Nicholas T. Ventham

Beyond Gene Discovery in Inflammatory Bowel Disease: The Emerging Role of Epigenetics

In the past decade, there have been fundamental advances in our understanding of genetic factors that contribute to the inflammatory bowel diseases (IBDs) Crohn’s disease and ulcerative colitis. The latest international collaborative studies have brought the number of IBD susceptibility gene loci to 163. However, genetic factors account for only a portion of overall disease variance, indicating a need to better explore gene-environment interactions in the development of IBD. Epigenetic factors can mediate interactions between the environment and the genome; their study could provide new insight into the pathogenesis of IBD. We review recent progress in identification of genetic factors associated with IBD and discuss epigenetic mechanisms that could affect development and progression of IBD.

MicroRNAs: new players in IBD

MicroRNAs (miRNAs) are small non-coding RNAs, 18–23 nucleotides long, which act as post-transcriptional regulators of gene expression. miRNAs are strongly implicated in the pathogenesis of many common diseases, including IBDs. This review aims to outline the history, biogenesis and regulation of miRNAs. The role of miRNAs in the development and regulation of the innate and adaptive immune system is discussed, with a particular focus on mechanisms pertinent to IBD and the potential translational applications.

Systematic review and meta-analysis of continuous local anaesthetic wound infiltration versus epidural analgesia for postoperative pain following abdominal surgery

Local anaesthetic wound infiltration techniques reduce opiate requirements and pain scores. Wound catheters have been introduced to increase the duration of action of local anaesthetic by continuous infusion. The aim was to compare these infiltration techniques with the current standard of epidural analgesia.

Inflammatory Bowel Disease Associates with Proinflammatory Potential of the Immunoglobulin G Glycome

Background:Glycobiology is an underexplored research area in inflammatory bowel disease (IBD), and glycans are relevant to many etiological mechanisms described in IBD. Alterations in N-glycans attached to the immunoglobulin G (IgG) Fc fragment can affect molecular structure and immunological function. Recent genome-wide association studies reveal pleiotropy between IBD and IgG glycosylation. This study aims to explore IgG glycan changes in ulcerative colitis (UC) and Crohns disease (CD). Methods:IgG glycome composition in patients with UC (n = 507), CD (n = 287), and controls (n = 320) was analyzed by ultra performance liquid chromatography. Results:Statistically significant differences in IgG glycome composition between patients with UC or CD, compared with controls, were observed. Both UC and CD were associated with significantly decreased IgG galactosylation (digalactosylation, UC: odds ratio [OR] = 0.71; 95% confidence interval [CI], 0.5–0.9; P = 0.01; CD: OR = 0.41; CI, 0.3–0.6; P = 1.4 × 10−9) and significant decrease in the proportion of sialylated structures in CD (OR = 0.46, CI, 0.3–0.6, P = 8.4 × 10−8). Logistic regression models incorporating measured IgG glycan traits were able to distinguish UC and CD from controls (UC: P = 2.13 × 10−6 and CD: P = 2.20 × 10−16), with receiver–operator characteristic curves demonstrating better performance of the CD model (area under curve [AUC] = 0.77) over the UC model (AUC = 0.72) (P = 0.026). The ratio of the presence to absence of bisecting GlcNAc in monogalactosylated structures was increased in patients with UC undergoing colectomy compared with no colectomy (FDR-adjusted, P = 0.05). Conclusions:The observed differences indicate significantly increased inflammatory potential of IgG in IBD. Changes in IgG glycosylation may contribute to IBD pathogenesis and could alter monoclonal antibody therapeutic efficacy. IgG glycan profiles have translational potential as IBD biomarkers.

The role of glycosylation in IBD

A number of genetic and immunological studies give impetus for investigating the role of glycosylation in IBD. Experimental mouse models have helped to delineate the role of glycosylation in intestinal mucins and to explore the putative pathogenic role of glycosylation in colitis. These experiments have been extended to human studies investigating the glycosylation patterns of intestinal mucins as well as levels of glycans of serum glycoproteins and expression of glycan receptors. These early human studies have generated interesting hypotheses regarding the pathogenic role of glycans in IBD, but have generally been restricted to fairly small underpowered studies. Decreased glycosylation has been observed in the intestinal mucus of patients with IBD, suggesting that a defective inner mucus layer might lead to increased bacterial contact with the epithelium, potentially triggering inflammation. In sera, decreased galactosylation of IgG has been suggested as a diagnostic marker for IBD. Advances in glycoprofiling technology make it technically feasible and affordable to perform high-throughput glycan pattern analyses and to build on previous work investigating a much wider range of glycan parameters in large numbers of patients.

