Medical therapy of stricturing Crohn's disease: what the gut can learn from other organs - a systematic review

Ultrasound in Pediatric Inflammatory Bowel Disease-A Review of the State of the Art and Future Perspectives

Inflammatory bowel disease (IBD) comprises a group of relapsing, chronic diseases of the gastrointestinal tract that, in addition to adults, can affect children and adolescents. To detect relapses of inflammation, these patients require close observation, frequent follow-up, and therapeutic adjustments. While reference standard diagnostics include anamnestic factors, laboratory and stool sample assessment, performing specific imaging in children and adolescents is much more challenging than in adults. Endoscopic and classic cross-sectional imaging modalities may be invasive and often require sedation for younger patients. For this reason, intestinal ultrasound (IUS) is becoming increasingly important for the non-invasive assessment of the intestine and its inflammatory affection. In this review, we would like to shed light on the current state of the art and provide an outlook on developments in this field that could potentially spare these patients more invasive follow-up procedures.

Downregulation of Heat Shock Protein 72 Contributes to Fibrostenosis in Crohn's Disease

Background/Aims

Crohn's disease (CD) with recurrent inflammation can cause intestinal fibrostenosis due to dysregulated deposition of extracellular matrix. However, little is known about the pathogenesis of fibrostenosis. Here, we performed a differential proteomic analysis between normal, inflamed, and fibrostenotic specimens of patients with CD and investigated the roles of the candidate proteins in myofibroblast activation and fibrosis.

Methods

We performed two-dimensional difference gel electrophoresis and identified candidate proteins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and orbitrap liquid chromatography-mass spectrometry. We also verified the levels of candidate proteins in clinical specimens and examined their effects on 18Co myofibroblasts and Caco-2 intestinal epithelial cells.

Results

We identified five of 30 proteins (HSP72, HSPA5, KRT8, PEPCK-M, and FABP6) differentially expressed in fibrostenotic CD. Among these proteins, the knockdown of heat shock protein 72 (HSP72) promoted the activation and wound healing of myofibroblasts. Moreover, knockdown of HSP72 induced the epithelial-mesenchymal transition of intestinal epithelial cells by reducing E-cadherin and inducing fibronectin and α-smooth muscle actin, which contribute to fibrosis.

Conclusions

HSP72 is an important mediator that regulates myofibroblasts and epithelial-mesenchymal transition in fibrosis of CD, suggesting that HSP72 can serve as a target for antifibrotic therapy.

Contrast-Enhanced Multispectral Optoacoustic Tomography for Functional Assessment of the Gastrointestinal Tract

Real-time imaging and functional assessment of the intestinal tract and its transit pose a significant challenge to conventional clinical diagnostic methods. Multispectral optoacoustic tomography (MSOT), a molecular-sensitive imaging technology, offers the potential to visualize endogenous and exogenous chromophores in deep tissue. Herein, a novel approach using the orally administered clinical-approved fluorescent dye indocyanine green (ICG) for bedside, non-ionizing evaluation of gastrointestinal passage is presented. The authors are able to show the detectability and stability of ICG in phantom experiments. Furthermore, ten healthy subjects underwent MSOT imaging at multiple time points over eight hours after ingestion of a standardized meal with and without ICG. ICG signals can be visualized and quantified in different intestinal segments, while its excretion is confirmed by fluorescent imaging of stool samples. These findings indicate that contrast-enhanced MSOT (CE-MSOT) provides a translatable real-time imaging approach for functional assessment of the gastrointestinal tract.

Factors associated with the efficacy and safety of endoscopic dilatation of symptomatic strictures in Crohn's disease: a retrospective cohort study

OBJECTIVE

Endoscopic balloon dilatation (EBD) is a standard treatment for intestinal strictures in Crohn's disease (CD). No evidence-based guidelines exist regarding the balloon diameter or the balloon pressure to be used, with recent studies suggesting the use of a smaller diameter than classically used. We sought to analyze the factors associated with safety and efficacy of EBD in CD strictures, particularly looking at balloon diameter and dilatation pressure.

METHODS

We conducted a monocentric retrospective study of patients who underwent EBD between 2005 and 2020.

RESULTS

Our endoscopy department performed EBD in 94 CD patients during the considered period. The mean size of balloon dilatation was 16 mm (±2.5; including 21 patients with balloon <14 mm) and the mean dilatation pressure was 5.3 atm (±1.5). No perforation was observed. Over a median follow-up of 5.6 years, the probability of being operated was 5.4% at 1 year and 10.4% at 3 years. Smaller height (HR = 0.90, p = 0.022) and a higher BMI (HR = 1.23, p = 0.014) were associated with the risk of operation. The probability of being operated or redilated was 30.1% at 1 year and 52.5% at 3 years. No factor was significantly associated with this risk. The size of the balloon had no impact on outcomes.

CONCLUSION

In this retrospective cohort, including a significant proportion of CD patients dilated with balloon <14 mm, no perforation was observed and the size of the balloon or the dilatation pressure had no impact on the risk of surgery or redilatation.

Function and therapeutic potential of transient receptor potential ankyrin 1 in fibrosis

The transient receptor potential (TRP) protein superfamily is a special group of cation channels expressed in different cell types and signaling pathways. In this review, we focus on TRPA1 (transient receptor potential ankyrin 1), an ion channel in this family that exists in the cell membrane and shows a different function from other TRP channels. TRPA1 usually has a special activation effect that can induce cation ions, especially calcium ions, to flow into activated cells. In this paper, we review the role of TRPA1 in fibroblasts. To clarify the relationship between fibroblasts and TRPA1, we have also paid special attention to the interactions between TRPA1 and inflammatory factors leading to fibroblast activation. TRPA1 has different functions in the fibrosis process in different organs, and there have also been interesting discussions of the mechanism of TRPA1 in fibroblasts. Therefore, this review aims to describe the function of TRP channels in controlling fibrosis through fibroblasts in different organ inflammatory and immune-mediated diseases. We attempt to prove that TRPA1 is a target for fibrosis. In fact, some clinical trials have already proven that TRPA1 is a potential adjuvant therapy for treating fibrosis.

Mesenteric Adipose Tissue Contributes to Intestinal Fibrosis in Crohn's Disease Through the ATX-LPA Axis

BACKGROUND AND AIMS

Intestinal fibrostenosis is an important cause of surgical intervention in patients with Crohn's disease [CD]. Hypertrophic mesenteric adipose tissue [MAT] is associated with the disease process of CD. The purpose of this study was to investigate the contribution of MAT to intestinal fibrosis.

METHODS

MAT from surgical specimens of fibrostenotic CD patients and controls was collected for measurement of the levels of autotaxin [ATX] and lysophosphatidic acid [LPA]. ATX was inhibited in vivo in DNBS [dinitrobenzene sulfonic acid]-induced colitis mice, which were evaluated for colonic inflammation and fibrosis. 3T3-L1 cells and primary colonic fibroblasts were used in vitro to investigate the interaction between MAT and intestinal fibrosis, as well as the molecular mechanism underlying this interaction.

RESULTS

MAT adjacent to the fibrostenotic intestine in CD patients showed an activated ATX-LPA axis. An in vivo study indicated that inhibition of ATX was associated with the improvement of morphology and function of diseased MAT, which was combined with ameliorated intestinal inflammation and fibrosis in DNBS-instilled mice. In vitro studies showed that hypoxia stimulated adipocyte ATX expression and that LPA stabilized adipocyte HIF-1α protein, forming an ATX-LPA-HIF-1α amplification loop and aggravating adipocyte dysfunction. LPA secreted by adipocytes bound to LPA1 on the surface of fibroblasts, promoted their proliferation and differentiation, and increased the expression of fibrosis-related factors.

