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1.  Type-2 Diabetes Risk Variants and Colorectal Cancer Risk: The Multiethnic Cohort and PAGE Studies 
Gut  2011;60(12):1703-1711.
Diabetes has been positively associated with the risk of colorectal cancer. We investigated whether recently established risk variants for diabetes also have effects on colorectal cancer.
Nineteen SNPs associated with type-2 diabetes (T2D) in genome-wide association studies were tested in a case-control study of 2,011 colorectal cancer cases and 6,049 controls nested in the Multiethnic Cohort as part of the Population Architecture using Genomics and Epidemiology (PAGE) initiative. Odds ratios (OR) and 95% Confidence Intervals (CI) were estimated by unconditional logistic regression to evaluate the association between SNPs and colorectal cancer risk, adjusting for age, sex, and race/ethnicity. Permutation testing was conducted to correct for multiple hypothesis testing.
Four type 2 diabetes SNPs were associated with colorectal cancer risk: rs7578597 (THADA), rs864745 (JAZF1), rs5219 (KCNJ11), and rs7961581 (TSPAN8, LGR5). The strongest association was for the rs7578597 (THADA) Thr1187Ala missense polymorphism (Ptrend = 0.004 adjusted for multiple testing) with the high risk allele for colorectal cancer being the low risk allele for diabetes. Similar patterns of associations were seen with further adjustment for diabetes status and body mass index. The association of diabetes status with colorectal cancer risk was somewhat weakened after adjustment for these SNPs.
Our findings suggest that diabetes risk variants also influence colorectal cancer susceptibility, possibly through different mechanisms than for diabetes.
PMCID: PMC4332884  PMID: 21602532
colorectal cancer; SNPs; type 2 diabetes
2.  [No title available] 
PMCID: PMC3681892  PMID: 23455445
3.  [No title available] 
PMCID: PMC3976427  PMID: 23408348
4.  [No title available] 
PMCID: PMC4020522  PMID: 23946381
5.  Intracellular activation of trypsinogen in transgenic mice induces acute but not chronic pancreatitis 
Gut  2011;60(10):1379-1388.
Background and aims
Premature intra-acinar activation of trypsinogen is widely considered key for both the initiation of acute pancreatitis and the development of chronic pancreatitis. However, the biological consequences of intracellular trypsinogen activation have not been directly examined. To do so, a new mouse model was developed.
Mice were engineered to conditionally express an endogenously activated trypsinogen within pancreatic acinar cells (PACE-trypon). Hallmarks of pancreatitis were determined and findings were correlated to the level (zygosity) and extent (temporal and spatial) of conditional PACE-trypon expression. Furthermore, the impact of acinar cell death in PACE-trypon mice was assessed and compared with a model of selective diphtheria toxin (DT)-mediated induction of acinar apoptosis.
Initiation of acute pancreatitis was observed with high (homozygous), but not low (heterozygous) levels of PACE-trypon expression. Subtotal (maximal-rapid induction) but not limited (gradual-repetitive induction) conditional PACE-trypon expression was associated with systemic complications and mortality. Rapid caspase-3 activation and apoptosis with delayed necrosis was observed, and loss of acinar cells led to replacement with fatty tissue. Chronic inflammation or fibrosis did not develop. Selective depletion of pancreatic acinar cells by apoptosis using DT evoked similar consequences.
Intra-acinar activation of trypsinogen is sufficient to initiate acute pancreatitis. However, the primary response to intracellular trypsin activity is rapid induction of acinar cell death via apoptosis which facilitates resolution of the acute inflammation rather than causing chronic pancreatitis. This novel model provides a powerful tool to improve our understanding of basic mechanisms occurring during pancreatitis.
PMCID: PMC4304390  PMID: 21471572
6.  Loss of GM-CSF signalling in non-haematopoietic cells increases NSAID ileal injury 
Gut  2010;59(8):1066-1078.
Administration of granulocyte-macrophage colony stimulating factor (GM-CSF) relieves symptoms in Crohn's disease (CD). It has been reported that reduced GM-CSF bioactivity is associated with more aggressive ileal behaviour and that GM-CSF-null mice exhibit ileal barrier dysfunction and develop a transmural ileitis following exposure to non-steroidal anti-inflammatory drugs (NSAIDs). STAT5 signalling is central to GM-CSF action. It was therefore hypothesised that GM-CSF signalling in non-haematopoietic cells is required for ileal homeostasis.
Bone marrow (BM) chimeras were generated by reconstituting irradiated GM-CSF receptor (gm-csfr) β chain or GM-CSF (gm-csf) deficient mice with wild type BM (WTBM→GMRKO and WTBM→GMKO). Intestinal barrier function and the response to NSAID-induced ileal injury were examined. Expression of gm-csf, gm-csfr or stat5 in Caco-2 and HT-29 intestinal epithelial cell (IEC) lines was knocked down and the effect of GM-CSF signalling on IEC survival and proliferation was determined.
