Florian Rieder

3rd European Evidence-based Consensus on the Diagnosis and Management of Crohn’s Disease 2016: Part 1: Diagnosis and Medical Management

This paper is the first in a series of two publications relating to the European Crohn’s and Colitis Organisation [ECCO] evidence-based consensus on the diagnosis and management of Crohn’s disease and concerns the methodology of the consensus process, and the classification, diagnosis and medical management of active and quiescent Crohn’s disease. Surgical management as well as special situations including management of perianal Crohn’s disease of this ECCO Consensus are covered in a subsequent second paper [Gionchetti et al JCC 2016].

Intestinal fibrosis in IBD—a dynamic, multifactorial process

Intestinal fibrosis is a common and potentially serious complication of IBD that results from the reaction of intestinal tissue to the damage inflicted by chronic inflammation. The traditional view that fibrosis is inevitable or irreversible in patients with IBD is progressively changing in light of improved understanding of the cellular and molecular mechanisms that underlie the pathogenesis of fibrosis in general, and, in particular, intestinal fibrosis. These mechanisms are complex and dynamic, and involve multiple cell types, interconnected cellular events and a large number of soluble factors. In addition, owing to a breakdown of the epithelial barrier during inflammation of the gut, luminal bacterial products induce an innate immune response, which is triggered by activation of immune and nonimmune cells alike. Comprehension of the mechanisms of intestinal fibrosis will create a conceptual and practical framework that could achieve the specific blockade of fibrogenic pathways, allow for the estimation of risk of fibrotic complications, permit the detection of early fibrotic changes and, eventually, enable the development of treatments customized to the type and stage of each patients IBD.

Wound healing and fibrosis in intestinal disease

The mechanisms of wound healing in general have gained interest in recent years, as it has become obvious that the tightly regulated process of tissue repair and regeneration is of great importance for organ homeostasis. Insufficient as well as excessive tissue repair both impair gastrointestinal function. Formation of ulcers and fistulas on the one hand, and of fibrosis and stricture on the other, represent just two sides of one medal. So far, the physiological pathways involved in intestinal wound healing are only partially understood. During acute and chronic intestinal inflammation, macrophages and neutrophils induce local tissue damage by secreting reactive oxygen radicals and tissue-degrading enzymes. This is followed by the release of pro-inflammatory cytokines, as well as chemotactic and cell-activating peptides previously bound to the matrix. If tissue damage is severe, myofibroblasts migrate to the sites of the defect. This migratory function, the ability to contract the wound area and the production of extracellular matrix (ECM) by intestinal myofibroblast cells certainly have important roles in the physiological situation and are altered by chronic inflammation. Available treatments of intestinal strictures, fibrosis and fistulas are insufficient and unsatisfactory. New therapeutic approaches are urgently needed. Future intervention should involve stronger and more selective prevention of the continuous tissue damage and a change in wound healing by modulation of myofibroblast migration and ECM synthesis. Severe mucosal tissue damage requiring efficient wound healing is a main feature of inflammatory bowel disease (IBD), with its two entities Crohn’s disease and ulcerative colitis. During radiation enteritis1,2 or chronic ischaemic enteritis,3,4 the bowel wall is similarly damaged, with subsequent inflammation. Furthermore, cystic fibrosis also may lead to colonic wall thickening, fibrotic colonopathy and stricture formation.5,6,7,8,9,10 In rare cases, recurrent diverticulitis also may cause colonic strictures.11,12 During …

Crohn's disease complicated by strictures: a systematic review

The occurrence of strictures as a complication of Crohns disease is a significant clinical problem. No specific antifibrotic therapies are available. This systematic review comprehensively addresses the pathogenesis, epidemiology, prediction, diagnosis and therapy of this disease complication. We also provide specific recommendations for clinical practice and summarise areas that require future investigation.

Inflammation-induced endothelial-to-mesenchymal transition: a novel mechanism of intestinal fibrosis.

In addition to mesenchymal cells, endothelial cells may contribute to fibrosis through the process of endothelial-to-mesenchymal transition (EndoMT). We investigated whether human intestinal microvascular endothelial cells (HIMEC) undergo EndoMT and contribute to fibrosis in human and experimental inflammatory bowel disease (IBD). HIMEC were exposed to TGF-β1, IL-1β, and TNF-α or supernatants of lamina propria mononuclear cells (LPMC) and evaluated for morphological, phenotypic, and functional changes compatible with EndoMT. Genomic analysis was used to identify transcription factors involved in the transformation process. Evidence of in situ and in vivo EndoMT was sought in inflamed human and murine intestine. The combination of TGF-β1, IL-1β and TNF-α, or activated LPMC supernatants induced morphological and phenotypic changes consistent with EndoMT with a dominant effect by IL-1. These changes persisted after removal of the inducing agents and were accompanied by functional loss of acetylated LDL-uptake and migratory capacity, and acquisition of de novo collagen synthesis capacity. Sp1 appeared to be the main transcriptional regulator of EndoMT. EndoMT was detected in microvessels of inflammatory bowel disease (IBD) mucosa and experimental colonic fibrosis of Tie2-green fluorescent protein (GFP) reporter-expressing mice. In conclusion, chronic inflammation induces transdifferentiation of intestinal mucosal microvascular cells into mesenchymal cells, suggesting that the intestinal microvasculature contributes to IBD-associated fibrosis through the novel process of EndoMT.