CONCLUSIONS

The ATX-LPA axis regulated intestinal fibrosis by influencing the proliferation and differentiation of intestinal fibroblasts. Inhibiting this axis may be a therapeutic target for intestinal fibrosis in CD.

Evaluation of dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging for predicting muscular hyperplasia/hypertrophy in Crohn's disease

OBJECTIVES

The existence of smooth muscle alteration in Crohn's disease (CD) is often neglected. It has been found that muscular hyperplasia/hypertrophy rather than fibrosis was the primary component of bowel wall thickening. This study aimed to assess the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted imaging for the characterization of histopathologic tissue composition of CD, particularly smooth muscle hypertrophy, as well as inflammation and fibrosis.

METHODS

The study included patients diagnosed with CD who received MRI examination 30 days before resection from August 2016 to December 2020. A semiquantitative histological grading scheme was employed to evaluate the pathological tissues. Resected sections were matched with MRI according to pathological marks. Parameters evaluated included: mural thickness, T2 ratio, apparent diffusion coefficient value; and maximum enhancement, initial slope of increase, perfusion parameters of DCE-MRI and enhancement pattern. These parameters were compared with location-matched histopathological grade.

RESULTS

Ninety-one sections were enrolled in this retrospective study. When active inflammation is moderate or severe, volume transfer coefficient (K^trans), maximum enhancement (ME) and initial slope of increase (ISI) are lower, mural thickness is higher when a certain degree of smooth muscle alteration is present. When active inflammation is absent or mild, ME, mural thickness and ISI can differentiate the presence of predominant muscular alteration. By combining ME and thickness comparisons against their cutoff values to create a combined ordinal parameter, the area under the curve value for whether significant muscular alteration coexists with moderate or severe active inflammation was found to be 0.953.

CONCLUSIONS

MRI predicts the degree of inflammation, and can distinguish the degree of muscular alteration coexists with moderate or severe active inflammation with reasonable accuracy.

Current and Emerging Approaches to the Diagnosis and Treatment of Crohn's Disease Strictures

The management and understanding of Crohn's disease (CD) continues to evolve quickly. Intestinal strictures were previously thought to be an inevitable result of irreversible fibrosis caused by chronic inflammation. However, increased understanding of the dynamic nature of strictures and of the pathophysiology of this condition has highlighted emerging targets for potential treatment. In the diagnosis of strictures, a distinction must be made between inflammatory and fibrotic types, as the former may respond to medical therapy. Emerging technologies, such as dual-energy computed tomography enterography and iodine density, have allowed more accurate characterization of strictures. Surgical and endoscopic treatment remains the mainstay for fibrotic strictures, but developments in systemic and intralesional biologic therapy have shown efficacy. This article reviews the pathophysiology of this debilitating complication of CD as well as current and emerging diagnostics and treatments.

International consensus to standardise histopathological scoring for small bowel strictures in Crohn's disease

OBJECTIVE

Effective medical therapy and validated trial outcomes are lacking for small bowel Crohn's disease (CD) strictures. Histopathology of surgically resected specimens is the gold standard for correlation with imaging techniques. However, no validated histopathological scoring systems are currently available for small bowel stricturing disease. We convened an expert panel to evaluate the appropriateness of histopathology scoring systems and items generated based on panel opinion.

DESIGN

Modified RAND/University of California Los Angeles methodology was used to determine the appropriateness of 313 candidate items related to assessment of CD small bowel strictures.

RESULTS

In this exercise, diagnosis of naïve and anastomotic strictures required increased bowel wall thickness, decreased luminal diameter or internal circumference, and fibrosis of the submucosa. Specific definitions for stricture features and technical sampling parameters were also identified. Histopathologically, a stricture was defined as increased thickness of all layers of the bowel wall, fibrosis of the submucosa and bowel wall, and muscularisation of the submucosa. Active mucosal inflammatory disease was defined as neutrophilic inflammation in the lamina propria and any crypt or intact surface epithelium, erosion, ulcer and fistula. Chronic mucosal inflammatory disease was defined as crypt architectural distortion and loss, pyloric gland metaplasia, Paneth cell hyperplasia, basal lymphoplasmacytosis, plasmacytosis and fibrosis, or prominent lymphoid aggregates at the mucosa/submucosa interface. None of the scoring systems used to assess CD strictures were considered appropriate for clinical trials.

CONCLUSION

Standardised assessment of gross pathology and histopathology of CD small bowel strictures will improve clinical trial efficiency and aid drug development.

Paediatric Ulcerative Colitis Is a Fibrotic Disease and Is Linked with Chronicity of Inflammation

BACKGROUND AND AIMS

Intestinal fibrosis has recently been characterised in adult ulcerative colitis and may affect motility, diarrhoea, and the symptom of urgency. We aimed to charactersze the presence of fibrosis in paediatric patients with ulcerative colitis, and its link to severity and chronicity of mucosal inflammation, as well as clinical factors of severity.

METHODS

We performed a single-centre cross-sectional study in children ages 1-18 years with ulcerative colitis, undergoing colectomy or proctocolectomy. Tissue cross-sections were derived from proximal, mid, and distal colon and rectum, and inflammation and fibrosis were graded based on previously developed scores. Clinical data were collected prospectively.

RESULTS

From 62 patients, 205 intestinal sections were evaluated. Median age at diagnosis was 13 years, 100% had extensive colitis, and all resections were done for refractory disease. The presence, chronicity, and degree of inflammation were linked with the presence of fibrosis. Thickness of the muscularis mucosa was also linked with presence and chronicity of inflammation. The overall submucosal fibrosis burden was associated with prior anti-tumour necrosis factor use.

CONCLUSIONS

Paediatric patients with ulcerative colitis exhibit colorectal submucosal fibrosis and muscularis mucosa thickening, which correlate with the presence, chronicity, and degree of mucosal inflammation. Fibrosis should be recognised as a complication of paediatric ulcerative colitis, and ulcerative colitis should be considered a progressive disease.

Native T1 Mapping and Magnetization Transfer Imaging in Grading Bowel Fibrosis in Crohn's Disease: A Comparative Animal Study

In this study, we investigated the utility of native T₁ mapping in differentiating between various grades of fibrosis and compared its diagnostic accuracy to magnetization transfer imaging (MTI) in a rat model of CD. Bowel specimens (64) from 46 CD model rats undergoing native T₁ mapping and MTI were enrolled. The longitudinal relaxation time (T₁ value) and normalized magnetization transfer ratio (MTR) were compared between none-to-mild and moderate-to-severe fibrotic bowel walls confirmed by pathological assessments. The results showed that the correlation between the T₁ value and fibrosis (r = 0.438, p < 0.001) was lower than that between the normalized MTR and fibrosis (r = 0.623, p < 0.001). Overall, the T₁ values (t = −3.066, p = 0.004) and normalized MTRs (z = 0.081, p < 0.001) in none-to-mild fibrotic bowel walls were lower than those in moderate-to-severe fibrotic bowel walls. The area under the curve (AUC) of the T₁ value (AUC = 0.716, p = 0.004) was significantly lower than that of the normalized MTR (AUC = 0.881, p < 0.001) in differentiating moderate-to-severe fibrosis from none-to-mild fibrosis (z = −2.037, p = 0.042). Our results support the view that the T₁ value could be a promising imaging biomarker in grading the fibrosis severity of CD. However, the diagnostic performance of native T₁ mapping was not superior to MTI.

Ileal Crohn's Disease Exhibits Similar Transmural Fibrosis Irrespective of Phenotype

INTRODUCTION

In Crohn's disease (CD), the assessment of transmural inflammation and fibrosis is of utmost importance. This study aimed to quantify these parameters in CD ileal specimens and correlate them with disease progression.

