Persistent Diarrhea in Patients With Crohn's Disease After Mucosal Healing Is Associated With Lower Diversity of the Intestinal Microbiome and Increased Dysbiosis

BACKGROUND & AIMS

In patients with inflammatory bowel diseases (IBDs), symptoms do not always associate with the severity of endoscopic inflammation and can persist after mucosal healing. We investigated whether symptoms in patients with successfully treated IBD are related to the composition of the intestinal microbiome.

METHODS

We analyzed 590 tissue biopsy specimens from 215 patients with IBD and 48 healthy individuals (controls). We obtained mucosal biopsy specimens from 2 colon sites (ascending and rectosigmoid) and from the terminal ileum along with clinical data. Bacterial DNA was extracted from the biopsy specimens and the V4 region of 16s ribosomal RNA sequenced by Miseq and processed using the QIIME v1.9 pipeline.

RESULTS

Mucosal biopsy specimens from patients with Crohn's disease (CD) who achieved mucosal healing (Mayo scores of 0-1 or segmental endoscopic severity CD scores of 0-5) had lower Chao1 diversity than biopsy specimens from patients with ulcerative colitis (UC) or unclassified IBD (IBD-U), or controls. After endoscopic evidence of improvement in patients with UC or IBD-U, diversity of the tissue-associated microbiota did not differ significantly from that of controls. Colon biopsy specimens from patients with CD had lower microbial diversity, before and after healing (segmental endoscopic severity CD scores, 0-2), than colon biopsy specimens from controls (P < .002). In patients with CD who achieved mucosal healing, residual clinical activity (CD activity index scores >150; P = .03) and persistent diarrhea were associated with reduced microbial diversity (P = .01). Continued diarrhea was associated with a trend toward dysbiosis, based on the microbial dysbiosis index (P = .059). In patients with UC or IBD-U with moderate to severe inflammation, increasing severity of diarrhea was associated with reduced microbial diversity (P = .03).

CONCLUSIONS

In an analysis of biopsy specimens from patients with IBD and controls, we found that despite endoscopic evidence of improvement or remission, α-diversity of the tissue-associated intestinal microbiome remained lower in patients with CD than in controls. This observation, along with the reduced Chao1 diversity and greater dysbiosis in intestinal microbiota of patients with residual symptoms of IBD, indicates that microbiome composition could be associated with persistent diarrhea.

Clinical Features and Genetic Risk of Demyelination Following Anti-TNF Treatment

BACKGROUND

Anti-TNF exposure has been linked to demyelination events. We sought to describe the clinical features of demyelination events following anti-TNF treatment and to test whether affected patients were genetically predisposed to multiple sclerosis [MS].

METHODS

We conducted a case-control study to describe the clinical features of demyelination events following anti-TNF exposure. We compared genetic risk scores [GRS], calculated using carriage of 43 susceptibility loci for MS, in 48 cases with 1219 patients exposed to anti-TNF who did not develop demyelination.

RESULTS

Overall, 39 [74%] cases were female. The median age [range] of patients at time of demyelination was 41.5 years [20.7-63.2]. The median duration of anti-TNF treatment was 21.3 months [0.5-99.4] and 19 [36%] patients were receiving concomitant immunomodulators. Most patients had central demyelination affecting the brain, spinal cord, or both. Complete recovery was reported in 12 [23%] patients after a median time of 6.8 months [0.1-28.7]. After 33.0 months of follow-up, partial recovery was observed in 29 [55%] patients, relapsing and remitting episodes in nine [17%], progressive symptoms in three [6%]: two [4%] patients were diagnosed with MS. There was no significant difference between MS GRS scores in cases (mean -3.5 × 10-4, standard deviation [SD] 0.0039) and controls [mean -1.1 × 10-3, SD 0.0042] [p = 0.23].

CONCLUSIONS

Patients who experienced demyelination events following anti-TNF exposure were more likely female, less frequently treated with an immunomodulator, and had a similar genetic risk to anti-TNF exposed controls who did not experience demyelination events. Large prospective studies with pre-treatment neuroimaging are required to identify genetic susceptibility loci.

