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BackgroundThe risks and impact of COVID19 disease and vaccination in patients with Immune Mediated Inflammatory Diseases (IMID) remain incompletely understood. IMID patients and particularly patients receiving immunosuppressive treatment were excluded from the original, registrational phase-3 COVID19 vaccination efficacy and safety trials. Real-world observational data can help to fill this gap in knowledge. The BELCOMID study aims to explore the interaction between IMIDs, immune-modulating treatment modalities and SARS-CoV-2 infection and vaccination in a real-life patient cohort.MethodsA multidisciplinary, prospective, observational cohort study was set up. Consecutive patients with IMIDs of the gut, joints and skin followed at two high-volume referral centers were invited. Both patients under conventional treatment or targeted immune modulating therapies were included. Patient data and serological samples were collected at 3 predefined periods (before COVID19 vaccination, before booster vaccination, after booster vaccination). Primary endpoints were positive PCR-test and SARS-CoV-2 serology reflecting previous SARS-CoV-2 infection or vaccination. Associations with IMID treatment modality and IMID disease activity were assessed. Results of the first two inclusion periods (before booster vaccination) are reported.ResultsAt the first inclusion period data was assessed of 2165 IMID-patients before COVID19 vaccination. At the second inclusion period, data of 2065 patients was collected of whom 1547 had received complete baseline COVID19 vaccination and 222 were partially vaccinated. SARS-CoV-2 infection rate remained low in both groups. No significant increase in IMID flare-up rate was noted in patients with prior SARS-CoV-2 infection. Multiple logistic regression analyses did not show a significant influence of IMID-treatment modality or IMID activity on SARS-CoV-2 infection risk (based on PCR positivity or N-serology). Patients treated with conventional immunomodulators, systemic steroids, and patients on advanced therapies such as biologics or small molecules, had reduced S-antibody seroconversion. S-antibody response was also lower in patients without prior SARS-CoV-2 infection and in active smokers. A subset of patients (4.1%) had no S- nor N-antibody seroconversion following complete baseline vaccination.ConclusionThe BELCOMID study results confirm the benign course of COVID19 infection and vaccination in a large real-life IMID-population. However, our results underscore the need for repeated vaccination and smoking cessation in patients with IMIDs treated with immune-modulating therapies or systemic steroids during the pandemic.

Short-chain fatty acids as well as their bacterial producers are of increasing interest in inflammatory bowel diseases. Although less studied compared to butyrate, acetate might also be of interest as it may be less toxic to epithelial cells, stimulate butyrate-producing bacteria by cross-feeding, and have anti-inflammatory and barrier-protective properties. Moreover, one of the causative factors of the probiotic potency of Saccharomyces cerevisae var. boulardii is thought to be its high acetate production. Therefore, the objective was to preclinically assess the effects of high acetate concentrations on inflammation and barrier integrity in organoid-based monolayer cultures from ulcerative colitis patients. Confluent organoid-derived colonic epithelial monolayers (n = 10) were exposed to basolateral inflammatory stimulation or control medium. After 24 h, high acetate or control medium was administered apically for an additional 48 h. Changes in TEER were measured after 48 h. Expression levels of barrier genes and inflammatory markers were determined by qPCR. Pro-inflammatory proteins in the supernatant were quantified using the MSD platform. Increased epithelial resistance was observed with high acetate administration in both inflamed and non-inflamed conditions, together with decreased expression levels of IL8 and TNFα and CLDN1. Upon high acetate administration to inflamed monolayers, upregulation of HIF1α, MUC2, and MKI67, and a decrease of the majority of pro-inflammatory cytokines was observed. In our patient-derived human epithelial cell culture model, a protective effect of high acetate administration on epithelial resistance, barrier gene expression, and inflammatory protein production was observed. These findings open up new possibilities for acetate-mediated management of barrier defects and inflammation in IBD. ispartof: International Journal Of Molecular Sciences vol:24 issue:1 pages:1-14 ispartof: location:Switzerland status: published

