat grain. These proteins have the capacity to form a viscoelastic network, and thus wheat is used in numerous processed foods. Therefore, a large amount of gluten protein is ingested by humans. However, because of their high proline and glutamine content, gluten peptides are relatively resistant to complete digestion by human digestive proteases because those enzymes are deficient in prolyl endopeptidasic activity. The incomplete digestion of gluten proteins generates high molecular weight oligopeptides that remain in the lumen of the small intestine; some of these are capable of triggering the inflammatory process associated with celiac disease (CD). Nevertheless, there are several reasons why gut microbiota should be taken into account when considering the metabolism of proteins in the human intestine. For example, there are bacteria in the oral cavity that have the ability to hydrolyze gluten peptides, and there are bacteria in the large intestine with the ability to digest gliadin peptides. These bacteria could generate different digestion processes for gluten proteins in CD patients and in healthy people. Therefore, this review examines gluten metabolism throughout the gastrointestinal tract, and the role of the gut microbiota in this process.