Toward an antifibrotic therapy for inflammatory bowel disease

AI-luminating Artificial Intelligence in Inflammatory Bowel Diseases: A Narrative Review on the Role of AI in Endoscopy, Histology, and Imaging for IBD

Endoscopy, histology, and cross-sectional imaging serve as fundamental pillars in the detection, monitoring, and prognostication of inflammatory bowel disease (IBD). However, interpretation of these studies often relies on subjective human judgment, which can lead to delays, intra- and interobserver variability, and potential diagnostic discrepancies. With the rising incidence of IBD globally coupled with the exponential digitization of these data, there is a growing demand for innovative approaches to streamline diagnosis and elevate clinical decision-making. In this context, artificial intelligence (AI) technologies emerge as a timely solution to address the evolving challenges in IBD. Early studies using deep learning and radiomics approaches for endoscopy, histology, and imaging in IBD have demonstrated promising results for using AI to detect, diagnose, characterize, phenotype, and prognosticate IBD. Nonetheless, the available literature has inherent limitations and knowledge gaps that need to be addressed before AI can transition into a mainstream clinical tool for IBD. To better understand the potential value of integrating AI in IBD, we review the available literature to summarize our current understanding and identify gaps in knowledge to inform future investigations.

Efficacy of exclusive enteral nutrition on the mucosal healing of different gastrointestinal segments in children with Crohn's disease

OBJECTIVE

To investigate the association between disease location and segmental mucosal healing (SMH) following exclusive enteral nutrition (EEN) in children with Crohn's disease (CD).

METHODS

Treatment-naive pediatric patients with endoscopically active CD treated with EEN alone as induction therapy were retrospectively enrolled from January 1, 2017 to June 30, 2022. The simple endoscopic score for CD (SES-CD) was employed to score disease activity in the upper gastrointestinal (GI) tract (esophagus, stomach, duodenum), rectum, left colon, transverse colon, right colon, and terminal ileum. While the Lewis score assessed that of the small bowel from the jejunum to the proximal ileum (except the terminal ileum). The variation in the total scores for each segment and SES-CD subscores for each ileocolonic segment from baseline to 1 year after EEN therapy and the segmental endoscopic outcomes and potential predictors associated with SMH for the segments scored by SES-CD were evaluated.

RESULTS

Overall, 82 children with CD were enrolled. Except for the upper GI segment, scores in other segments declined significantly from baseline to EEN completion (all P < 0.001). We analyzed 486 segments (79, 80, 81, 82, 82 and 82 from upper GI tract, terminal ileum, right colon, transverse colon, left colon, and rectum) and found that the segmental SES-CD at baseline (odds ratio [OR] 0.62, 95% confidence interval [CI] 0.55-0.70, P < 0.001) and upper GI location (OR 0.25, 95% CI 0.11-0.55, P = 0.001) were associated with SMH at EEN completion.

CONCLUSION

Disease location of the upper GI segment in pediatric CD was associated with SMH following EEN therapy.

A comprehensive metabolite fingerprint of fibrostenosis in patients with Crohn's disease

Intestinal fibrostenosis in patients with Crohn's disease (CD) is a common and untreatable comorbidity that is notoriously difficult to monitor. We aimed to find metabolites associated with the presence of fibrostenosis in patients with CD using targeted and untargeted metabolomics analyses of serum and primary cell cultures using hyphenated ultra-high performance liquid chromatography high-resolution mass spectrometry. Targeted metabolomics revealed 11 discriminating metabolites in serum, which were enriched within the arginine and proline metabolism pathway. Based on untargeted metabolomics and discriminant analysis, 166 components showed a high predictive value. In addition, human intestinal fibroblasts isolated from stenotic tissue were characterized by differential levels of medium-chain dicarboxylic acids, which are proposed as an energy source through beta-oxidation, when oxidative phosphorylation is insufficient. Another energy providing pathway in such situations is anaerobic glycolysis, a theory supported by increased expression of hexokinase 2 and solute carrier family 16 member 1 in stenotic fibroblasts. Of interest, four (unannotated) metabolic components showed a negative correlation with hexokinase 2 gene expression. Together, this study provides a discriminative metabolic fingerprint in the serum and in intestinal fibroblasts of stenotic and non-stenotic patients with CD suggestive for increased production of building blocks for collagen synthesis and increased glycolysis.

