Identification and characterization of intestinal lactobacilli strains capable of degrading immunotoxic peptides present in gluten

Aim: Identify and characterize bacteria from the proximal gastrointestinal tract of pigs capable of degrading immunogenic gluten peptides. Methods and Results: Bacteria were cultured from the small intestine of pigs fed a 20% gluten diet and from an enrichment media with the 18-mer peptide LQLQPFPQPQLPYPQPQL. Isolates were screened for the production of specialized proteolytic enzymes and the ability to degrade and remove metastable peptides from α-gliadin (16-mer and 33-mer) and ω-gliadin (17-mer), with established roles in the aetiology of coeliac disease. Degradation was determined by ELISA and mass spectrometry (UHPLC-MS/MS in MRM mode), and hydrolysis fragments were characterized by LC-MS/MS. Four strains from the species Lactobacillus ruminis, Lactobacillus johnsonii, Lactobacillus amylovorus and Lactobacillus salivarius showed the highest peptide-degrading activities. Strains displayed different degradation rates and cleavage patterns that resulted in reduction but not complete removal of immunotoxic epitopes. Conclusions: We employed a unique enrichment process to select for bacteria adapted to the conditions of the proximal gastrointestinal tract with the ability to partially detoxify well-characterized peptides involved in coeliac disease. Significance and Impact of the Study: This study provides a basis for the selection of Lactobacillus strains for probiotic applications aimed to reduce epitope-containing gluten peptides before reaching the epithelium of the small intestine of patients with coeliac disease.