Predictors of fibrostenotic Crohn's disease

Total flavone of Abelmoschus manihot regulates autophagy through the AMPK/mTOR signaling pathway to treat intestinal fibrosis in Crohn's disease

BACKGROUND AND AIM

Drug therapy is the treatment of choice for Crohn's disease because it effectively controls or prevents intestinal inflammation. The purpose was to research the molecular mechanism of the total flavones of Abelmoschus manihot (TFA) on intestinal fibrosis in Crohn's disease.

METHODS

A 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis model and IGF-1-treated intestinal fibroblasts were established. Then, TFA, 3-MA, and compound C were used treatments. Hematoxylin and eosin, Masson, and Picrosirius red staining were performed to observe the colon tissue. Immunohistochemical staining was used to detect α-SMA expression. Flow cytometry, CCK8, wound healing, and Transwell assays were conducted to determine apoptosis, proliferation, invasion, and migration. Col1a1 and Col3a1 levels were detected using quantitative polymerase chain reaction. Proteins related to autophagy and apoptosis were detected using western blotting.

RESULTS

TFA treated intestinal fibrosis in chronic Crohn's disease. Colon length was the shortest in the ethanol + TNBS group, and TFA treatment significantly improved the situation. Intestinal fibrosis and the percentage of collagen area decreased after TFA treatment. TFA reduced fibrosis by enhancing autophagy stimulation, whereas an autophagy inhibitor reversed the TFA effect. TFA also inhibited migration, proliferation, and collagen synthesis in intestinal fibroblasts. Moreover, it enhanced autophagy and apoptosis of intestinal fibroblasts. TFA upregulated p-AMPK expression and decreases p-mTOR levels. Compound C partially rescued the effect of TFA, indicating that TFA affected intestinal fibroblasts via the AMPK/mTOR pathway in vitro and in vivo. TFA also downregulated Col1a1 and Col3a1 expression.

CONCLUSION

TFA regulates autophagy through AMPK/mTOR signaling pathway to treat intestinal fibrosis, which may provide a new therapy for Crohn's disease treatment.

Anastomotic Configuration and Temporary Diverting Ileostomy Do Not Increase Risk of Anastomotic Stricture in Postoperative Crohn's Disease

INTRODUCTION

Surgical management of Crohn's disease (CD) is common. Postoperative complications include anastomotic stricturing (AS). The natural history and risk factors for AS have not been elucidated.

METHODS

A retrospective cohort study of patients with CD who underwent ileocolonic resection (ICR) with ≥1 postoperative ileocolonoscopy between 2009 and 2020. Postoperative ileocolonoscopies with corresponding cross-sectional imaging were evaluated for evidence of AS without neoterminal ileal extension. Severity of AS and endoscopic intervention at time of detection were collected. Primary outcome was development of AS. Secondary outcome was time to AS detection.

RESULTS

A total of 602 adult patients with CD underwent ICR with postoperative ileocolonoscopy. Of these, 426 had primary anastomosis, and 136 had temporary diversion at time of ICR. Anastomotic configuration consisted of 308 side-to-side, 148 end-to-side, and 136 end-to-end. One hundred ten (18.3%) patients developed AS with median time of 3.2 years to AS detection. AS severity at time of detection was associated with need for repeat surgical resection for AS. On multivariable Cox proportional hazard regression, anastomotic configuration and temporary diversion were not associated with risk of or time to AS. Preoperative stricturing disease was associated with decreased time to AS (adjusted hazard ratio 1.8; P = 0.049). Endoscopic ileal recurrence before AS was not associated with subsequent AS detection.

DISCUSSION

AS is a relatively common postoperative CD complication. Patients with previous stricturing disease behavior are at increased risk of AS. Anastomotic configuration, temporary diversion, and ileal CD recurrence do not increase risk of AS. Early detection and intervention for AS may help prevent progression to repeat ICR.

How to Evaluate Fibrosis in IBD?

In this review, we will describe the importance of fibrosis in inflammatory bowel disease (IBD) by discussing its distinct impact on Crohn's disease (CD) and ulcerative colitis (UC) through their translation to histopathology. We will address the existing knowledge on the correlation between inflammation and fibrosis and the still not fully explained inflammation-independent fibrogenesis. Finally, we will compile and discuss the recent advances in the noninvasive assessment of intestinal fibrosis, including imaging and biomarkers. Based on the available data, none of the available cross-sectional imaging (CSI) techniques has proved to be capable of measuring CD fibrosis accurately, with MRE showing the most promising performance along with elastography. Very recent research with radiomics showed encouraging results, but further validation with reliable radiomic biomarkers is warranted. Despite the interesting results with micro-RNAs, further advances on the topic of fibrosis biomarkers depend on the development of robust clinical trials based on solid and validated endpoints. We conclude that it seems very likely that radiomics and AI will participate in the future non-invasive fibrosis assessment by CSI techniques in IBD. However, as of today, surgical pathology remains the gold standard for the diagnosis and quantification of intestinal fibrosis in IBD.

Inflammatory bowel disease-associated intestinal fibrosis

Fibrosis is characterized by a proliferation of fibroblasts and excessive extracellular matrix following chronic inflammation, and this replacement of organ tissue with fibrotic tissue causes a loss of function. Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract, and intestinal fibrosis is common in IBD patients, resulting in several complications that require surgery, such as a stricture or penetration. This review describes the pathogenesis and various factors involved in intestinal fibrosis in IBD, including cytokines, growth factors, epithelial-mesenchymal and endothelial-mesenchymal transitions, and gut microbiota. Furthermore, histopathologic findings and scoring systems used for stenosis in IBD are discussed, and differences in the fibrosis patterns of ulcerative colitis and Crohn's disease are compared. Biomarkers and therapeutic agents targeting intestinal fibrosis are briefly mentioned at the end.

Biomechanical Properties of Strictures in Crohn’s Disease: Can Dynamic Contrast-Enhanced Ultrasonography and Magnetic Resonance Enterography Predict Stiffness?

Strictures and abdominal pain often complicate Crohn’s disease (CD). The primary aim was to explore whether parameters obtained by preoperative contrast-enhanced (CE) ultrasonography (US) and dynamic CE MR Enterography (DCE-MRE) of strictures associates with biomechanical properties. CD patients undergoing elective small intestinal surgery were preoperatively examined with DCE-MRE and CEUS. The excised intestine was distended utilizing a pressure bag. Luminal and outer bowel wall cross-sectional areas were measured with US. The circumferential stricture stiffness (Young’s modulus E) was computed. Stiffness was associated with the initial slope of enhancement on DCE-MRE (ρ = 0.63, p = 0.007), reflecting active disease, but lacked association with CEUS parameters. For structural imaging parameters, inflammation and stricture stiffness were associated with prestenotic dilatation on US (τ_b = 0.43, p = 0.02) but not with MRE (τ_b = 0.01, p = 1.0). Strictures identified by US were stiffer, 16.8 (14.0–20.1) kPa, than those graded as no or uncertain strictures, 12.6 (10.5–15.1) kPa, p = 0.02. MRE global score (activity) was associated with E (ρ = 0.55, p = 0.018). Elastography did not correlate with circumferential stiffness. We conclude that increasing activity defined by the initial slope of enhancement on DCE-MRE and MRE global score were associated with stricture stiffness. Prestenotic dilatation on US could be a potential biomarker of CD small intestinal stricture stiffness.

