Polysaccharide from fermented mycelium of Inonotus obliquus attenuates the ulcerative colitis and adjusts the gut microbiota in mice

Ulcerative colitis (UC) is a disease characterized by chronic inflammation of the colon. Polysaccharides not only have biological activities but also can regulate gut microbiota to alleviate the symptoms of UC. In this study, polysaccharide extracted from mycelium of Inonotus obliquus (IOP) was prescribed to treat UC induced by dextran sodium sulfate (DSS) in mice. Compared to model control group (MC), IOP-Low, IOP-Medium and IOP-High (IOP-L, IOP-M and IOP-H) treatment groups increased the body weight rate by 6.0%-9.6%, colon length by 8.57%-25.14% and superoxide dismutase (SOD) activity by 53.8-110.4 U/mg, while decreased the malondialdehyde (MDA) content by 37.4%-64.8%, myeloperoxidase (MPO) activity by 29.0%-46.9%, and the concentration of nitric oxide (NO) by 24.8-35.6 μmol/L. IOP treatment also promoted the secretion of interleukin (IL)-10 but suppressed those of interleukin (IL)-6, interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Simultaneously, analysis of high-throughput sequencing indicated that IOP reduced the ratio of Firmicutes to Bacteroidetes (F/B) at phylum level, and increased the relative abundance of Bacteroides and Lactobacillus at genus level. In brief, IOP may be a promising alternative medicine for UC remedy by regulating the anti-inflammatory level, the anti-oxidative ability and the gut microbiota composition.