Evaluation of novel local anesthetic wound infiltration techniques for postoperative pain following colorectal resection surgery: a meta-analysis

BACKGROUND: Novel local anesthetic blocks have become increasingly popular in the multimodal pain management following abdominal surgery, but have not been evaluated in a procedure-specific manner in colorectal surgery. OBJECTIVE: This study aims to evaluate the efficacy of novel local anesthetic techniques in colorectal surgery. DATA SOURCES: Electronic literature search of PubMed, EMBASE, and Cochrane databases (date range, January 1990 to February 2013) STUDY SELECTION: Randomized controlled trials comparing a novel local anesthetic technique with placebo/routine analgesia in adults undergoing open or laparoscopic colonic or rectal resection were selected. INTERVENTIONS: This is a meta-analysis of randomized controlled trials evaluating novel local anesthetic wound infiltration techniques such as wound catheter, transversus abdominis plane block, and intraperitoneal instillation in colorectal surgical procedures. The comparator group was defined as placebo/routine analgesia. OUTCOME MEASURES: The primary outcome was opiate requirement at 24 hours. Secondary outcomes included opiate requirements at 48 hours, pain numerical rating score at 24 and 48 hours at rest and on movement, recovery (length of stay, nausea and vomiting, time until bowel movement and diet resumption), and complications. Subgroup analysis was performed to evaluate specific local anesthetic techniques and open and laparoscopic surgery. RESULTS: Twelve randomized controlled trials compared local anesthetic techniques with placebo/routine analgesia. Local anesthetic techniques demonstrated a significant reduction in opiate requirement at 48 hours. Local anesthetic techniques were also associated with lower pain scores on movement at 24 and 48 hours, shorter length of stay, and earlier resumption of diet. LIMITATIONS: The diverse study design led to statistical heterogeneity in several analyses. CONCLUSIONS: Novel local anesthetic wound infiltration techniques in colorectal surgery appear to reduce opiate requirements, to reduce pain scores, and to improve recovery in comparison with placebo/routine analgesia.

Two-stage Genome-wide Methylation Profiling in Childhood-onset Crohn's Disease Implicates Epigenetic Alterations at the VMP1/MIR21 and HLA Loci

Background:As a result of technological and analytical advances, genome-wide characterization of key epigenetic alterations is now feasible in complex diseases. We hypothesized that this may provide important insights into gene-environmental interactions in Crohns disease (CD) and is especially pertinent to early onset disease. Methods:The Illumina 450K platform was applied to assess epigenome-wide methylation profiles in circulating leukocyte DNA in discovery and replication pediatric CD cohorts and controls. Data were corrected for differential leukocyte proportions. Targeted replication was performed in adults using pyrosequencing. Methylation changes were correlated with gene expression in blood and intestinal mucosa. Results:We identified 65 individual CpG sites with methylation alterations achieving epigenome-wide significance after Bonferroni correction (P < 1.1 × 10−7), and 19 differently methylated regions displaying unidirectional methylation change. There was a highly significant enrichment of methylation changes around GWAS single nucleotide polymorphisms (P = 3.7 × 10−7), notably the HLA region and MIR21. Two-locus discriminant analysis in the discovery cohort predicted disease in the pediatric replication cohort with high accuracy (area under the curve, 0.98). The findings strongly implicate the transcriptional start site of MIR21 as a region of extended epigenetic alteration, containing the most significant individual probes (P = 1.97 × 10−15) within a GWAS risk locus. In extension studies, we confirmed hypomethylation of MIR21 in adults (P = 6.6 × 10−5, n = 172) and show increased mRNA expression in leukocytes (P < 0.005, n = 66) and in the inflamed intestine (P = 1.4 × 10−6, n = 99). Conclusions:We demonstrate highly significant and replicable differences in DNA methylation in CD, defining the disease-associated epigenome. The data strongly implicate known GWAS loci, with compelling evidence implicating MIR21 and the HLA region.