Elevated levels of GM-CSF autoantibodies in ileal CD were found to be associated with dysregulation of IEC survival and proliferation. GM-CSF receptor-deficient mice and WTBM→GMRKO chimeras exhibited ileal hyperpermeability. NSAID exposure induced a transmural ileitis in GM-CSF receptor-deficient mice and WTBM→GMRKO chimeras. Transplantation of wild type BM into GM-CSF-deficient mice prevented NSAID ileal injury and restored ileal barrier function. Ileal crypt IEC proliferation was reduced in WTBM→GMRKO chimeras, while STAT5 activation in ileal IEC following NSAID exposure was abrogated in WTBM→GMRKO chimeras. Following knock down of gm-csf, gm-csfr α or β chain or stat5a/b expression in Caco-2 cells, basal proliferation was suppressed. GM-CSF normalised proliferation of Caco-2 cells exposed to NSAID, which was blocked by stat5a/b RNA interference.
Loss of GM-CSF signalling in non-haematopoietic cells increases NSAID ileal injury; furthermore, GM-CSF signalling in non-haematopoietic cells regulates ileal epithelial homeostasis via the STAT5 pathway. The therapeutic use of GM-CSF may therefore be beneficial in chronic ileitis associated with CD.
PMCID: PMC4296557  PMID: 20584783
7.  A pH-sensitive, neurogenic pathway mediates disease severity in a model of post-ERCP pancreatitis 
Gut  2008;57(11):1566-1571.
Endoscopic retrograde cholangiopancreatography (ERCP) has a high risk of pancreatitis although the underlying mechanisms are unclear. Transient receptor potential vanilloid 1 (TRPV1) is a cation channel expressed on C and Ad fibres of primary sensory neurons and is activated by low pH. TRPV1 activation causes release of inflammatory mediators that produce oedema and neutrophil infiltration. We previously demonstrated that neurogenic factors contribute to the pathogenesis of pancreatitis. Resiniferatoxin (RTX) is a TRPV1 agonist that, in high doses, defunctionalises C and Ad fibres. When we discovered that the pH of radio-opaque contrast solutions used for ERCP was 6.9, we hypothesised that low pH may contribute to the development of contrast-induced pancreatitis via activation of TRPV1.
Rats underwent equal pressure pancreatic ductal injection of contrast solutions at varying pH with or without RTX.
Contrast solution (pH 6.9) injected into the pancreatic duct caused a significant increase in pancreatic oedema, serum amylase, neutrophil infiltration, and histological damage. Solutions of pH 7.3 injected at equal pressure caused little damage. The severity of the pancreatitis was significantly increased by injection of solutions at pH 6.0. To determine if the effects of low pH were mediated by TRPV1, RTX was added to the contrast solutions. At pH levels of 6.0 and 6.9, RTX significantly reduced the severity of pancreatitis.
Contrast solutions with low pH contribute to the development of pancreatitis through a TRPV1-dependent mechanism. It is possible that increasing the pH of contrast solution and/or adding an agent that inhibits primary sensory nerve activation may reduce the risk of post-ERCP pancreatitis.
PMCID: PMC4284069  PMID: 18625695
8.  Effect of Ribavirin on Viral Kinetics and Liver Gene Expression in Chronic Hepatitis C 
Gut  2013;63(1):10.1136/gutjnl-2012-303852.
Ribavirin improves treatment response to pegylated-interferon (PEG-IFN) in chronic hepatitis C but the mechanism remains controversial. We studied correlates of response and mechanism of action of ribavirin in treatment of hepatitis C.
70 treatment-naïve patients were randomized to 4 weeks of ribavirin (1000–1200 mg/d) or none, followed by PEG-IFN alfa-2a and ribavirin at standard doses and durations. Patients were also randomized to a liver biopsy 24 hours before, or 6 hours after starting PEG-IFN. Hepatic gene expression was assessed by microarray and interferon-stimulated gene (ISG) expression quantified by nCounter platform. Temporal changes in ISG expression were assessed by qPCR in peripheral-blood mononuclear cells (PBMC) and by serum levels of IP-10.
After four weeks of ribavirin monotherapy, HCV levels decreased by 0.5±0.5 log10 (p=0.009 vs. controls) and ALT by 33% (p<0.001). Ribavirin pretreatment, while modestly augmenting ISG induction by PEG-IFN, did not modify the virological response to subsequent PEG-IFN and ribavirin treatment. However, biochemical, but not virological response to ribavirin monotherapy predicted response to subsequent combination treatment (rapid virological response, 71% in biochemical responders vs. 22% non-responders, p=0.01; early virological response, 100% vs. 68%, p=0.03, sustained virological response 83% vs. 41%, p=0.053). Ribavirin monotherapy lowered serum IP-10 levels but had no effect on ISG expression in PBMC.
Ribavirin is a weak antiviral but its clinical effect seems to be mediated by a separate, indirect mechanism, which may act to reset interferon-responsiveness in HCV-infected liver.
PMCID: PMC3778097  PMID: 23396509
Interferon-stimulated genes; hepatic gene expression; ribavirin mechanism; hepatitis C virus; viral kinetics
9.  Local hypersensitivity reaction in transgenic mice with squamous epithelial IL-5 overexpression provides a novel model of eosinophilic oesophagitis 
Gut  2012;63(1):10.1136/gutjnl-2012-303631.