Microbial dysbiosis is an established finding in patients with inflammatory bowel disease (IBD), but host-microbial interactions are poorly understood. We aimed to unravel the effect of microbiota exposure on intestinal epithelial cells. Confluent Transwell® organoid monolayers of eight UC patients and eight non-IBD controls were co-cultured for six hours with microbiota (3x108 cells) of UC patients or a healthy volunteer (HV), in the presence or absence of an inflammatory cytokine mix. Transepithelial electrical resistance (TEER), fluorescein isothiocyanate (FITC) dextran measurements, and RNA sequencing were performed on epithelial cells, and 16S rRNA sequencing on microbiota samples before and after co-culture. Transcriptomic response following microbiota exposure was not different between epithelial cells from UC patients or non-IBD controls. Following UC microbiota exposure, but not HV microbiota, a strong decrease in epithelial barrier integrity was observed in both UC and HV epithelial cells by TEER and FITC dextran measurements. Exposure of inflamed epithelium to UC microbiota induced transcriptomic stress pathways including activation of EGR1, MAPK and JAK/STAT signaling, as well as AP-1 family and FOSL transcripts. Stress responses after HV microbiota stimulation were milder. We conclude that not the epithelial cell origin (UC versus non-IBD) but the microbial donor drives transcriptomic responses, as exposure to UC microbiota was sufficient to induce stress responses in all epithelial cells. Further research on therapies to restore the microbial balance, to remove the constant trigger of dysbiosis, is required. ispartof: GUT MICROBES vol:14 issue:1 ispartof: location:United States status: Published online

Therapeutic drug monitoring (TDM) has emerged as a useful tool for optimising the use of biologics, and in particular anti-tumour necrosis factor (anti-TNF) therapy, in inflammatory bowel disease (IBD). However, challenges remain and are hindering the widespread implementation of TDM in clinical practice. These barriers include identification of the optimal drug concentration to target, the lag time between sampling and results, and the proper interpretation of anti-drug antibody titres among different assays. Solutions to overcome these barriers include the harmonisation of TDM assays and the use of point-of-care testing. Other unmet needs include well designed prospective studies and randomised controlled trials focusing on proactive TDM, particularly during induction therapy. Future studies should also investigate the utility of TDM for biologics other than anti-TNF therapies in both IBD and other immune-mediated inflammatory diseases such as rheumatoid arthritis and psoriasis, and the use of pharmacokinetic modelling dashboards and pharmacogenetics towards individual personalised medicine. ispartof: LANCET GASTROENTEROLOGY & HEPATOLOGY vol:7 issue:2 pages:171-185 ispartof: location:Netherlands status: published

Additional file 2: Coding tree.

INTRODUCTION: Patients with ulcerative colitis (UC) regard rapid onset of action among the most important aspects of their treatment. We used the partial Mayo Clinic Score (pMCS) and component patient-reported subscores to assess the rapidity and sustainability of response to filgotinib, a once-daily, oral Janus kinase 1 preferential inhibitor, in adults with moderately to severely active UC in the phase 2b/3 SELECTION trial. The association between early symptomatic improvements and health-related quality of life (HRQoL) outcomes was also assessed. METHODS: In these post hoc analyses of the double-blinded, randomized, placebo-controlled 58-week SELECTION trial (NCT02914522), rectal bleeding and stool frequency diary data on days 1-15 and pMCS remission and response at multiple time points including weeks 10 and 58 were evaluated. HRQoL was assessed using the Inflammatory Bowel Disease Questionnaire at weeks 10 and 58. RESULTS: Filgotinib 200 mg relative to placebo improved rectal bleeding and stool frequency within 7 days ( P < 0.05). By week 2, greater proportions of filgotinib 200 mg-treated patients than placebo-treated patients achieved pMCS remission (biologic-naive, 15.1% vs 8.0%, P = 0.0410; biologic-experienced, 10.3% vs 4.2%, P = 0.0274). A similar treatment effect was observed at week 58 ( P < 0.0001). Day 7 rectal bleeding and stool frequency subscores were associated with the Mayo Clinic Score response at weeks 10 and 58. Patients in pMCS remission at weeks 10 and 58 had greater improvements in the Inflammatory Bowel Disease Questionnaire score than those not in pMCS remission. DISCUSSION: Filgotinib 200 mg daily resulted in rapid and sustained improvements in both UC symptoms and HRQoL. ispartof: AMERICAN JOURNAL OF GASTROENTEROLOGY vol:118 issue:1 pages:138-147 ispartof: location:United States status: published