Xanthohumol Interferes with the Activation of TGF-β Signaling in the Process Leading to Intestinal Fibrosis

Fibrosis has various biological processes and affects almost every organ, especially in patients with inflammatory bowel disease, including Crohn's disease, who experience discomfort caused by intestinal fibrosis, which is a problem that needs to be resolved. TGF-β signaling is known to act as a key regulator of intestinal fibrosis, and its modulation could be an excellent candidate for fibrosis therapy. Xanthohumol (XN) has various effects, including anti-inflammation and anti-cancer; however, the detailed mechanism of TGF-β signaling has not yet been studied. The purpose of this study was to investigate the mechanism underlying the anti-fibrotic effect of XN on TGF-β1-induced intestinal fibrosis using primary human intestinal fibroblasts (HIFs). In this study, to check the anti-fibrotic effects of XN on intestinal fibrosis, we assessed the expression of fibrosis-related genes in TGF-β1-stimulated HIFs by qPCR, immunoblotting, and immunofluorescence staining. As a result, XN showed the ability to reduce the expression of fibrosis-associated genes increased by TGF-β1 treatment in HIFs and restored the cell shape altered by TGF-β1. In particular, XN repressed both NF-κB- and Smad-binding regions in the α-SMA promoter, which is important in fibrosis. In addition, XN inhibited NF-κB signaling, including phosphorylated-IkBα and cyclooxygenase-2 expression, and TNF-α-stimulated transcriptional activity of NF-κB. XN attenuated TGF-β1-induced phosphorylation of Smad2 and Smad3, and the transcriptional activity of CAGA. Particularly, XN interfered with the binding of TGF-Receptor I (TβRI) and Smad3 by binding to the kinase domain of the L45 loop of TβRI, thereby confirming that the fibrosis mechanism did not proceed further. In conclusion, XN has an inhibitory effect on TGF-β1-induced intestinal fibrosis in HIFs, significantly affecting TGF-β/Smad signaling.

Management of Crohn's stricture: medical, endoscopic and surgical therapies

Patients with Crohn's disease are at high risk of presenting with or developing a bowel stricture during the course of their disease. The available therapeutic options to manage a symptomatic Crohn's stricture include medical therapy (mainly biologics), surgical resection and endoscopic interventions. The choice of therapeutic modality depends on the clinical presentation of the stricture, the nature of the stricture (inflammatory vs fibrotic, primary vs anastomotic) and its anatomical characteristics on endoscopy and imaging (length, number, location of strictures and severity of obstruction). The aim herein is to provide an overview of the comprehensive assessment of a Crohn's stricture and to review the indications of the different therapeutic modalities, their success rates and their limitations to help clinicians properly evaluate and manage Crohn's strictures.

Outcomes of Passable and Non-passable Strictures in Clinical Trials of Crohn's Disease: A Post-hoc Analysis

BACKGROUND AND AIMS

There is paucity of evidence on the reversibility of Crohn's disease [CD]-related strictures treated with therapies. We aimed to describe the clinical and endoscopic outcomes of CD patients with non-passable strictures.

METHODS

This was a post-hoc analysis of three large CD clinical trial programmes examining outcomes with infliximab, ustekinumab, and azathioprine, which included data on 576 patients including 105 with non-passable strictures and 45 with passable strictures, as measured using the Simple Endoscopic Score for Crohn's Disease [SES-CD]. The impact of non-passable strictures on achieving clinical remission [CR] and endoscopic remission [ER] was assessed using multivariate logistic regression models. CR was defined as a Crohn's Disease Activity Index [CDAI] <150, clinical response as a CDAI reduction of ≥100 points, and ER as SES-CD score <3.

