Differential responses on gut microbiota and microbial metabolome of 2′-fucosyllactose and galactooligosaccharide against DSS-induced colitis

Prebiotics are effective in modulating gut microbiota and may further benefit colitis remission. 2'-fucosyllactose (2'FL) and galactooligosaccharide (GOS) are the main prebiotics in human and animal milk, respectively. This study aimed to investigate the colitis-preventing effects of 2'FL and GOS, and explore the underlying mechanisms involving the gut microbiota. The chronic colitis was induced by 1.5 % dextran sulfate sodium (DSS) for 4 consecutive cycles and manifested as aggravation of colitis symptoms, gut barrier disruption, and colonic inflammation. We found that 2'FL was more effective than GOS against colitis at the same dosage (500 mg/kg bw). 2'FL and GOS have a differential response on gut microbiota, reflecting the inhibition of Romboutsia and the enrichment of Akkermansia, Bifidobacterium, Faecalibaculum, and unclassified_f_Lachnosipiaceae. In addition, the differential response on microbial metabolome was reflected in the elevation of secondary bile acids, which activated Takeda G protein-coupled receptor 5 (TGR5) and further suppressed the nuclear factor-κB (NF-κB) pathway. Furthermore, fecal bacterial transplantation confirmed the critical role of gut microbiota in the prevention of colitis by 2'FL and GOS. Overall, microbiota and microbial metabolites are essential parts of 2'FL and GOS against colitis, and their differential responses may account for different effects in alleviating colitis.