METHODS

This is a retrospective unicentric study based on the analysis of archived specimens (n = 103) of primary ileal resection. Data were retrieved from a prospective national inflammatory bowel disease registry. Two pathologists, blinded for CD phenotype and clinical indications for surgery, examined 3 sections per patient and graded inflammation and fibrosis, based on a histopathological score.

RESULTS

Penetrating (B3, n = 74) CD exhibited significantly higher inflammation in diseased areas, compared with stricturing (B2, n = 29) disease (score 3: 96% vs 76%, P = 0.005 in inflamed areas; 78% vs 55%, P = 0.019 in most affected areas). This was also observed for the comparison of B2 CD with B3 CD with (B3s, n = 54) and without associated stricture (B3o, n = 20): B3s vs B2: 81% vs 55%, P = 0.033 in most affected areas; B3o vs B2: 100% vs 76%, P = 0.006 in inflamed areas; 70% vs 55%, P = 0.039 in most affected areas. We could not show differences in fibrosis scores between the subphenotypes. Postoperative new penetrating events occurred only in B3s (n = 6, 11%, P = 0.043) patients. The changing of biologic therapy after surgery correlated with severe inflammation at the proximal ileal margin (55% changed vs 25% not changed, P = 0.035).

DISCUSSION

In our cohort, fibrosis scores and fibromuscular changes were comparable, irrespective of CD phenotype. Inflammation severity was the major differentiator between penetrating and stricturing disease.JOURNAL/cltg/04.03/01720094-202104000-00012/inline-graphic1/v/2021-04-13T161901Z/r/image-tiff.

Prevention and Treatment of Stricturing Crohn's Disease - Perspectives and Challenges

Introduction: Fibrostenosis is a hallmark of Crohn's disease (CD), remains a challenge in today's clinical management of inflammatory bowel disease patients and represents a key event in the disease course necessitating improved preventative strategies and a multidisciplinary approach to diagnosis and management. With the advent of anti-fibrotic therapies and well-defined clinical endpoints for stricturing CD, there is promise to impact the natural history of disease.Areas covered: This review summarizes current evidence in the natural history of stricturing Crohn's disease, discusses management approaches as well as future perspectives on intestinal fibrosis.Expert opinion: Currently, there are no specific therapies to prevent progression to fibrosis or to treat it after it becomes clinically apparent. In addition to the international effort by the Stenosis Therapy and Anti-Fibrotic Research (STAR) consortium to standardize definitions and propose endpoints in the management of stricturing CD, further research to improve our understanding of mechanisms of intestinal fibrosis will help pave the way for the development of future anti-fibrotic therapies.

Systematic review with meta-analysis: efficacy of balloon-assisted enteroscopy for dilation of small bowel Crohn's disease strictures

BACKGROUND

Evidence for endoscopic balloon dilation of small intestinal strictures in Crohn's disease (CD) using balloon-assisted enteroscopy is scarce.

AIM

To evaluate endoscopic balloon dilation for the treatment of small intestinal CD strictures using balloon-assisted enteroscopy.

METHODS

Citations in Embase, MEDLINE, and Cochrane were systematically reviewed. In a meta-analysis of 18 studies with 463 patients and 1189 endoscopic balloon dilations, technical success was defined as the ability to dilate a stricture. Individual data were also obtained on 218 patients to identify outcome-relevant risk factors.

RESULTS

In the pooled per-study analysis, technical success rate of endoscopic balloon dilation was 94.9%, resulting in short-term clinical efficacy in 82.3% of patients. Major complications occurred in 5.3% of patients. During follow-up, 48.3% of patients reported symptom recurrence, 38.8% were re-dilated and 27.4% proceeded to surgery. On the per-patient-based multivariable analysis, that patients with disease activity in the small intestine had lower short-term clinical efficacy (odds ratio 0.32; 95% confidence interval 0.14-0.73, P = 0.007). Patients with concomitant active disease in the small and/or large intestine had an increased risk to proceed toward surgery (hazard ratio 1.85; 95% confidence interval 1.09-3.13, P = 0.02 and hazard ratio 1.77; 95% confidence interval 1.34-2.34, P < 0.001).

CONCLUSIONS

Balloon-assisted enteroscopy for dilatation of CD-associated small intestinal strictures has high short-term technical and clinical efficacy and low complication rates. However, up to two-thirds of patients need re-dilation or surgery.

No effect of a liquid diet in the management of patients with stricturing Crohn's disease

PURPOSE

Patients with stricturing Crohn's disease (CD) may experience episodes of intestinal sub-occlusions, which in many cases lead to surgery. The aim of this study was to examine whether adding a liquid diet to medical therapy could improve the management of patients with stricturing CD.

METHODS

Medical records of CD outpatients with a small bowel stricture, either receiving (group 1) or not (group 2) a 24-h liquid diet every 10-14 days, were retrospectively analyzed. Number of sub-occlusive episodes, frequency, and timing of intestinal resections for strictures were analyzed.

RESULTS

During the 12-month follow-up, there was no significant difference in the occurrence of new sub-occlusive episodes between the 2 groups (10/37 patients (27%) in group 1 vs 9/45 patients (20%) in group 2). Similarly, the number of patients undergoing bowel resections for sub-occlusive episodes non-responsive to medical therapy did not statistically differ between the two groups (9 patients (24.3%) in group 1 vs 7 patients (15.5%) in group 2). In group 1, surgeries were equally distributed along the 12-months of follow-up, while 85.7% of patients in group 2 underwent intestinal resection within the first 3 months of follow-up.

CONCLUSION

Adding a liquid diet to medical therapy does not help management of patients with stricturing CD.

Intestinal stenosis in Crohn's disease shows a generalized upregulation of genes involved in collagen metabolism and recognition that could serve as novel anti-fibrotic drug targets

BACKGROUND AND AIMS

Crohn's disease (CD) can be complicated by intestinal fibrosis. Pharmacological therapies against intestinal fibrosis are not available. The aim of this study was to determine whether pathways involved in collagen metabolism are upregulated in intestinal fibrosis, and to discuss which drugs might be suitable to inhibit excessive extracellular matrix formation targeting these pathways.

METHODS

Human fibrotic and non-fibrotic terminal ileum was obtained from patients with CD undergoing ileocecal resection due to stenosis. Genes involved in collagen metabolism were analyzed using a microfluidic low-density TaqMan array. A literature search was performed to find potential anti-fibrotic drugs that target proteins/enzymes involved in collagen synthesis, its degradation and its recognition.

RESULTS

mRNA expression of collagen type I (COL1A1, 0.76 ± 0.28 versus 37.82 ± 49.85, p = 0.02) and III (COL3A1, 2.01 ± 2.61 versus 68.65 ± 84.07, p = 0.02) was increased in fibrotic CD compared with non-fibrotic CD. mRNA expression of proteins involved in both intra- and extracellular post-translational modification of collagens (prolyl- and lysyl hydroxylases, lysyl oxidases, chaperones), collagen-degrading enzymes (MMPs and cathepsin-K), and collagen receptors were upregulated in the fibrosis-affected part. A literature search on the upregulated genes revealed several potential anti-fibrotic drugs.

CONCLUSION

Expression of genes involved in collagen metabolism in intestinal fibrosis affected terminal ileum of patients with CD reveals a plethora of drug targets. Inhibition of post-translational modification and altering collagen metabolism might attenuate fibrosis formation in the intestine in CD. Which compound has the highest potential depends on a combination anti-fibrotic efficacy and safety, especially since some of the enzymes play key roles in the physiology of collagen.

