Upadacitinib Reduces Crohn's Disease Symptoms Within the First Week of Induction Therapy.

BACKGROUND & AIMS: Upadacitinib (UPA), an oral Janus kinase inhibitor, is approved to treat moderately to severely active Crohn's disease (CD). Because symptomatic response is an important initial treatment goal for patients, we evaluated the rapidity of symptomatic improvement in patients with CD receiving UPA 45 mg once daily (UPA45) induction therapy. METHODS: This post hoc analysis included pooled data from 2 phase 3, multicenter, double-blind, 12-week induction trials (U-EXCEL and U-EXCEED) and 1 maintenance trial (U-ENDURE). Daily diary data for the first 15 days of UPA45 or placebo (PBO) treatment were used to analyze improvement in very soft/liquid stool frequency (SF) and abdominal pain score (APS). Clinical outcomes were evaluated at every study visit. RESULTS: Overall, 1021 patients (n = 674 UPA45; n = 347 PBO) were analyzed. UPA45 demonstrated greater efficacy vs PBO for SF <3 and APS ≤1, providing rapid relief by day 5 or 6, regardless of prior biologic exposure. Mean changes in SF and APS were greater with UPA45 beginning at week 2 (-2.0 and -0.5, respectively; P < .001) and were maintained through week 12 (-3.0 and -1.0, respectively; P < .001) vs PBO. The first achievement of daily SF/APS clinical remission occurred earlier with UPA45 (median, 13 d) vs PBO (median, 32 d), and patients treated with UPA45 showed improved rates of SF/APS clinical remission (21.1% UPA45 vs 8.9% PBO) and clinical response (58.8% UPA45 vs 37.9% PBO) starting at week 2 (both P ≤ .01). CONCLUSIONS: UPA45 provided rapid relief of clinical symptoms within the first week of treatment in patients with CD. CLINICALTRIALS: gov numbers: NCT03345849, NCT03345836, and NCT03345823.

Human Leukocyte Antigen Signatures as Pathophysiological Discriminants of Microscopic Colitis Subtypes.

BACKGROUND AND AIMS: Microscopic colitis [MC] is currently regarded as an inflammatory bowel disease that manifests as two subtypes: collagenous colitis [CC] and lymphocytic colitis [LC]. Whether these represent a clinical continuum or distinct entities is, however, an open question. Genetic investigations may contribute important insight into their respective pathophysiologies. METHODS: We conducted a genome-wide association study [GWAS] meta-analysis in 1498 CC, 373 LC patients, and 13 487 controls from Europe and the USA, combined with publicly available MC GWAS data from UK Biobank and FinnGen [2599 MC cases and 552 343 controls in total]. Human leukocyte antigen [HLA] alleles and polymorphic residues were imputed and tested for association, including conditional analyses for the identification of key causative variants and residues. Genetic correlations with other traits and diagnoses were also studied. RESULTS: We detected strong HLA association with CC, and conditional analyses highlighted the DRB1*03:01 allele and its residues Y26, N77, and R74 as key to this association (best p = 1.4 × 10-23, odds ratio [OR] = 1.96). Nominally significant genetic correlations were detected between CC and pneumonia [rg = 0.77; p = 0.048] and oesophageal diseases [rg = 0.45, p = 0.023]. An additional locus was identified in MC GWAS analyses near the CLEC16A and RMI2 genes on chromosome 16 [rs35099084, p = 2.0 × 10-8, OR = 1.31]. No significant association was detected for LC. CONCLUSION: Our results suggest CC and LC have distinct pathophysiological underpinnings, characterised by an HLA predisposing role only in CC. This challenges existing classifications, eventually calling for a re-evaluation of the utility of MC umbrella definitions.

Downregulated Mucosal Autophagy, Alpha Kinase-1 and IL-17 Signaling Pathways in Active and Quiescent Ulcerative Colitis.

