Background and Aims: Very-early-onset inflammatory bowel disease [VEO-IBD] is a form of IBD that is distinct from that of children with an older onset. We compared changes over time in the incidence and phenotype at diagnosis between two groups according to age at IBD diagnosis: VEO-IBD diagnosed before the age of 6 years, and early-onset IBD [EO-IBD] ]. Rectal bleeding and mucous stools were more common in patients with VEO-IBD, whereas weight loss and abdominal pain were more frequent in those with EO-IBD. Regarding CD, isolated colonic disease was more common in the VEO-IBD group [39% vs 14%; p = 0.003]. Conclusions:In this large population-based cohort, the incidence of VEO-IBD was low and stable from 1988 to 2011, with a specific clinical presentation. These results suggest a probable genetic origin for VEO-IBD, whereas the increase in EO-IBD might be linked to environmental factors.

Background and aims Intestinal fibrosis is a common complication of Crohn’s disease (CD). It is characterised by an accumulation of fibroblasts differentiating into myofibroblasts secreting excessive extracellular matrix. The potential role of the intestinal epithelium in this fibrotic process remains poorly defined. Methods We performed a pilot proteomic study comparing the proteome of surface epithelium, isolated by laser-capture microdissection, in normal and fibrotic zones of resected ileal CD strictures (13 zones collected in 5 patients). Proteins of interests were validated by immunohistochemistry (IHC) in ileal and colonic samples of stricturing CD (n=44), pure inflammatory CD (n=29) and control (n=40) subjects. The pro-fibrotic role of one selected epithelial protein was investigated through in-vitro experiments using HT-29 epithelial cells and a CCD-18Co fibroblast to myofibroblast differentiation model. Results Proteomic study revealed an endoplasmic reticulum (ER) stress proteins increase in the epithelium of CD ileal fibrotic strictures, including Anterior gradient protein 2 homolog (AGR2) and Binding-immunoglobulin protein (BiP). This was confirmed by IHC. In HT-29 cells, tunicamycin-induced ER stress triggered AGR2 intracellular expression and its secretion. Supernatant of these HT-29 cells, pre-conditioned by tunicamycin, led to a myofibroblastic differentiation when applied on CCD-18Co fibroblasts. By using recombinant protein and blocking agent for AGR2, we demonstrated that the secretion of this protein by epithelial cells can play a role in the myofibroblastic differentiation. Conclusions The development of CD fibrotic strictures could involve epithelial ER stress and particularly the secretion of AGR2.

Introduction Congenital chloride diarrhoea (CLD) is a rare autosomal recessive disease caused by mutations in the solute family carrier 26 member 3 (SLC26A3) gene. Patients suffer from life-long watery diarrhea and chloride loss. Inflammatory bowel disease (IBD) has been reported in individual patients with CLD and in scl26a3-deficient mice. Methods We performed an international multicentre analysis to build a CLD cohort and to identify cases with IBD. We assessed clinical and genetic characteristics of subjects and studied the cumulative incidence of CLD-associated IBD. Results In a cohort of 72 patients with CLD caused by 17 different SLC26A3 mutations, we identified 12 patients (17%) diagnosed with IBD. Nine patients had Crohn’s disease, two ulcerative colitis, and one IBD-unclassified (IBD-U). Prevalence of IBD in our cohort of CLD is higher than the highest prevalence of IBD in Europe (p < 0.0001). The age of onset was variable (13.5 years, IQR: 8.5 – 23.5 years). Patients with CLD and IBD had lower z-score for height than those without IBD. 4/12 patients had required surgery (ileostomy formation n=2, ileocaecal resection due to ileocaecal valve stenosis n=1, and colectomy due to stage II transverse colon cancer n=1). At last follow-up, 5/12 were on biologics (adalimumab, infliximab, or vedolizumab), 5/12 on immunosuppressant (azathioprine or mercaptopurine), one on 5-ASA and one off-treatment. Conclusions A substantial proportion of patients with CLD develop IBD. This suggests potential involvement of SL26A3-mediated anion transport in IBD pathogenesis. Patients with CLD-associated IBD may require surgery for treatment failure or colon cancer.