RESULTS

After 1 year of treatment, patients with non-passable strictures demonstrated the ability to achieve passable or no strictures in 62.5% of cases, with 52.4% and 37.5% attaining CR and ER, respectively. However, patients with non-passable strictures at baseline were less likely to demonstrate symptom improvement compared with those with passable or no strictures, with reduced odds of 1-year CR (adjusted odds ratio [aOR] 0.17, 95% CI 0.03-0.99, p = 0.048). No significant differences were observed between patients with non-passable strictures at baseline and those with passable or no strictures in rates of ER [aOR 0.82, 95% CI 0.23-2.85, p = 0.751] at 1 year.

CONCLUSIONS

Patients with non-passable strictures can achieve symptomatic and endoscopic remission when receiving therapies used to treat CD, although they are less likely to obtain CR compared with patients without non-passable strictures. These findings support the importance of balancing the presence of non-passable strictures in trial arms.

Chronic inflammation and other changes are significant components of clinically fibrotic strictures in Crohn's disease: a histological study of resected strictures clinically characterized as noninflamed

BACKGROUND

Strictures related to Crohn's disease due to fibrosis are a result of an exaggerated tissue remodelling response to inflammation, characterized by accumulation of collagen-rich extracellular matrix produced by mesenchymal cells.

OBJECTIVES

The objective of this study was to characterize histological changes seen in resected 'fibrotic' strictures to better understand individual components of intestinal stenosis.

METHODS

We identified patients undergoing surgery for ileal Crohn's disease secondary to symptomatic stricturing disease (Montreal B2) using the histopathology database at Queen Elizabeth Hospital in Birmingham, UK, between 2012 and 2017. Phenotypic data were recorded and resection specimens reviewed. Two independent pathologists applied the semiquantitative scoring system previously developed by us to the microscopic images. Data were analyzed using the possible maximum total score (%PMTS).

RESULTS

Forty-eight patients (M = 25) were included. with median disease duration of 7 years (range 0.25-39 years); nearly two-thirds had ileocolonic distribution (L3). In this cohort, despite presurgery diagnosis of noninflamed fibrosis, chronic inflammation was noted to be a prominent component of all strictures. The histological scoring showed presence of several other prominent findings such as muscular hyperplasia and volume expansion.There was statistically significant positive correlation between chronic inflammation and fibrosis and muscular hyperplasia.

CONCLUSION

The histological features of Crohn's disease-related strictures show multiple changes in multiple layers and not simply fibrosis. In our cohort, despite the observation prior to surgery that strictures were clinically considered fibrotic, the finding of chronic inflammation as a dominant component at a histological level in the resection is important. The findings might suggest that one of the main drivers of progressive fibrosis is the inflammatory component, which probably is never fully resolved.

Development of an Objective Model to Define Near-Term Risk of Ileocecal Resection in Patients with Terminal Ileal Crohn Disease

BACKGROUND

The decision to either escalate medical therapy or proceed to ileocecal resection (ICR) in patients with terminal ileal Crohn disease (CD) remains largely subjective. We sought to develop a risk score for predicting ICR at 1 year from computed tomography or magnetic resonance enterography (CTE/MRE).

METHODS

We conducted a retrospective cohort study including all consecutive adult (> 18 years) patients with imaging findings of terminal ileal CD (Montreal classification: B1, inflammatory predominant; B2, stricturing; or B3, penetrating) on CTE/MRE between January 1, 2016, and December 31, 2016. The risk for ICR at 6 months and at 1 year of CTE/MRE and risk factors associated with ICR, including demographics, CD-specific immunosuppressive therapeutics, and disease presentation at the time of imaging, were determined.

RESULTS

Of 559 patients, 121 (21.6%) underwent ICR during follow-up (1.4 years [IQR 0.21-1.64 years]); the risk for ICR at 6 months and at 1 year was 18.2% (95% CI 14.7%-21.6%) and 20.5% (95% CI 16.8%-24.1%), respectively. Multivariable analysis revealed Montreal classification (B2, hazard ratio [HR] 2.73, and B3, HR 6.80, both P < 0.0001), upstream bowel dilation (HR 3.06, P < 0.0001), and younger age (19-29 years reference, 30-44 years, HR 0.83 [P = 0.40]; 45-59 years, HR 0.58 [P = 0.04], and 60+ years, HR 0.45 [P = 0.01]) to significantly increase the likelihood of ICR. A predictive nomogram for interval ICR was developed based on these significant variables.

