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

Abstract

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.

Selected Probiotic Lactobacilli Have the Capacity To Hydrolyze Gluten Peptides during Simulated Gastrointestinal Digestion

“…Indeed, gluten-degrading bacteria have been isolated from the gastrointestinal tracts of humans and pigs (21)(22)(23)(24)(25). Previously, it was shown that Lactobacillus rhamnosus GG improves the intestinal permeability of Caco-2 cells when exposed to gliadin peptides (26).…”

Differential Hallmarks of Celiac Versus Non-Celiac Gluten Sensitivity

“…Recently, it was shown that GFD treatment signiicantly altered proportions of these bacterial groups and that restoration of normal bacterial lora took many months and possibly years [14,15]. It was also shown that increased presence of some of the bacterial species involved in gluten metabolism leads to enteritis [13]. Our group recently demonstrated that Streptococcaceae and Lactobacillaceae families were enriched in GS rhesus macaque model of CD, while Coriobacteriaceae predominated in healthy animals [14].…”

“…It has been reported that bacteria involved in gluten metabolism predominantly belong to phylum Firmicutes, in particular, those from the genus Lactobacillus, followed by Streptococcus, Staphylococcus, and Clostridia [13,14]. Recently, it was shown that GFD treatment signiicantly altered proportions of these bacterial groups and that restoration of normal bacterial lora took many months and possibly years [14,15].…”

“…Dysbiotic bacterial species that could be potentially regulated in this fashion by inlammatory miRNAs included members of the Streptococcaceae and Lactobacillaceae families that are known to play roles in metabolism of gluten [13]. As biological and regulatory functions of miRNAs include host cell efects such as expression of epithelial tight junction proteins, more work remains to be performed to characterize regulatory relationships and pathways pertinent to miRNA molecules that inluence dysbiotic gut microbiota in NCGS and CD individuals.…”

Review paper. Gluten-related disorders and schizophrenia - potential linking mechanisms, diagnostic and therapeutic challenge

“…At various levels of the digestive tract bacteria forming the intestinal flora is different e.g. colon is dominated by Firmicutes, Bacteroidetes and Actinobacteria [64,65]. The composition of the intestinal microbiome depends on the diet [65,66,67], stress, suffered infections, the hygienic condition and the use of drugs, including antibiotics [68].…”