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DNA methylation analysis on PBL obtained from male patients with UC-PSC, UC and HC

ABSTRACT: Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disease affecting the intra- and extrahepatic bile ducts, and is strongly associated with ulcerative colitis (UC). In this study, we explored the peripheral blood DNA methylome and its immune cell composition in patients with PSC-UC, UC, and healthy controls (HC) with the aim to develop a predictive assay in distinguishing patients with PSC-UC from those with UC alone. The peripheral blood DNA methylome of male patients with PSC and concomitant UC, UC and HCs was profiled using the Illumina HumanMethylation Infinium EPIC BeadChip (850K) array. Differentially methylated CpG position (DMP) and region (DMR) analyses were performed alongside gradient boosting classification analyses to discern PSC-UC from UC patients. As observed differences in the DNA methylome could be the result of differences in cellular populations, we additionally employed mass cytometry to characterize the immune cell compositions. Genome wide methylation analysis revealed no differentially methylated positions between PSC-UC and UC patients. Nonetheless, using gradient boosting we were capable of discerning PSC-UC from UC with an area under the receiver operator curve (AUROC) of 0.80. Four CpG sites annotated to the NINJ2 gene were found to strongly contribute to the predictive performance. While mass cytometry analyses corroborated the largely similar blood cell composition among patients with PSC-UC, UC and HC, a higher abundance of myeloid cells was observed in UC compared to PSC-UC patients.

PROVIDER: EGAS00001005832 | EGA |

REPOSITORIES: EGA

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Project description:Background: Patients suffering from primary sclerosing cholangitis (PSC) often also have ulcerative colitis (UC). Cross-disease genetic and microbiome studies across PSC und UC patients indicated that UC in PSC is a separate disease entity from primary UC, but expression studies for PSC are lacking. In this study, we performed a molecular comparison of whole blood expression levels in PSC only, PSC patients with additional UC diagnosis (PSC/UC), and UC, using a large collection of whole blood transcriptome data. Methods: We conducted whole blood RNA-Seq experiments for 495 UC patients, 220 PSC patients (of whom 177 have also a UC diagnosis), and 320 healthy controls from Germany and Norway. Differential expression analyses, gene ontology and coexpression analyses and random forest machine learning were performed to identify genes, ontologies and transcriptional features that discriminate diagnoses. Results: The blood transcriptome in UC and PSC is dominated by neutrophil activation genes. In UC, but not in PSC (neither PSC alone nor PSC/UC), there is upregulation of genes for ribosomes, mitochondria and energy metabolism genes in conjunction with antibody transcript expression. In PSC, there is an increase in modules related to apoptosis and expression of genes of interferon-I-related ontologies. Random forest analysis could poorly discriminate PSC alone from PSC/UC (AUROC 0.56), but could discriminate PSC, UC, and controls with high accuracy (AUROC UC vs controls 0.95, PSC vs controls 0.88, UC vs PSC 0.986). The main coexpression modules are enriched in neutrophil degranulation and antibody production genes relevant for distinguishing PSC, UC, and controls. Conclusions: PSC and UC share neutrophil-related transcriptional upregulation in whole blood (e.g. S100A12). UC is characterised by upregulation of modules involved in antibody production (MZB1, IGJ) and increased metabolic activity (PDK4, ribosomal genes), while PSC differs from UC by interferon (IFIT1) and apoptosis upregulation (G0S2). Supported by machine learning results, PSC and UC are interpreted as molecularly separate entities, while PSC/UC and PSC are indistinguishable.

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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DNA methylation analysis on PBL obtained from male patients with UC-PSC, UC and HC

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