Revisiting fibrosis in inflammatory bowel disease: the gut thickens

Intestinal fibrosis, which is usually the consequence of chronic inflammation, is a common complication of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. In the past few years, substantial advances have been made in the areas of pathogenesis, diagnosis and management of intestinal fibrosis. Of particular interest have been inflammation-independent mechanisms behind the gut fibrotic process, genetic and environmental risk factors (such as the role of the microbiota), and the generation of new in vitro and in vivo systems to study fibrogenesis in the gut. A huge amount of work has also been done in the area of biomarkers to predict or detect intestinal fibrosis, including novel cross-sectional imaging techniques. In parallel, researchers are embarking on developing and validating clinical trial end points and protocols to test novel antifibrotic agents, although no antifibrotic therapies are currently available. This Review presents the state of the art on the most recently identified pathogenic mechanisms of this serious IBD-related complication, focusing on possible targets of antifibrotic therapies, management strategies, and factors that might predict fibrosis progression or response to treatment.

Current Topics of the Mechanism of Intestinal Fibrosis in Crohn’s Disease

Intestinal fibrosis is one of the most common intestinal complications observed in inflammatory bowel disease, especially Crohn’s disease (CD). Intestinal fibrosis in CD is associated with chronic inflammation resulting from immunologic abnormalities and occurs as a form of tissue repair during the anti-inflammatory process. Various types of immune cells and mesenchymal cells, including myofibroblasts, are intricately involved in causing intestinal fibrosis. It is often difficult to treat intestinal fibrosis as intestinal stricture may develop despite treatment aimed at controlling inflammation. Detailed analysis of the pathogenesis of intestinal fibrosis is critical towards advancing the development of future therapeutic applications.

Pathogenesis and management of gastrointestinal inflammation and fibrosis: from inflammatory bowel diseases to endoscopic surgery

Gastrointestinal fibrosis is a state of accumulated biological entropy caused by a dysregulated tissue repair response. Acute or chronic inflammation in the gastrointestinal tract, including inflammatory bowel disease, particularly Crohn’s disease, induces fibrosis and strictures, which often require surgical or endoscopic intervention. Recent technical advances in endoscopic surgical techniques raise the possibility of gastrointestinal stricture after an extended resection. Compared to recent progress in controlling inflammation, our understanding of the pathogenesis of gastrointestinal fibrosis is limited, which requires the development of prevention and treatment strategies. Here, we focus on gastrointestinal fibrosis in Crohn’s disease and post-endoscopic submucosal dissection (ESD) stricture, and we review the relevant literature.

Correlation between age of onset and gastrointestinal stenosis in hospitalized patients with Crohn's disease

BACKGROUND

Patients affected by Crohn's disease (CD) are more likely to develop gastrointestinal stenosis and often undergo surgery during the duration of disease.

AIM

To identify the risk factors for gastrointestinal stenosis in hospitalized CD patients in China.

METHODS

The clinical data of CD patients hospitalized at the Seventh Medical Center, Chinese People's Liberation Army General Hospital from January 2010 to December 2018 were included. Patients with gastrointestinal stenosis were compared to those without gastrointestinal stenosis for clinical variables. The risk factors for gastrointestinal stenosis were identified using univariate and multivariable logistic regression analyses. The treatments for patients with gastrointestinal stenosis were analyzed, and the characteristics of different treatment methods were discussed.

RESULTS

The incidence of gastrointestinal stenosis was 59.02% in the 122 hospitalized CD patients. Age of onset of more than 40 years (odds ratio [OR] = 3.072, 95% confidence interval [CI]: 1.298-7.272, P = 0.009) and duration of disease of more than 5 years (OR = 2.101, 95%CI: 1.002-4.406, P = 0.048) were associated with the occurrence of gastrointestinal stenosis. Fifteen (20.83%) patients did not undergo surgery and received internal medicine and nutrition treatment. Surgical treatments were performed in 72.22% (52) of cases. The rate of postoperative complications was 15.38% (8 cases), and during a median follow-up period of 46 mo, 11.54% (6 cases) underwent reoperation. A total of 29.17% (21 cases) were treated with endoscopic therapy, and during a median follow-up period of 32 mo, 76.19% (16 cases) had no surgical event, 23.81% (5 cases) failed to avoid surgical treatments, and no serious postoperative complications occurred after endoscopic therapy.

CONCLUSION

Age of onset of more than 40 years and duration of disease of more than 5 years may be strongly correlated with a higher risk of gastrointestinal stenosis in hospitalized CD patients. Endoscopic therapy for gastrointestinal stenosis is relatively safe and effective, and may help to prevent or delay surgery.

Strictures in Crohn's Disease: From Pathophysiology to Treatment

Despite recent advances aimed to treat transmural inflammation in Crohn's disease (CD) patients, the progression to a structuring behavior still represents an issue for clinicians. As inflammation becomes chronic and severe, the attempt to repair damaged tissue can result in an excessive production of extracellular matrix components and deposition of connective tissue, thus favoring the formation of strictures. No specific and accurate clinical predictors or diagnostic tools for intestinal fibrosis exist, and to date, no genetic or serological marker is in routine clinical use. Therefore, intestinal fibrosis is usually diagnosed when it becomes clinically evident and strictures have already occurred. Anti-fibrotic agents such as tranilast, peroxisome proliferator-activated receptor gamma agonists, rho kinase inhibitors, and especially mesenchymal stem cell therapy have provided interesting results, but most of the evidence has been derived from studies performed in vitro. Therefore, current therapy of fibrotic strictures relies mainly on endoscopic and surgical procedures. Although its long-term outcomes may be debated, endoscopic balloon dilation appears to be the safest and most effective approach to treat appropriately selected strictures. The use of endoscopic stricturotomy is currently limited by the expertise needed to perform it and by the few data available in the literature. Some good results have been achieved by the positioning of self-expandable metal stents (SEMS). However, there is no concordance regarding the type of stent to use and for how long it should be left in place. The development of new specific SEMS may lead to better outcomes and to an increased use of this alternative in CD-related strictures.

