Prospective role of proteolytic microorganisms from fermented foods in degradation of gluten and their implications for celiac disease

Gluten, the main storage protein in wheat, barley, and rye, contains sequences rich in proline and glutamine that resist complete gastrointestinal degradation resulting in generation of immunogenic peptides. The peptides contain immunogenic epitopes that, following deamidation by tissue transglutaminase 2 (TG2), can be presented by HLA-DQ2/DQ8 molecules to gluten-specific CD4 + T cells, resulting in intestinal inflammation. This gluten-induced intestinal inflammation is known as celiac disease (CD) in susceptible individuals. A gluten-free diet (GFD) has been recognised as gold standard treatment to date, which requires lifelong strict compliance, therefore demanding alternative novel therapies. Fermented foods have emerged as promising reservoirs for selection of gluten-degrading probiotic strains as adjunctive therapeutic candidates. These strains may hydrolyse gluten and its immunogenic gluten peptides through specialised array of proteolytic enzymatic systems comprising endopeptidases, prolyl endopeptidases, aminopeptidases and dipeptidyl peptidases. This review critically examines the significance of gluten-degrading microorganisms with probiotic potential from fermented foods and their proteolytic enzyme system. Owing to their origin from fermented foods, the effect of fermentation parameters such as pH, strain selection, and substrate composition is also highlighted. The assessment of studies indicates that the fermentation mediated by selected gluten-degrading strains reduces the gluten content; however, these did not detoxify the immunogenic peptides completely. The potential strains support intestinal health through modulation of gut microbiota and attenuation of inflammatory responses which has been validated through in vitro and clinical studies, although their efficacy in managing CD remains unestablished. However, strain-specific differences, incomplete degradation of immunogenic peptides, and the lack of standardised protocols for evaluating gluten detoxification remain significant barriers to their application. Key points Fermented foods serve as a key reservoir for gluten-degrading microorganismsStrain-specific enzymes and fermentation conditions affect gluten hydrolysis.Clinical efficacy of potential strains has yet to be conclusively established.