Eosinophilic oesophagitis (EoE) is a chronic inflammatory condition of the oesophagus with limited treatment options. No previous transgenic model has specifically targeted the oesophageal mucosa to induce oesophageal eosinophilia.
We developed a mouse model that closely resembles EoE by utilising oxazolone haptenation in mice with transgenic overexpression of an eosinophil poietic and survival factor (interleukin (IL)-5) in resident squamous oesophageal epithelia.
Overexpression of IL-5 in the healthy oesophagus was achieved in transgenic mice (L2-IL5) using the squamous epithelial promoter Epstein–Barr virus ED-L2. Oxazolone-challenged L2-IL5 mice developed dose-dependent pan-oesophageal eosinophilia, including eosinophil microabscess formation and degranulation as well as basal cell hyperplasia. Moreover, oesophagi expressed increased IL-13 and the eosinophil agonist chemokine eotaxin-1. Treatment of these mice with corticosteroids significantly reduced eosinophilia and epithelial inflammation.
L2-IL5 mice provide a novel experimental model that can potentially be used in preclinical testing of EoE-related therapeutics and mechanistic studies identifying pathogenetic features associated with mucosal eosinophilia.
PMCID: PMC3884674  PMID: 23161496
10.  Therapeutic targeting of GSK3β enhances the Nrf2 antioxidant response and confers hepatic cytoprotection in hepatitis C 
Gut  2014;64(1):168-179.
Impaired adaptive response to oxidative injuries is a fundamental mechanism central to the pathogenesis of chronic hepatitis C (CHC). Glycogen synthase kinase (GSK) 3β is an indispensable regulator of the oxidative stress response. However, the exact role of GSK3β in CHC is uncertain and was examined.
GSK3β and Nrf2 signaling pathways were examined in JFH1 hepatitis C virus (HCV) infected Huh 7.5.1 hepatocytes and also in liver biopsy specimens from CHC patients.
HCV infection elicited prominent Nrf2 antioxidant response in hepatocytes, marked by elevated expression of the Nrf2 dependent molecule heme oxygenase-1 and subsequent protection from apoptotic cell death. Inhibitory phosphorylation of GSK3β seems to be essential and sufficient for HCV induced Nrf2 response. Mechanistically, GSK3β physically associated and interacted with Nrf2 in hepatocytes. In silico analysis revealed that Nrf2 encompasses multiple GSK3β phosphorylation consensus motifs, denoting Nrf2 as a cognate substrate of GSK3β. In the presence of TGFβ1, the HCV induced GSK3β phosphorylation was blunted via a protein phosphatase 1-dependent mechanism and the cytoprotective Nrf2 response drastically impaired. Lithium, a selective inhibitor of GSK3β, counteracted the effects of TGFβ1. In liver biopsy specimens from CHC patients, the expression of phosphorylated GSK3β positively correlated with Nrf2 expression and was inversely associated with the degree of liver injury. Moreover, CHC patients who received long-term lithium carbonate therapy primarily for concomitant psychiatric disorders exhibited much less liver injury, associated with enhanced hepatic expression of Nrf2.
Inhibition of GSK3β exerts hepatoprotection in CHC possibly through its direct regulation of Nrf2 antioxidant response.
PMCID: PMC4263291  PMID: 24811996
glycogen synthase kinase 3β; chronic hepatitis C; NF-E2 related factor-2; transformation growth factor β1; antioxidant response
11.  Plasma antibodies to oral bacteria and risk of pancreatic cancer in a large European prospective cohort study 
Gut  2012;62(12):10.1136/gutjnl-2012-303006.
Examine the relationship between antibodies to 25 oral bacteria and pancreatic cancer risk in a prospective cohort study.
We measured antibodies to oral bacteria in prediagnosis blood samples from 405 pancreatic cancer cases and 416 matched controls, nested within the European Prospective Investigation into Cancer and Nutrition study (EPIC). Analyses were conducted using conditional logistic regression and additionally adjusted for smoking status and body mass index.
Individuals with high levels of antibodies against Porphyromonas gingivalis ATTC 53978, a pathogenic periodontal bacteria, had a 2-fold higher risk of pancreatic cancer than individuals lower levels of these antibodies (odds ratio [OR], 2.14; 95% confidence interval [CI], 1.05–4.36; >200 ng/ml vs ≤200 ng/ml). To explore the association with commensal (non-pathogenic) oral bacteria, we performed a cluster analysis and identified 2 groups of individuals, based on their antibody profiles. A cluster with overall higher levels of antibodies had a 45% lower risk of pancreatic cancer than a cluster with overall lower levels of antibodies (OR, 0.55; 95% CI, 0.36–0.83).
Periodontal disease might increase the risk for pancreatic cancer. Moreover, increased levels of antibodies against specific commensal oral bacteria, which can inhibit growth of pathogenic bacteria, might reduce the risk of pancreatic cancer. Studies are needed to determine whether oral bacteria have direct effects on pancreatic cancer pathogenesis or serve as markers of the immune response.