Murine Precision-cut Intestinal Slices as a Potential Screening Tool for Antifibrotic Drugs

BACKGROUND

Intestinal fibrosis is a hallmark of Crohn's disease. Here, we investigated the impact of several putative antifibrotic compounds on the expression of fibrosis markers using murine precision-cut intestinal slices.

METHODS

Murine precision-cut intestinal slices were cultured for 48 hours in the presence of profibrotic and/or antifibrotic compounds. The fibrotic process was studied on gene and protein level using procollagen 1a1 (Col1α1), heat shock protein 47 (Hsp47), fibronectin (Fn2), and plasminogen activator inhibitor-1 (Pai-1). The effects of potential antifibrotic drugs mainly inhibiting the transforming growth factor β (TGF-β) pathway (eg, valproic acid, tetrandrine, pirfenidone, SB203580, and LY2109761) and compounds mainly acting on the platelet-derived growth factor (PDGF) pathway (eg, imatinib, sorafenib, and sunitinib) were assessed in the model at nontoxic concentrations.

RESULTS

Murine precision-cut intestinal slices remained viable for 48 hours, and an increased expression of fibrosis markers was observed during culture, including Hsp47, Fn2, and Pai-1. Furthermore, TGF-β1 stimulated fibrogenesis, whereas PDGF did not have an effect. Regarding the tested antifibrotics, pirfenidone, LY2109761, and sunitinib had the most pronounced impact on the expression of fibrosis markers, both in the absence and presence of profibrotic factors, as illustrated by reduced levels of Col1α1, Hsp47, Fn2, and Pai-1 after treatment. Moreover, sunitinib significantly reduced Hsp47 and Fn2 protein expression and the excretion of procollagen 1.

CONCLUSIONS

Precision-cut intestinal slices can successfully be used as a potential preclinical screening tool for antifibrotic drugs. We demonstrated that sunitinib reduced the expression of several fibrosis markers, warranting further evaluation of this compound for the treatment of intestinal fibrosis.

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.

Levels of Intestinal Inflammation and Fibrosis in Resection Specimens after Preoperative Anti-Tumor Necrosis Factor Alpha Treatment in Patients with Crohn's Disease: A Comparative Pilot Study

Background

Strictures are a common complication in Crohn's disease (CD), found in more than 50% of patients. They are characterized by the excessive deposition of extracellular proteins in the tissue as a result of the chronic inflammatory process. The effect of anti-tumor necrosis factor alpha (TNF-α) therapy on the development of fibrosis is not yet fully understood.

Aim

To investigate whether the degree of intestinal inflammation and fibrosis is correlated with preoperative anti-TNF-α) therapy on the development of fibrosis is not yet fully understood.

Methods

This unblinded, prospective, single tertiary center, pilot cohort study included all adult patients with CD who underwent elective, laparoscopic, or open intestinal resection. Preoperative investigations included measurement of blood TNF-α) therapy on the development of fibrosis is not yet fully understood.

Results

Histopathological specimens from 10 patients with CD who underwent ileocecal or ileocolic resections were retrieved. Four of those patients were on anti-TNF-α) therapy on the development of fibrosis is not yet fully understood. α) therapy on the development of fibrosis is not yet fully understood. α) therapy on the development of fibrosis is not yet fully understood. p=0.01). Anti-TNF-α) therapy on the development of fibrosis is not yet fully understood. α) therapy on the development of fibrosis is not yet fully understood. α) therapy on the development of fibrosis is not yet fully understood.

Conclusions

Patients who underwent preoperative anti-TNF-α treatment had a higher fibrosis score than controls.α) therapy on the development of fibrosis is not yet fully understood.

Inhibition of plasminogen activator inhibitor-1 attenuates against intestinal fibrosis in mice

Background/Aims

Intestinal fibrosis is a major complication of Crohn’s disease (CD). The profibrotic protein transforming growth factor-β (TGF-β) has been considered to be critical for the induction of the fibrotic program. TGF-β has the ability to induce not only the expression of extracellular matrix (ECM) including collagen, but also the production of plasminogen activator inhibitor-1 (PAI-1) that prevents enzymatic degradation of the ECM during the onset of fibrotic diseases. However, the significance of PAI-1 in the developing intestinal fibrosis has not been fully understood. In the present study, we examined the actual expression of PAI-1 in fibrotic legion of intestinal inflammation and its correlation with the abnormal ECM deposition.

Methods

Chronic intestinal inflammation was induced in BALB/c mice using 8 repeated intrarectal injections of 2,4,6-trinitrobenzene sulfonic acid (TNBS). TM5275, a PAI-1 inhibitor, was orally administered as a carboxymethyl cellulose suspension each day for 2 weeks after the sixth TNBS injection.

Results

Using a publicly available dataset (accession number, GSE75214) and TNBS-treated mice, we observed increases in PAI-1 transcripts at active fibrotic lesions in both patients with CD and mice with chronic intestinal inflammation. Oral administration of TM5275 immediately after the onset of intestinal fibrosis upregulated MMP-9 (matrix metalloproteinase 9) and decreased collagen accumulation, resulting in attenuation of the fibrogenesis in TNBS-treated mice.

Conclusions

PAI-1-mediated fibrinolytic system facilitates collagen degradation suppression. Hence, PAI-1 inhibitor could be applied as an anti-fibrotic drug in CD treatment.

Endoscopic management of strictures in patients with Crohn's disease - A multi-center experience in Taiwan

BACKGROUND/PURPOSE

Inflammatory bowel disease (IBD) is a chronic gastrointestinal (GI) disorder that causes relapsing inflammation and severe mucosal damage in the intestine. Crohn's disease (CD)-related stricturing complications are a major cause of surgery, disability, and reduced quality of life. Endoscopic balloon dilation (EBD) has been shown to reliably delay or prevent surgery in patients with stricturing CD. However, cases of EBD performed for stricture in CD in Taiwan are rare. In this study, we want to evaluate the experiences regarding EBD for stricturing CD in Taiwan.

METHODS

We conducted a retrospective analysis of 9 medical centers in Taiwan. Patients with CD-related strictures who were treated with EBD were included and analyzed.

RESULTS

In nine medical centers, a total of 26 CD patients (19 male, 7 female, mean disease duration 75.4 ± 65.2 months) underwent 42 EBD procedures during the study period. Among the subjects, an 83.3% (35/42) EBD success rate was seen, but 26.9% (7/26) patients underwent surgery after ineffective EBD. In the surgery group, the the small bowel strictures was high compared with the non-surgery group (p = 0.01). There were no significant differences in disease phenotype, disease duration or history of fistulizing disease. In the surgery group, immunosuppressant use was high, and 5-aminosalicylic acid (5-ASA) use was low compared with the non-surgery group. After EBD, the physicians tended to change the drugs, especially increasing the use of biologic agents.

CONCLUSION

EBD is a safe and effective procedure for CD-related stricture, with a 83.3% success rate in Taiwan.

Histopathology Scoring Systems of Stenosis Associated With Small Bowel Crohn's Disease: A Systematic Review

BACKGROUND & AIMS

Stenosis is a common complication of Crohn's disease (CD) that has no effective medical therapy. Development of antifibrotic agents will require testing in randomized controlled trials. Computed tomography enterography- and magnetic resonance enterography-based technologies might be used to measure outcomes in these trials. These approaches have been validated in studies of patients with symptomatic strictures who underwent imaging evaluations followed by resection with histopathologic grading of the intestinal tissue for inflammation and/or fibrosis (the reference standard). Imaging findings have correlated with findings from quantitative or semiquantitative histologic evaluation of the degree of fibromuscular stenosis and/or inflammation on the resection specimen. However, it is not clear whether histologic findings are an accurate reference standard. We performed a systematic review of all published histologic scoring systems used to assess stenosing CD.