Third European Evidence-based Consensus on Diagnosis and Management of Ulcerative Colitis. Part 1: Definitions, Diagnosis, Extra-intestinal Manifestations, Pregnancy, Cancer Surveillance, Surgery, and Ileo-anal Pouch Disorders

aDepartment of Pharmacology and Therapeutics, University of Porto; MedInUP, Centre for Drug Discovery and Innovative Medicines; Centro Hospitalar São João, Porto, Portugal bIBD Unit, DIMEC, University of Bologna, Bologna, Italy cDepartment of Gastroenterology and Hepatology, Chaim Sheba Medical Center, Tel Hashomer, Israel dGastrointestinal Unit ASST Fatebenefratelli Sacco—University of Milan—Milan, Italy eIBD Unit Complesso Integrato Columbus, Gastroenterological and Endocrino-Metabolical Sciences Department, Fondazione Policlinico Universitario Gemelli Universita’ Cattolica del Sacro Cuore, Rome, Italy fDepartment of Gastroenterology, IBD Unit, University Hospital Santiago De Compostela (CHUS), A Coruña, Spain gDepartment of Gastroenterology, North Zealand University Hospital, Frederikssund, Denmark hFirst Department of Medicine, Semmelweis University, Budapest, Hungary iIBD Unit, St Mark’s Hospital, Middlesex, UK jDepartment of Gastroenterology, University Hospital of Ghent, Ghent, Belgium kInstitute of Pathology, Medical University of Graz, Graz, Austria lDepartment of Gastroenterology, Pennine Acute Hospitals NHS Trust; Institute of Inflammation and Repair, University of Manchester, Manchester, UK mUnit of General Surgery, Second University of Naples, Napoli, Italy nMaria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology, Department of Oncological Gastroenterology Warsaw; Medical Centre for Postgraduate Education, Department of Gastroenterology, Hepatology and Clinical Oncology, Warsaw, Poland oDepartment of Medicine, University of Cambridge, Cambridge, UK pImperial College London; Chelsea and Westminster Hospital, London, UK qDepartment of Pathobiology /NC22, Lerner Research Institute; Department of Gastroenterology, Hepatology and Nutrition/A3, Digestive Disease and Surgery Institute, Cleveland Clinic Foundation, Cleveland, OH, USA

Cellular and molecular mechanisms of intestinal fibrosis

Fibrosis is a chronic and progressive process characterized by an excessive accumulation of extracellular matrix (ECM) leading to stiffening and/or scarring of the involved tissue. Intestinal fibrosis may develop in several different enteropathies, including inflammatory bowel disease. It develops through complex cell, extracellular matrix, cytokine and growth factor interactions. Distinct cell types are involved in intestinal fibrosis, such as resident mesenchymal cells (fibroblasts, myofibroblasts and smooth muscle cells) but also ECM-producing cells derived from epithelial and endothelial cells (through a process termed epithelial- and endothelial-mesenchymal transition), stellate cells, pericytes, local or bone marrow-derived stem cells. The most important soluble factors that regulate the activation of these cells include cytokines, chemokines, growth factors, components of the renin-angiotensin system, angiogenic factors, peroxisome proliferator-activated receptors, mammalian target of rapamycin, and products of oxidative stress. It soon becomes clear that although inflammation is responsible for triggering the onset of the fibrotic process, it only plays a minor role in the progression of this condition, as fibrosis may advance in a self-perpetuating fashion. Definition of the cellular and molecular mechanisms involved in intestinal fibrosis may provide the key to developing new therapeutic approaches.

Evidence for a role of epithelial mesenchymal transition during pathogenesis of fistulae in Crohn's disease

Background: The pathogenesis of fistulae in Crohns disease (CD) patients is barely understood. We recently showed that more than two‐thirds of CD fistulae are covered with flat, mesenchymal‐like cells (transitional cells [TC]) forming a patchy basement membrane. Epithelial‐to‐mesenchymal transition (EMT) is a process of reprogramming epithelial cells, allowing them to migrate more effectively and giving epithelial cells an “invasive” potential. EMT has been suggested to be crucial in fibrosis found in different tissues and diseases. We therefore investigated whether EMT could be involved in the pathogenesis of fistulae formation in CD. Methods: In all, 18 perianal fistulae, 2 enteroenteric, and 1 enterovesical fistulae from 17 CD patients were analyzed. In addition 2 perianal fistulae of non‐CD patients were studied. Hematoxylin and eosin staining, immunohistochemistry for the expression of cytokeratins 8 and 20, &bgr;6‐integrin, E‐cadherin, &bgr;‐catenin, vimentin, and TGF‐&bgr;1 and 2 were performed according to standard techniques. Results: The TC covering perianal or enteroenteric fistulae were strongly positive for cytokeratins 8 and 20 but negative for vimentin, indicating their epithelial origin. &bgr;6‐Integrin and TGF‐&bgr; had the highest staining intensities in the transitional zone between the epithelium and the TC. Expression of junctional proteins such as E‐cadherin was reduced in TC as compared to regular fistulae epithelium. In addition, a translocation of &bgr;‐catenin from the membrane to the cytoplasm was observed. Conclusions: Our data for the first time indicate an expression pattern of epithelial and mesenchymal markers in TC associated with fistulae formation that is characteristic for EMT. Studying the pathways of EMT during intestinal fistulae formation may help to develop new therapeutic strategies.