PMCID: PMC3815505  PMID: 22990306
infection; oral bacteria; pancreatic cancer; periodontal disease
12.  Sex-specific associations between body mass index, waist circumference and the risk of Barrett’s oesophagus: a pooled analysis from the international BEACON consortium 
Gut  2013;62(12):10.1136/gutjnl-2012-303753.
Barrett’s oesophagus is a precursor lesion of oesophageal adenocarcinoma, a cancer that, in the USA, has increased in incidence over 600% during the past 40 years. Barrett’s oesophagus and oesophageal adenocarcinoma are much more common among men than among women; this finding is unexplained and most earlier studies lacked sufficient numbers of women to evaluate sex-specific risk factors. We leveraged the power of an international consortium to assess sex-specific relationships between body mass index (BMI), abdominal circumference and Barrett’s oesophagus.
Four case–control studies provided a total of 1102 cases (316 women, 786 men) and 1400 population controls (436 women, 964 men) for analysis. Study-specific estimates, generated using individual participant data, were combined using random effects meta-analysis.
Waist circumference was significantly associated with Barrett’s oesophagus, even after adjustment for BMI; persons in the highest versus the lowest quartiles of waist circumference had approximately 125% and 275% increases in the odds of Barrett’s oesophagus among men and women, respectively (OR 2.24, 95% CI 1.08 to 4.65, I2=57; OR 3.75, 95% CI 1.47 to 9.56, I2=0). In contrast, there was no evidence of a significant association between BMI and the risk of Barrett’s oesophagus, with or without adjustment for waist circumference.
Waist circumference, independent of BMI, was found to be a risk factor for Barrett’s oesophagus among both men and women. Future studies examining the biological mechanisms of this association will extend our knowledge regarding the pathogenesis of Barrett’s oesophagus.
PMCID: PMC3823827  PMID: 23355549
13.  CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis 
Gut  2014;63(12):1960-1971.
In chronic liver injury, angiogenesis, the formation of new blood vessels from pre-existing ones, may contribute to progressive hepatic fibrosis and to development of hepatocellular carcinoma. Although hypoxia-induced expression of vascular endothelial growth factor (VEGF) occurs in advanced fibrosis, we hypothesized that inflammation may endorse hepatic angiogenesis already at early stages of fibrosis.
Angiogenesis in livers of c57BL/6 mice upon carbon tetrachloride (CCl4) or bile duct ligation (BDL) induced chronic hepatic injury was non-invasively monitored using in vivo contrast-enhanced micro-computed tomography (CT) and ex vivo anatomical μCT after hepatic Microfil perfusion. Functional contributions of monocyte-derived macrophage subsets for angiogenesis were explored by pharmacological inhibition of CCL2 using the Spiegelmer mNOX-E36.
Contrast-enhanced in vivo μCT imaging allowed non-invasively monitoring the close correlation of angiogenesis, reflected by functional hepatic blood vessel expansion, with experimental fibrosis progression. On a cellular level, inflammatory monocyte-derived macrophages massively accumulated in injured livers, co-localized with newly formed vessels in portal tracts and exhibited pro-angiogenic gene profiles including up-regulated VEGF and MMP9. Functional in vivo and anatomical ex vivo μCT analyses demonstrated that inhibition of monocyte infiltration by targeting the chemokine CCL2 prevented fibrosis-associated angiogenesis, but not fibrosis progression. Monocyte-derived macrophages primarily fostered sprouting angiogenesis within the portal vein tract. Portal vein diameter as a measure of portal hypertension depended on fibrosis, but not on angiogenesis.
Inflammation-associated angiogenesis is promoted by CCL2-dependent monocytes during fibrosis progression. Innovative in vivo μCT methodology can accurately monitor angiogenesis and anti-angiogenic therapy effects in experimental liver fibrosis.
PMCID: PMC4216733  PMID: 24561613
liver fibrosis; angiogenesis; monocytes; computed tomography; chemokines
14.  A Randomized Trial of Sheathed vs. Standard Forceps for Obtaining Uncontaminated Biopsy Specimens of Microbiota from the Terminal Ileum 
Gut  2011;60(8):1043-1049.
The study of intestinal microbiota has been revolutionized by the use of molecular methods, including terminal restriction fragment length polymorphism (T-RFLP) analysis. A number of microbiota studies of Crohn’s disease patients have examined samples from stool or from the neoterminal ileum with a standard biopsy forceps, which could be contaminated by colonic bacteria when the forceps passes through the colonoscope channel.
To determine whether sheathed biopsy forceps are able to obtain terminal ileal microbiota samples with less colonic bacterial contamination compared to unsheathed (standard) biopsy forceps.
Prospective randomized single center-study.
Patients and Methods
We obtained four (paired) biopsy specimens from adjacent locations in the terminal ileum using the sheathed and standard forceps of 27 consecutive subjects undergoing colonoscopy and characterized the microbiota using T-RFLP. We calculated the Bray Curtis similarity index (BCI) between samples (sheathed vs. unsheathed forceps) within patients and tested for significant differences across all patients.
There was not a significant difference in the microbial diversity of samples obtained using sheathed vs. unsheathed forceps. The difference in microbial diversity between patients was much greater than the variability within patients by proximal vs. distal site or by forceps type.