Conducting Translational Gastrointestinal Research in the Era of COVID-19

Spread of the novel coronavirus SARS-CoV-2 has resulted in a global pandemic that is affecting the health and economy of all World Health Organization [WHO] regions. Clinical and translational research activities have been affected drastically by this global catastrophe. In this document we provide a suggested roadmap for resuming gastrointestinal translational research activities, emphasising physical distancing and use of personal protective equipment. We discuss modes of virus transmission in enclosed environments [including clinical workplaces and laboratories] and potential risks of exposure in the endoscopy environment for research staff. The proposed guidelines should be considered in conjunction with local institutional and government guidelines so that translational research can be resumed as safely as possible.

COVID-19 Pandemic: Which IBD Patients Need to Be Scoped-Who Gets Scoped Now, Who Can Wait, and how to Resume to Normal

Endoscopy is an essential component in the management of inflammatory bowel disease [IBD]. There is a risk of SARS-CoV-2 transmission during endoscopic procedures. The International Organization for the study of IBD [IOIBD] has developed 11 position statements, based on an online survey, that focus on how to prioritise endoscopies in IBD patients during the COVID-19 pandemic, alternative modes for disease monitoring, and ways to triage the high number of postponed endoscopies after the pandemic. We propose to pre-screen patients for suspected or confirmed COVID-19 and test for SARS-CoV-2 before endoscopy if available. High priority endoscopies during pandemic include acute gastrointestinal bleed, acute severe ulcerative colitis, new IBD diagnosis, cholangitis in primary sclerosing cholangitis, and partial bowel obstruction. Alternative modes of monitoring using clinical symptoms, serum inflammatory markers, and faecal calprotectin should be considered during the pandemic. Prioritising access to endoscopy in the post-pandemic period should be guided by control of COVID-19 in the local community and availability of manpower and personal protective equipment. Endoscopy should be considered within 3 months after the pandemic for patients with a past history of dysplasia and endoscopic resection for dysplastic lesion. Endoscopy should be considered 3-6 months after the pandemic for assessment of postoperative recurrence or new biologic initiation. Endoscopy can be postponed until after 6 months of pandemic for routine IBD surveillance and assessment of mucosal healing.

Associations of NOD2 polymorphisms with Erysipelotrichaceae in stool of in healthy first degree relatives of Crohn's disease subjects

BACKGROUND

Genetic analyses have identified many variants associated with the risk of inflammatory bowel disease (IBD) development. Among these variants, the ones located within the NOD2 gene have the highest odds ratio of all IBD genetic risk variants. Also, patients with Crohn's disease (CD) have been shown to have an altered gut microbiome, which might be a reflection of inflammation itself or an effect of other parameters that contribute to the risk of the disease. Since NOD2 is an intracellular pattern recognition receptor that senses bacterial peptidoglycan in the cytosol and stimulates the host immune response (Al Nabhani et al., PLoS Pathog 13:e1006177, 2017), it is hypothesized that NOD2 variants represent perfect candidates for influencing host-microbiome interactions. We hypothesized that NOD2 risk variants affect the microbiome composition of healthy first degree relative (FDR) of CD patients and thus potentially contribute to an altered microbiome state before disease onset.

METHODS

Based on this, we studied a large cohort of 1546 healthy FDR of CD patients and performed a focused analysis of the association of three major CD SNPs in the coding region of the NOD2 gene, which are known to confer a 15-40-fold increased risk of developing CD in homozygous or compound heterozygous individuals.

RESULTS

Our results show that carriers of the C allele at rs2066845 was significantly associated with an increase in relative abundance in the fecal bacterial family Erysipelotrichaceae.

CONCLUSIONS

This result suggests that NOD2 polymorphisms contribute to fecal microbiome composition in asymptomatic individuals. Whether this modulation of the microbiome influences the future development of CD remains to be assessed.

