Effects And Related Mechanisms Of Isomaltulose Alleviating Colitis In Mice

Objective: Ulcerative colitis(UC)is a chronic,progressive,and potentially disabling disease of the colon mucosa,characterized by symptoms such as purulent and bloody diarrhea,abdominal pain,and tenesmus.Under traditional treatment modalities,UC remains a chronic and incurable disease,and therapeutic drugs can produce varying degrees of side effects.As a supplement or alternative to conventional therapies,the development of gut microecological therapeutic strategies such as prebiotics and probiotics is particularly critical.Isomaltulose is a functional sweetener with good prebiotic properties,including low cariogenicity,low glycemic index and low insulin response,and no side effects have been reported.Thus,it is of great importance to explore the effects and the underlying mechanisms of isomaltulose in alleviating colitis.Methods: Healthy C57BL/6J mice(18-20g)were randomly divided into NC group,model(DSS)group and Iso MTL group,with 6 mice in each group.Each group was treated as follows:(1)NC group: no treatment for all 3 weeks;(2)DSS group: DSS-induced colitis in the last week;(3)Iso MTL group: isomaltulose(400 mg per kg per day)for all 3 weeks,and DSS-induced colitis in the last week.The modeling cycle was 21 days,during which mice were observed daily for fecal conditions(diarrhea and hematochezia),weight,food intake and water intake of the mice were recorded,and they were euthanized on the twentysecond day of the cycle.The colons were taken,photographed and the length were measured.Spleens were harvested and triturated to extract primary cells.H&E staining was used to observe the histological and pathological changes of colon structure.The secretion of mucin by goblet cells in colon tissue was detected by alcian blue staining.Real-time quantitative polymerase chain reaction(RT-q PCR)was used to detect the m RNA expression of inflammatory cytokines and intestinal tight junction(ZO-1,Occludin and Claudin-1)in colon tissue.The protein expressions of intestinal tight junction proteins(ZO-1 and Occludin)were detected by western blot.Enzyme linked immunosorbent assay(ELISA)was used to measure the contents of interleukin-1β(IL-1β),interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)in serum.Colon tissues were used for transcriptome sequencing to screen differentially expressed genes,and KEGG and GO pathway enrichment analysis were performed.The differentiation of primary spleen cells of mice was detected by flow cytometry.Changes in gut microbiota of mice were detected using16 S r RNA sequencing technology.Results: The body weight of mice in DSS group decreased significantly(P<0.001)and the length of colon shortened significantly(P<0.001)within 7 days after DSS treatment,while isomalmaltose administration(400mg/kg/day)effectively alleviated the weight loss(P<0.05)and colon length shortened(P<0.05)caused by DSS.Compared with NC group,TNF-α,IL-1β and IL-6 in DSS group were significantly increased.However,supplementation with isomaltulose significantly reduced the level of these proinflammatory cytokines.Histopathological examination in DSS group showed inflammatory cell infiltration,gland loss and mucosal epithelial necrosis.In contrast,the isomaltulose group showed an increase in the number of glands,a decrease in mucosal epithelial integrity and inflammatory cell infiltration.In the meanwhile,isomaltulose significantly increased the expression of tight junction protein ZO-1(P<0.01)and Occludin(P<0.05),and restored the gene transcription levels of ZO-1(P<0.01),Occludin(P<0.001)and Claudin-1(P<0.01)decreased by DSS.A total of 984 differentially expressed genes were screened by transcriptome analysis.The KEGG pathway analysis of the first 20immune-related pathways indicated that the effect of isomaltulose was significantly related to Th17-mediated immunity.Flow cytometry showed that isomaltulose could inhibit the differentiation of primary T cells into T helper type 17(Th17)cells and increase the number of regulatory T(Treg)cells.The regulatory effect of isomaltulose on gut microbiota was further determined by 16 S r RNA sequencing.Spearman correlation analysis showed that gut microbiota was significantly correlated with inflammatory factors,T cells and intestinal tight junction protein.Conclusion: This study demonstrated that isomaltulose could prevent adjuvant treatment of UC by maintaining intestinal immune homeostasis and remodeling gut microbiota.Given its low glycemic index and low insulin response,isomaltulose is expected to be used as an adjuvant therapy for UC patients who need to control blood sugar in the future,which is a promising therapeutic agent.In addition,the study found that isomaltulose could promote the expression of intestinal tight junction proteins and improve the integrity of the intestinal mucosal barrier.Thus,this study provides a new idea and method for the treatment of UC,which is worth further research and application.