Portulaca oleracea L. polysaccharide ameliorates ulcerative colitis by regulating the immune system and gut microbiota

Abstract

This study aims to clarify the characteristics of the water-soluble polysaccharide from Portulaca oleracea L. (POL-P) and further explore its potential mechanism on ulcerative colitis (UC). POL-P was prepared and identified by gel permeation chromatography (GPC), high-performance liquid chromatography (HPLC), and scanning electron microscopy (SEM). The protective effect of POL-P was evaluated in a mouse model of UC induced by dextran sulfate sodium (DSS). Under the premise of confirming the efficacy of POL-P, we performed an integrated approach of transmission electron microscopy (TEM), fluorescence-activated cell sorting (FACS), enzyme-linked immunosorbent assay (ELISA), and 16S rRNA high-throughput sequencing to explore the effects of POL-P on the intestinal immunity and intestinal flora structure of UC mice and to further analyzed the related mechanism of POL-P in alleviating UC. ResultsThe molecular weight of POL-P was 40 kDa. POL-P contained mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, and arabinose, with a molar ratio of 1.2:13.2:33.5:1.2:3.3:32.2:15.4. The in vivo efficacy results showed that 0.8 g/kg POL-P significantly ameliorated colonic pathological damage and alleviated colon inflammation by improving the blood status and regulating the levels of IL-6, IL-17, TNF-α, and IL-10. Additionally, POL-P decreased specific immune responses, which was attributed to inhibiting the function of dendritic cells and balancing T-lymphocyte subsets. Furthermore, POL-P suppressed pathogens and ameliorated DSS-induced microbiota dysbiosis. ConclusionPOL-P functions as a novel polymer compound to alleviate UC by regulating immune and gut microbiota.