A global consensus on the definitions, diagnosis and management of fibrostenosing small bowel Crohn's disease in clinical practice.

Fibrostenosis of the small bowel is common in patients with Crohn's disease. No consensus recommendations on definition, diagnosis and management in clinical practice are currently available. In this Consensus Statement, we present a clinical practice RAND/UCLA appropriateness study on the definition, diagnosis and clinical management of fibrostenosing Crohn's disease. It was conducted by a panel of 28 global experts and one patient representative. Following a systematic literature review, 526 candidate items grouped into 136 questions were generated and subsequently evaluated for appropriateness. Strictures are best defined as wall thickening, luminal narrowing and prestenotic dilation. Cross-sectional imaging is required for accurate diagnosis of fibrostenosing Crohn's disease, and it is recommended before making treatment decisions. It should also assess the degree of inflammation in the bowel wall. Multiple options for medical anti-inflammatory, endoscopic and surgical therapies were suggested, including follow-up strategies following therapy. This Consensus Statement supports clinical practice through providing guidance on definitions, diagnosis and therapeutic management of patients with fibrostenosing small bowel Crohn's disease.

MRI radiomics enhances radiologists' ability for characterizing intestinal fibrosis in patients with Crohn's disease.

OBJECTIVES: We aimed to develop MRI-based radiomic models (RMs) to improve the diagnostic accuracy of radiologists in characterizing intestinal fibrosis in patients with Crohn's disease (CD). METHODS: This retrospective study included patients with refractory CD who underwent MR before surgery from November 2013 to September 2021. Resected bowel segments were histologically classified as none-mild or moderate-severe fibrosis. RMs based on different MR sequence combinations (RM1: T2WI and enhanced-T1WI; RM2: T2WI, enhanced-T1WI, diffusion-weighted imaging [DWI], and apparent diffusion coefficient [ADC]); RM3: T2WI, enhanced-T1WI, DWI, ADC, and magnetization transfer MRI [MTI]), were developed and validated in an independent test cohort. The RMs' diagnostic performance was compared to that of visual interpretation using identical sequences and a clinical model. RESULTS: The final population included 123 patients (81 men, 42 women; mean age: 30.26 ± 7.98 years; training cohort, n = 93; test cohort, n = 30). The area under the receiver operating characteristic curve (AUC) of RM1, RM2, and RM3 was 0.86 (p = 0.001), 0.88 (p = 0.001), and 0.93 (p = 0.02), respectively. The decision curve analysis confirmed a progressive improvement in the diagnostic performance of three RMs with the addition of more specific sequences. All RMs performance surpassed the visual interpretation based on the same MR sequences (visual model 1, AUC = 0.65, p = 0.56; visual model 2, AUC = 0.63, p = 0.04; visual model 3, AUC = 0.77, p = 0.002), as well as the clinical model composed of C-reactive protein and erythrocyte sedimentation rate (AUC = 0.60, p = 0.13). CONCLUSIONS: The RMs, utilizing various combinations of conventional, DWI and MTI sequences, significantly enhance radiologists' ability to accurately characterize intestinal fibrosis in patients with CD. CRITICAL RELEVANCE STATEMENT: The utilization of MRI-based RMs significantly enhances the diagnostic accuracy of radiologists in characterizing intestinal fibrosis. KEY POINTS: MRI-based RMs can characterize CD intestinal fibrosis using conventional, diffusion, and MTI sequences. The RMs achieved AUCs of 0.86-0.93 for assessing fibrosis grade. MRI-radiomics outperformed visual interpretation for grading CD intestinal fibrosis.

Gut Dysbiosis Drives Inflammatory Bowel Disease Through the CCL4L2-VSIR Axis in Glycogen Storage Disease.

