Distinct Bacteria Found in Duodenums of Celiacs

Duodenal bacteria from patients with celiac disease (CD) vs healthy individuals have distinct effects on gluten breakdown and immunogenicity*, according to a study published in the October issue of Gastroenterology. Oct. 5, 2016 (HealthDay News)¹

*Immunogenicity is the ability of a particular substance, such as an antigen or epitope, to provoke an immune response

Alberto Caminero, Ph.D., from McMaster University in Hamilton, Canada, and colleagues colonized germ-free C57BL/6 mice with bacteria isolated from the small intestine of CD patients as well as healthy controls.

Gliadin amount and proteolytic activities were measured in intestinal contents after gluten lavage. The peptides produced by bacteria were characterized by liquid chromatography tandem mass spectrometry, and after receiving a three-day gluten challenge, their immunogenic potential was evaluated using peripheral blood mononuclear cells from celiac patients.

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• The researchers found that distinct gluten-degradation patterns were produced by bacterial colonizations in the mouse small intestine.
• An opportunistic pathogen from CD patients, Pseudomonas aeruginosa, exhibited elastase activity and produced peptides that better crossed the mouse intestinal barrier. Gluten-specific T cells from CD patients were activated by P. aeruginosa-modified gluten peptides.
• Gluten peptides produced by human and P. aeruginosa proteases were degraded by Lactobacillus spp from the duodenum of non-CD controls, reducing their immunogenicity.

• “Small intestinal bacteria exhibit distinct gluten metabolic patterns in vivo, increasing or reducing gluten peptide immunogenicity,” the authors write. “This microbe-gluten-host interaction may modulate autoimmune risk in genetically susceptible persons and may underlie the reported association of dysbiosis and CD.”

• ¹https://www.doctorslounge.com/index.php/news/pb/66956
• DOI: https://dx.doi.org/10.1053/j.gastro.2016.06.041
• Alberto Caminero, Heather J. Galipeau, Justin L. McCarville, Chad W. Johnston, Steve P. Bernier, Amy K. Russell, Jennifer Jury, Alexandra R. Herran, Javier Casqueiro, Jason A. Tye-Din, Michael G. Surette, Nathan A. Magarvey, Detlef Schuppan, Elena F. Verdu