An Extremes of Phenotype Approach Confirms Significant Genetic Heterogeneity in Patients with Ulcerative Colitis

Background and Aims: Ulcerative colitis [UC] is a major form of inflammatory bowel disease globally. Phenotypic heterogeneity is defined by several variables including age of onset and disease extent. The genetics of disease severity remains poorly understood. To further investigate this, we performed a genome wide association [GWA] study using an extremes of phenotype strategy. Methods: We conducted GWA analyses in 311 patients with medically refractory UC [MRUC], 287 with non-medically refractory UC [nonMRUC] and 583 controls. Odds ratios [ORs] were calculated for known risk variants comparing MRUC and non-MRUC, and controls. Results: MRUC–control analysis had the greatest yield of genome-wide significant single nucleotide polymorphisms [SNPs] [2018], including lead SNP = rs111838972 [OR = 1.82, p = 6.28 × 10−9] near MMEL1 and a locus in the human leukocyte antigen [HLA] region [lead SNP = rs144717024, OR = 12.23, p = 1.7 × 10−19]. ORs for the lead SNPs were significantly higher in MRUC compared to non-MRUC [p < 9.0 × 10−6]. No SNPs reached significance in the non-MRUC–control analysis (top SNP, rs7680780 [OR 2.70, p = 5.56 × 10−8). We replicate findings for rs4151651 in the Complement Factor B [CFB] gene and demonstrate significant changes in CFB gene expression in active UC. Detailed HLA analyses support the strong associations with MHC II genes, particularly HLA-DQA1, HLA-DQB1 and HLA-DRB1 in MRUC. Conclusions: Our MRUC subgroup replicates multiple known UC risk variants in contrast to non-MRUC and demonstrates significant differences in effect sizes compared to those published. Non-MRUC cases demonstrate lower ORs similar to those published. Additional risk and prognostic loci may be identified by targeted recruitment of individuals with severe disease.Sally Mortlock, Anton Lord, Grant Montgomery, Martha Zakrzewski, Lisa A.Simms, Krupa Krishnaprasad, Katherine Hanigan, James D. Doecke, Alissa Walsh, Ian C. Lawrance, Peter A.Bampton, Jane M. Andrews, Gillian Mahy, Susan J. Connor, Miles P.Sparrow, Sally Bell, Timothy H. Florin, Jakob Begun, Richard B. Gearry, Graham L. Radford-Smit

IBD risk loci are enriched in multigenic regulatory modules encompassing putative causative genes.

GWAS have identified >200 risk loci for Inflammatory Bowel Disease (IBD). The majority of disease associations are known to be driven by regulatory variants. To identify the putative causative genes that are perturbed by these variants, we generate a large transcriptome data set (nine disease-relevant cell types) and identify 23,650 cis-eQTL. We show that these are determined by ∼9720 regulatory modules, of which ∼3000 operate in multiple tissues and ∼970 on multiple genes. We identify regulatory modules that drive the disease association for 63 of the 200 risk loci, and show that these are enriched in multigenic modules. Based on these analyses, we resequence 45 of the corresponding 100 candidate genes in 6600 Crohn disease (CD) cases and 5500 controls, and show with burden tests that they include likely causative genes. Our analyses indicate that ≥10-fold larger sample sizes will be required to demonstrate the causality of individual genes using this approach

