Intestinal microbiota and probiotics in celiac disease

Abstract

Celiac disease (CD) is a common chronic autoimmune enteropathy caused by gluten intake. To date, the only therapy for CD is the complete exclusion of dietary sources of grains and any food containing gluten. It has been hypothesized that the intestinal microbiota is somehow involved in CD. For this reason, probiotics are appearing as an interesting adjuvant in the dietetic management of CD. This review aims to discuss the characteristics of the microbiota in CD subjects and the use of probiotics as a novel therapy for CD. Comparisons between children with CD and controls show that their microbiota profiles differ; the former have fewer lactobacilli and bifidobacteria. Specific probiotics have been found to digest or alter gluten polypeptides. It has also been demonstrated that some bacterial species belonging to the genera Lactobacillus and Bifidobacterium exert protective properties on epithelial cells from damage caused by gliadin.

FIG 1

Different cereal-derived products and intestinal inflammation in CD subjects. Consumption of food-derived products containing wheat, barley, and rye by individuals genetically susceptible to CD leads to villous atrophy, intestinal inflammation, and disassembly of tight junctions.

FIG 2

Inflammation process and possible routes of probiotic action in the maintenance of CD. In CD patients, increased epithelial tight junction permeability (“leaky gut”) favors the entrance of non-well-digested gluten peptides from the lumen to the lamina propria. Once there, they are deamidated by the tissue transglutaminase (tTG) enzyme and presented to CD4⁺ T immune cells by the human leukocyte antigen (HLA) in antigen-presenting cells (APCs), which in CD patients is often of the haplotypes DQ2 and DQ8. Thereafter, Th1 and Th2 immune responses are triggered, resulting in autoimmunity, mucosal inflammation, and the growth of unfavorable microbiota, worsening the prognosis of disease. Three large arrows indicate where probiotics could act.