Background: Improved mucosal immune profiling in active and quiescent colonic inflammatory bowel disease (IBD) is needed to develop therapeutic options for treating and preventing flares. This study therefore aimed to provide a comprehensive mucosal characterization with emphasis on immunological host response of patients with active ulcerative colitis (UC active), UC during remission (UC remission) and active colonic Crohn's disease (CD active). Methods: Colonic biopsies from 47 study subjects were collected for gene expression and pathway analyses using the NanoString host-response panel, including 776 genes and 56 immune-related pathways. Results: The majority of mucosal gene expression and signaling pathway scores were increased in active IBD (n=27) compared to healthy subjects (n=10). However, both active IBD and UC remission (n=10) demonstrated decreased gene expression and signaling pathway scores related to autophagy, alpha kinase-1 and IL-17 signaling pathways compared to healthy subjects. Further, UC remission was characterized by decreased scores of several signaling pathways linked to homeostasis along with increased mononuclear cell migration pathway score as compared to healthy subjects. No major differences in the colonic mucosal gene expression between CD active (n=7) and UC (n=20) active were observed. Conclusion: This study indicates that autophagy, alpha kinase-1 and IL-17 signaling pathways are persistently downregulated in UC irrespective of disease activity. Further, UC patients in remission present a unique mucosal environment, potentially preventing patients from reaching and sustaining true homeostasis. These findings may enable better comprehension of the remitting and relapsing pattern of colonic IBD and guide future treatment and prevention of flares.

Age determines the risk of familial inflammatory bowel disease-A nationwide study.

BACKGROUND AND AIMS: To estimate familial aggregation of inflammatory bowel disease (IBD), we performed a nationwide, case-control study and examined the odds for patients with IBD (vs controls) to have a first-degree relative (FDR) with IBD, by age of diagnosis, type of family history and IBD subtype. To assess the incidence of future IBD in relatives of incident IBD patients, we performed a cohort study. METHODS: Individuals diagnosed with IBD (N = 50,667) between 2003 and 2017 with at least one FDR were identified from Swedish national registers and compared to general population controls (N = 506,720) with at least one FDR. We used logistic regression to calculate adjusted odds ratios (ORs) and Cox regression to estimate hazard ratios (HRs). RESULTS: Compared to controls, IBD cases more often had a mother (3.0% vs 0.9%, OR = 3.5; 95% CI: 3.3-3.7), father (2.9% vs 0.8%, OR = 3.5; 95% CI: 3.3-3.7), full sibling (5.3% vs 1.5%, OR = 3.6; 95% CI: 3.4-3.8) and child (2.4% vs 0.9%, OR = 2.6; 95% CI: 2.4-2.8) with IBD. The strength of association increased with the number of affected FDRs and was modified by subtype of IBD and age of diagnosis. Highest ORs were observed for paediatric IBD among paediatric-onset Crohn's disease (OR = 10.6; 95% CI: 8.2-13.5) and paediatric-onset ulcerative colitis (OR = 8.4; 95% CI: 6.4-10.9) cases. The 10-year cumulative incidence of IBD was 1.7% in full-siblings of incident IBD patients vs 0.4% among full-siblings of reference individuals. CONCLUSION: The variations in the strength of familial IBD and future risk of IBD in FDRs support differences in genetic predisposition and call for targeted approaches in potential screening programmes.

Detailed Transcriptional Landscape of Peripheral Blood Points to Increased Neutrophil Activation in Treatment-Naïve Inflammatory Bowel Disease.

BACKGROUND AND AIMS: Inflammatory bowel disease [IBD] is a chronic relapsing disorder of the gastrointestinal tract, which generally manifests as Crohn's disease [CD] or ulcerative colitis [UC]. These subtypes are heterogeneous in terms of disease location and histological features, while sharing common clinical presentation, genetic associations and, thus, common immune regulatory pathways. METHODS: Using miRNA and mRNA coupled transcriptome profiling and systems biology approaches, we report a comprehensive analysis of blood transcriptomes from treatment-naïve [n = 110] and treatment-exposed [n = 177] IBD patients as well as symptomatic [n = 65] and healthy controls [n = 95]. RESULTS: Broadly, the peripheral blood transcriptomes of CD and UC patients were similar. However, there was an extensive gene deregulation in the blood of IBD patients, while only a slight deregulation in symptomatic controls, when compared with healthy controls. The deregulated mRNAs and miRNAs are mainly involved in the innate immunity and are especially enriched in neutrophil activation-related pathways. Oxidative phosphorylation and neutrophil activation-related modules were found to be differentially co-expressed among treatment-naïve IBD as compared to healthy controls. In the deregulated neutrophil activation-related co-expression module, IL1B was identified as the central gene. Levels of co-expression among IL1B and chemosensing receptor [CXCR1/2 and FPR1/2] genes were reduced in the blood of IBD patients when compared with healthy controls. CONCLUSIONS: Immune dysregulation seen in peripheral blood transcriptomes of treatment-naïve IBD patients is mainly driven by neutrophil activation.