Waiting times for colonoscopy and colorectal cancer diagnosis

Objective: To evaluate whether prolonged waiting times for colonoscopy in public hospitals could result in delayed diagnosis of colorectal carcinoma. Design, setting and patients: Analysis of all outpatient colonoscopies performed at a Western Australian tertiary teaching hospital, 1 November 2003 – 31 October 2005. Colonoscopy data, corresponding pathological findings, category of urgency at referral for colonoscopy, and waiting time for colonoscopy were obtained. Patients were coded as having cancer if it was diagnosed by colonoscopy or if colonoscopy identified a lesion subsequently diagnosed as cancer. Main outcome measures: Colorectal carcinoma detected by outpatient colonoscopy and length of waiting time to colonoscopy. Results: 1632 outpatient colonoscopies were recorded. Category I patients received a colonoscopy within the recommended 30 days from referral. Median waiting times for Category II and Category III patients exceeded recommendations (observed, 113 days and 258 days; recommended, within 90 days and 180 days, respectively), although the number of cancers detected was low (2.4% and 0.6% of referrals, respectively in each category). Early- and late-stage cancers had similar median waiting times from referral to diagnosis. Age over 65 years and the blood-loss indications — a positive faecal occult blood test or iron deficiency/anaemia — were predictors of an increased risk of carcinoma at colonoscopy. Conclusions: Waiting time for colonoscopy was not associated with an increase in the proportion of late-stage cancers diagnosed. Age over 65 years and evidence of blood loss increased the likelihood of a cancer diagnosis

Secreted protein acidic and rich in cysteine (SPARC) exacerbates colonic inflammatory symptoms in dextran sodium sulphate-induced murine colitis

Background Secreted Protein Acidic and Rich in Cysteine (SPARC) is expressed during tissue repair and regulates cellular proliferation, migration and cytokine expression. The aim was to determine if SPARC modifies intestinal inflammation. Methods Wild-type (WT) and SPARC-null (KO) mice received 3% dextran sodium sulphate (DSS) for 7 days. Inflammation was assessed endoscopically, clinically and histologically. IL-1β, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17A, IL-12/IL23p40, TNF-α, IFN-γ, RANTES, MCP-1, MIP-1α, MIP-1β, MIG and TGF-β1 levels were measured by ELISA and cytometric bead array. Inflammatory cells were characterised by CD68, Ly6G, F4/80 and CD11b immunofluorescence staining and regulatory T cells from spleen and mesenteric lymph nodes were assessed by flow cytometry. Results KO mice had less weight loss and diarrhoea with less endoscopic and histological inflammation than WT animals. By day 35, all (n = 13) KO animals completely resolved the inflammation compared to 7 of 14 WT mice (p<0.01). Compared to WTs, KO animals at day 7 had less IL1β (p = 0.025) and MIG (p = 0.031) with higher TGFβ1 (p = 0.017) expression and a greater percentage of FoxP3+ regulatory T cells in the spleen and draining lymph nodes of KO animals (p<0.01). KO mice also had fewer CD68+ and F4/80+ macrophages, Ly6G+ neutrophils and CD11b+ cells infiltrating the inflamed colon. Conclusions Compared to WT, SPARC KO mice had less inflammation with fewer inflammatory cells and more regulatory T cells. Together, with increased TGF-β1 levels, this could aid in the more rapid resolution of inflammation and restoration of the intestinal mucosa suggesting that the presence of SPARC increases intestinal inflammation

