Synergistic protective effects of β-glucan and <i>Lactobacillus johnsonii</i> NSP009 in ulcerative colitis

The combination of probiotics and prebiotics has emerged as a promising strategy for managing ulcerative colitis (UC). Among these, β-glucan (BG) and <i>Lactobacillus johnsonii</i> have individually shown potential in alleviating colitis, with BG notably enriching <i>L. johnsonii</i> populations, suggesting a synergistic therapeutic potential when combined. This study investigates the protective effects of a novel synbiotic formulation, BG and <i>L. johnsonii</i> NSP009 (LJ), termed BGLJ, in a dextran sulfate sodium (DSS)-induced colitis mouse model. Our results reveal that BGLJ significantly mitigated DSS-induced weight loss, reduced the disease activity index, and alleviated intestinal inflammation and barrier dysfunction. Notably, BGLJ markedly increased <i>L. johnsonii</i> abundance in mouse feces, with LJ producing substantial levels of indole-3-lactic acid (ILA), an aryl hydrocarbon receptor (AhR) agonist. BGLJ treatment robustly elevated ILA levels in the gut, activating AhR and upregulating IL-22 production. Collectively, our findings highlight the therapeutic potential of the BGLJ-based synbiotic in maintaining intestinal homeostasis and underscore its promise as a novel intervention for UC management.