T-RFLP is based on PCR amplification, so it is not always sensitive to rare bacterial species.
Standard unsheathed forceps appear to be sufficient for microbiota sample collection from the terminal ileum.
PMCID: PMC4244887  PMID: 21317176
Terminal Ileum; Terminal restriction fragment length polymorphism; Microbiota; Microbial diversity; Crohn’s disease
15.  Reciprocal Changes in Vanilloid (TRPV1) and Endocannabinoid (CB1) Receptors Contribute to Visceral Hyperalgesia in the Water Avoidance Stressed Rat 
Gut  2008;58(2):202-210.
Increasing evidence suggests that chronic stress plays an important role in the pathophysiology of several functional gastrointestinal disorders. We investigated whether CB1 and TRPV1 receptors are involved in stress induced visceral hyperalgesia.
Male rats were exposed to 1-hour water avoidance (WA) stress daily for 10 consecutive days. The visceromotor response (VMR) to colorectal distension (CRD) was measured. Immunofluorescence and Western blot analysis were used to assess the expression of CB1 and TRPV1 receptors in DRG neurons.
WA stressed rats demonstrated a significant increase in the serum corticosterone levels and fecal pellet output compared to controls supporting stimulation of the HPA axis. The VMR increased significantly at pressures of 40 and 60 mmHg in WA stress rats compared with controls, respectively, and was associated with hyperalgesia. The endogenous CB1 agonist anandamide was increased significantly in DRGs from stressed rats. Immunofluorescence and Western blot analysis showed a significant decrease in CB1 and reciprocal increase in TRPV1 expression and phosphorylation in DRG neurons from stressed rats. These reciprocal changes in CB1 and TRPV1 were reproduced by treatment of control DRGs with anandamide in vitro. In contrast, treatment of control DRGs in vitro with the CB1 receptor agonist WIN 55,212-2 decreased the levels of TRPV1 and TRPV1 phosphorylation. Treatment of WA stress rats in situ with WIN or the TRPV1 antagonist capsazepine prevented the development of visceral hyperalgesia and blocked the up-regulation of TRPV1.
These results suggest that the endocannabinoid (CB1) and TRP (TRPV1) pathways may play a potentially important role in stress-induced visceral hyperalgesia.
PMCID: PMC4236191  PMID: 18936104
TRPV1; CB1; visceral hyperalgesia; stress; dorsal root ganglion
16.  The intermediate filament protein vimentin is a regulator of NOD2 activity 
Gut  2012;62(5):695-707.
Mutations in nucleotide-binding oligomerisation domain-containing protein 2 (NOD2) remain the strongest genetic determinants for Crohn’s disease (CD). Having previously identified vimentin as a novel NOD2-interacting protein, we aimed to investigate the regulatory effects of vimentin on NOD2 function and the association of variants in Vim to CD susceptibility.
Co-immunoprecipitation, fluorescent microscopy and fractionation were used to confirm the interaction between NOD2 and vimentin. HEK293 cells stably expressing wild-type NOD2 or NOD2-frameshift variant (L1007fs) and SW480 colonic epithelial cells were used alongside the vimentin inhibitor Withaferin-A (WFA) to assess effects on NOD2 function using nuclear factor-kappaB (NF-κB) reporter gene, GFP-LC3-based autophagy, and bacterial gentamicin protection assays. International GWAS meta-analysis data were used to test for association of SNPs in Vim to CD susceptibility.
The leucine rich repeat (LRR) domain of NOD2 contained the elements required for vimentin binding; CD-associated polymorphisms disrupted this interaction. NOD2 and vimentin co-localised at the cell plasma membrane and cytosolic mislocalisation of the L1007fs and R702W variants correlated with an inability to interact with vimentin. Use of WFA demonstrated that vimentin was required for NOD2-dependent NF-κB activation, MDP-induced autophagy induction, and that NOD2 and vimentin regulated the invasion and survival properties of a CD-associated adherent-invasive strain E.coli strain. Genetic analysis revealed an association signal across the haplotype block containing Vim.
Vimentin is an important regulator of NOD2 function and a potential novel therapeutic target in the treatment of CD. Additionally, Vim is a candidate susceptibility gene for CD, supporting the functional data.
PMCID: PMC4225453  PMID: 22684479
inflammatory bowel disease; Crohn’s disease; NOD2; vimentin; E.coli; autophagy; genetic association studies
17.  Comprehensive functional analysis of chymotrypsin C (CTRC) variants reveals distinct loss-of-function mechanisms associated with pancreatitis risk 
Gut  2012;62(11):1616-1624.
The digestive enzyme chymotrypsin C (CTRC) protects against pancreatitis by promoting degradation of trypsinogen and thereby curtailing potentially harmful trypsinogen activation. Loss-of-function variants in CTRC increase the risk for chronic pancreatitis. The aim of the present study was to perform comprehensive functional analysis of all missense CTRC variants identified to date.
We investigated secretion, activity and degradation of 27 published and 5 novel CTRC mutants. We also assessed the effect of 5 mutants on endoplasmic reticulum (ER) stress.