NAFLD, the changing face of IBD

Background It is estimated that up to 5% of inflammatory bowel disease (IBD) patients have clinically significant liver disease due to multifactorial causes such as underlying Primary Sclerosing Cholangitis, pharmacotherapy, fatty liver disease or nodular regenerative hyperplasia. In recent years, transient elastography (TE), which uses the sonic detection of liver stiffness to predict hepatic fibrosis has increasingly replaced the need for a liver biopsy. It has been validated in patients with chronic hepatitis C as an accurate non-invasive predictor of advance fi brosis and cirrhosis. Aims Our aim was to evaluate the prevalence of clinically significant liver disease in IBD patients as defi ned by an increased liver stiffness measurement (LSM) using Transient Elastography (FibroScan®). Methods 110 random IBD patients and 55 non-IBD control patients (composed of patient relatives and hospital staff) had their LSM recorded. The median reading in kilopascals (kPa) of 10 successful acquisitions was recorded by a nurse trained in performing TE. Age, gender, body mass index (BMI), history of liver disease, presence of diabetes, number of cigarettes smoked and standard drinks of alcohol consumed per week, were recorded and entered as covariates in multivariate analysis. Results Of the 110 IBD patients, 71 (64.5%) had Crohn’s disease. There were no significant differences in mean age (43 ± 15 yrs vs. 41 ± 17 yrs), gender (males, 47% vs. 51%) and number of standard alcoholic drinks consumed per week (6 ± 9 vs. 4 ± 7) between IBD patients and non-IBD controls respectively (P > 0.05). IBD patients smoked significantly more cigarettes per week compared to non-IBD controls (15 ± 42 vs. 1 ± 6, P = 0.001). Four IBD patients had diabetes compared to none in the non-IBD group. Seven patients in the IBD group (6.4%) had an LSM reading of greater than 8 kPa compared to none in non-IBD control group. One patient, had an LSM of 14.9 kPa, normal liver function tests and evidence of portal hypertension on ultrasound. Although the overall LSM in the IBD group was higher, there was no statistical difference between the mean LSM reading of IBD patients (5.2 ± 2.5 kPa) and non-IBD controls (4.8 ± 1.2 kPa) on univariate (P = 0.22) and multivariate (P = 0.67) analysis. IBD patients had a significantly higher BMI compared to non-IBD controls (26 ± 4.6 vs. 24 ± 3.3, P = 0.04) and this was the only independent predictor of a high LSM reading on multivariate analysis (P < 0.0001). Conclusion IBD patients are more likely to have a higher BMI compared to non-IBD subjects and this is the main reason for their higher LSM reading. This implies that non-alcoholic fatty liver disease may be a significant cause of occult liver disease in IBD patients and attention should be paid to optimise metabolic risk factors such as minimising corticosteroid use

The role of a plant-based diet in the pathogenesis, etiology and management of the inflammatory bowel diseases

© 2020 Informa UK Limited, trading as Taylor & Francis Group. Introduction: Inflammatory Bowel Disease (IBD) carries a significant burden on an individual’s quality-of-life and on the healthcare system. The majority of patients use dietary modifications to manage their symptoms, despite limited research to support these changes. There is emerging data that a plant-based diet will be of benefit to IBD patients. Areas covered: A literature review on the pathogenesis and potential benefits of dietary management of IBD. Expert opinion: A Westernized diet has been associated with IBD risk and relapse; hence a plant-based diet may be of benefit to IBD patients through reducing inflammation and restoring symbiosis. Dietary therapy can be an important adjunct therapy, however, better quality studies are still required

Emu Oil reduces disease severity in a mouse model of chronic ulcerative colitis

OBJECTIVE:Ulcerative colitis (UC) is characterized by mucosal inflammation and ulceration of the large intestine. Emu Oil (EO) has been reported to protect the intestine against mucositis, NSAID-enteropathy, UC-associated colorectal cancer and acute UC. We aimed to determine whether EO could reduce the severity chronic UC in mice. METHODS:Female C57BL/6 mice (n = 10/group) were orally administered (gavage) water (Groups 1-2) or EO (Groups 3: low dose-80 µl and 4: high dose-160 µl), thrice weekly. Group 1 mice consumed plain drinking water throughout the trial. Groups 2-4 mice underwent two cycles [each consisting of seven days dextran sulfate sodium (DSS; 2% w/v) and 14 days water], followed by a third DSS week. All mice were euthanized two days later (day 51). Bodyweight, disease activity index (DAI), burrowing activity, myeloperoxidase activity, crypt depth and histologically assessed damage severity were assessed. p < .05 was considered significant. RESULTS:DSS decreased bodyweight and increased DAI compared to normal controls (p < .05), which was partially attenuated by both EO doses (p < .05). Burrowing activity was impaired in DSS-controls compared to normal controls (days 27 and 40); an effect prevented by both EO doses (p < .05). DSS increased colonic myeloperoxidase activity and crypt depth compared to controls (p < .05), with no significant EO effect. Moreover, DSS increased colonic damage severity compared to normal controls (p < .001). Importantly, both EO doses decreased distal colonic damage severity compared to DSS-controls (p < .001). CONCLUSIONS:Emu Oil attenuated clinically- and histologically-assessed disease severity in a mouse model of chronic UC. Emu Oil demonstrates promise as an adjunct to conventional treatment options for UC management.Romina Safaeian, Gordon S. Howarth, Ian C. Lawrance, Debbie Trinder and Suzanne Mashtou