Selective deletion of MyD88 signaling in α-SMA positive cells ameliorates experimental intestinal fibrosis via post-transcriptional regulation

Intestinal fibrosis leading to strictures remains a significant clinical problem in inflammatory bowel diseases (IBD). The role of bacterial components in activating intestinal mesenchymal cells and driving fibrogenesis is largely unexplored. Tamoxifen-inducible α-SMA promoter Cre mice crossed with floxed MyD88 mice were subjected to chronic dextran sodium sulfate colitis. MyD88 was deleted prior to or after induction of colitis. Human intestinal myofibroblasts (HIMF) were exposed to various bacterial components and assessed for fibronectin (FN) and collagen I (Col1) production. RNA sequencing was performed. Post-transcriptional regulation was assessed by polysome profiling assay. Selective deletion of MyD88 in α-SMA-positive cells prior to, but not after induction of, experimental colitis decreased the degree of intestinal fibrosis. HIMF selectively responded to flagellin with enhanced FN or Col1 protein production in a MyD88-dependent manner. RNA sequencing suggested minimal transcriptional changes induced by flagellin in HIMF. Polysome profiling revealed higher proportions of FN and Col1 mRNA in the actively translated fractions of flagellin exposed HIMF, which was mediated by eIF2 alpha and 4EBP1. In conclusion, selectivity of flagellin-induced ECM secretion in HIMF is post-transcriptionally regulated. The results may represent a novel and targetable link between the gut microbiota and intestinal fibrogenesis.

Serum biomarkers of fibrostenotic Crohn's disease: Where are we now?

Intestinal fibrosis and subsequent stricture formation are major clinical challenges in inflammatory bowel disease, resulting in an increased rate of operation and poor prognosis compared with those without. With the changing perception that intestinal fibrosis is irreversible to the point of view that it is reversible in recent years, various candidate serum biomarkers have been studied over the past decades, which may stratify patients based on their risks of developing stenosis and enable the detection of early stages of fibrosis. However, reliable and accurate biomarkers are still unavailable due to conflicting results and the lack of high-quality evidence. In this review we summarized the serum biomarkers that have been proposed for intestinal fibrosis in recent years, which includes gene polymorphisms or variants, epigenetic markers, extracellular matrix components, growth factors, and antibodies, aiming to provide clues for future research.

The Role of Immunomodulators and Biologics in the Medical Management of Stricturing Crohn's Disease

Crohn's disease is a progressive and disabling inflammatory disease involving the gastrointestinal tract. It usually produces inflammatory lesions in the ileocolonic region, but up to half of patients will also develop complications such as strictures in the long term. Indeed, a proportion of patients have progression of the disease with the development of stricturing lesions because there are no drugs that effectively prevent or reverse established fibrosis, and hence these patients are usually treated with surgery or endoscopic balloon dilation. Fibrotic lesions are always associated with some degree of inflammatory changes, but there is little evidence supporting the use of medical therapy in this context. Here, we discuss the most important findings on the possible use of immunomodulators or biologics in the prevention and treatment of intestinal strictures in Crohn's disease patients. Recent evidence demonstrates that these drugs may also be effective in treating lesions with high levels of collagen deposition, and thus might, at least in some patients, reduce the progression of the disease and bowel damage, and further avoid the need for surgery and a disabling course in the long term.

Fibrostenotic strictures in Crohn's disease

The use of biologic agents including anti-tumor necrosis factor monoclonal antibodies followed by anti-integrins and anti-interleukins has drastically changed the treatment paradigm of Crohn’s disease (CD) by improving clinical symptoms and mucosal healing. However, up to 70% of CD patients still eventually undergo surgery mainly due to fibrostenotic strictures. There are no specific anti-fibrotic drugs yet. This review comprehensively addresses the mechanism, prediction, diagnosis and treatment of the fibrostenotic strictures in CD. We also introduce promising anti-fibrotic agents which may be available in the near future and summarize challenges in developing novel therapies to treat fibrostenotic strictures in CD.

Risk factors associated with progression to intestinal complications of Crohn disease

BACKGROUND

Crohn disease is a chronic bowel disease that causes serious complications. Prevalence of Crohn disease is increasing. Studies have shown that the behavior of the disease is not stable and severe complications secondary to behavior change over time have been shown. In this study, we aimed to evaluate the prognostic risk factors associated with phenotypic change in Crohn disease in a Turkish patient cohort.

METHODS

Patients followed up from March 1986 to August 2011 were evaluated for demographic and clinical characteristics to determine possible risk factors and initial clinical phenotype of the disease based on the Montreal classification. The cumulative probabilities of developing stricturing or penetrating intestinal complications were estimated using the Kaplan-Meier analysis. Univariate and multivariate Cox-proportional hazard models were used to assess associations between baseline clinical characteristics and intestinal complications.

RESULTS

Three hundred and thirty patients (mean age, 30.6 ± 11.1 years; 148 female) were included in the study. Mean follow-up duration was 7.4 ± 5.3 years (range: 1.0-25.0 years). At baseline 273 patients had inflammatory-type disease, 57 patients experienced stricturing/penetrating intestinal complications before or at the time of diagnosis. The cumulative probability of developing complicated disease was 37.4% at 5 years, 54.3% at 10 years, 78.8% at 25 years. Independent predictors associated with progression to intestinal complications were current smoking, perianal disease, extra-intestinal manifestations, and location of disease.

CONCLUSIONS

Location of disease is the most powerful indicator for the development of stenosis and penetrating complications in inflammatory-type disease. Patients with ileal involvement should be considered for more aggressive immunosuppressive therapy.

Efficacy and safety of endoscopic balloon dilation in inflammatory bowel disease: results of the large multicenter study of the ENEIDA registry

BACKGROUND

There is no information regarding the outcome of Crohn's disease (CD) patients treated with endoscopic balloon dilation (EBD) in non-referral hospitals, nor on the efficacy of EBD in ulcerative colitis (UC). We report herein the results of the largest series published to date.

AIM

To assess the efficacy and safety of EBD for inflammatory bowel disease (IBD) stenosis performed in 19 hospitals with different levels of complexity and to determine factors related to therapeutic success.

METHODS

We identified IBD patients undergoing EBD in the ENEIDA database. Efficacy of EBD was compared between CD and UC and between secondary and tertiary hospitals. Predictive factors of therapeutic success were assessed with multivariate analysis.

RESULTS

Four-hundred dilations (41.2% anastomotic) were performed in 187 IBD patients (13 UC/Indeterminate colitis). Technical and therapeutic success per dilation was achieved in 79.5% and 55.3%, respectively. Therapeutic success per patient was achieved in 78.1% of cases (median follow-up: 40 months) with 49.7% requiring more than one dilation. No differences related to either diagnosis or hospital complexity was found. Technical success [OR 4.12 (95%CI 2.4-7.1)] and not receiving anti-TNF at the time of dilation [OR 1.7 (95% CI 1.1-2.6)] were independently related to therapeutic success per dilation. A stricture length ≤ 2 cm [HR 2.43 (95% CI 1.11-5.31)] was a predictive factor of long-term success per patient. The rate of major complications was 1.3%.

