Bioactive arabinoxylan oligomers via colonic fermentation and enzymatic catalysis: Evidence of interaction with toll-like receptors from in vitro, in silico and functional analysis

Dietary fibers (DF) from plant-based foods promote health benefits through their physicochemical properties and fermentation by the gut microbiota, often studied in relation to changes in gut microbiota profile and production of gut microbiota-derived metabolites. Here, we characterized structural motifs (i.e., oligomers) produced during DF breakdown upon colonic fermentation and explored their interaction with toll-like receptors (TLRs) present on the surface of human intestinal and immune system cells. Wheat arabinoxylan (WAX) was subjected to in vitro colonic fermentation, with its structural motifs identified and tracked throughout the fermentation process. Using carbohydrate-active enzymes, six well-defined fractions of arabinoxylans and linear xylans identified during colonic fermentation were produced and tested for interaction with tool-like receptors (TLR)2 and TLR4 via reporter cell assay. The results showed structure-dependent effects, with TLR2 inhibition and TLR4 activation varying based on the degree of polymerization and branching. Molecular docking confirmed that minor structural changes in oligomers structure significantly influenced these interactions. The study supports the hypothesis that oligomers and polysaccharides affect cell receptors through complex, multi-receptor interactions, and highlights the potential for enzymatic tailoring of DF to create functional ingredients with targeted effects on human health.