Patients with glycogen storage disease type Ib (GSD-Ib) frequently have inflammatory bowel disease (IBD). however, the underlying etiology remains unclear. Herein, this study finds that digestive symptoms are commonly observed in patients with GSD-Ib, presenting as single or multiple scattered deep round ulcers, inflammatory pseudo-polyps, obstructions, and strictures, which differ substantially from those in typical IBD. Distinct microbiota profiling and single-cell clustering of colonic mucosae in patients with GSD are conducted. Heterogeneous oral pathogenic enteric outgrowth induced by GSD is a potent inducer of gut microbiota immaturity and colonic macrophage accumulation. Specifically, a unique population of macrophages with high CCL4L2 expression is identified in response to pathogenic bacteria in the intestine. Hyper-activation of the CCL4L2-VSIR axis leads to increased expression of AGR2 and ZG16 in epithelial cells, which mediates the unique progression of IBD in GSD-Ib. Collectively, the microbiota-driven pathomechanism of IBD is demonstrated in GSD-Ib and revealed the active role of the CCL4L2-VSIR axis in the interaction between the microbiota and colonic mucosal immunity. Thus, targeting gut dysbiosis and/or the CCL4L2-VISR axis may represent a potential therapy for GSD-associated IBD.

A novel multidisciplinary machine learning approach based on clinical, imaging, colonoscopy, and pathology features for distinguishing intestinal tuberculosis from Crohn's disease.

OBJECTIVES: Differentiating intestinal tuberculosis (ITB) from Crohn's disease (CD) remains a diagnostic dilemma. Misdiagnosis carries potential grave implications. We aim to establish a multidisciplinary-based model using machine learning approach for distinguishing ITB from CD. METHODS: Eighty-two patients including 25 patients with ITB and 57 patients with CD were retrospectively recruited (54 in training cohort and 28 in testing cohort). The region of interest (ROI) for the lesion was delineated on magnetic resonance enterography (MRE) and colonoscopy images. Radiomic features were extracted by least absolute shrinkage and selection operator regression. Pathological feature was extracted automatically by deep-learning method. Clinical features were filtered by logistic regression analysis. Diagnostic performance was evaluated by receiver operating characteristic (ROC) curve and decision curve analysis (DCA). Delong's test was applied to compare the efficiency between the multidisciplinary-based model and the other four single-disciplinary-based models. RESULTS: The radiomics model based on MRE features yielded an AUC of 0.87 (95% confidence interval [CI] 0.68-0.96) on the test data set, which was similar to the clinical model (AUC, 0.90 [95% CI 0.71-0.98]) and higher than the colonoscopy radiomics model (AUC, 0.68 [95% CI 0.48-0.84]) and pathology deep-learning model (AUC, 0.70 [95% CI 0.49-0.85]). Multidisciplinary model, integrating 3 clinical, 21 MRE radiomic, 5 colonoscopy radiomic, and 4 pathology deep-learning features, could significantly improve the diagnostic performance (AUC of 0.94, 95% CI 0.78-1.00) on the bases of single-disciplinary-based models. DCA confirmed the clinical utility. CONCLUSIONS: Multidisciplinary-based model integrating clinical, MRE, colonoscopy, and pathology features was useful in distinguishing ITB from CD.

Diet-omics in the Study of Urban and Rural Crohn disease Evolution (SOURCE) cohort.

Crohn disease (CD) burden has increased with globalization/urbanization, and the rapid rise is attributed to environmental changes rather than genetic drift. The Study Of Urban and Rural CD Evolution (SOURCE, n = 380) has considered diet-omics domains simultaneously to detect complex interactions and identify potential beneficial and pathogenic factors linked with rural-urban transition and CD. We characterize exposures, diet, ileal transcriptomics, metabolomics, and microbiome in newly diagnosed CD patients and controls in rural and urban China and Israel. We show that time spent by rural residents in urban environments is linked with changes in gut microbial composition and metabolomics, which mirror those seen in CD. Ileal transcriptomics highlights personal metabolic and immune gene expression modules, that are directly linked to potential protective dietary exposures (coffee, manganese, vitamin D), fecal metabolites, and the microbiome. Bacteria-associated metabolites are primarily linked with host immune modules, whereas diet-linked metabolites are associated with host epithelial metabolic functions.

Intestinal strictures in Crohn's disease: An update from 2023.