CONCLUSIONS

EBD can be performed with similar efficacy and safety in hospitals with differing levels of complexity and it might be a suitable treatment for UC with short stenosis. To achieve a technical success and the short length of the stenosis seem to be critical for long-term therapeutic success.

Endoscopic management of Crohn’s strictures

Symptomatic intestinal strictures develop in more than one third of patients with Crohn’s disease (CD) within 10 years of disease onset. Strictures can be inflammatory, fibrotic or mixed and result in a significant decline in quality of life, frequently requiring surgery for palliation of symptoms. Patients under the age of 40 with perianal disease are more likely to suffer from disabling ileocolonic disease thus may have a greater risk for fibrostenotic strictures. Treatment options for fibrostenotic strictures are limited to endoscopic and surgical therapy. Endoscopic balloon dilatation (EBD) appears to be a safe, less invasive and effective alternative modality to replace or defer surgery. Serious complications are rare and occur in less than 3% of procedures. For non-complex strictures without adjacent fistulizaation or perforation that are less than 5 cm in length, EBD should be considered as first-line therapy. The aim of this review is to present the current literature on the endoscopic management of small bowel and colonic strictures in CD, which includes balloon dilatation, adjuvant techniques of intralesional injection of steroids and anti-tumor necrosis factor, and metal stent insertion. Short and long-term outcomes, complications and safety of EBD will be discussed.

Identifying intestinal fibrosis and inflammation by spectroscopic photoacoustic imaging: an animal study in vivo

Crohn's disease (CD) is a chronic autoimmune disease characterized by obstructing intestinal strictures. Conventional imaging modalities can identify the strictures but cannot characterize whether a stricture is predominantly inflammatory or fibrotic. The purpose of this study is to examine the capability of photoacoustic (PA) imaging to characterize intestinal fibrosis and inflammation in vivo. Intestinal strictures in a rat model of CD were imaged with a PA-ultrasound parallel imaging system. Internal and external illuminations were attempted, both with transcutaneous PA signal reception. The PA signal magnitudes acquired at wavelengths targeting individual molecular components and the derived functional information showed significant differences between the inflammatory and fibrotic strictures, consistent with histological inflammation and fibrosis.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

Optimisation of Intestinal Fibrosis and Survival in the Mouse S. Typhimurium Model for Anti-fibrotic Drug Discovery and Preclinical Applications

BACKGROUND AND AIMS

Intestinal fibrosis is a frequent complication in Crohn's disease [CD]. The mouse Salmonella typhimurium model, due to its simplicity, reproducibility, manipulability, and penetrance, is an established fibrosis model for drug discovery and preclinical trials. However, the severity of fibrosis and mortality are host- and bacterial strain-dependent, thus limiting the original model. We re-evaluated the S. typhimurium model to optimise fibrosis and survival, using commercially available mouse strains.

METHODS

Fibrotic and inflammatory markers were evaluated across S. typhimurium ΔaroA:C57bl/6 studies performed in our laboratory. A model optimisation study was performed using three commercially available mouse strains [CBA/J, DBA/J, and 129S1/SvImJ] infected with either SL1344 or ΔaroA S. typhimurium. Fibrotic penetrance was determined by histopathology, gene expression, and αSMA protein expression. Fibrosis severity, penetrance, and survival were analysed across subsequent CBA studies.

RESULTS

Fibrosis severity and survival are both host- and bacterial strain-dependent. Marked tissue fibrosis and 100% survival occurred in the CBA/J strain infected with SL1344. Subsequent experiments demonstrated that CBA/J mice develop extensive intestinal fibrosis, characterised by transmural tissue fibrosis, a Th1/Th17 cytokine response, and induction of pro-fibrotic genes and extracellular matrix proteins. A meta-analysis of subsequent SL1344:CBA/J studies demonstrated that intestinal fibrosis is consistent and highly penetrant across histological, protein, and gene expression markers. As proof-of-concept, we tested the utility of the SL1344:CBA/J fibrosis model to evaluate efficacy of CCG-203971, a novel anti-fibrotic drug.

CONCLUSION

The S. typhimurium SL1344:CBA/J model is an optimised model for the study of intestinal fibrosis.

MCL-1 is modulated in Crohn's disease fibrosis by miR-29b via IL-6 and IL-8

The miR-29 family is involved in fibrosis in multiple organs, including the intestine where miR-29b facilitates TGF-β-mediated up-regulation of collagen in mucosal fibroblasts from Crohn’s disease (CD) patients. Myeloid cell leukemia-1 (MCL-1), a member of the B-cell CLL/Lymphoma 2 (BCL-2) apoptosis family, is involved in liver fibrosis and is targeted by miR-29b via its 3’-UTR in cultured cell lines. We investigate the role of MCL-1 and miR-29b in primary intestinal fibroblasts and tissue from stricturing CD patients. Transfection of CD intestinal fibroblasts with pre-miR-29b resulted in a significant increase in the mRNA expression of MCL-1 isoforms [MCL-1Long (L)/Extra Short (ES) and MCL-1Short (S)], although MCL-1S was expressed at significantly lower levels. Western blotting predominantly detected the anti-apoptotic MCL-1L isoform, and immunofluorescence showed that staining was localised in discrete nuclear foci. Transfection with pre-miR-29b or anti-miR-29b resulted in a significant increase or decrease, respectively, in MCL-1L foci. CD fibroblasts treated with IL-6 and IL-8, inflammatory cytokines upstream of MCL-1, increased the total mass of MCL-1L-positive foci. Furthermore, transfection of intestinal fibroblasts with pre-miR-29b resulted in an increase in mRNA and protein levels of IL-6 and IL-8. Finally, immunohistochemistry showed reduced MCL-1 protein expression in fibrotic CD samples compared to non-stricturing controls. Together, our findings suggest that induction of MCL-1 by IL-6/IL-8 may surmount any direct down-regulation by miR-29b via its 3’-UTR. We propose that an anti-fibrotic miR-29b/IL-6 IL-8/MCL-1L axis may influence intestinal fibrosis in CD. In the future, therapeutic modulation of this pathway might contribute to the management of fibrosis in CD.

