Biological pathways involved in the development of inflammatory bowel disease

Molecular mechanisms of somatostatin-mediated intestinal epithelial barrier function restoration by upregulating claudin-4 in mice with DSS-induced colitis

Intestinal barrier dysfunction plays a crucial role in the pathogenesis of ulcerative colitis (UC). Previous studies have shown somatostatin (SST) can protect intestinal barrier structure possibly through upregulating tight junction (TJ) protein expression, but the mechanisms of this upregulation remain undefined. This study aimed to investigate the molecular mechanisms of interaction of SST with its downstream regulatory elements in DSS-induced colitis mice. In DSS-induced colitis mice, exogenous SST supplement (octreotide) effectively ameliorated disease progression, restored colonic barrier structure and function, and stimulated claudin-4 expression. Similar effects were also observed for SST on Caco-2 cells intervened by TNF-α. SST receptor 5 (SSTR5) agonist L-817,818 upregulated the claudin-4 expression whereas the SSTR2 agonist seglitide could not reverse TNF-α-induced reduction of claudin-4. SST treatment significantly decreased the phosphorylation levels of ERK1/2 and p38 induced by TNF-α. PD-98059 (ERK1/2 pathway inhibitor) but not SB-202190 (p38 pathway inhibitor) could reverse TNF-α-induced suppression of claudin-4 expression. Both inhibitors could improve the TJ barrier function damaged by TNF-α. Our studies suggest that the protective effect of SST on intestinal barrier achieved by upregulating claudin-4 expression through activation of SSTR5 and suppression of the ERK1/2 pathways. These findings will benefit the development of novel treatment regimens for UC.

Identification of Candidate Genes Related to Inflammatory Bowel Disease Using Minimum Redundancy Maximum Relevance, Incremental Feature Selection, and the Shortest-Path Approach

Identification of disease genes is a hot topic in biomedicine and genomics. However, it is a challenging problem because of the complexity of diseases. Inflammatory bowel disease (IBD) is an idiopathic disease caused by a dysregulated immune response to host intestinal microflora. It has been proven to be associated with the development of intestinal malignancies. Although the specific pathological characteristics and genetic background of IBD have been partially revealed, it is still an overdetermined disease and the blueprint of all genetic variants still needs to be improved. In this study, a novel computational method was built to identify genes related to IBD. Samples from two subtypes of IBD (ulcerative colitis and Crohn's disease) and normal samples were employed. By analyzing the gene expression profiles of these samples using minimum redundancy maximum relevance and incremental feature selection, 21 genes were obtained that could effectively distinguish samples from the two subtypes of IBD and the normal samples. Then, the shortest-path approach was used to search for an additional 20 genes in a large network constructed using protein-protein interactions based on the above-mentioned 21 genes. Analyses of the 41 genes obtained indicate that they are closely associated with this disease.

Bowel preparation with polyethylene glycol electrolyte powder lowers serum levels of IL-6 and CRP in patients with mild to moderate active ulcerative colitis

AIM: To explore whether bowel preparation with polyethylene glycol electrolyte powder lowers serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in patients with mild to moderate active ulcerative colitis.

METHODS: Twenty-three patients diagnosed with mild to moderate ulcerative colitis at the First Affiliated Hospital of Zhengzhou University were included. All patients took polyethylene glycol electrolyte powder for bowel preparation before colonoscopy. Peripheral blood samples were collected to detect serum levels of IL-6 and CRP by enzyme-linked immunosorbent assay (ELISA).

RESULTS: The levels of serum IL-6 and CRP were significantly lower in patients with bowel preparation than in patients without (19.25 pg/mL ± 2.24 pg/mL vs 12.38 pg/mL ± 1.25 pg/mL, 16.16 pg/mL ± 7.25 pg/mL vs 9.45 pg/mL ± 6.21 pg/mL, P < 0.05).

CONCLUSION: Bowel preparation with polyethylene glycol electrolyte powder lowers serum levels of IL-6 and CRP in patients with mild to moderate active ulcerative colitis.