Alginate Oligosaccharides Regulate Gut Microbiota Homeostasis and Short-Chain Fatty Acid Metabolism, and Ameliorate Inflammatory Bowel Disease

To investigate the effect of alginate oligosaccharides (AOS) on dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD) in mice and to explore the possible mechanism based on the effect of AOS on the intestinal flora and short-chain fatty acids (SCFAs).

Male C57BL/6 mice were provided with 1.5% DSS for 5 days for acute colitis modeling. Meanwhile, mice were orally administrated with gradient doses of AOS (0.5, 1, and 1.5 g/kg) for 9 days. On day 10, body mass, colon length, disease activity index (DAI), and tissue damage were assessed. Polymerase chain reaction was used to assess the mRNA expression levels of tumor necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), interleukin-6 (IL-6), IL-1β, the tight junction protein zonula occluden-1 (ZO-1) and G protein-coupled receptor 43 (GPR43). SCFAs production was measured by high performance liquid chromatography (HPLC) and the microbial community was analyzed by high-throughput sequencing.

AOS significantly alleviated the symptoms of colitis, such as body mass loss, colon shortening, and tissue damage, and reduced the mRNA expression of TNF-α, NF-κB, IL-6 and IL-1β, while increasing the expression levels of ZO-1 and GPR43. Additionally, AOS significantly increased the number of Propionibacterium, while inhibiting the growth of Enterococcus and Actinomyces; high-dose AOS also enhanced the production of colonic lactate, acetate, and propionate.

AOS play a positive role in ameliorating DSS-induced colitis in mice, and the effect may be associated with the regulation of the intestinal flora and SCFAs. Hence, AOS have the potential as a functional food ingredient to alleviate intestinal inflammation.