Mechanisms, Management, and Treatment of Fibrosis in Patients With Inflammatory Bowel Diseases

In the last 10 years, we have learned much about the pathogenesis, diagnosis, and management of intestinal fibrosis in patients with inflammatory bowel diseases. Just a decade ago, intestinal strictures were considered to be an inevitable consequence of long-term inflammation in patients who did not respond to anti-inflammatory therapies. Inflammatory bowel diseases-associated fibrosis was seen as an irreversible process that frequently led to intestinal obstructions requiring surgical intervention. This paradigm has changed rapidly, due to the antifibrotic approaches that may become available. We review the mechanisms and diagnosis of this serious complication of inflammatory bowel diseases, as well as factors that predict its progression and management strategies.

Serum Glycoproteome Profiles for Distinguishing Intestinal Fibrosis from Inflammation in Crohn's Disease

Background

Reliable identification and quantitation of intestinal fibrosis in the setting of co-existing inflammation due to Crohn’s disease (CD) is difficult. We aimed to identify serum biomarkers which distinguish inflammatory from fibrostenotic phenotypes of CD using serum glycoproteome profiles.

Methods

Subjects with fibrostenotic and inflammation-predominant CD phenotypes (n = 20 per group) underwent comparison by quantitative serum glycoproteome profiles as part of a single tertiary care center cohort study. Following lectin elution, glycoproteins underwent liquid chromatography followed by tandem mass spectrometry. Identified candidate biomarkers of fibrosis were also measured by serum ELISA, a widely available technique.

Results

Five (5) glycoproteins demonstrated a ≥20% relative abundance change in ≥80% of subjects, including cartilage oligomeric matrix protein (COMP) and hepatocyte growth factor activator (HGFA). COMP (431.7±112.7 vs. 348.7±90.5 ng/mL, p = 0.012) and HGFA (152.7±66.5 vs. 107.1±38.7 ng/mL, p = 0.031) serum levels were elevated in the fibrostenotic vs. inflammatory CD groups using ELISA. Within the fibrostenotic group, intra-individual changes of candidate biomarkers revealed HGFA levels significantly declined following the resection of all diseased intestine (152.7±66.5 vs. 107.1±38.7 ng/mL, p = 0.015); COMP levels were unchanged. Immunohistochemical staining confirmed the presence of COMP in the submucosa and muscularis of resected fibrostenotic tissue.

Conclusions

In this biomarker discovery study, several serum glycoproteins, specifically COMP and HGFA, differ between between predominately inflammatory and fibrostenotic CD phenotypes. The development of blood-based biomarkers of fibrosis would provide an important complement to existing prognostic tools in IBD, aiding decisions on therapeutic intensity and mechanism selection, surgery, and the monitoring of future anti-fibrotic therapies for CD.

European Crohn's and Colitis Organisation Topical Review on Prediction, Diagnosis and Management of Fibrostenosing Crohn's Disease

This ECCO topical review of the European Crohn's and Colitis Organisation [ECCO] focused on prediction, diagnosis, and management of fibrostenosing Crohn's disease [CD]. The objective was to achieve evidence-supported, expert consensus that provides guidance for clinical practice.

Evidence of Crohn's disease-related anti-glycoprotein 2 antibodies in patients with celiac disease

BACKGROUND

Autoantibodies to exocrine-pancreatic glycoprotein 2 (anti-GP2) are Crohn's disease (CD) markers. However, CD-specific antibodies have also been found in celiac-disease (CeD) patients, in which type 1 diabetes-specific autoantibodies against endocrine pancreatic targets can be present. We investigated whether anti-GP2 are also present in CeD, a disease like CD which is also characterised by intestinal mucosal inflammation with barrier impairment.

METHODS

Antibodies against GP2, tissue transglutaminase (tTG), deamidated gliadin (dGD), glutamic decarboxylase (GAD), and islet antigen-2 (IA2) were tested in sera from 73 CD patients, 90 blood donors (BD), and 79 (58 de novo) CeD patients (2 consecutive sera were available from 40 patients).

RESULTS

IgA and/or IgG anti-GP2 were found in 15/79 (19.0%) CeD patients on at least one occasion, in 25/73 (34.2%) CD patients, and in 4/90 (4.4%) BD (CeD vs. CD, p=0.042; BD vs. CeD and CD, p<0.001, respectively). Amongst the 58 de novo CeD patients, anti-GP2 IgA and/or IgG were present in 11 (19.0%). Anti-GP2 IgA was significantly less prevalent in CeD compared with CD (p=0.004). Anti-GP2 IgA and IgG in CD patients demonstrated a significantly higher median level compared to patients with CeD (p<0.001, p=0.008, respectively). IgA anti-GP2 levels correlated significantly with IgA anti-tTG and anti-dGD levels in CeD Spearman's coefficient of rank correlation (ρ)=0.42, confidence interval (CI): 0.26-0.56, p<0.001; ρ=0.54, CI 0.39-0.65, p<0.001, respectively.

CONCLUSIONS

The presence of anti-GP2 in CeD patients supports the notion that loss of tolerance to GP2 can probably be a manifestation of an autoinflammatory process in this intestinal disorder.

Genetic Influences on the Development of Fibrosis in Crohn's Disease

Fibrostenotic strictures are an important complication in patients with Crohn’s disease (CD), very often necessitating surgery. This fibrotic process develops in a genetically susceptible individual and is influenced by an interplay with environmental, immunological, and disease-related factors. A deeper understanding of the genetic factors driving this fibrostenotic process might help to unravel the pathogenesis, and ultimately lead to development of new, anti-fibrotic therapy. Here, we review the genetic factors that have been associated with the development of fibrosis in patients with CD, as well as their potential pathophysiological mechanism(s). We also hypothesize on clinical implications, if any, and future research directions.

Biomarkers of intestinal fibrosis - one step towards clinical trials for stricturing inflammatory bowel disease

Intestinal fibrosis, caused by an excessive deposition of extracellular matrix components, and subsequent stricture development are a common complication of inflammatory bowel disease. However, currently there are no biomarkers which reliably predict the risk of developing intestinal strictures or identify early stages of fibrosis prior to clinical symptoms. Candidate biomarkers of intestinal fibrosis, including gene variants (i.e. nucleotide-binding oligomerization domain-2 gene), serum microRNAs (miR-19, miR-29), serum extracellular matrix proteins (i.e. collagen, fibronectin) or enzymes (i.e. tissue inhibitor of matrix metalloproteinase-1), serum growth factors (i.e. basic fibroblast growth factor, YKL-40), serum anti-microbial antibodies (i.e. anti-Saccharomyces cerevisiae) and circulating cells (i.e. fibrocytes) have shown conflicting results on relatively heterogeneous patients' cohorts, and none of them was proven to be strictly specific for fibrostenosis, but rather predictive of a disease disabling course. In this review we critically reassess the diagnostic and prognostic value of serum biomarkers of intestinal fibrosis in inflammatory bowel disease.

Intestinal Fibrosis and Liver Fibrosis: Consequences of Chronic Inflammation or Independent Pathophysiology?

