A postbiotic exopolysaccharide synergizes with Lactobacillus acidophilus to reduce intestinal inflammation in a mouse model of colitis.

Ulcerative colitis (UC) is an inflammatory bowel disease marked by gut inflammation and microbial dysbiosis. Exopolysaccharides (EPS) from probiotic bacteria have been shown to regulate microbial composition and metabolism, but their role in promoting probiotic growth and alleviating inflammation in UC remains unclear. Here, we investigate BLEPS-1, a novel EPS derived from Bifidobacterium longum subsp. longum XZ01, for its ability to promote the growth of Lactobacillus strains. We then tested a synbiotic formulation of BLEPS-1 and L. acidophilus in a DSS-induced UC mouse model. The combination of BLEPS-1 and L. acidophilus alleviated DSS-induced intestinal inflammation, outperforming either component alone. Administration of BLEPS-1 decreased the proportion of M1 macrophages in the intestine, while M2 macrophages were more abundant following L. acidophilus treatment. Together, BLEPS-1 and L. acidophilus synergistically modulated macrophage polarization toward the M2-type. Administration of BLEPS-1 and L. acidophilus together modulated gut microbiota composition and altered the gut metabolic profile, with BLEPS-1 and L. acidophilus promoting metabolism of short-chain fatty acids and aromatic amino acids, respectively. Our study identified a novel synbiotic formulation with potent immunomodulatory and metabolic activity, laying the groundwork for a promising therapeutic strategy to treat intestinal inflammatory diseases such as colitis.