Dietary Guidance From the International Organization for the Study of Inflammatory Bowel Diseases

Recent evidence points to a plausible role of diet and the microbiome in the pathogenesis of both Crohn's disease (CD) and Ulcerative Colitis (UC). Dietary therapies based on exclusion of table foods and replacement with nutritional formulas and/or a combination of nutritional formulas and specific table foods may induce remission in CD. In UC, specific dietary components have also been associated with flare of disease. While evidence of varying quality has identified potential harmful or beneficial dietary components, physicians and patients at the present time do not have guidance as to which foods are safe, may be protective or deleterious for these diseases. The current document has been compiled by the nutrition cluster of the International Organization for the Study of Inflammatory Bowel Diseases (IOIBD) based on the best current evidence to provide expert opinion regarding specific dietary components, food groups and food additives that may be prudent to increase or decrease in the diet of patients with inflammatory bowel diseases to control and prevent relapse of inflammatory bowel diseases.

Ulcerative Colitis Patients Continue to Improve Over the First Six Months of Vedolizumab Treatment: 12-Month Clinical and Mucosal Healing Effectiveness

Background

Vedolizumab (VDZ) is a humanized monoclonal IgG1 antibody which inhibits leukocyte vascular adhesion and migration into the gastrointestinal tract through α4β7 integrin blockade.

Aims

We retrospectively assessed the 12-month, real-world efficacy and safety of VDZ as induction and maintenance therapy in adult patients with ulcerative colitis (UC).

Methods

The rates of clinical remission (CR, partial Mayo score < 2), steroid-free clinical remission (SFCR), and mucosal healing were assessed with nonresponder imputation analysis. Baseline independent predictors of clinical remission were investigated, and adverse events were recorded.

Results

We analyzed outcomes in 74 patients; 32% were anti-TNF naïve, 68% had pancolitis, and 46% were on systemic steroids at baseline. At week six, week 14, six months and one year, the CR rates were 26%, 34%, 39% and 39% respectively, and the SFCR rates were 24%, 31%, 38% and 39%, respectively. Among patients not in CR after induction, the probability of remission at six months was 20%. Sustained SFCR between weeks 14 and 52 and between weeks 22 and 52 was found in 69% and 86% of the patients, respectively. Steroid-free clinical remission at 12 months was significantly associated with remission after the induction phase (OR = 30.4; 95% CI, 6 to 150; P < 0.001). Mucosal healing rate at one year was 39%. The most common side effect was headache (7%).

Conclusions

Increasing remission rates were observed over the first six months of VDZ treatment. One-fifth of patients not in remission post-induction achieved remission by six months of continued therapy. Mucosal healing was associated with higher rates of one-year steroid-free remission and VDZ treatment continuation.

Identification of Target Golimumab Levels in Maintenance Therapy of Crohn's Disease and Ulcerative Colitis Associated With Mucosal Healing

INTRODUCTION

Golimumab is approved as a therapy for ulcerative colitis (UC) patients. Recent data also demonstrate efficacy in Crohn's disease (CD); however, little is known about target drug levels to achieve endoscopic remission.

METHODS

We performed a retrospective analysis of IBD patients on maintenance golimumab. Median trough levels were compared using Kruskal-Wallis test, and logistic regression was used to construct a probabilistic model to determine sensitivity and specificity of levels predicting mucosal healing.

RESULTS

Fifty-eight patients on maintenance golimumab were included (n = 39 CD, n = 19 UC/IBD-unclassified [IBDU]). Forty percent (n = 23) were cotreated with an immunomodulator, 95% (n = 55) of patients were anti-TNF experienced, and 15.5% (n = 9) had 3 or more prior biologic therapies. Forty-four percent of patients achieved mucosal healing with endoscopic response in a further 26% of patients. Clinical remission was recorded in 41% of patients, and 82% had clinical response. Patients were treated with doses generally higher than the approved maintenance dose. In CD patients, median golimumab trough levels were higher in patients with mucosal healing (8.8 μg/mL vs 5.08 μg/mL, P = 0.03). After calculation of a receiver operating characteristic (ROC) curve for mucosal healing vs nonresponse, a trough level >8 μg/mL was associated with mucosal healing, with 67% sensitivity, 88% specificity, and a likelihood ratio of 3:4.