Crohn's disease (CD) is a chronic inflammatory disease that leads to intestinal stricture in nearly 35% of cases within 10 years of initial diagnosis. The unknown pathogenesis, lack of universally accepted criteria, and absence of an effective management approach remain unconquered challenges in structuring CD. The pathogenesis of stricturing CD involves intricate interactions between factors such as immune cell dysbiosis, fibroblast activation, and microecology imbalance. New techniques such as single-cell sequencing provide a fresh perspective. Non-invasive diagnostic tools such as serum biomarkers and novel cross-sectional imaging techniques offer a precise understanding of intestinal fibrostenosis. Here, we provide a timely and comprehensive review of the worthy advancements in intestinal strictures in 2023, aiming to dispense cutting-edge information regarding fibrosis and to build a cornerstone for researchers and clinicians to make greater progress in the field of intestinal strictures.

Comparative analysis of [18F]F-FAPI PET/CT, [18F]F-FDG PET/CT and magnetization transfer MR imaging to detect intestinal fibrosis in Crohn's disease: A prospective animal model and human cohort study.

PURPOSE: Accurately and early detection of intestinal fibrosis in Crohn's disease (CD) is crucial for clinical management yet remains an unmet need. Fibroblast activation protein inhibitor (FAPI) PET/CT has emerged as a promising tool to assess fibrosis. We aimed to investigate the diagnostic capability of [18F]F-FAPI PET/CT in detecting intestinal fibrosis and compared it with[18F]F-FDG PET/CT and magnetization transfer MR imaging (MTI). METHODS: Twenty-two rats underwent TNBS treatment to simulate fibrosis development, followed by three quantitative imaging sessions within one week. Mean and maximum standardized uptake values (SUVmean and SUVmax) were calculated on[18F]F-FAPI and [18F]F-FDG PET/CT, along with normalized magnetization transfer ratio on MTI. Intestinal fibrosis was assessed pathologically, with MTI serving as imaging standard for fibrosis. The diagnostic efficacy of imaging parameters in fibrosis was compared using pathological and imaging standards. Ten patients with 34 bowel strictures were prospectively recruited to validate their diagnostic performance, using the identical imaging protocol. RESULTS: In CD patients, the accuracy of FAPI uptake (both AUCs = 0.87, both P ≤ 0.01) in distinguishing non-to-mild from moderate-to-severe fibrosis was higher than FDG uptake (both AUCs = 0.82, P ≤ 0.01) and comparable to MTI (AUCs = 0.90, P ≤ 0.001). In rats, FAPI uptake responded earlier to fibrosis development than FDG and MTI; consistently, during early phase, FAPI uptake showed a stronger correlation (SUVmean: R = 0.69) with pathological fibrosis than FDG (SUVmean: R = 0.17) and MTI (R = 0.52). CONCLUSION: The diagnostic efficacy of [18F]F-FAPI PET/CT in detecting CD fibrosis is superior to [18F]F-FDG PET/CT and comparable to MTI, exhibiting great potential for early detection of intestinal fibrosis.

Deep learning model to differentiate Crohn's disease from intestinal tuberculosis using histopathological whole slide images from intestinal specimens.

Crohn's disease (CD) and intestinal tuberculosis (ITB) share similar histopathological characteristics, and differential diagnosis can be a dilemma for pathologists. This study aimed to apply deep learning (DL) to analyze whole slide images (WSI) of surgical resection specimens to distinguish CD from ITB. Overall, 1973 WSI from 85 cases from 3 centers were obtained. The DL model was established in internal training and validated in external test cohort, evaluated by area under receiver operator characteristic curve (AUC). Diagnostic results of pathologists were compared with those of the DL model using DeLong's test. DL model had case level AUC of 0.886, 0.893 and slide level AUC of 0.954, 0.827 in training and test cohorts. Attention maps highlighted discriminative areas and top 10 features were extracted from CD and ITB. DL model's diagnostic efficiency (AUC = 0.886) was better than junior pathologists (*1 AUC = 0.701, P = 0.088; *2 AUC = 0.861, P = 0.788) and inferior to senior GI pathologists (*3 AUC = 0.910, P = 0.800; *4 AUC = 0.946, P = 0.507) in training cohort. In the test cohort, model (AUC = 0.893) outperformed senior non-GI pathologists (*5 AUC = 0.782, P = 0.327; *6 AUC = 0.821, P = 0.516). We developed a DL model for the classification of CD and ITB, improving pathological diagnosis accuracy effectively.