None of the mutants exhibited a gain of function such as increased secretion or activity. In contrast, 11 mutants showed marked loss of function, 3 mutants had moderate functional defects, whereas 18 mutants were functionally similar to wild-type CTRC. The functional deficiencies observed were diminished secretion, impaired catalytic activity and degradation by trypsin. Mutants with a secretion defect caused ER stress that was proportional to the loss in secretion. ER stress was not associated with loss-of-function phenotypes related to catalytic defect or proteolytic instability.
Pathogenic CTRC variants cause loss of function by three distinct but mutually non-exclusive mechanisms that affect secretion, activity and proteolytic stability. ER stress may be induced by a subset of CTRC mutants but does not represent a common pathological mechanism of CTRC variants. This phenotypic dataset should aid in the classification of the clinical relevance of CTRC variants identified in patients with chronic pancreatitis.
PMCID: PMC3660471  PMID: 22942235
chronic pancreatitis; chymotrypsin C; trypsinogen; trypsin; endoplasmic reticulum stress
18.  CCL20 mediates lipopolysaccharide induced liver injury and is a potential driver of inflammation and fibrosis in alcoholic hepatitis 
Gut  2014;63(11):1782-1792.
Chemokines are known to play an important role in the pathophysiology of alcoholic hepatitis (AH), a form of acute-on-chronic liver injury frequently mediated by gut derived lipopolysaccharide (LPS). In our study, we hypothesise that chemokine CCL20, one of the most upregulated chemokines in patients with AH, is implicated in the pathogenesis of AH by mediating LPS induced liver injury.
CCL20 gene expression and serum levels and their correlation with disease severity were assessed in patients with AH. Cellular sources of CCL20 and its biological effects were evaluated in vitro and in vivo in chronic, acute and acute-on-chronic experimental models of carbon tetrachloride and LPS induced liver injury. RNA interference technology was used to knockdown CCL20 in vivo.
CCL20 hepatic and serum levels were increased in patients with AH and correlated with the degree of fibrosis, portal hypertension, endotoxaemia, disease severity scores and short term mortality. Moreover, CCL20 expression was increased in animal models of liver injury and particularly under acute-on-chronic conditions. Macrophages and hepatic stellate cells (HSCs) were identified as the main CCL20 producing cell types. Silencing CCL20 in vivo reduced LPS induced aspartate aminotransferase and lactate dehydrogenase serum levels and hepatic proinflammatory and profibrogenic genes. CCL20 induced proinflammatory and profibrogenic effects in cultured primary HSCs.
Our results suggest that CCL20 upregulation is strongly associated with LPS and may not only represent a new potential biomarker to predict outcome in patients with AH but also an important mediator linking hepatic inflammation, injury and fibrosis in AH.
PMCID: PMC4092046  PMID: 24415562
19.  Postinduction serum infliximab trough level and decrease of C-reactive protein level are associated with durable sustained response to infliximab: a retrospective analysis of the ACCENT I trial 
Gut  2014;63(11):1721-1727.
Serum infliximab trough levels correlate with efficacy; dose escalation is often beneficial in patients with Crohn's disease who stop responding to infliximab treatment.
To carry out a post hoc analysis of A Crohn's Disease Clinical Trial Evaluating Infliximab in a New Long-term Treatment Regimen I (ACCENT I) to evaluate the association between serum infliximab trough levels and C-reactive protein (CRP) after 14 weeks of induction treatment with durable sustained long-term response (Crohn's Disease Activity Index decrease ≥70 points and reduction ≥25% from baseline).
ACCENT I was a multicentre, randomised, placebo-controlled study. Week 14 trough levels and CRP percentage decrease from baseline to week 14 were compared between patients with and without durable sustained response through week 54. Sensitivity and specificity were determined to predict durable sustained response. Receiver operating characteristic (ROC) curves identified optimal cut-off points; logistic regression determined ORs.
After induction with 5 mg/kg infliximab, 25% (37/147) and 33% (47/144) of patients sustained week 14 response to infliximab 5 or 10 mg/kg, respectively, administered every 8 weeks without dose escalation, through week 54. Median week 14 trough levels of patients with and without durable sustained response to infliximab 5 mg/kg were 4.0 and 1.9 μg/mL, respectively (p=0.0331). Optimal predictors of durable sustained response to maintenance infliximab 5 mg/kg were week 14 trough level ≥3.5 µg/mL and ≥60% CRP decrease (ORs (95% CI), 3.5 (1.1 to 11.4) and 7.3 (1.4 to 36.7)), respectively, in patients with raised baseline CRP (>8.0 mg/L); area under the ROC curve was 0.75 for both predictors. A ≥3.5 µg/mL week 14 infliximab serum level did not predict durable sustained response to 10 mg/kg maintenance infliximab.
Patients with durable sustained response to maintenance infliximab 5 mg/kg had higher postinduction trough levels than patients without durable sustained response. Serum infliximab trough levels ≥3.5 µg/mL and ≥60% CRP decrease were significantly associated with durable sustained response.
PMCID: PMC4215276  PMID: 24474383
20.  LncRNA profile study reveals a three-lncRNA signature associated with the survival of patients with oesophageal squamous cell carcinoma  
Gut  2014;63(11):1700-1710.