CONCLUSION

Treatment with golimumab was associated with mucosal healing in 44% of all IBD patients. Higher golimumab levels were associated with mucosal healing in CD. These findings support the need for prospective studies to determine target golimumab levels in IBD, which may impact current clinical practices in relation to selection of maintenance dosing.

A9 BACTERIAL BILE SALT HYDROLASE GENE ABUNDANCE IS ASSOCIATED WITH RORC GENE EXPRESSION IN INTESTINAL MUCOSA OF INFLAMMATORY DISEASE PATIENTS

Background

The role of gut microbes involved in bile acid metabolism and their impact on mucosal immune regulation is beginning to be appreciated. For instance, changes in microbial bile salt hydrolase (BSH) activity which deconjugates bile acids in the gastrointestinal tract of gnotobiotic mice, significantly alters gene expression patterns of immune-related genes in ileum. Moreover, bile acid dysmetabolism may participate in the chronic inflammation loop of Inflammatory bowel disease (IBD).

Aims

We carried out an integrated mucosal microbiome-transcriptome analysis to elucidate associations between microbial bile-acid metabolizing function and host gene expression.

Methods

Crohn’s disease (CD), ulcerative colitis (UC) and IBD unclassified (IBDU) patients were recruited prior to scheduled colonoscopy performed as part of clinical care. Only patients with non-inflamed mucosa defined as a segmental simple endoscopic score 0–2 in CD and a segmental Mayo endoscopic score of 0 in UC/IBDU were included in this analysis to minimize the effect of inflammation on gene expression. Biopsy samples were obtained from terminal ileum, ascending colon and sigmoid colon, and microbial DNA and human RNA was extracted. V4 region of 16S rRNA gene was sequenced and the relative abundance of bile acid-metabolizing genes was inferred using PICRUSt. RNA-seq was used to sequence total human RNA and a supervised transcript reduction analysis focus upon 65 genes previously associated with bile acid metabolism and IBD was utilized. Associations between microbiome clusters of orthologous groups (COGs), transcriptome, diagnosis (CD vs UC/IBDU), and biopsy site were analyzed using linear mixed-effects model with lmer4 function in R. An adjusted-p value after false discovery rate correction &lt; 0.05 was considered significant.

Results

A total of 126 samples from 86 subjects were analyzed corresponding to 35 CD and 51 UC/IBDU. Mean age for the total cohort was 34.7 ± 11 years and 35 (40.6%) were females. There was a significant negative correlation between relative abundance of bacterial bsh genes (COG3049) and human RORC gene (p &lt; 0.03). This association was independent of type of diagnosis and biopsy site. There was no association among other analyzed bacterial COGs and host genes.

Conclusions

Using an integrative microbiome-host transcriptome approach, our data provide new evidence linking microbial bile acid deconjugation (bsh genes) and host gene expression in the mucosal-luminal interface in quiescent IBD-affected tissue. Nuclear receptor RORC is pivotal in the differentiation and function of innate lymphoid cells and T-helper 17 cells. Modulation of this pathway by bile acids or gut bacteria involved in their metabolism could shed light on the immune role of bile acids in IBD patients.

Funding Agencies

CAG, CIHRNational Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Development and Validation of a Test to Monitor Endoscopic Activity in Patients With Crohn's Disease Based on Serum Levels of Proteins

BACKGROUND & AIMS

Noninvasive tests to measure endoscopic activity in patients with Crohn's disease (CD) have limitations. We aimed to develop a test to identify patients in remission, based on endoscopic analysis, and monitor CD activity based on serum levels of proteins.

