Protective Effect And Possible Mechanism Of Cicer Arietinum Polysaccharide On Ulcerative Colitis In Mice

Ulcerative colitis(UC)is a chronic,recurring inflammatory disease that has been increasingly prevalent worldwide due to rapid economic development.Currently,the therapeutic options for UC have some limitations and may come with certain side effects.However,there is promising potential in utilizing polysaccharides derived from natural resources.These polysaccharides possess many advantages,including high safety,remarkable curative effect and low cost.Because of their notable anti-inflammatory and immunomodulatory activities,polysaccharides are considered to be one of the potential functional food ingredients for the prevention or treatment of UC.Peas and chickpeas are two common types of legumes in our daily life,which contain a variety of beneficial and highly utilized nutrients with various functional activities such as antioxidant,antitumor,anti-inflammatory,and intestinal health promotion.The biological activities of peas and chickpeas are attributed,in part,to the presence of non-starch polysaccharides.Therefore,in this study,peas and chickpeas were selected as objects to extract polysaccharides and determine their basic physical and chemical properties.Subsequently,a dextran sulfate sodium(DSS)-induced colitis mouse model was employed to evaluate and compare the protective effects of Pisum sativum polysaccharides and Cicer arietinum polysaccharides in the colitis mice.Furthermore,the Cicer arietinum polysaccharides with a more pronounced intervention effect was further investigating for unveiling its impact on regulating intestinal immune responses in colitis mice.Finally,the possible mechanism of Cicer arietinum polysaccharides in alleviating ulcerative colitis was preliminarily explored using metabolomics and 16 S r DNA sequencing technology.The main research contents and results of this paper are as follows:(1)This study aimed to explore the structural characteristics of Pisum sativum polysaccharides and Cicer arietinum polysaccharides,along with their protective effects against colitis.Pisum sativum polysaccharides(PP)and Cicer arietinum polysaccharides(CP)were extracted through water extraction and alcohol precipitation.Subsequently,their basic physical and chemical properties were determined.The protective effects of PP and CP on colitis were evaluated and compared by constructing a DSS-induced model of ulcerative colitis.In terms of physical and chemical properties,the results showed that PP had a high content of uronic acids,with a molecular weight of 610 k Da as the primary component.PP was mainly composed of monosaccharides such as Ara(20.1%),Gal(15.1%)and Gal A(13.1%),which indicated that PP possesses a pectin-like structure.On the other hand,CP was dominated by neutral sugars and comprised three distinct components with molecular weights of 260 k Da,29 k Da and 4.0 k Da.CP was mainly composed of monosaccharides such as Gal(16.9%),Ara(13.1%)and Glc(10.4%),suggesting that CP is a heteropolysaccharide with an arabinogalactan structure.In terms of the intervention effect on colitis,medium-dose CP(M-CP)and high-dose CP(H-CP)intervention could significantly delay the weight loss of mice and reduce the disease activity index(DAI)score,while PP intervention did not delay the weight loss of mice and reduce the DAI score.Medium and high doses of PP and CP significantly reduced the histopathological scores of colon tissue.These findings indicated that both PP and CP possess protective effects against ulcerative colitis in mice,with CP demonstrating a superior protective effect.(2)The effects of Cicer arietinum polysaccharides on intestinal immune regulation in colitis mice were studied.From the perspective of intestinal immunity,the protective effects of CP on colitis mice were further explored.The results demonstrated that H-CP intervention could significantly reduce the DAI score,histopathological score,as well as the levels of pro-inflammatory factors including TNF-α and IL-1β in mice with colitis.Notably,H-CP treated colitis mice also had an increased level of immune factor s Ig A.Moreover,H-CP supplementation also showed a trend to delay the shortening of colon and increase the levels of anti-inflammatory factors,specifically IL-10 and IL-22.The intervention of positive drugs and M-CP also demonstrated alleviating effects against colitis in mice,although the improvement of colon histopathology and s Ig A secretion was not as significant as that of H-CP.In summary,CP intervention can improve the intestinal immune imbalance of mice,which is manifested by the decreased pro-inflammatory factor levels and increased immune factor s Ig A levels.These finding suggested that H-CP exhibited better protection against DSS-induced colitis in mice compared to M-CP,showing a certain dose-dependent manner.(3)The effects of Cicer arietinum polysaccharides on the metabolome of colonic contents in colitis mice were analyzed.The effects of CP on the metabolome of colonic contents in colitis mice were analyzed by liquid phase-mass spectrometry(UPLC-Q-TOF/MS).The results showed that compared with normal mice,the concentrations of secondary bile acids,L-tryptophan,indoles and sphingosine in the intestinal of colitis model mice changed significantly,which may involve alterations in linoleic acid metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,sphingolipid metabolism and other metabolic pathways.The observed changes in these metabolites and metabolic pathways provide insights into the potential causes of increased intestinal inflammatory response and disordered immune response in DSS-induced colitis mice.CP intervention significantly changed the colonic intestinal metabolome.Specifically,M-CP intervention up-regulated the concentration of colonic L-tryptophan and down-regulated sphingosine,which were colitis-related metabolites.On the other hand,H-CP intervention up-regulated the concentration of colonic secondary bile acids and down-regulated the concentration of colitis-related metabolites such as sphingosine.The down-regulation of sphingosine concentration may be the key factor in CP’s protective effect on colitis in mice,which may contribute to the alleviation of intestinal inflammation and immune disorders in mice.Overall,the protective effects of CP on DSS-induced colitis in mice may be closely related to the decrease in sphingosine or changes in sphingolipid metabolism and other pathways in the colonic metabolite profile.(4)The effects of Cicer arietinum polysaccharides on intestinal short-chain fatty acid content and flora composition in colitis mice were explored.At the end of the CP intervention,the short-chain fatty acid content and p H value of the cecum contents of mice were measured,and the composition of the fecal intestinal flora of mice was analyzed.The results showed that CP intervention significantly increased the content of acetic acid in cecal contents and decreased its p H value.Alpha and Beta diversity analysis of intestinal flora showed that CP intervention did not change the overall composition of intestinal flora.At the phylum level and genus level,CP intervention changed the structure of intestinal flora to close the normal group;further analysis of the differential characteristic bacteria showed that the intervention of H-CP reduced the relative abundance of Lachnospiraceae＿NK4A136,Helicobacter and Clostridia＿UCG-014 in feces,and increased the relative abundance of Lactobacillus and Akkermansia.Among them,Lactobacillus has the potential to play a protective role in colitis mice as a probiotic.In summary,CP may improve colonic inflammation by reducing intestinal p H,increasing acetic acid content and regulating flora composition(promoting the proliferation of beneficial bacteria and inhibiting the activity of harmful bacteria).In conclusion,this thesis evaluated and compared the protective effects of Pisum sativum polysaccharides and Cicer arietinum polysaccharides against DSS-induced ulcerative colitis,and found that Cicer arietinum polysaccharides had better protective effect.The protective effect of Cicer arietinum polysaccharides against colitis was closely related to the decreased levels of intestinal pro-inflammatory factors TNF-α,IL-6 and IL-1β,increased levels of immune factor s Ig A,changed colonic metabolites(especially the decrease of sphingosine concentration and the change of sphingolipid metabolic pathway),decreased intestinal environment p H and shaped intestinal flora(such as increase in the abundance of beneficial bacteria like Lactobacillus and decrease in the abundance of harmful bacteria like Helicobacter and Clostridia＿UCG-014)in mice.This study provides a theoretical basis for the development of colitis adjuvant therapy products and highlights the significant potential for the high-value utilization of Cicer arietinum polysaccharides.