Summary Background Ileal and colonic Crohn's disease seem to be two separate entities. Aims To describe the main physiological distinctions between the small and the large intestine and to analyse the differences between ileal and colonic Crohn's disease. Methods The relevant literature was critically examined and synthesised. Results The small and large intestine have fundamental distinctions (anatomy, cellular populations, immune defence, microbiota). The differences between ileal and colonic Crohn's disease are highlighted by a heterogeneous body of evidence including clinical features (natural history of the disease, efficacy of treatments, and monitoring), epidemiological data (smoking status, age, gender) and biological data (genetics, microbiota, immunity, mesenteric fat). However, the contribution of these factors to disease location remains poorly understood. Conclusion The classification of ileal and colonic Crohn's disease as distinct subphenotypes is well supported by the literature. Understanding of these differences could be exploited to develop more individualised patient care.

Background Congenital chloride diarrhea (CLD) is a rare autosomal recessive disease caused by the mutation in member 3 of the solute carrier 26 (SLC26A3). The phenotypic expression is a life-long severe watery Chloride rich diarrhea. Anecdotal association with inflammatory bowel disease (IBD) has been reported suggesting that underlying molecular mechanisms could represent part of an evolving association between IBD and channelopathies. We aimed to investigate this association in a cohort of CLD pediatric patients. Methods A European-based call for cases was made in CLD patients followed up in five different countries. A case report form for each patient was then completed. Results A total of 74 patients with CLD with a range of different CLD mutations were enrolled in the study. Twelve patients of 64 (16%) demonstrated colonic inflammation and were finally diagnosed with IBD: 8 patients with Crohn’s Disease, 2 with Ulcerative Colitis, and 2 IBD-like colitis (IBD-U). The diagnosis was made at a median of 12 years old (IQR: 6–30). Patients had different ethnicities (7 European, 2 Middle East, 1 North Africa, 1 Pakistan, 1 Central Africa). Among the 12 IBD, 2 had a 5-ASA-based treatment, 3 required immunosuppressant and 6 had biologics (Infliximab, Adalimumab and Vedolizumab). Three patients underwent surgery for ileostomy formation for CD that was non-responsive to multiple line of biologics (anti-TNF and anti-integrin): one had colectomy the remnant two colon preservation. Clinical characteristics, such as premature delivery, low weight at birth, fecal Cl- at diagnosis and amount of Cl- supplementation (mmol/kg) did not differ between patients with or without IBD. All patients underwent genotyping for CLD diagnosis and we did not find any specific genetic mutation linked to the development of IBD. Conclusion Sixteen percent of patients enrolled with CLD in our cohort developed IBD. Despite different presentations (CD, UC, IBD-U) all patients had colonic without ileal/small bowel involvement, in line with preliminary murine models of CLD demonstrating a role of colonic mucous layer in the development of colonic inflammation (Xiao et al Acta Physiol Oxf Engl 2014; 211:161–175). Patients’ IBD treatment included a wide range with variable success. Patients with IBD did not differ in their clinical characteristics or genetic mutations compared with non-IBD CLD patients. The role of genetic variants outside the CLD-gene and the microbiome in this association are under investigation.