METHODS

We developed a test to measure 13 proteins in blood (ANG1, ANG2, CRP, SAA1, IL7, EMMPRIN, MMP1, MMP2, MMP3, MMP9, TGFA, CEACAM1, and VCAM1), called the endoscopic healing index [EHI], using samples from 278 patients with CD from a multinational training cohort. We validated the test using 2 independent cohorts of patients with CD: 116 biologic-naive patients with early-stage CD (validation cohort 1) and 195 biologic-exposed patients with chronic CD (validation cohort 2). The ability of the test to identify patients with active disease vs patients in remission (defined as a simple endoscopic score for CD of ≤2 and ≤1 in each segment, or a total CD endoscopic index of severity score <3) was assessed by using area under receiver operating characteristic curve (AUROC) analysis. The diagnostic accuracy of the test was compared with that of measurement of serum C-reactive protein (CRP) and fecal calprotectin.

RESULTS

The EHI scores range from 0 to 100 units; higher scores indicate more severe CD activity, based on endoscopy findings. The EHI identified patients in remission with an AUROC of 0.962 in validation cohort 1 (95% confidence interval, 0.942-0.982) and an AUROC of 0.693 in validation cohort 2 (95% confidence interval, 0.619-0.767), regardless of CD location or phenotype. A cutoff value of 20 points identified patients in remission with the highest level of sensitivity (97.1% in validation cohort 1 and 83.2% in validation cohort 2), with specificity values of 69.0% and 36.6%, respectively. A cutoff value of 50 points identified patients in remission with the highest level of specificity (100% in validation cohort 1 and 87.8% in validation cohort 2), with sensitivity values of 37.3% and 30.0%, respectively. The EHI identified patients in remission with a significantly higher AUROC value than the test for CRP (0.876, P < .001 in validation cohort 1 and 0.624, P = .109 in validation cohort 2). In analysis of patients with available FC measurements, the AUROC value for the EHI did not differ significantly from that of measurement of FC (AUROC, 0.950 for EHI vs AUROC, 0.923 for FC; P = .147 in validation cohort 1 and AUROC, 0.803 for EHI vs AUROC, 0.854 for FC; P = .298 in validation cohort 2).

CONCLUSIONS

We developed an index called the EHI to identify patients with CD in endoscopic remission based on blood levels of 13 proteins. The EHI identified patients with resolution of endoscopic disease activity, with good overall accuracy, although with variation between the 2 cohorts assessed. The EHI AUROC values were comparable to measurement of FC and higher than measurement of serum CRP. The test might be used in practice to assess endoscopic activity in patients with CD.

Histological Markers of Clinical Relapse in Endoscopically Quiescent Ulcerative Colitis

BACKGROUND

In ulcerative colitis (UC) patients who have achieved mucosal healing, active microscopic colonic mucosal inflammation is commonly observed. We aimed to assess the association between histological activity and disease relapse in endoscopically quiescent UC.

METHODS

Ulcerative colitis patients with endoscopically quiescent disease and ≥12 months of follow-up were included. Biopsies were reviewed for the presence of basal plasmacytosis (BPC) and active histological inflammation, defined as a Geboes score (GS) ≥3.2. Primary outcome measures were disease relapse at 18 months and time to first relapse after index colonoscopy.

RESULTS

Seventy-six UC patients (51% male; mean age, 38.6 years; median follow-up [range], 75.2 [2-118] months) were included. Sixty-two percent had an endoscopic Mayo score of 0 at index colonoscopy. Basal plasmacytosis was present in 46% and active histological inflammation in 30% of subjects. Presence of BPC was associated with a significantly shorter time to disease relapse (P = 0.01). Active histological inflammation was significantly associated with clinical relapse at 18 months (P = 0.0005) and shorter time to clinical relapse (P = 0.0006). Multivariate analysis demonstrated active histological inflammation to be independently associated with clinical relapse at 18 months and time to clinical relapse.

CONCLUSIONS

In endoscopically quiescent UC, active histological inflammation and the presence of BPC are adjunctive histological markers associated with increased likelihood of disease relapse. Although prospective studies are required, the presence of these histological markers should be a factor considered when making therapeutic decisions in UC.

