Regulatory Effect Of Highland Barley β-Glucan On Dss-Induced Colitis In Mice

At present,the researches on the physiological activity of cereals by scholars in various countries are mainly focused on oat crops,while the research on barley crops such as highland barley is relatively rare.Recent studies have found that highland barley is rich in a variety of nutrients that could reduce blood lipids,and prevent heart disease and diabetes.Especially,highland barley is rich inβ-glucan,a soluble dietary fiber that cannot be digested and decomposed by human digestive enzymes,which plays an important regulatory role in the intestinal mucus layer,immune response and intestinal flora.Inflammatory enteritis（IBD）is a group of chronic and easily relapsed intestinal inflammation.Currently,the clinical treatment of IBD is mainly based on drug remission,and there is a lack of effective and long-term treatment.In this study,we speculated that highland barleyβ-glucan could be used as a natural dietary therapy to alleviate inflammatory enteritis based on its physiological activity characteristics.In this study,Tibetan Highland Barley Ximala 22β-glucan was used as the raw material.After protein removal by enzymatic method and purification by DEAE Sepharose Fast Flow column,the structure of the sample was further analyzed by Fourier transform infrared spectroscopy（FTIR）and nuclear magnetic resonance(¹³C)spectroscopy,as well as simulating the in vitro digestion process.To clarify the relationship between highland barleyβ-glucan and intestinal health by dietary intervention with different doses of highland barleyβ-glucan in colitis mice,we will provide some new ideas for the treatment of Inflammatory bowel diseases（IBD）.The main research results are as follows.1.Purification and structural identification of highland barley beta-glucan.The protein content of highland barleyβ-glucan was reduced from 4.971%to 0.154%by1%（m/v）trypsin solution,and the purity of highland barleyβ-glucan was improved from81.21%to 92.35%by purification on a DEAE Sepharose Fast Flow column.At the same time,the structure of the sample was analyzed by Fourier transform infrared spectroscopy and ¹³C nuclear magnetic resonance spectroscopy,which showed that the sample wasβ-D-（1,3）（1,4）glucan.2.In vitro simulation of the digestion of highland barleyβ-glucan in human saliva,gastric juice and small intestinal fluid.The results of simulated in vitro digestion showed that the contents of total sugars and reducing sugars of highland barleyβ-glucan were basically unchanged after simulated digestion in saliva,gastric juice and intestinal fluid.The molecular weight of highland barleyβ-glucan detected by gel permeation chromatography during the digestive process showed no significant changes,indicating that the highland barleyβ-glucan sample was resistant to gastrointestinal digestion and reached the small intestine smoothly.3.Study on the tissue damage of highland barleyβ-glucan on colitis mice.The extent of tissue damage was characterized by assessing disease activity index（DAI）,colon length,and colon tissue injury slice score of colitis mice.From the experimental results,feeding with 10%highland barleyβ-glucan diet could significantly reduce DAI value,inhibit the shortening of the colon,reduce the tissue damage caused by colitis in mice,and improve the symptoms of colitis.4.Effects of highland barleyβ-glucan on immune response of colitis mice.The activities of myeloperoxidase（MPO）in colon tissue and the content of serum cytokines in mice with colitis were detected using ELISA kit.The results showed that 10%highland barleyβ-glucan significantly reduced the content of MPO in colonic tissue of mice with colitis.Compared with the mice in the enteritis group,the contents of pro-inflammatory cytokines TNF-α,IL-1β,and IL-6 in serum of 10%highland barleyβ-glucan were decreased by 29.30%,44.69%and 37.94%,respectively,and the content of anti-inflammatory cytokine IL-10 was increased by 456%,indicating that 10%glucan could significantly reduce the inflammation level of mice with colitis and regulate immune response.5.Effects of highland barleyβ-glucan on intestinal barrier of mice with colitis.The Alixine Blue staining and FITC-Dextran tracer method were used to detect the intestinal mucosal integrity and intestinal permeability,and the RT-q PCR technology was used to detect the changes in transcription levels of genes related to the intestinal barrier.The study found that 10%highland barley dextran significantly up-regulated the transcription of genes encoding tight junction proteins Claudin-1 and ZO-1.Compared with the enteritis group,the recovery degree of intestinal mucus layer in the 10%highland barley dextran group was higher,and the expression level of MUC2 gene was significantly higher than that in the enteritis group.These results indicated that 10%dietary intervention of highland barleyβ-glucan could protect the integrity of intestinal barrier and avoid the damaged intestinal tissue from contacting with intestinal toxic contents,pathogenic bacteria or opportunistic pathogens.6.16S-r DNA analysis of intestinal flora in mice.At the phylum level,Bacteroides and Firmicutes accounted for 78%of the total intestinal flora in the intestinal microorganisms of the 10%highland barleyβ-glucan group,while the Bacteroides/Firmicutes ratio of the 10%highland barleyβ-glucan group was higher than that of the control group,and the Proteomicron of the enteritis group was increased.At the genus level,the proportion of potential probiotic ackermanni in 10%highland barleyβ-glucan mouse feces was significantly increased.