Older age is a risk factor for inadequate energy intake during acute, severe IBD and is associated with shorter time to relapse.

BACKGROUND: Effects of nutritional intake on inflammatory bowel disease (IBD) flare resolution are unknown. We hypothesised that nutritional factors during hospitalisation for acute severe IBD are associated with risk of subsequent relapse. We also studied risk factors for inadequate energy intake. METHODS: Patients admitted to the Karolinska Hospital Gastroenterology ward with IBD flare during 2015-2016 were retrospectively identified. In total, 91 patients were included. Data on nutrition, disease factors, inflammatory markers, and daily energy requirement were extracted. Requirement of new systemic steroid prescription, intensification of biological therapy, readmission, surgery, and calprotectin level were individually used as proxies for disease relapse. Follow-up was one year after discharge. Adjustments for age and sex were made where appropriate. RESULTS: Overall, 19%, 31%, and 45% of patients had days with energy intake <30, <50, and <70% of calculated requirement. Older age was associated with a higher number of days with energy intake <30, <50, and <70% of calculated requirement (regression coefficient 0.03, 0.04, 0.06 respectively, p = .012, .017, .008). The number of days with energy intake <30 and <70% of the calculated requirement and the length of the hospitalisation were associated with shorter time to new steroid prescription (hazard ratio 1.3, 1.1, 1.04 respectively, p = .016, .034, .011). CRP and calprotectin were not associated with relapse. CONCLUSION: Older age is a predictor of inadequate energy intake during hospitalisation for acute severe IBD. Inadequate energy intake adjusted for age and sex during IBD flare was better predictor of time to the next steroid-requiring relapse than inflammatory markers.

Serum zonulin in patients with inflammatory bowel disease: a pilot study.

BACKGROUND: In recent years it has been supposed that impaired intestinal permeability represents an early event preceding the onset of inflammatory bowel disease (IBD). Since zonulin has been proposed as a biomarker of intestinal permeability, we investigated its role in patients with IBD and the correlation between serum and fecal zonulin. METHODS: A total of 118 IBD patients (86 Crohn's disease [CD] and 32 ulcerative colitis [UC]) and 23 healthy controls (HC) were prospectively enrolled. A serum sample was collected for all the subjects included in the study. A stool specimen collected in the same day of blood drawing was available for a subgroup of 33 IBD patients. Serum and fecal zonulin were tested by ELISA. Non-parametric statistical tests were used for data analysis. RESULTS: Serum zonulin concentration was higher in IBD patients compared to HC (34.5 [26.5-43.9] ng/mL vs. 8.6 [6.5-12.0] ng/mL, P<0.001) showing an area under the curve of 0.98 for their discrimination. No difference in serum zonulin concentration was observed between patients with CD and those with UC (P=0.074). An inverse correlation was observed between serum zonulin concentration and disease duration (rs=-0.30, P=0.001); no correlation was observed between serum and fecal zonulin (rs=0.15, P=0.394). CONCLUSIONS: Serum zonulin is highly sensitive for the evaluation of intestinal permeability in IBD patients. There is no correlation between zonulin values in serum and feces.

Female-Specific Association Between Variants on Chromosome 9 and Self-Reported Diagnosis of Irritable Bowel Syndrome.