Analysis of Genetic Association of Intestinal Permeability in Healthy First-degree Relatives of Patients with Crohn's Disease

Excessive intestinal permeability or intestinal barrier dysfunction as measured by various assays has been observed in various diseases. However, little is known about the factors contributing to altered gut permeability in these diseases. Our objective was to determine the genetic determinants of altered gut permeability as measured by the lactulose mannitol fractional excretion ratio (LacMan ratio) in 1075 healthy first-degree relatives of patients with Crohn's disease (CD). In a targeted analysis of single nucleotide polymorphisms (SNPs) located in genes associated with intestinal barrier function related or not to inflammatory bowel disease, we did not find a significant association with intestinal permeability. In an untargeted genome-wide association analysis, the top 100 associations were located in 22 genomic loci, although they were not statistically significant after correction for multiple testing (raw P values [1.8 × 10-7 - 1.4 × 10-5]. The lowest P value was obtained for rs9616637 (22q13.33, C22orf34), for which the minor allele A was associated with a decreased LacMan ratio. These results suggest that host genetic background has limited contribution toward intestinal permeability. Despite this, our study is currently the largest of its kind assessing gut permeability in vivo. It remains possible that smaller genetic effect sizes on LacMan ratio are not detectable in this sized cohort. Larger studies are warranted to identify the potential genetic contribution to intestinal permeability.

Differential miRNA Expression in Ileal and Colonic Tissues Reveals an Altered Immunoregulatory Molecular Profile in Individuals With Crohn's Disease versus Healthy Subjects

BACKGROUND

MicroRNAs [miRNAs] are key modulators of gene expression in Crohn's disease [CD] and may drive tissue-specific molecular alterations underlying CD susceptibility. In this study, we analysed differential miRNA expression between CD and healthy subjects across ileal and colonic tissues.

METHODS

A cohort of CD and healthy control [HC] subjects was recruited and clinical data collected. Endoscopically quiescent CD [CDq] was defined as inactive or mild by the Simple Endoscopic Score for CD. Total RNA was extracted from endoscopic biopsies taken from the terminal ileum and sigmoid colon. miRNA expression was quantified using NanoString Technologies. Statistical significance was assessed across biopsy site and diagnosis per miRNA, and corrected for multiple testing.

RESULTS

In total, 23 CDq and 38 HC subjects were enrolled; 112 samples were included in the analysis, 51 from the ileum and 61 from the colon. We found 47 miRNAs differentially expressed by biopsy site in healthy tissue. Nine miRNAs were differentially expressed across HC and CDq, accounting for biopsy location. One of these, miR-223-3p, showed age and sex effects. We identified miRNA expression driven by diagnosis targeting genes involved in chemokine and cytokine signalling. miR-31-5p expression was driven by location and may be a biomarker for location subtypes in CD.

CONCLUSIONS

We identified differentially expressed miRNAs in healthy ileal and colonic tissues. We discovered spatial miRNA expression patterns in CD and HC, suggesting site-specific regulation in subjects with no or minimal intestinal inflammation. These miRNAs target genes involved in immunoregulatory processes, suggesting a functional, tissue-specific role in CD.

Associations between quantitative evaluation of bowel wall microvascular flow by contrast-enhanced ultrasound and indices of disease activity in Crohn's disease patients using both bolus and infusion techniques

PURPOSE

The aim is to investigate whether baseline contrast-enhanced ultrasound (CEUS) correlates with indices of activity in Crohn's disease (CD) and can predict response to medical treatment.

METHODS

In this prospective study, symptomatic CD patients underwent baseline CEUS performed with Definity using both bolus and infusion methods. Time-intensity curves (TIC), peak intensity (PI), and area under curve (AUC) from a region of interest over the diseased bowel were calculated for both bolus and infusion acquisitions. We used Mann-Whitney U test for continuous and chi-square/two-tailed Fisher's exact test for categorical variable comparison and Spearman's correlation coefficient to correlate clinical score and CEUS kinetic parameters.