CONCLUSIONS

The presence of CD strictures, penetrating complications, and upstream bowel dilation on CTE/MRE, combined with young age, significantly predict ICR. The suggested risk model may facilitate objective therapeutic decision-making.

Pathogenesis of fibrostenosing Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease, which could affect any part of the gastrointestinal tract. A severe complication of CD is fibrosis-associated strictures, which can cause bowel obstruction. Unfortunately, there is no specific antifibrotic therapy available. More than 80% of the patients with CD will have to undergo at least 1 surgery in their life and recurrence of strictures after surgery is common. Investigations on the mechanism of fibrostenosing CD have revealed that fibrosis is mainly driven by expansion of mesenchymal cells including fibroblasts, myofibroblasts, and smooth muscle cells. Being exposed to a pro-fibrotic milieu, these cells increase the secretion of extracellular matrix, as well as crosslinking enzymes, which drive tissue stiffness and remodeling. Fibrogenesis can become independent of inflammation in later stages of disease, which offers unique therapeutic potential. Exciting new evidence suggests smooth muscle cell hyperplasia as a strong contributor to luminal narrowing in fibrostenotic CD. Approval of new drugs in other fibrotic diseases, such as idiopathic pulmonary fibrosis, as well as new targets associated with fibrosis found in CD, such as cadherins or specific integrins, shed light on the development of novel antifibrotic approaches in CD.

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.

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.

Resveratrol and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract, comprising ulcerative colitis (UC) and Crohn's disease (CD). Progression of IBD leads to long-term impairment of intestinal structure and function. The pathogenesis of IBD is complex, involving environmental, immunological, genetic, microbial, and psychological factors. The conventional therapies and many existing biopharmaceuticals for IBD have limited efficacy or adverse effects. As a promising safe and effective therapy for IBD, resveratrol has been studied widely, as it has shown anti-inflammatory and antioxidant activity. Resveratrol's mechanism of action involves multiple immune responses and signaling pathways; it is absorbed quickly and metabolized into various derivatives. However, the poor water solubility and low bioavailability of resveratrol limit its clinical applications. Further research should attempt to improve the stability and oral bioavailability of resveratrol by modification and various delivery systems.

New endoscopic approach of anti-fibrotic therapy for inflammatory bowel disease

Fibrosis continues to be paid a great attention in not only basic research but also clinical practice, especially for the development of novel therapeutics in various fibrotic diseases. However, there remain several obstacles to translation in developing anti-fibrosis therapy. The present review documents our translational practice from target discovery to first-in-patient studies in the development of anti-fibrosis therapy for inflammatory bowel disease (IBD). First topic is a target selection. We have focused on the target that has an ability to regulate multifactorial cascades of fibrosis. Carbohydrate sulfotransferase 15 (CHST15) synthesizes matrix proteoglycan that regulates various pathogenic mediators and contributes to tissue remodeling during injury. Small interfering RNA (siRNA) targeting CHST15 inhibited activation of fibroblasts in vitro and reduced fibrosis in vivo. Second topic is a clinically feasible application. We established a safe and novel pancolonic delivery of siRNA, which is achieved by direct injection to extracellular matrix (ECM) through endoscope. Third topic is an endpoint for both nonclinical and clinical studies. We have focused on tissue-specific findings for co-existence of fibrosis in ulcerative lesions in IBD and investigated whether the balance of mucosal healing (MH) and fibrosis, which is evaluated by endoscopy and histology respectively, can be used for study endpoints. Phase 1 clinical trial of STNM01, a synthesized CHST15 siRNA, by a single dose endoscopic submucosal injection for non-healer patients with Crohn's disease showed high rates of MH. Analyses of biopsy specimens revealed that STNM01 reduced CHST15 expression at local lesions, repressed pre-existing fibrosis and repaired the damaged crypts. Thus, blockade of multifactorial modulator CHST15 in ECM showed a potential to treat tissue remodeling and skew fibrosis toward mucosal repair. Our practice suggests that target- and tissue-specific findings-based strategy would be a key to translation in developing anti-fibrosis therapy.