METHODS

We performed a comprehensive search of Embase and MEDLINE of studies through March 13, 2019, that used a histologic scoring system to characterize small bowel CD and assessed inflammatory and fibrotic alterations within the same adult individual. All scores fitting the criteria were included in our analysis, independent of the presence of stricturing disease, as long as inflammation and fibrosis were evaluated separately but in the same scoring system.

RESULTS

We observed substantial heterogeneity among the scoring systems, which were not derived from modern principles for evaluative index development. None had undergone formal validity or reliability testing. None of the existing indices had been constructed according to accepted methods for the development of evaluative indices. Basic knowledge regarding their operating properties were lacking. Specific indices for evaluating the important pathologic component of myofibroblast hypertrophy or hyperplasia have not been proposed.

CONCLUSIONS

In a systematic review of publications, we found a lack of validated histopathologic scoring systems for assessment of fibromuscular stenosis. Data that describe the operating properties of existing cross-sectional imaging techniques for stenosing CD should be questioned. Development and validation of a histopathology index is an important research priority.

Efficacy of Endoscopic Dilation of Gastroduodenal Crohn's Disease Strictures: A Systematic Review and Meta-Analysis of Individual Patient Data

BACKGROUND & AIMS

Little is known about the effects of endoscopic balloon dilation (EBD) for strictures of the upper gastrointestinal (UGI) tract in patients with Crohn's disease (CD). We performed a pooled analysis of the efficacy and safety of EBD for UGI CD-associated strictures.

METHODS

We searched Embase, Medline, and the Cochrane library, as well as bibliographies of relevant articles, for cohort studies of adults with CD and strictures of the stomach or duodenum (up to the ligament of Treitz) who underwent EBD through December 2016. We obtained data from 7 international referral centers on 94 patients who underwent 141 EBDs. We performed a patient-level meta-analysis of data from published and unpublished cohort studies to determine mechanical and clinical success. We performed a time-to-event analysis to assess symptom recurrence and need for redilation or surgery. The patients analyzed had strictures of the duodenum (n = 107), stomach (n = 30), or spanning both (n = 4).

RESULTS

The rate of technical success for EBD was 100%, with 87% short-term clinical efficacy; major complications arose from 2.9% of all procedures. During a median follow-up period of 23.1 months, 70.5% of patients had a recurrence of symptoms, 59.6% required redilation, and 30.8% required surgical intervention. Patients whose disease was located in the small bowel had a higher risk for symptom recurrence (hazard ratio [HR], 2.1; P = .003). Asian race (HR, 2.8; P < .001) and location of disease in the small bowel (HR, 1.9; P = .004) increased the need for redilation. Prestenotic dilation was a risk factor for needing surgery earlier (HR, 1.9; P = .001).

CONCLUSIONS

In a meta-analysis, we found EBD for CD-associated strictures of the UGI to be an effective alternative to surgery, with a high rate of short-term technical and clinical success, moderate long-term efficacy, and an acceptable rate of complications.

Impact of Angiotensin II Signaling Blockade on Clinical Outcomes in Patients with Inflammatory Bowel Disease

BACKGROUND

Preclinical data demonstrate that activation of the renin-angiotensin system (RAS) contributes to mucosal inflammation, and RAS inhibition by angiotensin-converting-enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) improves colitis in animal models. Less is known regarding the effects of RAS inhibition on clinical outcomes in inflammatory bowel disease (IBD) patients.

AIM

Evaluate the impact of ACEI and ARB on clinical outcomes in IBD.

METHODS

Rates of IBD-related hospitalizations, operations, and corticosteroid use were evaluated retrospectively in two groups. First, 111 IBD patients taking an ACEI or ARB were compared to nonusers matched 1:1 based on sex, age, diagnosis, disease location, and hypertension diagnosis. Second, outcomes in a cohort of 130 IBD patients were compared prior to and during ACEI/ARB exposure.

RESULTS

Compared to matched controls, all IBD patients together with ACEI/ARB exposure had fewer hospitalizations (OR 0.26, p < 0.01), operations (OR 0.08, p = 0.02), and corticosteroid prescriptions (OR 0.5, p = 0.01). Comparing outcomes before and during ACEI/ARB use, there were no differences in hospitalizations, operations, or corticosteroid use for all IBD patients together, but patients with UC had increased hospitalizations (0.08 pre- vs. 0.16 during ACEI/ARB exposure, p = 0.03) and decreased corticosteroid use (0.24 pre-ACEI/ARB vs. 0.12 during ACEI/ARB exposure, p < 0.01) during ACEI/ARB use.

CONCLUSIONS

IBD patients with ACEI/ARB exposure had fewer hospitalizations, operations, and corticosteroid use compared to matched controls. No differences in outcomes were observed in individuals on ACEI/ARB therapy when compared to a period of time prior to medication exposure.

Strictures in Crohn's Disease and Ulcerative Colitis: Is There a Role for the Gastroenterologist or Do We Always Need a Surgeon?

Symptomatic strictures occur more often in Crohn disease than in ulcerative colitis. The mainstay of endoscopic therapy for strictures in inflammatory bowel disease is endoscopic balloon dilation. Serious complications are rare, and risk factors for perforation include active inflammation, use of steroids, and dilation of ileorectal or ileosigmoid anastomotic strictures. This article presents current literature on strictures in inflammatory bowel disease. Focus is placed on the short- and long-term outcomes, complications, and safety of endoscopic balloon dilation for Crohn disease strictures. Adjuvant techniques, such as intralesional injection of steroids and anti-tumor necrosis factor, stricturotomy, and stent insertion, are briefly discussed.

Assessment of Crohn's disease-associated small bowel strictures and fibrosis on cross-sectional imaging: a systematic review

Patients with Crohn's disease commonly develop ileal and less commonly colonic strictures, containing various degrees of inflammation and fibrosis. While predominantly inflammatory strictures may benefit from a medical anti-inflammatory treatment, predominantly fibrotic strictures currently require endoscopic balloon dilation or surgery. Therefore, differentiation of the main components of a stricturing lesion is key for defining the therapeutic management. The role of endoscopy to diagnose the nature of strictures is limited by the superficial inspection of the intestinal mucosa, the lack of depth of mucosal biopsies and by the risk of sampling error due to a heterogeneous distribution of inflammation and fibrosis within a stricturing lesion. These limitations may be in part overcome by cross-sectional imaging techniques such as ultrasound, CT and MRI, allowing for a full thickness evaluation of the bowel wall and associated abnormalities. This systematic literature review provides a comprehensive summary of currently used radiologic definitions of strictures. It discusses, by assessing only manuscripts with histopathology as a gold standard, the accuracy for diagnosis of the respective modalities as well as their capability to characterise strictures in terms of inflammation and fibrosis. Definitions for strictures on cross-sectional imaging are heterogeneous; however, accuracy for stricture diagnosis is very high. Although conventional cross-sectional imaging techniques have been reported to distinguish inflammation from fibrosis and grade their severity, they are not sufficiently accurate for use in routine clinical practice. Finally, we present recent consensus recommendations and highlight experimental techniques that may overcome the limitations of current technologies.

Targeting anti-fibrotic pathways in Crohn's disease - The final frontier?