BACKGROUND & AIMS: Genetic factors are believed to affect risk for irritable bowel syndrome (IBS), but there have been no sufficiently powered and adequately sized studies. To identify DNA variants associated with IBS risk, we performed a genome-wide association study (GWAS) of the large UK Biobank population-based cohort, which includes genotype and health data from 500,000 participants. METHODS: We studied 7,287,191 high-quality single nucleotide polymorphisms in individuals who self-reported a doctor's diagnosis of IBS (cases; n = 9576) compared to the remainder of the cohort (controls; n = 336,499) (mean age of study subjects, 40-69 years). Genome-wide significant findings were further investigated in 2045 patients with IBS from tertiary centers and 7955 population controls from Europe and the United States, and a small general population sample from Sweden (n = 249). Functional annotation of GWAS results was carried out by integrating data from multiple biorepositories to obtain biological insights from the observed associations. RESULTS: We identified a genome-wide significant association on chromosome 9q31.2 (single nucleotide polymorphism rs10512344; P = 3.57 × 10-8) in a region previously linked to age at menarche, and 13 additional loci of suggestive significance (P < 5.0×10-6). Sex-stratified analyses revealed that the variants at 9q31.2 affect risk of IBS in women only (P = 4.29 × 10-10 in UK Biobank) and also associate with constipation-predominant IBS in women (P = .015 in the tertiary cohort) and harder stools in women (P = .0012 in the population-based sample). Functional annotation of the 9q31.2 locus identified 8 candidate genes, including the elongator complex protein 1 gene (ELP1 or IKBKAP), which is mutated in patients with familial dysautonomia. CONCLUSIONS: In a sufficiently powered GWAS of IBS, we associated variants at the locus 9q31.2 with risk of IBS in women. This observation may provide additional rationale for investigating the role of sex hormones and autonomic dysfunction in IBS.

Dense genotyping of immune-related loci identifies HLA variants associated with increased risk of collagenous colitis.

OBJECTIVE: Collagenous colitis (CC) is a major cause of chronic non-bloody diarrhoea, particularly in the elderly female population. The aetiology of CC is unknown, and still poor is the understanding of its pathogenesis. This possibly involves dysregulated inflammation and immune-mediated reactions in genetically predisposed individuals, but the contribution of genetic factors to CC is underinvestigated. We systematically tested immune-related genes known to impact the risk of several autoimmune diseases for their potential CC-predisposing role. DESIGN: Three independent cohorts of histologically confirmed CC cases (N=314) and controls (N=4299) from Sweden and Germany were included in a 2-step association analysis. Immunochip and targeted single nucleotide polymorphism (SNP) genotype data were produced, respectively, for discovery and replication purposes. Classical human leucocyte antigen (HLA) variants at 2-digit and 4-digit resolution were obtained via imputation from single marker genotypes. SNPs and HLA variants passing quality control filters were tested for association with CC with logistic regression adjusting for age, sex and country of origin. RESULTS: Forty-two markers gave rise to genome-wide significant association signals, all contained within the HLA region on chromosome 6 (best p=4.2×10-10 for SNP rs4143332). Among the HLA variants, most pronounced risk effects were observed for 8.1 haplotype alleles including DQ2.5, which was targeted and confirmed in the replication data set (p=2.3×10-11; OR=2.06; 95% CI (1.67 to 2.55) in the combined analysis). CONCLUSIONS: HLA genotype associates with CC, thus implicating HLA-related immune mechanisms in its pathogenesis.

Downregulation of MicroRNA-21 in Colonic CD3+ T Cells in UC Remission.

BACKGROUND: In active inflammatory bowel disease (IBD), microRNA expression profiling consistently features disease-specific signatures, and microRNA-21 (miR-21) has been shown to be upregulated in the inflamed colon of patients with active ulcerative colitis (UC). However, the cellular sources of miR-21 expression in IBD tissues have not yet been identified. We sought to determine the expression levels of miR-21 and one of its downstream target genes, programmed cell death 4 (PDCD4), in CD3 T cells isolated from the colonic mucosa of patients with active IBD, inactive IBD, and non-IBD controls. METHODS: Colonic biopsies were treated with collagenase V. CD3 T cells were isolated using MACS CD3 positive selection. Total RNA was converted to cDNA. Real-time PCR reactions were performed with PCR primers for miR-21, SNORD95, PDCD4, and GAPDH. RESULTS: The expression of miR-21 was statistically significantly downregulated in CD3 T cells from patients with UC in remission as compared to active disease (P = 0.0193). miR-21 negatively regulates PDCD4 expression. As predicted, the mRNA level of PCDC4 in CD3 T cells was upregulated in UC and Crohn's disease in remission as compared to active disease (UC active versus UC remission: P = 0.0008, Crohn's disease active versus Crohn's disease remission: P = 0.0215) and in patients with UC in remission as compared to healthy controls (P = 0.0226). CONCLUSIONS: Although miR-21 expression is downregulated, PDCD4 is upregulated in CD3 T cells during the remission phase of UC. Our results indicate that miR-21 and related pathways in colonic T cells may play a role in limiting pathogenic T-cell responses and may constitute future target candidates to induce remission in UC.