Milk fat globule-epidermal growth factor 8 (MFGE8) prevents intestinal fibrosis.

OBJECTIVE: Intestinal fibrosis is considered an inevitable consequence of chronic IBD, leading to stricture formation and need for surgery. During the process of fibrogenesis, extracellular matrix (ECM) components critically regulate the function of mesenchymal cells. We characterised the composition and function of ECM in fibrostenosing Crohn's disease (CD) and control tissues. DESIGN: Decellularised full-thickness intestinal tissue platforms were tested using three different protocols, and ECM composition in different tissue phenotypes was explored by proteomics and validated by quantitative PCR (qPCR) and immunohistochemistry. Primary human intestinal myofibroblasts (HIMFs) treated with milk fat globule-epidermal growth factor 8 (MFGE8) were evaluated regarding the mechanism of their antifibrotic response, and the action of MFGE8 was tested in two experimental intestinal fibrosis models. RESULTS: We established and validated an optimal decellularisation protocol for intestinal IBD tissues. Matrisome analysis revealed elevated MFGE8 expression in CD strictured (CDs) tissue, which was confirmed at the mRNA and protein levels. Treatment with MFGE8 inhibited ECM production in normal control HIMF but not CDs HIMF. Next-generation sequencing uncovered functionally relevant integrin-mediated signalling pathways, and blockade of integrin αvß5 and focal adhesion kinase rendered HIMF non-responsive to MFGE8. MFGE8 prevented and reversed experimental intestinal fibrosis in vitro and in vivo. CONCLUSION: MFGE8 displays antifibrotic effects, and its administration may represent a future approach for prevention of IBD-induced intestinal strictures.

CT-based radiomics signature of visceral adipose tissue and bowel lesions for identifying patients with Crohn's disease resistant to infliximab.

PURPOSE: To develop a CT-based radiomics model combining with VAT and bowel features to improve the predictive efficacy of IFX therapy on the basis of bowel model. METHODS: This retrospective study included 231 CD patients (training cohort, n = 112; internal validation cohort, n = 48; external validation cohort, n = 71) from two tertiary centers. Machine-learning VAT model and bowel model were developed separately to identify CD patients with primary nonresponse to IFX. A comprehensive model incorporating VAT and bowel radiomics features was further established to verify whether CT features extracted from VAT would improve the predictive efficacy of bowel model. Area under the curve (AUC) and decision curve analysis were used to compare the prediction performance. Clinical utility was assessed by integrated differentiation improvement (IDI). RESULTS: VAT model and bowel model exhibited comparable performance for identifying patients with primary nonresponse in both internal (AUC: VAT model vs bowel model, 0.737 (95% CI, 0.590-0.854) vs. 0.832 (95% CI, 0.750-0.896)) and external validation cohort [AUC: VAT model vs. bowel model, 0.714 (95% CI, 0.595-0.815) vs. 0.799 (95% CI, 0.687-0.885)), exhibiting a relatively good net benefit. The comprehensive model incorporating VAT into bowel model yielded a satisfactory predictive efficacy in both internal (AUC, 0.840 (95% CI, 0.706-0.930)) and external validation cohort (AUC, 0.833 (95% CI, 0.726-0.911)), significantly better than bowel alone (IDI = 4.2% and 3.7% in internal and external validation cohorts, both p < 0.05). CONCLUSION: VAT has an effect on IFX treatment response. It improves the performance for identification of CD patients at high risk of primary nonresponse to IFX therapy with selected features from RM. CRITICAL RELEVANCE STATEMENT: Our radiomics model (RM) for VAT-bowel analysis captured the pathophysiological changes occurring in VAT and whole bowel lesion, which could help to identify CD patients who would not response to infliximab at the beginning of therapy. KEY POINTS: • Radiomics signatures with VAT and bowel alone or in combination predicting infliximab efficacy. • VAT features contribute to the prediction of IFX treatment efficacy. • Comprehensive model improved the performance compared with the bowel model alone.