An Outtier, Marc Ferrante Department of Gastroenterology and Hepatology, University Hospitals Leuven, KU Leuven, Leuven, BelgiumCorrespondence: Marc FerranteDepartment of Gastroenterology and Hepatology, University Hospitals Leuven, Herestraat 49, Leuven, 3000, BelgiumTel +32 16 34 42 18Fax +32 16 33 07 23Email marc.ferrante@uzleuven.beBackground: Pouchitis is the most common long-term complication in patients with ulcerative colitis who underwent restorative proctocolectomy with ileal pouch-anal anastomosis. The incidence of acute pouchitis is 20% after 1 year and up to 40% after 5 years. Chronic antibiotic-refractory pouchitis develops in approximately 10% of patients.Aim: To present a narrative review of published literature regarding the management of chronic antibiotic-refractory pouchitis.Methods: Current relevant literature was summarized and critically evaluated.Results: Clear definitions should be used to classify pouchitis into acute versus chronic, and responsive versus dependent versus refractory to antibiotics. Before treatment is started for chronic antibiotic-refractory pouchitis, secondary causes should be ruled out. There is a need for validated scoring systems to measure the severity of the disease. Because chronic antibiotic-refractory pouchitis is a rare condition, only small studies with often a poor study design have been performed. Treatments with antibiotics, aminosalicylates, steroids, immunomodulators and biologics have shown to be effective and safe for chronic antibiotic-refractory pouchitis. Also, treatments with AST-120, hyperbaric oxygen therapy, tacrolimus enemas, and granulocyte and monocyte apheresis suggested some efficacy.Conclusion: The available data are weak but suggest that therapeutic options for chronic antibiotic-refractory pouchitis are similar to the treatment strategies for inflammatory bowel diseases. However, randomized controlled trials are warranted to further identify the best treatment options in this patient population.Keywords: chronic antibiotic-refractory pouchitis, inflammatory bowel disease, biologics

Background. Intraoperative imaging for endourologic procedures is generally limited to single-plane fluoroscopic X-ray. The O-arm™ is a mobile cone-bean CT scanner that may have applications in urologic surgeries. Case Presentation. We present a case of an 85-year-old male with radiation cystitis and recurrent gross hematuria who was identified to have a bladder perforation on cystoscopy during emergent clot evacuation. Single-view fluoroscopic evaluation was inconclusive as to whether an intraperitoneal bladder perforation occurred. A portable cone-beam CT scan was used to acquire a 3-D CT cystogram, which demonstrated intraperitoneal contrast extravasation, confirming the diagnosis of an intraperitoneal bladder perforation. Conclusion. We report the first use of a portable cone-beam CT scanner to perform an intraoperative CT cystogram to diagnose an intraperitoneal bladder perforation and guide surgical management.

Background We aimed to describe the long-term impact of achieving endoscopic and deep remission among participants in the effect of tight control management on CD (CALM) trial. Methods We analysed medical records from patients with follow-up data since end of CALM. Patients were stratified by outcomes in CALM at 1 year: clinical remission (Crohn’s disease activity index, CDAI Results One hundred twenty-two patients with median age 29 years (IQR 22.5–37) and median disease duration 0.2 years (IQR 0.1–0.8) were included. Median follow-up time from end of CALM was 3.02 years (range 0.05–6.26 years). Fifty per cent were randomised to the tight control arm. There were no significant differences in baseline characteristics in patients with follow-up data and those lost to follow-up with the exception of a slightly higher CDEIS score in patients lost to follow-up (14.6 vs. 12.9, p = 0.04). Thirty-four patients (27.9%) had a major adverse outcome during follow-up. Patients in clinical remission at 1 year did not have significantly lower rates of the composite endpoint (log-rank p = 0.15). Patients in endoscopic and deep remission at the end of CALM were significantly less likely to have a major adverse event over time (Figures 1 and 2). After adjusting for age, disease duration, prior surgery, prior stricture, and randomisation arm, endoscopic remission (aHR 0.44, 95% CI 0.20–0.96, p = 0.038) and deep remission (aHR 0.25, 95% CI 0.09–0.72, p = 0.01) were significantly associated with lower risk of major adverse events. Conclusions Early CD patients who achieve endoscopic or deep remission after 1 year of intensive treatment are less likely to have disease progression over a median of 3 years.