Oesophageal cancer is one of the most deadly forms of cancer worldwide. Long non-coding RNAs (lncRNAs) are often found to have important regulatory roles.
To assess the lncRNA expression profile of oesophageal squamous cell carcinoma (OSCC) and identify prognosis-related lncRNAs.
LncRNA expression profiles were studied by microarray in paired tumour and normal tissues from 119 patients with OSCC and validated by qRT-PCR. The 119 patients were divided randomly into training (n=60) and test (n=59) groups. A prognostic signature was developed from the training group using a random Forest supervised classification algorithm and a nearest shrunken centroid algorithm, then validated in a test group and further, in an independent cohort (n=60). The independence of the signature in survival prediction was evaluated by multivariable Cox regression analysis.
LncRNAs showed significantly altered expression in OSCC tissues. From the training group, we identified a three-lncRNA signature (including the lncRNAs ENST00000435885.1, XLOC_013014 and ENST00000547963.1) which classified the patients into two groups with significantly different overall survival (median survival 19.2 months vs >60 months, p<0.0001). The signature was applied to the test group (median survival 21.5 months vs >60 months, p=0.0030) and independent cohort (median survival 25.8 months vs >48 months, p=0.0187) and showed similar prognostic values in both. Multivariable Cox regression analysis showed that the signature was an independent prognostic factor for patients with OSCC. Stratified analysis suggested that the signature was prognostic within clinical stages.
Our results suggest that the three-lncRNA signature is a new biomarker for the prognosis of patients with OSCC, enabling more accurate prediction of survival.
PMCID: PMC4215280  PMID: 24522499
Oesophageal Cancer
21.  An analysis of the learning curve to achieve competency at colonoscopy using the JETS database 
Gut  2014;63(11):1746-1754.
The number of colonoscopies required to reach competency is not well established. The primary aim of this study was to determine the number of colonoscopies trainees need to perform to attain competency, defined by a caecal intubation rate (CIR) ≥90%. As competency depends on completion, we also investigated trainee factors that were associated with colonoscopy completion.
The Joint Advisory Group on GI Endoscopy in the UK has developed a trainee e-portfolio from which colonoscopy data were retrieved. Inclusion criteria were all trainees who had performed a total of ≥20 colonoscopies and had performed ≤50 colonoscopies prior to submission of data to the e-portfolio. The primary outcome measure was colonoscopy completion. The number of colonoscopies required to achieve CIR ≥90% was calculated by the moving average method and learning curve cumulative summation (LC-Cusum) analysis. To determine factors which determine colonoscopy completion, a mixed effect logistic regression model was developed which allowed for nesting of patients within trainees and nesting of patients within hospitals, with various patient, trainee and training factors entered as fixed effects.
297 trainees undertook 36 730 colonoscopies. By moving average analysis, the cohort of trainees reached a CIR of 90% at 233 procedures. By LC-Cusum analysis, 41% of trainees were competent after 200 procedures. Of the trainee factors, the number of colonoscopies, intensity of training and previous flexible sigmoidoscopy experience were significant factors associated with colonoscopy completion.
This is the largest study to date investigating the number of procedures required to achieve competency in colonoscopy. The current training certification benchmark in the UK of 200 procedures does not appear to be an inappropriate minimum requirement. The LC-Cusum chart provides real time feedback on individual learning curves for trainees. The association of training intensity and flexible sigmoidoscopy experience with colonoscopy completion could be exploited in training programmes.
PMCID: PMC4215302  PMID: 24470280
22.  Acid-suppressive medications and risk of oesophageal adenocarcinoma in patients with Barrett’s oesophagus: a systematic review and meta-analysis 
Gut  2013;63(8):1229-1237.
Background and aims
Acid-suppressive medications, particularly proton pump inhibitors (PPIs), may decrease the risk of oesophageal adenocarcinoma (OAC) in patients with Barrett’s oesophagus (BO). We performed a systematic review with meta-analysis of studies evaluating the association between acid-suppressive medications (PPIs and histamine receptor antagonists (H2RAs)) and risk of OAC or high-grade dysplasia (BO-HGD) in patients with BO.
We performed a systematic search of multiple electronic databases and conference proceedings up to June 2013 to identify studies reporting the association between use of acid-suppressive medications and risk of OAC and/or BO-HGD in patients with BO. Summary ORs with 95% CIs were estimated.
We identified seven observational studies (2813 patients with BO, 317 cases of OAC or BO-HGD, 84.4% PPI users). On meta-analysis, PPI use was associated with a 71% reduction in risk of OAC and/or BO-HGD in patients with BO (adjusted OR 0.29; 95% CI 0.12 to 0.79). There was a trend towards a dose–response relationship with PPI use for >2–3 years protective against OAC or BO-HGD (three studies; PPI use >2–3 years vs <2–3 years: OR 0.45 (95% CI 0.19 to 1.06) vs 1.09 (0.47 to 2.56)). Considerable heterogeneity was observed. Two studies reported the association between H2RA use and risk of OAC and/or BO-HGD (1352 patients with BO, 156 cases of OAC, 25.4% on H2RAs), and both studies did not show a significant effect.