Background Intestinal fibrosis is a common complication of Crohn’s disease (CD) characterized by an accumulation of fibroblasts differentiating into activated myofibroblasts secreting excessive extracellular matrix. In in-vitro experiments, this myofibroblastic differentiation is elicited by a whole series of factors among which transforming growth factor-β1 (TGF-β1) seems to play a key role. The potential role of the intestinal epithelium in this fibrotic process remains poorly defined. Methods We performed a pilot proteomic study comparing the proteome of surface epithelium isolated by laser-capture microdissection in normal and fibrotic zones of resected ileal CD strictures (13 zones collected in 5 patients). The pro-fibrotic role of selected epithelial proteins was investigated through in-vitro experiments using HT-29 epithelial cells and a CCD-18Co fibroblast to myofibroblast differentiation model. Results Proteomic study revealed an endoplasmic reticulum (ER) stress proteins increase in the epithelium of CD ileal fibrotic strictures, including Anterior gradient protein 2 homolog (AGR2), Protein disulphide isomerase A6 (PDIA6) and Endoplasmic reticulum resident protein 44 (ERP44) which are 3 protein disulphide isomerases. In HT-29 cells, tunicamycin-induced ER stress triggered AGR2, PDIA6, ERP44 as well as TGF-β1 intracellular expression and their secretion. Supernatant of these HT-29 cells, pre-conditioned by tunicamycin (Tm), led to a myofibroblastic differentiation when applied on CCD-18Co fibroblasts. The application of blocking agents for AGR2, PDIA6, ERP44 or TGF-β1 in the supernatant of these Tm-pre-conditioned HT-29 cells, attenuated the myofibroblastic differentiation induced by this supernatant, suggesting a pro-fibrotic role of these secreted epithelial proteins. Conclusion The development of CD fibrotic strictures may involve ER stress in epithelial cells, releasing a whole set of proteins into their environment, including AGR2, PDIA6, ERP44 as well as TGF-β1, which could exercise a pro-fibrotic role through a paracrine action.

Background Evolution of Crohn's disease (CD) is often marked by fibrostenotic complications and available biotherapies cannot prevent or treat intestinal fibrosis. The pathophysiological mechanisms of intestinal fibrosis are multiple and poorly understood. The intestinal epithelium probably plays a key role. The endoplasmic reticulum stress (ERS) is involved in the pathophysiology of IBD and in fibrosis. Protein disulfide isomerases (PDIs) take part in the ER stress response, but their precise roles and associations with CD remain poorly characterized. We investigated the distribution of selected PDIs within the ileum and colon of adult and pediatric patients with inflammatory or stenosing CD. Methods Tissues from 72 pediatric and 47 adult CDs, and 26 pediatric and 48 adult patients without IBD were included from 4 tertiary hospitals. The degree of fibrosis and inflammatory infiltrate were evaluated. The distribution of 4 PDIs (AGR2, BiP, PDIA6, ERP44) within the tissues was studied by immunohistochemistry (IHC) using a semiquantitative scoring scale (0 to 4). Statistical tests used were ANOVA or Kruskal-Wallis (with post hoc test), T-Student and Mann-Whitney. Results The clinical characteristics of the patients included are described in Table 1. The PDIs provide an IHC signal which was mainly epithelial. The distribution of PDIs differed according to the segment studied (colon or ileum), the age of CD onset, location in the epithelium (surface, median crypt, or bottom of crypt), and the normal, inflammatory, and/or fibrotic features of the tissues. In the ileum of adult and pediatric CDs, the distribution of AGR2 was significantly higher in the epithelium adjacent to fibro-inflammatory tissues (p<0.01). In pediatric cases, AGR2 increased significantly with the fibrosis grade within the surface epithelium of the ileum (Fig. 1). The distributions of the other PDIs (BiP, ERP44 and PDIA6) were rather influenced by the inflammatory infiltrates and varied in adult and pediatric CD. The distribution of BiP was significantly higher in tissues with acute and/or chronic inflammation and independent from fibrosis. In adults, the distribution of PDIA6 in the colonic epithelium was significantly higher in CD cases compared to non-CD cases. Conclusion Our results suggest that the studied PDIs may have different roles in the ERS response within the intestinal epithelium in adult and pediatric CD. These PDIs need to be functionally explored further to better understand their specific involvement in inflammation and fibrosis in CD. The increase of AGR2 in fibro-inflammatory tissues, not observed with other PDIs, suggests a specific link between AGR2 and intestinal fibrosis.

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