Crohn’s Disease

#### The bottom line Crohn’s disease is a chronic inflammatory disorder that can affect any part of the gastrointestinal tract. Although the disease most commonly presents at a young age, it can affect people of all ages. Patients often present with persistent diarrhoea, abdominal pain, and weight loss. Crohn’s disease has a global impact on patients’ education, work, and social and family life. High quality multidisciplinary care, of which primary care is a key aspect, can attenuate relapse, prevent long term complications, and improve quality of life. In this review we provide a practical approach to the diagnosis, management, and long term care of patients with Crohn’s disease. #### Sources and selection criteria We carried out an electronic search of PubMed, the Cochrane Library, and Ovid databases for articles using the term “Crohn’s disease”. We limited studies to those in adults and focused on high quality randomised control trials, meta-analyses, and systematic reviews. Crohn’s disease is an idiopathic, chronic relapsing immune mediated disease, the pathogenesis of which remains incompletely understood, although the condition is thought to arise from environmental priming and …

Central venous pressure and liver resection: a systematic review and meta analysis

BACKGROUND A liver resection under low central venous pressure (CVP) has become standard practice; however, the benefits beyond a reduction in blood loss are not well reported. Moreover, the precise method to achieve CVP reduction has not been established. A systematic review and meta-analysis of randomized controlled trials (RTCs) was performed to assess the effects of CVP on clinical outcome and to identify the optimum method of CVP reduction. METHODS EMBASE, Medline, PubMed and the Cochrane database were searched for trials comparing low CVP surgery with controls. The primary outcome was post-operative complications within 30 days. Secondary outcomes included estimated blood loss (EBL), blood transfusion rates and length of stay (LOS). Sub-group analysis was performed to assess the CVP reduction method on the outcome. RESULTS Eight trials were identified. No difference was observed in the morbidity rate between the high CVP and control groups [odds ratio (OR) = 0.96 (95% confidence interval (CI) 0.66, 1.40) P = 0.84, I(2) = 0%]. EBL [weighted mean difference (WMD) = -308.63 ml (95% CI -474.67, -142.58) P = < 0.001, I(2) = 73%] and blood transfusion rates [OR 0.65 (95% CI 0.44, 0.97) P = 0.040, I(2) = 37%] were significantly lower in the low CVP groups. Neither anaesthetic nor surgical methods of CVP reduction were associated with a reduced post-operative morbidity. CONCLUSION Low CVP surgery is associated with a reduction in EBL; however, this does not translate into an improvement in post-operative morbidity. The optimum method of CVP reduction has not been identified.

Serum Calprotectin: A Novel Diagnostic and Prognostic Marker in Inflammatory Bowel Diseases.

OBJECTIVES:There is an unmet need for novel blood-based biomarkers that offer timely and accurate diagnostic and prognostic testing in inflammatory bowel diseases (IBD). We aimed to investigate the diagnostic and prognostic utility of serum calprotectin (SC) in IBD.METHODS:A total of 171 patients (n=96 IBD, n=75 non-IBD) were prospectively recruited. A multi-biomarker model was derived using multivariable logistic regression analysis. Cox proportional hazards model was derived to assess the contribution of each variable to disease outcomes.RESULTS:SC correlated strongly with current biomarkers, including fecal calprotectin (FC) (n=50, ρ=0.50, P=1.6 × 10−4). SC was the strongest individual predictor of IBD diagnosis (odds ratio (OR): 9.37 (95% confidence interval (CI): 2.82–34.68), P=4.00 × 10−4) compared with other markers (C-reactive protein (CRP): OR 8.52 (95% CI: 2.75–28.63), P=2.80 × 10−4); albumin: OR 6.12 (95% CI: 1.82–22.16), P=0.004). In a subset of 50 patients with paired SC and FC, the area under receiver operating characteristic discriminating IBD from controls was better for FC than for SC (0.99, (95% CI 0.87–1.00) and 0.87 (95% CI:0.78–0.97), respectively; P=0.01). At follow-up (median 342 days; interquartile range: 88–563), SC predicted treatment escalation and/or surgery in IBD (hazard ratio (HR) 2.7, 95% CI: 1.1–4.9), in particular Crohn’s disease (CD) (HR 4.2, 95% CI 1.2–15.3). A model incorporating SC and either CRP or albumin has a positive likelihood ratio of 24.14 for IBD. At 1 year, our prognostic model can predict treatment escalation in IBD in 65% of cases (95% CI: 43–79%) and 80% (95% CI: 31–94%) in CD if ≥2 blood marker criteria are met.CONCLUSIONS:A diagnostic and prognostic model that combines SC and other blood-based biomarkers accurately predicts the inflammatory burden in IBD and has the potential to predict disease and its outcomes. Our data warrant further detailed exploration and validation in large multicenter cohorts.