Intestinal fibrosis with stricture formation affects up to half of patients with Crohn's disease (CD), resulting in impaired quality of life, increased risk of surgical intervention, and associated patient morbidity. The underlying pathophysiologic mechansisms responsible for initiating and perpetuating intestinal fibrosis are complex, dynamic, and implicate both inflammation-dependent and independent pathways. Previously thought to be an irreversible complication of long-standing inflammation unresponsive to medical therapy, fibrostenotic CD has been traditionally managed with endoscopic or surgical approaches. However, recent advances in our understanding of the humoral, cellular, and environmental pathways driving intestinal fibrosis has the potential to fundamentally change these management paradigms for CD-related strictures. Furthermore, the promise of fibrosis treatments in other organ systems has encouraged hope that anti-fibrotic treatment approaches for CD may be within reach. Here, we summarize the key breakthroughs in our molecular understanding of intestinal fibrosis, review current medical, endoscopic, and surgical treatment approaches to CD-related strictures, propose future directions for anti-fibrotic therapy in CD, and identify crucial research questions in this field that require additional investigation.

TRP channels in cardiac and intestinal fibrosis

It is now widely accepted that advanced fibrosis underlies many chronic inflammatory disorders and is the main cause of morbidity and mortality of the modern world. The pathogenic mechanism of advanced fibrosis involves diverse and intricate interplays between numerous extracellular and intracellular signaling molecules, among which the non-trivial roles of a stress-responsive Ca²⁺/Na⁺-permeable cation channel superfamily, the transient receptor potential (TRP) protein, are receiving growing attention. Available evidence suggests that several TRP channels such as TRPC3, TRPC6, TRPV1, TRPV3, TRPV4, TRPA1, TRPM6 and TRPM7 may play central roles in the progression and/or prevention of fibroproliferative disorders in vital visceral organs such as lung, heart, liver, kidney, and bowel as well as brain, blood vessels and skin, and may contribute to both acute and chronic inflammatory processes involved therein. This short paper overviews the current knowledge accumulated in this rapidly growing field, with particular focus on cardiac and intestinal fibrosis, which are tightly associated with the pathogenesis of atrial fibrillation and inflammatory bowel diseases such as Crohn's disease.

An expert consensus to standardise definitions, diagnosis and treatment targets for anti-fibrotic stricture therapies in Crohn's disease

BACKGROUND

Fibrotic stricture is a common complication of Crohn's disease (CD) affecting approximately half of all patients. No specific anti-fibrotic therapies are available; however, several therapies are currently under evaluation. Drug development for the indication of stricturing CD is hampered by a lack of standardised definitions, diagnostic modalities, clinical trial eligibility criteria, endpoints and treatment targets in stricturing CD.

AIM

To standardise definitions, diagnosis and treatment targets for anti-fibrotic stricture therapies in Chron's disease.

METHODS

An interdisciplinary expert panel consisting of 15 gastroenterologists and radiologists was assembled. Using modified RAND/University of California Los Angeles appropriateness methodology, 109 candidate items derived from systematic review and expert opinion focusing on small intestinal strictures were anonymously rated as inappropriate, uncertain or appropriate. Survey results were discussed as a group before a second and third round of voting.

RESULTS

Fibrotic strictures are defined by the combination of luminal narrowing, wall thickening and pre-stenotic dilation. Definitions of anastomotic (at site of prior intestinal resection with anastomosis) and naïve small bowel strictures were similar; however, there was uncertainty regarding wall thickness in anastomotic strictures. Magnetic resonance imaging is considered the optimal technique to define fibrotic strictures and assess response to therapy. Symptomatic strictures are defined by abdominal distension, cramping, dietary restrictions, nausea, vomiting, abdominal pain and post-prandial abdominal pain. Need for intervention (endoscopic balloon dilation or surgery) within 24-48 weeks is considered the appropriate endpoint in pharmacological trials.

CONCLUSIONS

Consensus criteria for diagnosis and response to therapy in stricturing Crohn's disease should inform both clinical practice and trial design.

Identification of Endpoints for Development of Antifibrosis Drugs for Treatment of Crohn's Disease

BACKGROUND & AIMS

Intestinal fibrosis is a challenge to management of patients with Crohn's disease (CD); there is an urgent need to expedite development of antifibrosis drugs for this disease. The International Organization for the Study of Inflammatory Bowel Disease (IOIBD) aimed to identify a set of endpoints that can be used to determine efficacy of antifibrosis agents tested in clinical trials of patients with CD.

METHODS

We conducted a systematic review to identify clinical, radiologic, biochemical, endoscopic, and composite endpoints used in assessing activity of fibrostenosing CD and response to treatment, and determined their operational properties. A panel of IOIBD experts performed a consensus process to identify the best endpoints for inclusion in clinical trials, through a 2-round, Delphi-style online survey.

RESULTS

A total of 36 potentially relevant endpoints for intestinal fibrosis were selected and assessed. Forty-eight physicians with expertise in inflammatory bowel disease, from 5 regions (North America, Europe, Middle East, Asia/Pacific, and Latin America), participated in the Delphi consensus process. A core set of 13 endpoints (complete clinical response, long-term efficacy, sustained clinical benefit, treatment failure, radiological remission, normal quality of life, clinical remission without steroids, therapeutic failure, deep remission, complete absence of occlusive symptoms, symptom-free survival, bowel damage progression, and no disability) were rated as critical. Agreement was high among the experts.

CONCLUSIONS

Members of the IOIBD reached expert consensus on a set of endpoints that can be used to assess antifibrosis agents in trials of patients with CD. Studies are needed to clarify methods for measuring these outcomes and validate measurement instruments.

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.

Magnetic Resonance Imaging Predicts Histopathological Composition of Ileal Crohn's Disease

BACKGROUND AND AIMS

Recently, smooth muscle hypertrophy has been suggested to be a contributor to small bowel lesions secondary to Crohn's disease [CD], in addition to inflammation and fibrosis. Here, we assess the value of magnetic resonance imaging [MRI] for the characterisation of histopathological tissue composition of small bowel CD, including inflammation, fibrosis, and smooth muscle hypertrophy.

METHODS

A total of 35 consecutive patients [male/female 17/18, mean age 33 years] with ileal CD, who underwent small bowel resection and a preoperative contrast-enhanced MRI examination within 1 month before surgery, were retrospectively included. Image assessment included qualitative [pattern/degree of enhancement, presence of ulcerations/fistulas/abscesses] and quantitative parameters [wall thickness on T2/T1-weighted images [WI], enhancement ratios, apparent diffusion coefficient [ADC], Clermont and Magnetic Resonance Index of Activity [MaRIA] scores). MRI parameters were compared with histopathological findings including active inflammation, collagen deposition, and muscle hypertrophy using chi square/Fisher or Mann-Whitney tests and univariate/multivariate logistic/linear regression analyses.

RESULTS

Forty ileal segments were analysed in 35 patients. Layered pattern at early-post-contrast phase was more prevalent (odds ratio [OR] = 8; p = 0.008), ADC was significantly lower [OR = 0.005; p = 0.022], and MaRIA score was significantly higher [OR = 1.125; p = 0.022] in inflammation grades 2-3 compared with grade 1. Wall thickness on T2WI was significantly increased [OR = 1.688; p = 0.043], and fistulas [OR = 14.5; p = 0.017] were more prevalent in segments with disproportionately increased muscle hypertrophy versus those with disproportionately increased fibrosis. MaRIA/Clermont scores, wall thickness on T1WI and T2WI, and ADC were all significantly correlated with degree of muscular hypertrophy.

CONCLUSIONS

MRI predicts the degree of inflammation, and can distinguish prominent muscle hypertrophy from prominent fibrosis in ileal CD with reasonable accuracy (area under receiver operating characteristic curve [AUROC] > 0.7).