Background

Intestinal fibrosis and liver fibrosis represent a significant burden for our patients and health-care systems. Despite the severe clinical problem and the observation that fibrosis is reversible, no specific antifibrotic therapies exist.

Summary

In this review, using an 'East-West' scientific collaboration, we summarize the current knowledge on principal mechanisms shared by intestinal fibrosis and liver fibrosis. We furthermore discuss inflammation as the cause of fibrogenesis in both entities, depict unique features of intestinal and hepatic fibrosis, and provide a future outlook on the development of antifibrotic therapies.

Key Messages

A collaborative effort in the field of fibrosis, covering multiple organ systems, will have the highest chance of leading to the development of a successful antifibrotic intervention.

Assessment of stricturing Crohn's disease: Current clinical practice and future avenues

Crohn’s disease (CD) is a chronic remittent idiopathic disease. Although the early phase of the disease is commonly characterized by inflammation-driven symptoms, such as diarrhea, the frequency of fibrostenotic complications in patients with CD increases over the long-term course of the disease. This review presents the current diagnostic options for assessing CD-associated strictures. In addition to the endoscopic evaluation of CD strictures, this review summarizes the currently available imaging modalities, including ultrasound and cross-sectional imaging techniques. In addition to stricture detection, differentiating between the primarily inflammatory strictures and the predominantly fibrotic ones is essential for selecting the appropriate treatment strategy (anti-inflammatory medical treatment vs endoscopical or surgical approaches). Therefore, recent imaging advances, such as contrast-enhanced ultrasound and ultrasound elastography, contribute to the development of non-invasive non-radiating imaging of CD-associated strictures. Finally, novel magnetic resonance imaging techniques, such as diffusion-weighted, motility and magnetization transfer imaging, as well as ¹⁸F-FDG PET/CT, molecular imaging approaches and biomarkers, are critically reviewed with regard to their potential role in assessing stricturing CD.

Therapeutic Armamentarium for Stricturing Crohn's Disease: Medical Versus Endoscopic Versus Surgical Approaches

One-third of patients with Crohn's disease (CD) present as stricturing phenotype characterized by progressive luminal narrowing and obstructive symptoms. The diagnosis and management of these patients have been intriguing and challenging. Immunomodulators and biologics have been successfully used in treating inflammatory and fistulizing CD. There are issues of efficacy and safety of biological agents in treating strictures in CD. Rapid mucosal healing from potent biological agents may predispose patients to the development of new strictures or worsening of existing strictures. On the other hand, strictures constitute one-fifth of the reasons for surgery in patients with CD. Disease recurrence is common at or proximal to the anastomotic site with the majority of these patients developing new endoscopic lesions within 1 year of surgery. The progressive nature of the disease with repetitive cycle of inflammation and stricture formation results in repeated surgery, with a risk of small bowel syndrome. There is considerable quest for bowel conserving endoscopic and surgical strategies. Endoscopic balloon dilation and stricturoplasty have emerged as valid alternatives to resection. Endoscopic balloon dilation has been shown to be feasible, safe, and effective for the short primary or anastomotic strictures. However, repeated dilations are often needed, and long-term outcomes of endoscopic balloon dilation remain to be investigated. The introduction of stricturoplasty has added another dimension to bowel saving strategy. Although postoperative recurrence rate after stricturoplasty is comparable with surgical resection, there are concerns for increased risk of malignancy in preserved bowel. Laparoscopic surgery has widely been performed with similar outcomes to open approach with fewer complications, quicker recovery, better cosmesis, and lower cost. All of these issues should be considered by physicians involved in the management of patients with stricturing CD.

Low Serum Levels of MicroRNA-19 Are Associated with a Stricturing Crohn's Disease Phenotype

BACKGROUND

Development of fibrosis and subsequent stricture formation in Crohn's disease (CD) increases morbidity and rates of surgery and reduces patients' quality of life. There are currently no biomarkers of intestinal fibrosis that might allow earlier identification and better management of patients at increased risk of stricture formation.

METHODS

MicroRNA profiling of serum from CD patients was used to identify microRNAs associated with stricture formation. Differential expression of miR-19a-3p and miR-19b-3p was validated by quantitative PCR in independent CD cohort of stricturing and nonstricturing patients (n = 46 and n = 62, respectively). Levels of miR-19a-3p and miR-19b-3p were also quantified in baseline serum samples, and expression compared between CD patients who subsequently developed stricture and those who did not (n = 11 and n = 44, respectively).

RESULTS

Serum levels of miR-19a-3p and miR-19b-3p in the array were lower in CD patients with a stricturing phenotype than in control CD patients (P = 0.007 and 0.008, respectively). The reduction in miR-19a-3p and 19b-3p was verified in a second cohort (P = 0.002). The association of miR-19-3p with stricturing CD was independent of potential confounding clinical variables, including disease duration, disease activity, site, gender, and age. Serum analyses in patients with 4 years of follow-up support the hypothesis that reduced miR-19a-3p and miR-19b-3p predate stricture development with a trend toward significance (P = 0.077 and P = 0.060, respectively).

CONCLUSIONS

These data identify miR-19-3p as a potential circulating marker of stricturing CD. Our data show that microRNAs have utility as noninvasive biomarkers of stricturing CD. Further longitudinal studies are required to determine the prognostic value of miR-19-3p at diagnosis.

Prostaglandin E₂ and polyenylphosphatidylcholine protect against intestinal fibrosis and regulate myofibroblast function

BACKGROUND

Intestinal fibrosis is a serious and often recurrent complication of inflammatory bowel disease despite surgical intervention. The anti-fibrotic potential of prostaglandin E2 (PGE2) and polyenylphosphatidylcholine (PC) was investigated using the murine model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic intestinal inflammation and fibrosis, and murine and human intestinal myofibroblasts.

METHODS

Mice were treated with TNBS enemas weekly for 2 or 6 weeks ± PGE2 (10 mg/kg/day orally) or PC (200 mg/kg/day orally). Inflammation and fibrosis were histologically assessed and scored. Pro-inflammatory cytokines, TLR4, and ECM-related gene expression from the colonic tissue and cultured myofibroblasts were assessed by RT-qPCR. The levels of α-SMA(+) staining and endogenous PGE2 in vivo were also assessed.

RESULTS

Both PGE2 and PC treatment significantly decreased TNBS-induced intestinal inflammation and excess collagen deposition in vivo. This was accompanied by decreased α-SMA(+) staining in the lamina propria and lower collagen type I (COL1α1) expression. Endogenous PGE2 levels demonstrated that PC was not being converted into PGE2, thus mediating its effects primarily via PGE2-independent pathways. Both PGE2 and the PC isoform, 1,2-dilinoleoylphosphatidylcholine (DLPC), regulated primary mouse myofibroblast and CCD-18co COL1α1 production, and induced lower collagen type I to III and TGF-β1 to TGF-β3 ratios, demonstrating their ability to induced normal healing in the presence of phorbol 12-myristate 13-acetate (protein kinase C-dependent inducer of collagen production).