Prevalence and prognostic value of hepatic histological alterations in patients with Crohn's disease.

UNLABELLED: Variable degrees of liver histological changes in patients with Crohn's disease (CD) have been reported. OBJECTIVE: To evaluate the liver histological alterations and their prognostic significance in patients affected by CD without abnormalities of liver biochemical parameters and ultrasound features. MATERIAL AND METHODS: A prospective, single-blind study, including 35 consecutive patients with CD that underwent bowel resection with a contemporary performance of liver biopsy from 1992 to 2003. EXCLUSION CRITERIA: the presence of standard causes of liver disease, such as alcohol consumption exceeding 20 g/day, primary sclerosing cholangitis, viral infections, celiac disease, metabolic syndrome and alterations of the metabolism. Patients were followed up with regular evaluation of hepatic cytolysis, cholestasis, synthesis and ultrasound performance. After a mean interval of 14 years (from May to December 2013), liver fibrosis was assessed by Fibroscan®. RESULTS: Histological alterations were shown in 60% of patients, without serious liver injuries (no case of inflammation or significant fibrosis). Fibroscan® was performed in 33 subjects and no significant changes were observed (mean value of liver stiffness: 5.2 ± 1.2 kPa). The minimal microscopic damage did not evolve either in patients with a normal histology or in those with an altered histology at baseline (p = 0.9). Only patients who took azathioprine had a statistically significant increase of liver stiffness values (5.7 ± 1.5 kPa vs 4.7 ± 1.3 kPa, p = 0.017). CONCLUSIONS: Patients with CD do not need additional examinations compared to the general population, unless clinical or biochemical abnormalities are found.

Glucose breath test and Crohn's disease: Diagnosis of small intestinal bacterial overgrowth and evaluation of therapeutic response.

OBJECTIVE: Small intestinal bacterial overgrowth (SIBO) is characterized by an abnormal proliferation of bacterial species in the small bowel. It has been shown that patients with Crohn's disease (CD) have a higher risk of SIBO development. The aim of the present study was to investigate SIBO prevalence in CD patients, possible clinical predictors of SIBO development and response to antibiotic therapy. MATERIAL AND METHODS: Sixty-eight patients (42 male, 26 female; mean age 49.3 ± 12.8 years) with CD reporting abdominal complaints were prospectively evaluated for SIBO with H2/CH4 glucose breath test (GBT). RESULTS: Of the 68 patients enrolled, 18 (26.5%) tested positive for SIBO. Patients with SIBO exhibited increased stool frequency and significant reduction of stool solidity (p = 0.014), were older than patients tested negative to GBT (54.3 ± 13.0 years vs. 47.5 ± 12.3 years, p = 0.049), reported a longer history of CD (21.2 ± 10.3 years vs. 15.7 ± 10.2 years, p = 0.031) and showed a significant higher frequency of prior surgery (p = 0.001), revealing an association of number of surgical procedures (OR = 2.8315, 95% CI = 1.1525-6.9569, p = 0.023) with SIBO. Breath test normalization occurred in 13/15 patients evaluated after antibiotic and probiotic therapy. Although vitamin B12 levels were lower in patients with SIBO (p = 0.045) and a significant improvement was found after treatment (p = 0.011), this could be due to the heterogeneity, regarding vitamin B12 treatment, in our cohort. CONCLUSION: SIBO is a frequent but underestimated condition in CD, which often mimics acute flare, effectively identified with GBT and could be treated with a combined antibiotic and probiotic therapy.

Power Doppler sonography to predict the risk of surgical recurrence of Crohn's disease.

PURPOSE: The aim of this work is to investigate the role of power Doppler sonography as an additional predictor of surgical recurrence in Crohn's disease. METHODS: A sample of 33 patients, with ileal or ileocolonic Crohn's disease, that had underwent intestinal resection, were retrospectively enrolled. All patients had bowel ultrasonography 7-16 months after resection. Power Doppler sonography of the preanastomotic ileum was evaluated as a possible prognostication tool to assess the risk of long-term need for reoperation. RESULTS: The absolute incidence of surgical recurrence in those who had a positive power Doppler was 42 %, while that of those who had a negative power Doppler was 28.6 %. Combining the power Doppler with bowel wall thickness, the surgical recurrence risk grew from 41.2 % of those with a positive power Doppler and thickness >3 mm to 55.6 % of those with a positive power Doppler and thickness >6 mm. CONCLUSIONS: Power Doppler look to be another useful prediction tool for the personalization of patient's care. It could be useful to perform power Doppler in all patients with a wall thickness >5 mm: for those who have a positive power Doppler it may be indicated as a more aggressive prophylactic therapy.

