Effect Of D-mannose And Glucose On Mice With Ulcerative Colitis

Background:Inflammatory bowel disease(IBD)is a chronic inflammatory disease of gastrointestinal tract,including ulcerative colitis and Crohn disease.Ulcerative colitis(UC)is a chronic and nonspecific colonic proctitis,which is mainly characterized by inflammatory reactions such as diarrhea,weight loss,bloody stool,intestinal pathological mucosal injury and so on.Although the mutation of UC susceptibility gene has nothing to do with race and nationality,it is more common in North America and Europe,suggesting that it is related to Western diet and lifestyle.Sugar is a common ingredient in food and beverages.Sugared foods,such as cakes,biscuits,ice cream,soft drinks and energy drinks,are very popular in western society.Many epidemiological studies have confirmed that the incidence of UC is closely related to sugar and carbohydrate rich diet.Glucose and mannose are two common monosaccharides.Glucose is the most widely distributed and important monosaccharide in nature.It is sweet and soluble in water.It is often added to cakes and beverages as an additive.The concentration of glucose in some beverages is as high as 20%.D-mannose is an isomer of glucose,which exists in many fruits.D-mannose is known to treat recurrent urinary tract infections in humans.Recent studies have shown that D-mannose can delay the disease development of UC related colorectal tumor mice,reflecting the important role of D-mannose in the treatment of colon diseases.In addition,recent studies have found that endotoxemia caused by high fructose diet(HFRD)can induce liver inflammation by activating toll like receptor(TLR)signal transduction in liver macrophages.We speculate that glucose,which is also six carbon sugar,may play a role in the development of inflammation.In this study,dextran sulfate sodium salt(DSS)was used to induce UC in mice.At the same time,the different effects of self drinking D-mannose and glucose at the same concentration on the development of UC were compared,and the feces were collected for 16S rRNA intestinal flora sequencing,in order to provide a theoretical basis for the clinical treatment of UC with D-mannose.Methods:1.Experimental grouping and animal model constructionC57BL/6 mice were randomly divided into control group,D-mannose group,glucose group,DSS group,DSS+D-mannose group and DSS+glucose group,with 10 mice in eachgroup.Each group was free to drink sterile water,20%D-mannose,20%glucose,3.5%DSS,3.5%DSS+20%mannose and 3.5%DSS+20%glucose for 7 days.The mice were killed on the 8th day.2.Effects of D-mannose and glucose on general conditions of mice with ulcerative colitisC57BL/6 mice were given DSS to construct the mouse model of acute UC,and to explore the effects of D-mannose and glucose on UC mice.The weight and blood in stool of mice were monitored daily,the length of colon and spleen were measured,the disease activity index(DAI)and spleen index were calculated,and the grade of occult blood was recorded.3.Effects of D-mannose and glucose on pathology,mucin,intestinal barrier and inflammatory factors in UC miceAfter the mice were killed,the anterior and middle colon were taken and stored at-80℃,and the changes of inflammatory factor IL-6、TNF-α in the anterior colon were detected by RT-qPCR;The contents of Mucin-2(MUC-2)and intestinal tight junction protein ZO-1 were detected by Western blot(WB)and immunohistochemistry in middle colon;The terminal colon was embedded in paraffin,stained with he and observed by routine pathology;The content of MUC-2 was detected by AB-PAS staining.4.Effects of D-mannose and glucose on intestinal flora of healthy mice and UC miceMouse feces were collected and sequenced based on bacterial 16S rRNA Gene sequence by high-throughput sequencing technology.The biodiversity,species composition,species differences and functional prediction of mice in each group were analyzed.Results:1.Compared with DSS group,DSS+D-mannose group had higher body mass[(84.02±3.47)g vs(89.71 ±2.02)g,P<0.001],significantly lower DAI score[(3.10±0.77)vs(2.43±0.32),P=0.002],significantly increased colon length[(5.20±0.03)cm vs(6.87±0.19)cm,P<0.001]and lower grade of occult blood[(3.20±0.13)vs(0.40±0.16),P<0.001];In DSS+glucose group,body mass decreased sharply(P<0.001),DAI score increased significantly(P=0.001),colon length shortened significantly(P<0.001),and occult blood grade was higher(P<0.001).2.Compared with DSS group,the pathological score of DSS+D-mannose group decreased[(6.00±0.37)vs(4.25±0.28),P<0.001],the content of MUC-2 increased[(8.65±0.27)vs(10.71 ±0.21),P<0.001,the content of colitis factor IL-6 decreased(P<0.05)and TNF-α The content decreased(P<0.001)and the content of intestinal tight junction protein ZO-1 increased(P<0.05);DSS+glucose group had higher histopathological score(P<0.001),decreased MUC-2 content[(8.65±0.27)vs(6.23±0.25),P<0.001],and increased content of inflammatory factors IL-6 and TNF-α(P<0.001).Intestinal tight junction protein ZO-1 content decreased(P<0.05).3.Compared with the control group,the intestinal flora of mice in D-mannose group and glucose group changed significantly.Shannon index decreased,verrucous microflora decreased and Firmicutes increased in D-mannose group;Shannon index increased and verrucous microflora increased in glucose group;Shannon index decreased(P<0.05),Chao index decreased(P<0.001)and ACE index decreased(P<0.001)in DSS group,Simpson index decreased(P<0.05).Compared with DSS group,the Shannon index,Chao index,ACE index and simpspn index in DSS+D-mannose group increased(P<0.05,P<0.05,P<0.01);In DSS+glucose group,the composition of intestinal microorganisms changed significantly,Proteus increased significantly,Firmicutes decreased significantly,and the diversity of flora decreased significantly,that is,Shannon index decreased(P<0.05),Chao index decreased(P<0.001),ACE index decreased(P<0.01).Conclusions:1.D-mannose can effectively improve the clinical symptoms of UC mice,while glucose aggravates the clinical symptoms of UC mice.2.D-mannose protects mice from UC by increasing the content of colonic mucin,increasing mucus barrier and reducing the release of inflammatory factors.3.D-mannose and glucose may affect the occurrence and development of UC by regulating intestinal flora and changing intestinal microecology..