CONCLUSION

PGE2 and PC both have potent anti-fibrogenic potentials in their ability to regulate inflammatory cell and myofibroblast accumulation within inflamed tissue, to decrease pro-inflammatory cytokine expression and to maintain normal healing in an inflammatory environment.

Intestinal fibrosis in Crohn's disease: role of microRNAs as fibrogenic modulators, serum biomarkers, and therapeutic targets

Inflammation often precedes fibrosis and stricture formation in patients with Crohn's disease. Established medical therapies reduce inflammation, but there are currently no specific therapies to prevent fibrosis or treat established fibrosis. Our understanding of the pathogenic processes underpinning fibrogenesis is limited compared with our knowledge of the events initiating and propagating inflammation. There are several biomarkers for intestinal inflammation, but there are none that reflect the development of fibrosis. MicroRNAs (miRNAs) are regulators of cellular activities including inflammation and fibrosis and may serve as biomarkers of disease processes. Differential serum and mucosal miRNA expression profiles have been identified between patients with inflammatory bowel disease with active and inactive inflammatory disease. In contrast, studies in patients with fibrotic phenotypes are comparatively few, although specific miRNAs have defined roles in the development of fibrosis in other organ systems. Here, we discuss the most recent research on miRNA and fibrogenesis with a particular emphasis on Crohn's disease. We also anticipate the potential of miRNAs in fulfilling current unmet translational needs in this patient group by focusing on the role of miRNAs as modulators of fibrogenesis and on their potential value as serum biomarkers and therapeutic targets in the management of fibrosis.

The correlation between tenascin-C expression, and formation of intestinal stricture

OBJECTIVE:

A strong correlation exists between tenascin-C induction, and acute inflammation. Generally increased tenascin-C concentrations are correlated with various inflammatory, and infectious diseases. In patients with diagnosis of Inflammatory Bowel Disease (IBD) presence of tenascin-C in colonic mucosa demonstrates tissue repair, and its mucosal concentrations are correlated with local disease activity Therefore plasma levels of tenascin-C have been demonstrated to be a helpful indicator of the activity of inflammatory bowel diseases. In this study, firstly in the literature, we aimed to display the correlation between tenascin-C expression, and formation of intestinal stricture.

METHODS:

A total of 43 patients (male, n=19; 44.2%; and female, n=24, 55.8%) aged between 19, and 63 years, with clinically, endoscopically, radiologically, and histopathologically confirmed definitive diagnosis of Crohn’s disease who were examined, diagnosed, and treated in the Gastroenterology Clinic of Haydarpasa Numune Training and Research Hospital between January 2011, and April 2012 were investigated. Serum tenascin-C levels were measured using commercial sandwich enzyme-linked immunosorbent assay Human Tenascin-C Purified Protein kit (Chemicon, Millipore(R), USA). Study groups were categorized based on the type of the disease as inflammatory (n=17; 39.5%), obstructive (27.2%), and fistule formation (n=10; 23.3%) Crohn’s disease. For statistical analysis SPSS (Statistical Package for Social Sciences) Statistics 15 program was used.

RESULTS:

Median tenascin- C value in the obstructive group (6.57 ng/mL; range, 4.26-21.87 ng/mL) was statistically significantly higher than that detected in the inflammatory (1.74 ng/mL; range,1.29-3.16 ng/mL), and fistulizing (1.44 ng/mL; range, 0.74-2.47 ng/mL) groups (p=0.002).

CONCLUSION:

Intestinal fibroblasts have an important role in the stricture formation process in CD. Transforming growth factor (TGF)-b1 cytokine is in the center of this process. A strong correlation exists between tenascin-C induction, and acute inflammation. As a known fact, serum tenascin-C levels can be used in the determination of activity of IBD. Starting from this point, serum tenascin-C levels can be useful in the categorization of the Crohn’s disease without the need for invasive methods. In the future, studies with larger patient series investigating use of serum tenascin-C in the prediction of stricturing Crohn’s disease should be conducted.

Mechanisms of initiation and progression of intestinal fibrosis in IBD

Intestinal fibrosis is a common complication of the inflammatory bowel diseases (IBDs). It becomes clinically apparent in >30% of patients with Crohn's disease (CD) and in about 5% with ulcerative colitis (UC). Fibrosis is a consequence of local chronic inflammation and is characterized by excessive extracellular matrix (ECM) protein deposition. ECM is produced by activated myofibroblasts, which are modulated by both, profibrotic and antifibrotic factors. Fibrosis depends on the balance between the production and degradation of ECM proteins. This equilibrium can be impacted by a complex and dynamic interaction between profibrotic and antifibrotic mediators. Despite the major therapeutic advances in the treatment of active inflammation in IBD over the past two decades, the incidence of intestinal strictures in CD has not significantly changed as the current anti-inflammatory therapies neither prevent nor reverse the established fibrosis and strictures. This implies that control of intestinal inflammation does not necessarily affect the associated fibrotic process. The conventional view that intestinal fibrosis is an inevitable and irreversible process in patients with IBD is also gradually changing in light of an improved understanding of the cellular and molecular mechanisms that underline the pathogenesis of fibrosis. Comprehension of the mechanisms of intestinal fibrosis is thus vital and may pave the way for the developments of antifibrotic agents and new therapeutic approaches in IBD.

Results of the 4th scientific workshop of the ECCO (I): pathophysiology of intestinal fibrosis in IBD

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal fibrosis in the disease course of inflammatory bowel disease (IBD). The objective was to better understand the pathophysiological mechanisms of intestinal fibrosis, to identify useful markers and imaging modalities of fibrosis in order to assess its presence and progression, and, finally, to point out possible approaches for the prevention and the treatment of fibrosis. The results of this workshop are presented in three separate manuscripts. This first section describes the most important mechanisms that contribute to the initiation and progression of intestinal fibrosis in IBD including the cellular and molecular mediators, the extracellular matrix molecules and matrix metalloproteinases/tissue inhibitors of metalloproteinases-system, the microbiota products, the role of fat, genetic and epigenetic factors, as well as the currently available experimental models. Furthermore, it identifies unanswered questions in the field of intestinal fibrosis and provides a framework for future research.

Results of the 4th scientific workshop of the ECCO (Group II): markers of intestinal fibrosis in inflammatory bowel disease

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on intestinal fibrosis in inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms and markers of intestinal fibrosis as well as to suggest new therapeutic targets to prevent or treat fibrosis. The results of this workshop are presented in three separate manuscripts. This section describes markers of fibrosis in IBD, identifies unanswered questions in the field and provides a framework for future studies addressing the unmet needs in the field of intestinal fibrosis.