Association of the novel serologic anti-glycan antibodies anti-laminarin and anti-chitin with complicated Crohn's disease behavior.

Background: We tested a panel of novel serological anti‐glycan antibodies including the previously unpublished anti‐laminarin IgA (Anti‐L) and anti‐chitin IgA (Anti‐C) carbohydrate antibodies for the presence in Crohns disease (CD) patients, diagnosis and differentiation of CD, association with complicated disease behavior, and marker stability over time. Methods: The presence of Anti‐L, Anti‐C, anti‐chitobioside IgA (ACCA), anti‐laminaribioside IgG (ALCA), anti‐mannobioside IgG (AMCA), and anti‐Saccaromyces cervisiae IgG (gASCA) carbohydrate antibodies were tested in serum samples from 824 participants (363 CD, 130 ulcerative colitis [UC], 74 other gastrointestinal diseases, and 257 noninflammatory bowel/gastrointestinal disease controls) of the German IBD‐network by enzyme‐linked immunosorbent assay (ELISA; Glycominds, Lod, Israel) and for perinuclear antineutrophil cytoplasmic antibody (pANCA) by immunofluorescence. Results: In all, 77.4% of the CD patients were positive for at least 1 of the anti‐glycan antibodies. gASCA or the combination of gASCA/pANCA remained most accurate for the diagnosis of CD, but the combined use of the antibodies improved differentiation of CD from UC. Several single markers as well as an increasing antibody response were independently linked to a severe disease phenotype, as shown for the occurrence of complications, CD‐related surgery, early disease onset, and ileal disease location. This was observed for both quantitative and qualitative antibody responses. The antibody status remained stable over time in most IBD patients. Conclusions: A panel of anti‐glycan antibodies including the novel Anti‐L and Anti‐C may aid in differentiation of CD from UC, is associated with complicated CD behavior and IBD‐related surgery, and is stable over time in a large patient cohort. Inflamm Bowel Dis 2009

T-Helper 2 Cytokines, Transforming Growth Factor β1, and Eosinophil Products Induce Fibrogenesis and Alter Muscle Motility in Patients With Eosinophilic Esophagitis

BACKGROUND & AIMS Patients with eosinophilic esophagitis (EoE) often become dysphagic from the combination of organ fibrosis and motor abnormalities. We investigated mechanisms of dysphagia, assessing the response of human esophageal fibroblasts (HEFs), human esophageal muscle cells (HEMCs), and esophageal muscle strips to eosinophil-derived products. METHODS Biopsy specimens were collected via endoscopy from the upper, middle, and lower thirds of the esophagus of 18 patients with EoE and 21 individuals undergoing endoscopy for other reasons (controls). Primary cultures of esophageal fibroblasts and muscle cells were derived from 12 freshly resected human esophagectomy specimens. Eosinophil distribution was investigated by histologic analyses of full-thickness esophageal tissue. Active secretion of EoE-related mediators was assessed from medium underlying mucosal biopsy cultures. We quantified production of fibronectin and collagen I by HEF and HEMC in response to eosinophil products. We also measured the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 by, and adhesion of human eosinophils to, HEFs and HEMCs. Eosinophil products were tested in an esophageal muscle contraction assay. RESULTS Activated eosinophils were present in all esophageal layers. Significantly higher concentrations of eosinophil-related mediators were secreted spontaneously in mucosal biopsy specimens from patients with EoE than controls. Exposure of HEFs and HEMCs to increasing concentrations of eosinophil products or co-culture with eosinophils caused HEFs and HEMCs to increase secretion of fibronectin and collagen I; this was inhibited by blocking transforming growth factor β1 and p38 mitogen-activated protein kinase signaling. Eosinophil binding to HEFs and HEMCs increased after incubation of mesenchymal cells with eosinophil-derived products, and decreased after blockade of transforming growth factor β1 and p38 mitogen-activated protein kinase blockade. Eosinophil products reduced electrical field-induced contraction of esophageal muscle strips, but not acetylcholine-induced contraction. CONCLUSIONS In an analysis of tissues samples from patients with EoE, we linked the presence and activation state of eosinophils in EoE with altered fibrogenesis and motility of esophageal fibroblasts and muscle cells. This process might contribute to the development of dysphagia.