BACKGROUND: Golimumab (GOL) is registered for moderate to severely active ulcerative colitis (UC). Data on the use of GOL in daily clinical practice are limited. Currently, it is unclear which factors are predictive of a favorable outcome. The goals of this study were to evaluate the mid-term outcome of GOL (week 26) in patients with moderate to severe UC and to determine predictors of favorable outcome. METHODS: Patients included in the SMART study (NCT02155335) were evaluated for their mid-term outcome. Demographic data, disease characteristics, and medical history were recorded retrospectively. Data on disease activity based on total Mayo score, previous and concomitant medication, GOL dosing, mucosal healing (Mayo 0 or 1), adverse events (colectomy, hospitalization), and biomarkers (C-reactive protein, fecal calprotectin, hemoglobin, and albumin) were collected at baseline and weeks 2, 6, 14, 26, and 52. GOL was dosed at 200 and 100 mg at weeks 0 and 2, respectively, and 50 mg (

Background Vedolizumab is a recently available monoclonal antibody targeting α4β7 integrin for the treatment of ulcerative colitis (UC) and Crohn’s disease (CD). Objective The objective of this article is to evaluate the efficacy of vedolizumab induction therapy in anti-TNF-refractory/intolerant UC and CD patients in real life. Methods A cohort of 149 moderately to severely active UC and CD patients who failed or showed intolerance to at least two TNF antagonists participated in a medical need program and received vedolizumab in 37 Belgian centers (April–September 2015). Rates of clinical response and remission were retrospectively evaluated at Week 10 for UC and Week 14 for CD using the physician’s global assessment (PGA), Mayo score and Harvey Bradshaw index (HBI) or Crohn's disease activity score (CDAI) scores. Results Eighty-four patients (29 UC, 55 CD) had sufficient data for analysis. For UC patients, clinical response was observed in 76% based on PGA and 59% based on the Mayo score. The corresponding percentages for CD patients were 80% for PGA and 65% for HBI/CDAI. Clinical remission rates were 10% and 40% for UC and CD, respectively. Steroid-free remission was observed in respectively 10% and 35%. Globally, corticosteroids were stopped in 14 out of 48 patients (29%). No new safety signals were reported. Conclusion Up to 70% TNF-refractory/intolerant UC and CD patients achieved a clinical response after 10 to 14 weeks of vedolizumab treatment in this real-life cohort.

ispartof: Acta Gastro-Enterologica Belgica vol:78 issue:1 pages:26-29 ispartof: location:Belgium status: published

ispartof: Gut status: submitted

The introduction of biologic agents and particularly of anti-tumor necrosis factor antibodies dramatically changed the therapeutic algorithm in patients with inflammatory bowel diseases. Although the efficacy of these agents has been demonstrated clearly, optimal treatment strategies are debated. Recent trials advocate the introduction of biologic agents at an early stage to prevent debilitating complications. However, significant adverse events have led to careful selection of patients who will benefit most from long-term treatment with biologic agents. Once on biologic therapy, scheduled maintenance therapy is recommended to minimize the risk of loss of response. Nevertheless, treatment adaptation is frequently necessary in patients who lose response. Interventions encompass strategies to increase drug exposure by increasing the dose or decreasing the dosing interval, or by changing to another biologic agent. Finally, it remains unclear if and when a biologic agent can be stopped in patients with long-standing remission

Background: Risankizumab, an anti-interleukin-23 antibody, was superior to placebo in achieving clinical and endoscopic remission at week 12 in a randomised, phase 2 induction study in patients with moderately to severely active Crohn���s disease. The efficacy and safety of extended intravenous induction and/or subcutaneous maintenance therapy with risankizumab was assessed. Methods: Following 12-week, double-blind, randomised, induction treatment comparing 200 mg or 600 mg intravenous risankizumab to placebo every 4 weeks, patients without deep remission, defined as clinical (Crohn���s Disease Activity Index 50% CDEIS reduction from baseline) was achieved by 35% and 55% of patients, respectively, and 29% of patients achieved deep remission. Risankizumab was well tolerated with no new safety signals. Interpretation: Extended induction treatment with open-label intravenous risankizumab was effective in increasing clinical response and remission rates at week 26. Open-label subcutaneous risankizumab maintained remission till week 52 in most patients who were in clinical remission at week 26. Selective blockade of interleukin-23 warrants further evaluation as treatment for Crohn���s disease., Boehringer Ingelheim