RESULTS

Twenty-one patients (9 men, 12 women, median age 32 years) were accrued. Fifteen patients had clinically active disease defined as Harvey-Bradshaw Index (HBI) score ≥5. Median values of baseline CEUS parameters PI (bolus: 26 vs 8.86; P = .023 and perfusion: 7.6 vs 3.2; P = .009) and AUC (bolus: 769 vs 248.8; P = .036 and perfusion: 188.9 vs 73.9; P = .012) differed significantly in patients with active vs inactive disease. Nine patients with active disease underwent escalated or new treatment. Five were nonresponders. Responders had higher median values of baseline parameters (PI, bolus: 35 vs 18.8; P = .556, and perfusion: 7.6 vs 3.9; P = 190), (AUC, bolus: 1473.9 vs 314; P = .111, and perfusion: 154.7 vs 74.4, P = .286).

CONCLUSIONS

CEUS kinetic parameters correlate with clinical and laboratory indices and are significantly higher in patients with active disease. The responders had higher CEUS kinetic parameters than nonresponders that did not reach statistical significance in our small cohort.

The Unsolved Link of Genetic Markers and Crohn's Disease Progression: A North American Cohort Experience

BACKGROUND

While progress has been made in the identification of Crohn's disease (CD) susceptibility loci, efforts to identify a genetic basis for disease progression have been less fruitful. The specific aim of this study was to build upon the major genetic advances made in IBD by applying genome-wide technologies toward predicting disease progression in CD.

METHODS

Crohn's disease cases (n = 1495) from 3 IBD centers were reviewed by experienced physicians. Clinical and demographic details were collected, focusing on the time to first disease progression. Genome-wide association (GWA) analysis was carried out on 3 clinical outcomes: 1) time to disease progression; 2) time to first abdominal surgery; and 3) a binary analysis of indolent vs progressive disease. Cox-proportional hazard and logistic regression models were used.

RESULTS

A GWA analysis was carried out to determine any genetic variation associated with the time to disease progression; 662 cases were included after quality control (QC) and exclusion of any cases with B2/B3 behavior at baseline (n = 450). There were 1360 cases included after QC in the time to abdominal surgery analysis. No variant reached genome-wide significance in any of the 3 analyses performed. Eight known IBD susceptibility single nucleotide polymorphism (SNPs) were found to be associated with time-to-abdominal surgery SMAD3 (rs17293632), CCR6 (rs1819333), CNTF (rs11229555), TSPAN14 (rs7097656), CARD9 (rs10781499), IPMK (rs2790216), IL10 (rs3024505), and SMURF1 (rs9297145) (P < 0.05).

CONCLUSION

Our GWA study failed to show any SNP-phenotype association reaching genome-wide significance. It is likely that multiple variables affect disease progression, with genetic factors potentially having only a small effect size.

The Prevalence and Clinical Associations of Subclinical Sacroiliitis in Inflammatory Bowel Disease

BACKGROUND

Sacroiliitis, an inflammatory arthropathy associated with ankylosing spondylitis (AS), is found in patients with inflammatory bowel disease (IBD) but may go undiagnosed. The aims of this study were to assess prevalence of sacroiliitis in IBD and to determine association between clinical characteristics of IBD and sacroiliitis.

METHODS

Inflammatory bowel disease patients undergoing abdomino-pelvic computed tomography (CT) for any indication (2006-2015) were identified. Using standardized CT scoring, sacroiliitis was confirmed. Two blinded readers used a standardised model where presence of ankylosis or erosion score >3 indicated sacroiliitis. Inflammatory bowel disease scoring was blinded to the presence of sacroiliitis. Demographics, IBD characteristics, clinical activity (Harvey Bradshaw Index >4, Mayo >2, as denoted by attending physician), endoscopic activity (Simple Endoscopic Score for Crohn's Disease >4/Mayo subscore >1), and arthritis/extraintestinal manifestations (EIMS) were recorded. Comparisons were made between those with/without sacroiliitis.