Based on meta-analysis of observational studies, the use of PPIs is associated with a decreased risk of OAC and/or BO-HGD in patients with BO. None of the studies showed an increased risk of OAC. PPI use should be considered in BO, and chemopreventive trials of PPIs in patients with BO are warranted.
PMCID: PMC4199831  PMID: 24221456
23.  Maternal B vitamin supplementation from preconception through weaning suppresses intestinal tumorigenesis in Apc1638N mouse offspring 
Gut  2011;60(12):1695-1702.
Variations in the intake of folate are capable of modulating colorectal tumorigenesis; however, the outcome appears to be dependent on timing. This study sought to determine the effect of altering folate (and related B vitamin) availability during in-utero development and the suckling period on intestinal tumorigenesis.
Female wildtype mice were fed diets either mildly deficient, replete or supplemented with vitamins B2, B6, B12 and folate for 4 weeks before mating to Apc1638N males. Females remained on their diet throughout pregnancy and until weaning. After weaning, all Apc1638N offspring were maintained on replete diets for 29 weeks.
At 8 months of age tumour incidence was markedly lower among offspring of supplemented mothers (21%) compared with those of replete (59%) and deficient (55%) mothers (p=0.03). Furthermore, tumours in pups born to deficient dams were most likely to be invasive (p=0.03). The expression of Apc, Sfrp1, Wif1 and Wnt5a—all of which are negative regulatory elements of the Wnt signalling cascade—in the normal small intestinal mucosa of pups decreased with decreasing maternal B vitamin intake, and for Sfrp1 this was inversely related to promoter methylation. β-Catenin protein was elevated in offspring of deficient dams.
These changes indicate a de-repression of the Wnt pathway in pups of deficient dams and form a plausible mechanism by which maternal B vitamin intake modulates tumorigenesis in offspring. These data indicate that maternal B vitamin supplementation suppresses, while deficiency promotes, intestinal tumorigenesis in Apc1638N offspring.
PMCID: PMC4193343  PMID: 21659408
24.  MTG16 contributes to colonic epithelial integrity in experimental colitis 
Gut  2012;62(10):1446-1455.
The myeloid translocation genes (MTGs) are transcriptional corepressors with both Mtg8−/− and Mtgr1−/− mice showing developmental and/or differentiation defects in the intestine. We sought to determine the role of MTG16 in intestinal integrity.
Baseline and stress induced colonic phenotypes were examined in Mtg16−/− mice. To unmask phenotypes, we treated Mtg16−/− mice with dextran sodium sulphate (DSS) or infected them with Citrobacter rodentium and the colons were examined for ulceration and for changes in proliferation, apoptosis and inflammation.
Mtg16−/− mice have altered immune subsets, suggesting priming towards Th1 responses. Mtg16−/− mice developed increased weight loss, diarrhoea, mortality and histological colitis and there were increased innate (Gr1+, F4/80+, CD11c+ and MHCII+; CD11c+) and Th1 adaptive (CD4) immune cells in Mtg16−/− colons after DSS treatment. Additionally, there was increased apoptosis and a compensatory increased proliferation in Mtg16−/− colons. Compared with wild-type mice, Mtg16−/− mice exhibited increased colonic CD4;IFN-γ cells in vehicle-treated and DSS-treated mice. Adoptive transfer of wildtype marrow into Mtg16−/− recipients did not rescue the Mtg16−/− injury phenotype. Isolated colonic epithelial cells from DSS-treated Mtg16−/− mice exhibited increased KC (Cxcl1) mRNA expression when compared with wild-type mice. Mtg16−/− mice infected with C rodentium had more severe colitis and greater bacterial colonisation. Last, MTG16 mRNA levels were reduced in human ulcerative colitis versus normal colon tissues.
These observations indicate that MTG16 is critical for colonocyte survival and regeneration in response to intestinal injury and provide evidence that this transcriptional corepressor regulates inflammatory recruitment in response to injury.
PMCID: PMC3663894  PMID: 22833394
25.  Advances in inflammatory bowel disease pathogenesis: linking host genetics and the microbiome 
Gut  2013;62(10):10.1136/gutjnl-2012-303954.
Studies of the genetics underlying inflammatory bowel diseases (IBD) have increased our understanding of the pathways involved in both ulcerative colitis (UC) and Crohn’s disease (CD) and focused attention on the role of the microbiome in these diseases. Full understanding of pathogenesis will require a comprehensive grasp of the delicate homeostasis between gut bacteria and the human host. In this review we present current evidence of microbiome-gene interactions in the context of other known risk factors and mechanisms, and describe the next steps necessary to pair genetic variant and microbiome sequencing data from patient cohorts. We discuss the concept of dysbiosis, proposing that the functional composition of the gut microbiome may provide a more consistent definition of dysbiosis and may more readily provide evidence of genome-microbiome interactions in future exploratory studies.
PMCID: PMC3822528  PMID: 24037875
Inflammation; inflammatory bowel disease; dysbiosis; genetics; genome-wide association studies; metagenomics; microbiome

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