Bowel Stiffness Assessed by Shear-Wave Ultrasound Elastography Predicts Disease Behavior Progression in Patients With Crohn's Disease.

INTRODUCTION: There is a lack of reliable predictors of disease behavior progression in patients with Crohn's disease (CD). Real-time shear-wave elastography (SWE) is a novel method for evaluating tissue stiffness. However, its value for assessing CD has not yet been investigated. We aimed to explore the value of SWE and other ultrasound parameters at diagnosis in predicting CD behavior progression. METHODS: We retrospectively collected data from patients with CD with the nonstenotic nonpenetrating disease (B1 phenotype based on the Montreal classification). All patients underwent intestinal ultrasound at baseline and were followed up. The end point was defined as disease behavior progression to stricturing (B2) or penetrating (B3) disease. Cox regression analysis was performed for the association between baseline characteristics and subsequent end points. In addition, a multivariate nomogram was established to predict the risk of disease behavior progression quantitatively. RESULTS: A total of 130 patients with CD with B1 phenotype were enrolled. Twenty-seven patients (20.8%) developed B2 or B3 disease, with a median follow-up of 33 months. Multivariate analysis identified that SWE was the only independent predictor of disease behavior progression (hazard ratio 1.08, 95% confidence interval 1.03-1.12, P = 0.001). A reverse of the HR appeared at the cutoff 12.75 kPa. The nomogram incorporating SWE and other clinical characteristics showed a good prediction performance (area under the curve = 0.792). DISCUSSION: Intestinal stiffness assessed using SWE is an independent predictor of disease behavior progression in patients with CD. Patients with CD with SWE >12.75 kPa at diagnosis are prone to progress toward stricturing or penetrating diseases.

Validation of disease severity index for predicting complicated disease in Crohn's disease: A comparison study with Lémann index.

BACKGROUND: Disease Severity Index (DSI) provides comprehensive assessment of bowel damage (BD). AIMS: To evaluate DSI in patients with Crohn's disease (CD) at high risk of disease progression, compared to Lémann Index (LI). METHODS: Patients with CD in our center were reviewed consecutively between 2017 and 2019. DSI, LI, and complicated CD course were analyzed. RESULTS: The median LI and DSI of included 300 patients were 1.63 (IQR 1.25-3.13) and 42 (IQR 32-51), respectively. 152 patients (50.7%) experienced a complicated disease course (median 5.1 months; IQR 1.1-20.2). DSI (AUC 0.66; 95% CI 0.60-0.72) better predicted a complicated course of CD over LI (AUC 0.56; 95% CI 0.50-0.63; P = 0.007). The cumulative probability of complicated CD course in severe patients was higher than those with 'mild CD' (P < 0.001). The Cox analysis identified DSI>43 (HR 2.18; 95% CI 1.54-3.09; P < 0.001), B2/3 vs. B1 (HR 2.80; 95% CI 1.99-3.94; P < 0.001), and a higher level of CRP (HR 1.01; 95% CI 1.00-1.02; P = 0.005) as independent prognostic factors for complicated CD. However, LI was not associated with complicated CD (P = 0.164). CONCLUSIONS: Higher DSI was associated with complicated disease outcomes. DSI might play a better role than LI in identifying patients at high risks of disease progression.

Serum 25-hydroxyvitamin D, type 2 diabetes, and liver-related outcomes: Secondary data analysis of a prospective recruited cohort.