Crohn's disease associated strictures

Crohn's disease (CD) is a chronic relapsing and remitting disease that can affect any segments of the gastrointestinal tract. More than 50% of patients with CD develop stricturing or penetrating complications within the first 10 years after diagnosis. Strictures can lead to intestinal obstruction, which is a common indication for surgery. Despite significant advances in the understanding of the pathogenesis of intestinal fibrostenosis, imaging and therapeutic armamentarium of CD, the risk of intestinal surgery remained significantly high. Endoscopic balloon dilation is a promising first-line alternative to surgery as it is less invasive and could preserve intestinal length. In this review, we will evaluate the literature on the mechanism of intestinal fibrosis, emerging imaging techniques, and management strategies for CD associated strictures.

CD16+ Macrophages Mediate Fibrosis in Inflammatory Bowel Disease

BACKGROUND AND AIMS

Fibrosis is a common complication of Crohn's disease [CD], and is related to dysregulated tissular repair following inflammation, in which macrophages play a central role. We have previously observed that STAT6-/- mice present delayed mucosal recovery after 2,4,6-trinitrobenzenesulfonic acid [TNBS]-induced colitis due to a deficiency in reparatory interleukin-4 [IL4]/STAT6-dependent M2 macrophages, which can be reverted by the exogenous transfer of this cell type. In the present study, we analyse the role of STAT6-dependent macrophages in intestinal fibrosis.

METHODS

Colitis was induced by weekly intra-rectal administration of TNBS [6 weeks] to STAT6-/- mice and wild-type [WT] animals. Colonic surgical resections were obtained from CD patients and from colon cancer patients.

RESULTS

Chronic colitis provoked a fibrogenic response in STAT6-/- mice, but not in WT animals. An accumulation of M2 macrophages, defined as CD206+ cells, was observed in WT mice, but not in STAT6-/- animals. Instead, the latter group showed an increase in CD16+ macrophages that correlated with the expression of fibrogenic markers. CD16+ macrophages were also increased in the damaged mucosa of Crohn's disease patients with stenotic or penetrating complications. Finally, administration of IL4-treated WT macrophages to STAT6-/- mice reduced TNBS-induced fibrosis.

CONCLUSIONS

Our study demonstrates that STAT6 deficiency dysregulates the macrophage response to inflammatory outbursts by increasing the presence of a population of CD16+ macrophages that seems to contribute to intestinal fibrosis.

Epithelial-mesenchymal transition in Crohn's disease

Crohn's disease (CD) is often accompanied by the complications of intestinal strictures and fistulas. These complications remain obstacles in CD treatment. In recent years, the importance of epithelial-mesenchymal transition in the pathogenesis of CD-associated fistulas and intestinal fibrosis has become apparent. Epithelial-mesenchymal transition refers to a dynamic change, wherein epithelial cells lose their polarity and adherence and acquire migratory function and fibroblast features. During formation of CD-associated fistulas, intestinal epithelial cells dislocate from the basement membrane and migrate to the lining of the fistula tracts, where they convert into transitional cells as a compensatory response under the insufficient wound healing condition. In CD-associated intestinal fibrosis, epithelial-mesenchymal transition may serve as a source of new fibroblasts and consequently lead to overproduction of extracellular matrix. In this review, we present current knowledge of epithelial-mesenchymal transition and its role in the pathogenesis of CD in order to highlight new therapy targets for the associated complications.

Treatment of Intestinal Fibrosis in Experimental Inflammatory Bowel Disease by the Pleiotropic Actions of a Local Rho Kinase Inhibitor

BACKGROUND

Intestinal fibrosis resulting in (sub)obstruction is a common complication of Crohn's disease (CD). Rho kinases (ROCKs) play multiple roles in TGFβ-induced myofibroblast activation that could be therapeutic targets. Because systemic ROCK inhibition causes cardiovascular side effects, we evaluated the effects of a locally acting ROCK inhibitor (AMA0825) on intestinal fibrosis.

METHODS

Fibrosis was assessed in mouse models using dextran sulfate sodium (DSS) and adoptive T-cell transfer. The in vitro and ex vivo effects of AMA0825 were studied in different cell types and in CD biopsy cultures.

RESULTS

ROCK is expressed in fibroblastic, epithelial, endothelial, and muscle cells of the human intestinal tract and is activated in inflamed and fibrotic tissue. Prophylactic treatment with AMA0825 inhibited myofibroblast accumulation, expression of pro-fibrotic factors, and accumulation of fibrotic tissue without affecting clinical disease activity and histologic inflammation in 2 models of fibrosis. ROCK inhibition reversed established fibrosis in a chronic DSS model and impeded ex vivo pro-fibrotic protein secretion from stenotic CD biopsies. AMA0825 reduced TGFβ1-induced activation of myocardin-related transcription factor (MRTF) and p38 mitogen-activated protein kinase (MAPK), down-regulating matrix metalloproteinases, collagen, and IL6 secretion from fibroblasts. In these cells, ROCK inhibition potentiated autophagy, which was required for the observed reduction in collagen and IL6 production. AMA0825 did not affect pro-inflammatory cytokine secretion from other ROCK-positive cell types, corroborating the selective in vivo effect on fibrosis.

CONCLUSIONS

Local ROCK inhibition prevents and reverses intestinal fibrosis by diminishing MRTF and p38 MAPK activation and increasing autophagy in fibroblasts. Overall, our results show that local ROCK inhibition is promising for counteracting fibrosis as an add-on therapy for CD.

Topic infliximab injection for refractory rectal stenosis in Crohn's disease: long-term follow-up in two patients

PURPOSE

TNF blockers are approved for intravenous or subcutaneous systemic therapy of many chronic inflammatory diseases. As it is not possible to achieve a sufficient local clinical improvement through systemic therapy in every patient, diverse approaches of topical therapy using TNF blockers have been investigated in recent years.

METHODS

In this paper, we report on long-term clinical results of originator infliximab (IFX) injections into symptomatic combined scarring and inflammatory stenoses of the rectum in two patients with Crohn's disease. Aiming at high tissue IFX levels, 25 mg of IFX was injected into each quadrant of the stenosis after endoscopic balloon dilatation. This off-label treatment was repeated as necessary, depending on the clinical success.

RESULTS

Topic IFX injection after balloon dilation reduced imperative stool pressure, isolated episodes of incontinence and incomplete emptying. Improvement lasted between 4 and 14 weeks in one patient and the treatment was repeated 13 times in the following 6.6 years. In the other patient, the technique was necessary only twice with no symptom recurrence in the subsequent 5.3 years.

CONCLUSION

Our experience suggests that topic application of a systemically approved anti-TNF substance may be a successful individualized therapy for refractory stenosis of the rectum in patients with Crohn's disease.

Significant contribution of TRPC6 channel-mediated Ca2+ influx to the pathogenesis of Crohn's disease fibrotic stenosis

Intestinal fibrosis is an intractable complication of Crohn's disease (CD), and, when occurring excessively, causes severe intestinal obstruction that often necessitates surgical resection. The fibrosis is characterized by an imbalance in the turnover of extracellular matrix (ECM) components, where intestinal fibroblasts/myofibroblasts play active roles in ECM production, fibrogenesis and tissue remodeling, which eventually leads to the formation of stenotic lesions. There is however a great paucity of knowledge about how intestinal fibrosis initiates and progresses, which hampers the development of effective pharmacotherapies against CD. Recently, we explored the potential implications of transient receptor potential (TRP) channels in the pathogenesis of intestinal fibrosis, since they are known to act as cellular stress sensors/transducers affecting intracellular Ca²⁺ homeostasis/dynamics, and are involved in a broad spectrum of cell pathophysiology including inflammation and tissue remodeling. In this review, we will place a particular emphasis on the intestinal fibroblast/myofibroblast TRPC6 channel to discuss its modulatory effects on fibrotic responses and therapeutic potential for anti-fibrotic treatment against CD-related stenosis.