RESULTS

Three hundred sixteen patients were included (50% male; 74% Crohn's disease [CD]). Computed tomography scoring identified 49 (16%) with sacroiliitis. Radiologists had reported sacroiliitis in 33% of these. Five patients had been to a spondylitis clinic. Thirty-three of 49 had abdominal x-rays; 64% of these fulfilled the imaging component of Modified New York criteria for AS. More than 5 sacroiliac erosions were associated with radiologist-reported sacroiliitis (P < 0.0001). There was no difference in prevalence between CD and ulcerative colitis. Sacroiliitis was associated with male sex (63.3% vs 47.9%; odds ratio [OR], 1.8; P = 0.04), known arthritis (41% vs 12%; OR, 4.7; P < 0.0001), pain as an IBD symptom (77.7% vs 56.9%; P = 0.03), and CD inflammatory phenotype (P = 0.01). Endoscopic activity, location, and extent were not associated.

CONCLUSIONS

Sacroiliitis is underdiagnosed in IBD and is associated with male sex, arthritis, and inflammatory CD. Data support targeted screening in at-risk patients.

Correction: Insights into the genetic epidemiology of Crohn's and rare diseases in the Ashkenazi Jewish population

[This corrects the article DOI: 10.1371/journal.pgen.1007329.].

Genetic effects on the commensal microbiota in inflammatory bowel disease patients

Several bacteria in the gut microbiota have been shown to be associated with inflammatory bowel disease (IBD), and dozens of IBD genetic variants have been identified in genome-wide association studies. However, the role of the microbiota in the etiology of IBD in terms of host genetic susceptibility remains unclear. Here, we studied the association between four major genetic variants associated with an increased risk of IBD and bacterial taxa in up to 633 IBD cases. We performed systematic screening for associations, identifying and replicating associations between NOD2 variants and two taxa: the Roseburia genus and the Faecalibacterium prausnitzii species. By exploring the overall association patterns between genes and bacteria, we found that IBD risk alleles were significantly enriched for associations concordant with bacteria-IBD associations. To understand the significance of this pattern in terms of the study design and known effects from the literature, we used counterfactual principles to assess the fitness of a few parsimonious gene-bacteria-IBD causal models. Our analyses showed evidence that the disease risk of these genetic variants were likely to be partially mediated by the microbiome. We confirmed these results in extensive simulation studies and sensitivity analyses using the association between NOD2 and F. prausnitzii as a case study.

Stricturing and Fistulizing Crohn's Disease Is Associated with Anti-tumor Necrosis Factor-Induced Psoriasis in Patients with Inflammatory Bowel Disease

BACKGROUND

Paradoxical development of psoriasis in patients on anti-TNF agents has been increasingly reported.

AIM

The aim was to characterize the prevalence and clinical characteristics of anti-TNF-associated psoriasis in a large cohort of inflammatory bowel disease patients.

METHODS

Medical records of patients with Crohn's disease or ulcerative colitis treated with anti-TNF therapy at a single, tertiary IBD center were identified between 2004 and 2016. Patients identified as having developed psoriasis while on anti-TNF underwent detailed retrospective review of dermatologic features and changes in IBD treatment prompted by the development of psoriasis.

RESULTS

Among 676 patients treated with anti-TNF (infliximab or adalimumab), the incidence of psoriasis was 10.7% (N = 72). Female gender (OR 1.88 [95% CI 1.12-3.17], p = 0.017), stricturing or fistulizing Crohn's disease (OR 1.83 [95% CI 1.04-3.21], p = 0.036) and upper GI Crohn's disease (OR 3.03 [95% CI 1.06-8.33], p = 0.039) were associated with psoriasis development. The median time to psoriasis onset was 569 days from initiation of anti-TNF, with onset occurring earlier in patients who developed psoriasis on adalimumab versus infliximab (457 vs. 790.5 days, p = 0.008). Overall, in 15/72 (20.8%), cases, cessation of the anti-TNF was required as a result of psoriasis. Plaque psoriasis was the most common type of psoriatic lesion (75%). Topical corticosteroids were the most common treatment for psoriasis.

CONCLUSION

We report a high incidence of anti-TNF-associated psoriasis that was associated with female gender, foregut disease location, and fistulizing and stricturing disease behavior. More prospective studies and genetic analyses evaluating possible pathophysiologic underpinnings of this problem are needed.