Exploring the genetics of irritable bowel syndrome: a GWA study in the general population and replication in multinational case-control cohorts.

OBJECTIVE: IBS shows genetic predisposition, but adequately powered gene-hunting efforts have been scarce so far. We sought to identify true IBS genetic risk factors by means of genome-wide association (GWA) and independent replication studies. DESIGN: We conducted a GWA study (GWAS) of IBS in a general population sample of 11,326 Swedish twins. IBS cases (N=534) and asymptomatic controls (N=4932) were identified based on questionnaire data. Suggestive association signals were followed-up in 3511 individuals from six case-control cohorts. We sought genotype-gene expression correlations through single nucleotide polymorphism (SNP)-expression quantitative trait loci interactions testing, and performed in silico prediction of gene function. We compared candidate gene expression by real-time qPCR in rectal mucosal biopsies of patients with IBS and controls. RESULTS: One locus at 7p22.1, which includes the genes KDELR2 (KDEL endoplasmic reticulum protein retention receptor 2) and GRID2IP (glutamate receptor, ionotropic, delta 2 (Grid2) interacting protein), showed consistent IBS risk effects in the index GWAS and all replication cohorts and reached p=9.31×10(-6) in a meta-analysis of all datasets. Several SNPs in this region are associated with cis effects on KDELR2 expression, and a trend for increased mucosal KDLER2 mRNA expression was observed in IBS cases compared with controls. CONCLUSIONS: Our results demonstrate that general population-based studies combined with analyses of patient cohorts provide good opportunities for gene discovery in IBS. The 7p22.1 and other risk signals detected in this study constitute a good starting platform for hypothesis testing in future functional investigations.

Fecal calprotectin is an effective diagnostic tool that differentiates inflammatory from functional intestinal disorders.

BACKGROUND: The clinical pictures of functional gastrointestinal disorders and inflammatory diseases can be quite similar leading to inappropriate and expensive investigations. Objective. To investigate fecal calprotectin (FC) diagnostic performance in different gastrointestinal conditions. MATERIAL AND METHODS: Stool specimens of 66 outpatients referred for colonoscopy were collected for further FC determination. Diagnostic accuracy was assessed by the area under the curve (AUC). Sensitivity (Se), specificity (Sp), positive (PPV), and negative predictive values (NPV) were calculated according to the presence of inflammation and the main final diagnosis. RESULTS: Histological inflammation was found in 45 (68%) patients: 24 had a diagnosis of inflammatory bowel disease (IBD) while 21 reported miscellaneous conditions (5 microscopic colitis, 2 eosinophilic colitis, and 14 nonspecific chronic colitis). The diagnosis in the 21 (32%) patients without inflammation was irritable bowel syndrome (IBS). Median FC values were 268 µg/g (95% CI, 151-343) and 49 µg/g (95% CI, 23-101) in patients with and without inflammation, respectively (p = 0.0001). AUC value of FC was 0.811 (Se = 68.9%, Sp = 71.4%, PPV = 83.8%, and NPV = 56.3% with a cutoff value of 100 µg/g) for discriminating between patients with and without inflammation and 0.931 (Se = 87.5%, Sp = 90.5%, PPV = 91.3%, and NPV = 86.4% with a cutoff value of 150 µg/g) for discriminating between patients with IBS and IBD. Using the cutoff value recommended by the manufacturer (50 µg/g), we found Se =100%, Sp =52.4%, PPV =70.6%, and NPV =100% for the diagnosis of IBD. CONCLUSIONS: FC appears to be a reliable noninvasive biomarker of intestinal inflammation useful to improve the appropriateness of colonoscopy requests.

Germline genetic contributions to risk for esophageal adenocarcinoma, Barrett's esophagus, and gastroesophageal reflux.