Role of glycogen synthase kinase-3β and PPAR-γ on epithelial-to-mesenchymal transition in DSS-induced colorectal fibrosis

Background

Intestinal fibrosis is characterized by abnormal production and deposition of extracellular matrix (ECM) proteins by activated myofibroblasts. The main progenitor cells of activated myofibroblasts are the fibroblasts and the epithelial cells, the latter through the epithelial-mesenchymal transition (EMT).

Aim

To evaluate the action of the new PPAR-γ modulator, GED-0507-34 Levo (GED) on the expression of EMT associated and regulatory proteins such as TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, and GSK-3β, in a mouse model of DSS-induced intestinal fibrosis.

Methods

Chronic colitis and fibrosis were induced by oral administration of 2.5% DSS (w/v) for 6 weeks. GW9662 (GW), a selective PPAR-γ inhibitor, was also administered by intraperitoneal injection at the dose of 1 mg/kg/day combined with GED treatment. All drugs were administered at the beginning of the second cycle of DSS (day 12). 65 mice were randomly divided into five groups (H₂O as controls n = 10, H₂O+GED n = 10, DSS n = 15, DSS+GED n = 15, DSS+GED+GW n = 15). The colon was excised for macroscopic examination and histological and morphometric analyses. The level of expression of molecules involved in EMT and fibrosis, like TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, GSK-3β and PPAR-γ, was assessed by immunohistochemistry, immunofluorescence, western blot and Real Time PCR.

Results

GED improved the DSS-induced chronic colitis and fibrosis. GED was able to reduce the expression of the main fibrosis markers (α-SMA, collagen I-III and fibronectin) as well as the pivotal pro-fibrotic molecules IL-13, TGF-β and Smad3, while it increased the anti-fibrotic PPAR-γ. All these GED effects were nullified by co-administration of GW with GED. Furthermore, GED was able to normalize the expression levels of E-cadherin and β-catenin and upregulated GSK-3β, that are all known to be involved both in EMT and fibrosis.

Conclusions

The DSS-induced intestinal fibrosis was improved by the new PPAR-γ modulator GED-0507-34 Levo through the modulation of EMT mediators and pro-fibrotic molecules and through GSK-3β induction.

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.

Crohn's Strictures-Moving Away from the Knife

Crohn's disease (CD) is a lifelong inflammatory bowel disease with a rapidly rising incidence in the pediatric population. A common complication of CD is the development of fibrotic strictures, which may be present at initial diagnosis or develop many years later. Clinical presentation depends on stricture location and degree of obstruction, and strictures frequently contain a mixture of inflammatory and fibrotic tissue. Histological examination of Crohn's strictures shows thickening of the muscular layers and the submucosa, where increased collagen deposition by activated myofibroblasts is concentrated around islands of smooth muscle cells and at the superficial margin of the muscularis propria. No antifibrotic therapies for Crohn's strictures exist. Profibrotic transforming growth factor-β (TGFβ)/bone morphogenetic protein signaling stimulates myofibroblast differentiation and extracellular matrix deposition. Understanding and targeting TGFβ1 downstream signaling is the main focus of current research, raising the possibility of specific antifibrotic therapy in CD becoming available in the future.

A Pooled Analysis of Efficacy, Safety, and Long-term Outcome of Endoscopic Balloon Dilation Therapy for Patients with Stricturing Crohn's Disease

BACKGROUND

Endoscopic balloon dilation (EBD) is widely used to manage Crohn's disease-associated strictures. However, most studies of the safety and efficacy are small and heterogenous. We performed a combined analysis of published studies and evaluated 676 comprehensive individual participant data sets to determine the overall effects of EBD.

METHODS

Citations from the Embase, MEDLINE, and the Cochrane library from 1991 through 2013 were systematically reviewed, and references of cited articles were assessed for relevant publications. We collected data from studies including ≥15 patients and additionally generated a unique individual patient database containing 676 individual data sets derived from 12 studies. Technical feasibility, short-term and long-term efficacies, and safety were evaluated.

RESULTS

In 1463 patients with Crohn's disease who underwent 3213 EBD procedures, 98.6% of strictures were ileal and 62% anastomotic. The technical success rate of the EBDs was 89.1% with a clinical efficacy of 80.8%. Complications occurred in 2.8% per procedure. After 24 months of follow-up, 73.5% of subjects underwent redilation and 42.9% surgical resection. In a multivariate analysis of 676 individual patients, a stricture length of ≤5 cm was associated with a surgery-free outcome; every 1 cm increase of stricture length increased the hazard of need for surgery by 8% (P = 0.008). Inflammation did not affect outcomes or rate of complications.

CONCLUSIONS

Based on a systematic literature review and analysis of data sets from 676 patients, EBD has a high rate of short-term technical and clinical efficacies, with substantial long-term efficacy and acceptable rates of complication.

Heterogeneity in endoscopic treatment of Crohn's disease-associated strictures: An international inflammatory bowel disease specialist survey

BACKGROUND

Crohn's disease (CD) is frequently complicated by intestinal strictures, which are commonly treated by endoscopic balloon dilation (EBD). However, available data on this area of treatment is limited. The aim of this study was to depict the heterogeneity of endoscopic management of CD-associated strictures among international CD specialists to identify common treatment standards.

METHODS

IBD experts of the International Organization for the Study of Inflammatory Bowel Disease (IOIBD), the European Crohn's and Colitis Organization (ECCO), and from the Prospective Value In IBD trials (PROVIT) completed a web-based questionnaire to evaluate their endoscopic experience, practice setting, and number of EBDs performed annually. Additionally, two case scenarios and technical practice parameters were investigated.

RESULTS

A total of 126 subjects from 15 countries completed the survey. The maximal length of dilated stricture was 4.5 ± 1.7 cm. The most commonly used maximal balloon size was graded as 15-18 mm. While 87.2 % of the participants favored EBD for anastomotic strictures, only 58.6 % did so in the case of naïve strictures. Only 35.7 % of physicians dilated actively inflamed strictures. Interventional endoscopists were more likely to dilate only clinically symptomatic strictures (p = 0.046). Surgeons favored surgical treatment of de novo ileocecal strictures compared to gastroenterologists (p = 0.026), reported a shorter stricture length being amendable by EBD (p = 0.045), and more frequently used concomitant therapies (p = 0.001). Operator experience increased the likelihood of EBD use in actively inflamed strictures (p = 0.002), maximum length of stricture, and maximum balloon size (p = 0.001).

CONCLUSIONS

EBD is a widely used treatment approach for stricturing CD. Individual approaches differ significantly based on background of the operator, experience level, and practice setting.

Computed Tomography and Magnetic Resonance Enterography in Crohn's Disease: Assessment of Radiologic Criteria and Endpoints for Clinical Practice and Trials

Early recognition of Crohn's disease with initiation of disease-modifying therapy has emerged as a prominent inflammatory bowel disease management strategy. Clinical practice and trials have often focused on patient symptoms, and more recently, serologic tests, stool inflammatory markers, and/or endoscopic inflammatory features for study entry criteria, treatment targets, disease activity monitoring, and to assess therapeutic response. Unfortunately, patient symptoms do not correlate well with biological disease activity, and endoscopy potentially misses or underestimates disease extent and severity in small bowel Crohn's disease. Computed tomography enterography and magnetic resonance enterography (MRE) are potential tools to identify and quantify transmural structural damage and disease activity in the small bowel. In this review, we discuss the role of computed tomography enterography and MRE in disease management algorithms in clinical practice. We also compare the currently developed MRE-based scoring systems, their strengths and pitfalls, as well as the role for MRE in clinical trials for Crohn's disease.

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.