In Crohn's disease fibrosis-reduced expression of the miR-29 family enhances collagen expression in intestinal fibroblasts

Intestinal fibrosis with stricture formation is a complication of CD (Crohn's disease) that may mandate surgical resection. Accurate biomarkers that reflect the relative contribution of fibrosis to an individual stricture are an unmet need in managing patients with CD. The miRNA-29 (miR-29) family has been implicated in cardiac, hepatic and pulmonary fibrosis. In the present study, we investigated the expression of miR-29a, miR-29b and miR-29c in mucosa overlying a stricture in CD patients (SCD) paired with mucosa from non-strictured areas (NSCD). There was significant down-regulation of the miR-29 family in mucosa overlying SCD compared with mucosa overlying NSCD. miR-29b showed the largest fold-decrease and was selected for functional analysis. Overexpression of miR-29b in CD fibroblasts led to a down-regulation of collagen I and III transcripts and collagen III protein, but did not alter MMP (matrix metalloproteinase)-3, MMP-12 and TIMP (tissue inhibitor of metalloproteinase)-1 production. TGF (transforming growth factor)-β1 up-regulated collagen I and III transcripts and collagen III protein as a consequence of the down-regulation of miR-29b, and TGF-β1-induced collagen expression was reversed by exogenous overexpression of miR-29b. Furthermore, serum levels of miR-29 were lower in patients with stricturing disease compared with those without. These findings implicate the miR-29 family in the pathogenesis of intestinal fibrosis in CD and provide impetus for the further evaluation of the miR-29 family as biomarkers.

The gut microbiome in intestinal fibrosis: environmental protector or provocateur?

In individuals with inflammatory bowel diseases, intestinal fibrosis is a serious clinical complication with no specific therapies. Patients develop bowel fistulae and strictures that usually require surgery and often reoccur. The main driver of gut fibrogenesis is believed to be chronic inflammation, which leads to mesenchymal cell recruitment and activation. Recent findings suggest that the environment--in particular, the microbiome--plays a critical role in this process.

Crohn's disease and smoking: is it ever too late to quit?

BACKGROUND

Smoking increases CD risk. The aim was to determine if smoking cessation at, prior to, or following, CD diagnosis affects medication use, disease phenotypic progression and/or surgery.

METHODS

Data on CD patients with disease for ≥5 yrs were collected retrospectively including the Montreal classification, smoking history, CD-related abdominal surgeries, family history, medication use and disease behaviour at diagnosis and the time when the disease behaviour changed.

RESULTS

1115 patients were included across six sites (mean follow-up-16.6 yrs). More non-smokers were male (p=0.047) with A1 (p<0.0001), L4 (p=0.028) and perianal (p=0.03) disease. Non-smokers more frequently received anti-TNF agents (p=0.049). (p=0.017: OR 2.5 95%CI 1.18-5.16) and those who ceased smoking prior to diagnosis (p=0.045: OR 2.3 95%CI 1.02-5.21) progressed to complicated (B2/B3) disease as compared to those quitting at diagnosis. Patients with uncomplicated terminal ileal disease at diagnosis more frequently developed B2/B3 disease than isolated colonic CD (p<0.0001). B2/B3 disease was more frequent with perianal disease (p<0.0001) and if i.v. steroids (p=0.004) or immunosuppressants (p<0.0001) were used. 49.3% (558/1115) of patients required at least one intestinal surgery. More smokers had a 2nd surgical resection than patients who quit at, or before, the 1st resection and non-smokers (p=0.044: HR=1.39 95%CI 1.01-1.91). Patients smoking >3 cigarettes/day had an increased risk of developing B2/B3 disease (p=0.012: OR 3.8 95%CI 1.27-11.17).

CONCLUSION

Progression to B2/B3 disease and surgery is reduced by smoking cessation. All CD patients regardless of when they were diagnosed, or how many surgeries, should be strongly encouraged to cease smoking.

The role of transforming growth factor (TGF)-β in modulating the immune response and fibrogenesis in the gut

Transforming growth factor (TGF)-β, a pleiotropic cytokine released by both immune and non-immune cells in the gut, exerts an important tolerogenic action by promoting regulatory T cell differentiation. TGF-β also enhances enterocyte migration and regulates extracellular matrix turnover, thereby playing a crucial role in tissue remodeling in the gut. In this review we describe the mechanisms by which abnormal TGF-β signaling impairs intestinal immune tolerance and tissue repair, thus predisposing to the onset of immune-mediated bowel disorders, such as inflammatory bowel disease and celiac disease. Additionally, we will discuss potential therapeutic strategies aiming at restoring physiologic TGF-β signaling in chronic intestinal diseases.

Mechanisms of tissue remodeling in inflammatory bowel disease

The clinical course of inflammatory bowel disease (IBD) is highly heterogeneous and often unpredictable, with multiple and serious complications that range from stricture formation to bowel obstruction or perforation, fistula formation and the need for surgery. All these problems are manifestations of tissue remodeling, a secondary but universal response to the insults of chronic inflammation. The factors involved in tissue remodeling are several, including the site and duration of inflammation, soluble molecules, the gut microbiota, and the type of mesenchymal cell response. The prototypical and most common type of tissue remodeling in IBD, and Crohn's disease (CD) in particular, is a fibrotic response, and this review will focus on the factors and mechanisms involved in fibrogenesis, and speculate on what is needed for the development of a rational treatment of intestinal fibrosis.

Magnetic resonance enterography: inflammatory bowel disease and beyond

This article addresses the current technique and protocols for magnetic resonance (MR) enterography, with a primary focus on inflammatory bowel disease (IBD) and a secondary detailed discussion of other diseases of the small bowel beyond IBD. A brief discussion of MR imaging for appendicitis is included, but the evaluation of appendicitis does not require an enterographic protocol. The focused key points and approach presented in this article are intended to enhance the reader's understanding to help improve patient compliance with the MR enterographic studies, overcome challenges, and improve interpretation.

Crohn's disease complicated by strictures: a systematic review

The occurrence of strictures as a complication of Crohn's 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.

Endoscopic management of inflammatory bowel disease strictures

Stricture formation is a common complication of Crohn’s disease, occurring in approximately one third of all patients with this condition. While the traditional management of such strictures has been largely surgical, there have been case series going back three decades highlighting the potential role of endoscopic balloon dilation in this clinical setting. This review article summarizes the stricture pathogenesis, focusing on known clinical and genetic risk factors. It then highlights the endoscopic balloon dilation research to date, with particular emphasis on three large recent case series. It concludes by describing the literature consensus regarding specific methodology and presenting avenues for future investigations.