BACKGROUND: Esophageal adenocarcinoma (EA) is an increasingly common cancer with poor survival. Barrett's esophagus (BE) is the main precursor to EA, and every year 0.12% to 0.5% of BE patients progress to EA. BE typically arises on a background of chronic gastroesophageal reflux (GERD), one of the risk factors for EA. METHODS: We used genome-wide association data to investigate the genetic architecture underlying GERD, BE, and EA. We applied a method to estimate the variance explained (array heritability, h(2)g) and the genetic correlation (rg) between GERD, BE, and EA by considering all single nucleotide polymorphisms (SNPs) simultaneously. We also estimated the polygenic overlap between GERD, BE, and EA using a prediction approach. All tests were two-sided, except in the case of variance-explained estimation where one-sided tests were used. RESULTS: We estimated a statistically significant genetic variance explained for BE (h(2)g = 35%; standard error [SE] = 6%; one-sided P = 1 × 10(-9)) and for EA (h(2)g = 25 %; SE = 5%; one-sided P = 2 × 10(-7)). The genetic correlation between BE and EA was found to be high (rg = 1.0; SE = 0.37). We also estimated a statistically significant polygenic overlap between BE and EA (one-sided P = 1 × 10(-6)), which suggests, together with the high genetic correlation, that shared genes underlie the development of BE and EA. Conversely, no statistically significant results were obtained for GERD. CONCLUSIONS: We have demonstrated that risk to BE and EA is influenced by many germline genetic variants of small effect and that shared polygenic effects contribute to risk of these two diseases.

Deep resequencing of GWAS loci identifies rare variants in CARD9, IL23R and RNF186 that are associated with ulcerative colitis.

Genome-wide association studies and follow-up meta-analyses in Crohn's disease (CD) and ulcerative colitis (UC) have recently identified 163 disease-associated loci that meet genome-wide significance for these two inflammatory bowel diseases (IBD). These discoveries have already had a tremendous impact on our understanding of the genetic architecture of these diseases and have directed functional studies that have revealed some of the biological functions that are important to IBD (e.g. autophagy). Nonetheless, these loci can only explain a small proportion of disease variance (~14% in CD and 7.5% in UC), suggesting that not only are additional loci to be found but that the known loci may contain high effect rare risk variants that have gone undetected by GWAS. To test this, we have used a targeted sequencing approach in 200 UC cases and 150 healthy controls (HC), all of French Canadian descent, to study 55 genes in regions associated with UC. We performed follow-up genotyping of 42 rare non-synonymous variants in independent case-control cohorts (totaling 14,435 UC cases and 20,204 HC). Our results confirmed significant association to rare non-synonymous coding variants in both IL23R and CARD9, previously identified from sequencing of CD loci, as well as identified a novel association in RNF186. With the exception of CARD9 (OR = 0.39), the rare non-synonymous variants identified were of moderate effect (OR = 1.49 for RNF186 and OR = 0.79 for IL23R). RNF186 encodes a protein with a RING domain having predicted E3 ubiquitin-protein ligase activity and two transmembrane domains. Importantly, the disease-coding variant is located in the ubiquitin ligase domain. Finally, our results suggest that rare variants in genes identified by genome-wide association in UC are unlikely to contribute significantly to the overall variance for the disease. Rather, these are expected to help focus functional studies of the corresponding disease loci.

Role of bowel ultrasound as a predictor of surgical recurrence of Crohn's disease.

BACKGROUND: In Crohn's disease natural history, about 80% of the patients require surgery, which is not curative: unfortunately, the disease recurs in many patients. OBJECTIVE: To investigate the role of intestinal ultrasound to predict the risk of post-operative surgical recurrence in Crohn's disease. MATERIAL AND METHODS: A total of 196 patients, with ileal or ileocolonic Crohn's disease, undergoing intestinal resection, were retrospectively enrolled. All patients underwent bowel ultrasonography 6-15 months after resection. Wall thickness at the anastomosis level was measured, and thickening >3 mm was evaluated as risk factor of long-term need for reoperation. RESULTS: Patients who have a bowel wall thickness >3 mm have an risk ratio (RR) of surgical recurrence = 2.1 [95% confidence interval (CI) = 1.12-3.74] higher than those with a thickness of ≤3 mm. The absolute incidence of new surgical intervention is 13% in patients with thickness of 3 mm, 28% in patients with thickness >3 mm, 29,1% with thickness >4 mm, 34% with thickness >5 mm, and 40% with thickness >6 mm. CONCLUSIONS: Bowel wall thickness >3 mm at ultrasound may be a non-invasive predictor of early surgical recurrence after ileo-colonic resection.