Diabetes exacerbates inflammatory bowel disease in mice with dietinduced obesity

BACKGROUND The increased prevalence of inflammatory bowel disease(IBD)among patients with obesity and type 2 diabetes suggests a causal link between these diseases,potentially involving the effect of hyperglycemia to disrupt intestinal barrier integrity.AIM To investigate whether the deleterious impact of diabetes on the intestinal barrier is associated with increased IBD severity in a murine model of colitis in mice with and without diet-induced obesity.METHODS Mice were fed chow or a high-fat diet and subsequently received streptozotocin to induce diabetic-range hyperglycemia.Six weeks later,dextran sodium sulfate was given to induce colitis.In select experiments,a subset of diabetic mice was treated with the antidiabetic drug dapagliflozin prior to colitis onset.Endpoints included both clinical and histological measures of colitis activity as well as histochemical markers of colonic epithelial barrier integrity.RESULTS In mice given a high-fat diet,but not chow-fed animals,diabetes was associated with significantly increased clinical colitis activity and histopathologic markers of disease severity.Diabetes was also associated with a decrease in key components that regulate colonic epithelial barrier integrity(colonic mucin layer content and epithelial tight junction proteins)in diet-induced obese mice.Each of these effects of diabetes in diet-induced obese mice was ameliorated by restoring normoglycemia.CONCLUSION In obese mice,diabetes worsened clinical and pathologic outcomes of colitis via mechanisms that are reversible with treatment of hyperglycemia.Hyperglycemia-induced intestinal barrier dysfunction offers a plausible mechanism linking diabetes to increased colitis severity.These findings suggest that effective diabetes management may decrease the clinical severity of IBD.

Identification of differentially expressed genes in ulcerative colitis and verification in a colitis mouse model by bioinformatics analyses

BACKGROUND Ulcerative colitis(UC)is an inflammatory bowel disease that is difficult to diagnose and treat.To date,the degree of inflammation in patients with UC has mainly been determined by measuring the levels of nonspecific indicators,such as C-reactive protein and the erythrocyte sedimentation rate,but these indicators have an unsatisfactory specificity.In this study,we performed bioinformatics analysis using data from the National Center for Biotechnology Information-Gene Expression Omnibus(NCBI-GEO)databases and verified the selected core genes in a mouse model of dextran sulfate sodium(DSS)-induced colitis.AIM To identify UC-related differentially expressed genes(DEGs)using a bioinformatics analysis and verify them in vivo and to identify novel biomarkers and the underlying mechanisms of UC.METHODS Two microarray datasets from the NCBI-GEO database were used,and DEGs between patients with UC and healthy controls were analyzed using GEO2R and Venn diagrams.We annotated these genes based on their functions and signaling pathways,and then protein-protein interactions(PPIs)were identified using the Search Tool for the Retrieval of Interacting Genes.The data were further analyzed with Cytoscape software and the Molecular Complex Detection(MCODE)app.The core genes were selected and a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis was performed.Finally,colitis model mice were established by administering DSS,and the top three core genes were verified in colitis mice using real-time polymerase chain reaction(PCR).RESULTS One hundred and seventy-seven DEGs,118 upregulated and 59 downregulated,were initially identified from the GEO2R analysis and predominantly participated in inflammation-related pathways.Seven clusters with close interactions in UC formed:Seventeen core genes were upregulated[C-X-C motif chemokine ligand 13(CXCL13),C-X-C motif chemokine receptor 2(CXCR2),CXCL9,CXCL5,C-C motif chemokine ligand 18,interleukin 1 beta,matrix metallopeptidase 9,CXCL3,formyl peptide receptor 1,complement component 3,CXCL8,CXCL1,CXCL10,CXCL2,CXCL6,CXCL11 and hydroxycarboxylic acid receptor 3]and one was downregulated[neuropeptide Y receptor Y1(NYP1R)]in the top cluster according to the PPI and MCODE analyses.These genes were substantially enriched in the cytokinecytokine receptor interaction and chemokine signaling pathways.The top three core genes(CXCL13,NYP1R,and CXCR2)were selected and verified in a mouse model of colitis using real-time PCR Increased expression was observed compared with the control mice,but only CXCR2 expression was significantly different.CONCLUSION Core DEGs identified in UC are related to inflammation and immunity inflammation,indicating that these reactions are core features of the pathogenesis of UC.CXCR2 may reflect the degree of inflammation in patients with UC.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice. METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe2+) iron salt or ferric (Fe3+) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated usingquantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria. RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg proteinvs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.