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

Abstract

Background and AimsCeliac 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 FindingsChanges 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.ConclusionsOur 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.

Colonization of germ-free mice with a mixture of three lactobacillus strains enhances the integrity of gut mucosa and ameliorates allergic sensitization

“…Western blotting was performed as previously described. 37 The membranes were blocked with 2% (w/v) dry milk in 0.05% PBS-Tween-20 for 1 h at room temperature and incubated overnight at 4 uC with antibodies against occludin (1 : 1000) ZO-1 (1 : 1000) (Thermo Fisher Scientific, Waltham, MA, USA) and b-actin (1 : 5000) (Abcam, Cambridge, UK). After incubation with the respective primary antibodies, secondary staining was conducted using horseradish peroxidase-conjugated species-specific antibodies (1 : 1000) (Thermo Fisher Scientific, Waltham, MA, USA) for 1 h at room temperature.…”

Intestinal stem cells and celiac disease

“…Regarding the deregulation of goblet cells in CD, Cinova et al [139] observed that gliadin fragments and/or IFN-γ were able to reduce the number of PAS-positive goblet cells and increase mucin secretion in rat intestinal loops; interestingly, these changes were more pronounced in the presence of potentially pathogenic enterobacteria, while the decrease in PAS-positive goblet cells by gliadin was reversed by probiotics (B. bifidum IATA-ES2).…”

Mucosal expression of claudins in children with celiac disease

“…In celiac disease, rodent studies suggest that gut microbiota influences mucosal integrity and plays a role in the early pathogenesis of CD (Cinova et al, 2011). In human celiac disease, intestinal flora may be a key component switching oral tolerance to immune response against gliadin (Ray et al, 2012).…”