Novel Bacteroides Vulgatus strain protects against gluten-induced break of human celiac gut epithelial homeostasis: a pre-clinical proof-of-concept study.

BACKGROUND AND AIMS: We have identified a decreased abundance of microbial species known to have a potential anti-inflammatory, protective effect in subjects that developed Celiac Disease (CeD) compared to those who did not. We aim to confirm the potential protective role of one of these species, namely Bacteroides vulgatus, and to mechanistically establish the effect of bacterial bioproducts on gluten-dependent changes on human gut epithelial functions. METHODS: We identified, isolated, cultivated, and sequenced a unique novel strain (20220303-A2) of B. vulgatus found only in control subjects. Using a human gut organoid system developed from pre-celiac patients, we monitored epithelial phenotype and innate immune cytokines at baseline, after exposure to gliadin, or gliadin plus B. vulgatus cell free supernatant (CFS). RESULTS: Following gliadin exposure, we observed increases in epithelial cell death, epithelial monolayer permeability, and secretion of pro-inflammatory cytokines. These effects were mitigated upon exposure to B. vulgatus 20220303-A2 CFS, which had matched phenotype gene product mutations. These protective effects were mediated by epigenetic reprogramming of the organoids treated with B. vulgatus CFS. CONCLUSIONS: We identified a unique strain of B. vulgatus that may exert a beneficial role by protecting CeD epithelium against a gluten-induced break of epithelial tolerance through miRNA reprogramming. IMPACT: Gut dysbiosis precedes the onset of celiac disease in genetically at-risk infants. This dysbiosis is characterized by the loss of protective bacterial strains in those children who will go on to develop celiac disease. The paper reports the mechanism by which one of these protective strains, B. vulgatus, ameliorates the gluten-induced break of gut epithelial homeostasis by epigenetically re-programming the target intestinal epithelium involving pathways controlling permeability, immune response, and cell turnover.

Role of Probiotics in Helicobacter pylori Eradication: Lessons from a Study of Lactobacillus reuteri Strains DSM 17938 and ATCC PTA 6475 (Gastrus®) and a Proton-Pump Inhibitor.

BACKGROUND: Meta-analyses involving >4000 subjects with probiotics added to antimicrobial Helicobacter pylori eradication therapy have reported a mean increase in the eradication rate of 12 to 14%. It is unclear how to translate that result into clinical practice. AIM: To evaluate whether administration of Lactobacillus reuteri plus a PPI without antibiotics would eradicate H. pylori infections. METHODS: This was a double-blind placebo-controlled randomized 2-site study of L. reuteri (Gastrus®) at a dose of 2 × 108 CFU, 7 times per day, or matching placebo plus 20 mg pantoprazole b.i.d. for 4 weeks. Cure was defined by negative 13C-UBT, 4 weeks after therapy. Sample size required ≥50% cure rates for using probiotics as a clinically useful monotherapy. RESULTS: Recruitment was halted after 56 subjects because of the low cure rate; there were 8 dropouts; 48 subjects completed therapy (71% women, average age 49 years). The cure rates per protocol were 3/24 (12.5%; 95% CI 2.6-32%) with L. reuteri vs. 1/24 (4.1%) with placebo. Side effects (most often diarrhea) occurred infrequently (in 5/28 vs. 3/28; active vs. placebo therapy) (P=0.53). CONCLUSION: L. reuteri plus a PPI therapy was unable to provide a clinically important rate of H. pylori eradication. The cure rate albeit low (12.5%) was essentially identical to that achieved when probiotics were added to antibiotic therapy. The incremental improvement was additive and independent of antimicrobial resistance or antibiotics use. Probiotics can reliably increase the cure rate to ≥90% only in regimens achieving cure rates of ∼80%. This trial is registered with NCT03404440.

Mechanism of degradation of immunogenic gluten epitopes from Triticum turgidum L. var. durum by sourdough lactobacilli and fungal proteases.

As shown by R5 antibody-based sandwich and competitive enzyme-linked immunosorbent assay (ELISA), selected sourdough lactobacilli, in combination with fungal proteases, hydrolyzed gluten (72 h at 37 degrees C) of various cultivars of Triticum turgidum L. var. durum to less than 20 ppm. Complementary electrophoretic, chromatography, and mass spectrometry techniques were used to characterize the gluten and epitope hydrolysis. Nine peptidases were partially purified from the pooled cytoplasmic extract of the sourdough lactobacilli and used to hydrolyze the 33-mer epitope, the most immunogenic peptide generated during digestion of Triticum species. At least three peptidases (general aminopeptidase type N [PepN], X-prolyl dipeptidyl aminopeptidase [PepX], and endopeptidase PepO) were necessary to detoxify the 33-mer without generation of related immunogenic epitopes. After 14 h of incubation, the combination of all or at least six different peptidases totally hydrolyzed the 33-mer (200 mM) into free amino acids. The same results were found for other immunogenic epitopes, such as fragments 57-68 of alpha 9-gliadin, 62-75 of A-gliadin, and 134-153 of gamma-gliadin. When peptidases were used for fermentation of durum wheat semolina, they caused the hydrolysis of gluten to ca. 2 ppm. The in vivo digestion was simulated, and proteins/peptides extracted from pepsin-trypsin (PT) digestion of durum wheat semolina fermented with selected sourdough lactobacilli induced the expression of gamma interferon and interleukin 2 at levels comparable to those of the negative control. Durum wheat semolina fermented with sourdough lactobacilli was freeze-dried and used for making Italian-type pasta. The scores for cooking and sensory properties for this pasta were higher that those of conventional gluten-free pasta.