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Embark cross-sectional study of inactive and active lesions from the ileum and colon of inflammatory bowel disease patients

ABSTRACT: Hypothesis: Gene expression differences in biopsies from patients with inflammatory bowel disease can be used to identify molecular heterogeneity within patients with active disease. Methods: Patients with a diagnosis of Crohn's disease, ulcerative colitis or normal healthy controls (with or without infectious colitis) underwent ileocolonoscopy. In healthy controls, biopsies were taken in the sigmoid colon (n=21), ascending/descending colon (n=25) and the terminal ileum (n=12). In patients with Crohn's disease, biopsies were taken in the ascending/descending colon (n=107) and terminal ileum (n=70) in uninflamed areas in all patients; in patients with mucosal lesions, additional biopsies were taken in inflamed regions of the ascending/descending colon (n=35) and terminal ileum (n=55). In ulcerative colitis patients, paired uninflamed sigmoid (n=48) and inflamed sigmoid biopsies (n=46) were taken. Biopsies were placed in RNAlater at the clinical site, frozen and shipped to Genentech, where they were disrupted using TissueLyzer beads, then RNA was isolated using RNeasy columns. RNA was hybridized to Agilent human 4x44kv1 arrays, dual channel, using universal reference.

ORGANISM(S): Homo sapiens

PROVIDER: GSE179285 | GEO | 2021/07/26

REPOSITORIES: GEO

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Project description:Background and aims: Mucosal abnormalities are potentially important in the primary pathogenesis of ulcerative colitis (UC). We investigated the mucosal transcriptomic expression profiles of biopsies from patients with UC and healthy controls (HC), taken from macroscopically non-inflamed tissue from the terminal ileum and three colonic locations with the objective of identifying abnormal molecules that might be involved in disease development. Methods: Whole-genome transcriptional analysis was performed on intestinal biopsies taken from 24 UC, 26 HC and 14 patients with CrohnM-bM-^@M-^Ys disease. Differential gene expression analysis was performed at each tissue location separately and results were then meta-analysed using FisherM-bM-^@M-^Ys method. Significantly differentially expressed genes were validated using qPCR. Gene location within the colon was determined using immunohistochemistry, subcellular fractionation, electron and confocal microscopy. DNA methylation was quantified by pyrosequencing. Results: Seven probes were abnormally expressed throughout the colon in UC patients with Family with sequence similarity member 5 C (FAM5C) being the most significantly underexpressed. Attenuated expression of FAM5C in UC was independent of inflammation, unrelated to phenotype or treatment, and remained low at rebiopsy approximately 23 months later. FAM5C is localised to the brush border of the colonic epithelium and expression is influenced by DNA methylation within its promoter. Conclusion: Genome-wide expression analysis of non-inflamed mucosal biopsies from UC patients identified FAM5C as significantly under-expressed throughout the colon in a major sub-set of patients with UC. Low levels of this gene could predispose to or contribute to the maintenance of the characteristic mucosal inflammation seen in this condition. Total RNA was extracted from the intestinal biopsies taken from macroscopically normal mucosa in the rectum, descending colon, ascending colon and terminal ileum in clinically quiescent Ulcerative colitis and Crohn's disease patients and compared to healthy controls. Normalized data for 26,261 probes out of 47,323 only. Criteria for inclusion not specified. The non-normalized matrix contains the complete non-normalized data for all probes.

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Embark cross-sectional study of inactive and active lesions from the ileum and colon of inflammatory bowel disease patients

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