Background The efficacy of a single administration of darvadstrocel (expanded allogeneic adipose-derived mesenchymal stem cells) for treating complex perianal fistulas in patients with Crohn’s disease was demonstrated in a randomized, double-blind trial (ADMIRE-CD [Adipose Derived Mesenchymal Stem Cells for Induction of Remission in Perianal Fistulizing Crohn\'s Disease] trial). The current chart review study (INSPECT [A retrospectIve chart review study evaluatINg the longer-term effectiveneSs of darvadstrocel in PatiEnts who CompleTed ADMIRE-CD]) evaluated the longer-term effectiveness and safety of darvadstrocel. Methods Eligible patients had completed at least 52 weeks in the ADMIRE-CD trial. Data on clinical remission and fistula relapse outcomes were collected retrospectively at 104 and 156 weeks after treatment. Adverse events of special interest (tumorigenicity and ectopic tissue formation) were collected up to 208 weeks after treatment. Results Eighty-nine patients were included (43 darvadstrocel patients, 46 control subjects). At 52, 104, and 156 weeks posttreatment, clinical remission was observed in 29 (67.4%) of 43, 23 (53.5%) of 43, and 23 (53.5%) of 43 darvadstrocel-treated patients, compared with 24 (52.2%) of 46, 20 (43.5%) of 46, and 21 (45.7%) of 46 control subjects, respectively. In patients with clinical remission at week 52, this remission was sustained at 104 and 156 weeks after treatment in 19 (65.5%) of 29 and 16 (55.2%) of 29 darvadstrocel-treated patients and in 17 (70.8%) of 24 and 13 (54.2%) of 24 control subjects, respectively. Time to fistula relapse and incidence of fistula relapse or new fistula occurrence were not significantly different between groups. Tumorigenicity was reported for 1 (2.2%) patient in the control group (malignant epidermoid carcinoma). No ectopic tissue formation was reported. Conclusions Real-world follow-up of patients from the ADMIRE-CD trial indicates that clinical remission of complex perianal fistulas can be sustained in the long term irrespective of whether it is achieved through darvadstrocel administration or maintenance treatment regimens and confirms a favorable long-term safety profile of darvadstrocel.

Background and Aims Early treatment of Crohn’s disease [CD] is required in order to optimize patient outcomes. To this end, we need to gain a better understanding of the molecular changes at the onset of CD. Methods As a model for the earliest mucosal CD lesions, we study post-operative recurrent CD [Rutgeerts score ≥ i2b]. We are the first to analyse gene and microRNA [miRNA] expression profiles in ileal biopsies from these patients, and compare them with those of newly diagnosed [≤18 months] and late-stage [>10 years after diagnosis] CD patients. Results Except for one gene [WNT5A], there are no differential genes in CD patients without post-operative recurrence [i0], showing that previous disease did not influence gene expression in the neoterminal ileum, and that this model can be used to study early mucosal CD lesions. Gene expression and co-expression network dysregulation is more pronounced in newly diagnosed and late-stage CD than in post-operative recurrent CD, with most important modules associated with [a]granulocyte adhesion/diapedesis, and cholesterol biosynthesis. In contrast, we found a role for snoRNAs/miRNAs in recurrent CD, highlighting the potential importance of regulatory RNAs in early disease stages. Immunohistochemistry confirmed the expression of key dysregulated genes in damaged/regenerating epithelium and immune cells in recurrent CD. Conclusions Aside from regulatory RNAs, there are no clear gene signatures separating post-operative recurrent, newly diagnosed, and late-stage CD. The relative contribution of dysregulated genes and networks differs, and suggests that surgery may reset the disease at the mucosal site, and therefore post-operative recurrent CD might be a good model a good model to study to study early mucosal CD lesions.

One third of patients with inflammatory bowel disease (IBD) inadequately respond to anti-TNF treatment and preclinical data suggest that matrix metalloproteinase-9 (MMP-9) is a novel therapeutic target. Here we show that IBD clinical and histopathological parameters found in wild type mice challenged with three different models of colitis, acute and chronic dextran sodium sulphate (DSS), and acute 2,4,6-trinitrobenzenesulfonic acid-induced colitis are not attenuated in MMP-9 knockout mice. We find similar colonic gene expression profiles in wild type and MMP-9 knockout mice in control and acute DSS conditions with the exception of eleven genes involved in antimicrobial response during colitis. Parameters of chronic colitis are similar in wild type and MMP-9 knockout mice. Pharmacological inhibition of MMP-9 with bio-active peptides does not improve DSS colitis. We suggest that MMP-9 upregulation is a consequence rather than a cause of intestinal inflammation and we question whether MMP-9 represents a disease target in IBD., Metalloproteinase-9 has been suggested as therapeutic target to treat inflammatory bowel disease. Here de Bruyn et al. show that genetic and pharmacological inhibition of metalloproteinase-9 does not ameliorate inflammation and fibrosis in mice challenged with acute and chronic colitis protocols.

BACKGROUND & AIMS: We investigated the effects of inducing deep remission in patients with early Crohn's disease (CD). METHODS: We collected follow-up data from 122 patients (mean age, 31.2 ± 11.3 y) with early, moderate to severe CD (median duration, 0.2 years; interquartile range, 0.1-0.5) who participated in the Effect of Tight Control Management on CD (CALM) study, at 31 sites, representing 50% of the original CALM patient population. Fifty percent of patients (n = 61) were randomly assigned to a tight control strategy (increased therapy based on fecal level of calprotectin, serum level of C-reactive protein, and symptoms), and 50% were assigned to conventional management. We categorized patients as those who were vs were not in deep remission (CD endoscopic index of severity scores below 4, with no deep ulcerations or steroid treatment, for 8 or more weeks) at the end of the follow-up period (median, 3.02 years; range, 0.05-6.26 years). The primary outcome was a composite of major adverse outcomes that indicate CD progression during the follow-up period: new internal fistulas or abscesses, strictures, perianal fistulas or abscesses, or hospitalization or surgery for CD. Kaplan-Meier and penalized Cox regression with bootstrapping were used to compare composite rates between patients who achieved or did not achieve remission at the end of the follow-up period. RESULTS: Major adverse outcomes were reported for 34 patients (27.9%) during the follow-up period. Significantly fewer patients in deep remission at the end of the CALM study had major adverse outcomes during the follow-up period (P = .01). When we adjusted for potential confounders, deep remission (adjusted hazard ratio, 0.19; 95% confidence interval, 0.07-0.31) was significantly associated with a lower risk of major adverse outcome. CONCLUSIONS: In an analysis of follow-up data from the CALM study, we associated induction of deep remission in early, moderate to severe CD with decreased risk of disease progression over a median time of 3 years, regardless of tight control or conventional management strategy. ispartof: GASTROENTEROLOGY vol:159 issue:1 pages:139-147 ispartof: location:United States status: published

Increased levels of tissue inhibitor of metalloproteinase-1 [TIMP-1] have been detected in both inflammatory and fibrotic lesions in Crohn's disease. In a murine model of chronic inflammation, fibrosis was associated with an increase in TIMP-1 and inhibition of matrix metalloproteinase [MMP]-mediated degradation. We investigated the effect of TIMP-1 deficiency in acute and chronic murine models of colitis. Colitis was induced via oral administration of dextran sodium sulphate [DSS] to B6.129S4-Timp1(tm1Pds)/J knock-out [KO] and C57BL/6J wild-type [WT] mice. Levels of inflammation and fibrosis were assessed and gelatin zymographies and gene expression microarrays were performed. Compared with WT mice, TIMP-1 KO mice had higher inflammatory parameters after acute DSS administration and developed less fibrosis after chronic DSS administration. MMP-2 levels were increased in WT versus TIMP-1 KO mice with acute colitis, whereas a trend for higher proMMP-9 levels was observed in WT versus TIMP-1 KO mice with chronic colitis. In control conditions, several immune-related genes [e.g Ido1, Cldn8] were differentially expressed between young TIMP-1 KO and WT mice, but to a lesser extent between older TIMP-1 KO and WT mice. In response to DSS, the gene expression pattern was significantly different between young TIMP-1 KO and WT mice, whereas it was similar in older TIMP-1 KO and WT mice. TIMP-1 deficiency leads to differential expression of immune-related genes and to attenuated development of fibrosis. Unravelling the role of TIMP-1 in intestinal remodelling is necessary to develop more effective and more targeted therapeutic strategies for intestinal fibrosis. This work was supported by a grant from the Broad Medical Research Program of the Broad Foundation [IBD-0319R]. C.B. and M.d.B. are supported by grants from the Agency for Innovation by Science and Technology in Flanders [IWT]. G.O. is supported by GOA 2013/15, and G.O., J.C. and G.V.A. are supported by a grant from the Fund for Scientific Research Flanders [FWO-Vlaanderen] [grant number: G077513N and G069014]. I.A. is a postdoctoral fellow and S.V., G.V.A., and M.F. are Senior Clinical Investigators of FWO-Vlaanderen.