BACKGROUND: The association of vitamin D deficiency, which is prevalent in type 2 diabetes mellitus (T2DM), with liver disease and related mortality has not been quantified. Our study aimed to (1) investigate whether there is a synergistic association of vitamin D deficiency and T2DM with liver-related outcomes and (2) explore whether high 25-hydroxyvitamin D [25(OH)D] concentrations are associated with a lower risk of liver-related outcomes in T2DM. METHOD: Leveraging the data from UK Biobank, we conducted 2 studies: study I assessed the joint associations of vitamin D deficiency [25(OH)D <50 nmol/L] and T2DM with liver-related outcomes among 439,276 participants, and study II explored the associations of vitamin D status with liver-related outcomes among 21,519 individuals with T2DM. Baseline T2DM was identified through medication, laboratory test, and electronic health-related records. Serum 25(OH)D was measured by direct competitive chemiluminescent immunoassay. Liver-related outcomes included 6 liver disease end points and mortality by overall liver disease, chronic liver disease, and severe liver disease. RESULTS: During an average follow-up duration of 11.6 years, we observed a significant positive additive interaction effect (all synergy index>1.0) of T2DM and vitamin D deficiency on the risk of liver-related outcomes. Compared with participants without either T2DM or vitamin D deficiency, the multivariable-adjusted HRs of overall liver diseases were 1.29 for participants without T2DM but with vitamin D deficiency, 1.73 for participants with T2DM but without vitamin D deficiency, and 2.19 for participants with both T2DM and vitamin D deficiency. In individuals with T2DM, we observed that participants without vitamin D deficiency were inversely associated with incident liver disease and related mortality (multivariable-adjusted HRs 0.41-0.81) when compared with individuals with vitamin D deficiency. CONCLUSIONS: There are positive synergistic associations of vitamin D deficiency and T2DM with liver-related outcomes. Inverse associations between serum 25(OH)D concentrations and liver-related outcomes were observed in individuals with T2DM.

A nomogram incorporating ileal and anastomotic lesions separately to predict the long-term outcome of Crohn's disease after ileocolonic resection.

Background: The Rutgeerts score (RS) is widely used to predict postoperative recurrence after ileocolonic resection for Crohn's disease (CD) based on the severity of lesions at the neoterminal ileum and anastomosis (RS i0-i4). However, the value of anastomotic ulcers remains controversial. Objectives: Our aim was to establish a nomogram model incorporating ileal and anastomotic lesions separately to predict the long-term outcomes of CD after ileal or ileocolonic resection. Design: A total of 136 patients with CD were included in this retrospective cohort study. Methods: Consecutive CD patients who underwent ileal or ileocolonic resections with postoperative ileocolonoscopy evaluation within 1 year after the surgery were included. The primary endpoint was postoperative clinical relapse (CR). An endoscopic classification separating ileal and anastomotic lesions was applied (Ix for neoterminal ileum lesions; Ax for anastomotic lesions). A nomogram was constructed to predict CR. The performance of the model was evaluated by the receiver-operating characteristic (ROC) curve and decision curve analysis (DCA). Results: CR was observed in 47.1% (n = 64) of patients within a median follow-up of 26.9 (interquartile range, 11.4-55.2) months. The risk of CR was significantly higher in patients with an RS ⩾ i2 assessed by the first postoperative endoscopy compared with patients with an RS ⩽ i1 (p < 0.001). Moreover, the cumulative rate of CR was significantly higher in patients with ileal lesions (I1-4) compared with patients without (I0) (p < 0.001). Besides, patients with anastomotic lesions (A1-3) had significantly higher rates of CR than patients without (A0) (p = 0.002). A nomogram, incorporating scores of postoperative ileal or anastomotic lesions, sex, L2-subtype and perianal disease, was established. The DCA analysis indicated that the nomogram had a higher benefit for CR, especially at the timeframe of 24-60 months after index endoscopy, compared to the traditional RS score. Conclusion: A nomogram incorporating postoperative ileal and anastomotic lesions separately was developed to predict CR in CD patients, which may serve as a practical tool to identify high-risk patients who need timely postoperative intervention.

Stricturing Crohn's Disease Single-Cell RNA Sequencing Reveals Fibroblast Heterogeneity and Intercellular Interactions.

BACKGROUND & AIMS: Fibroblasts play a key role in stricture formation in Crohn's disease (CD) but understanding its pathogenesis requires a systems-level investigation to uncover new treatment targets. We studied full-thickness CD tissues to characterize fibroblast heterogeneity and function by generating the first single-cell RNA sequencing (scRNAseq) atlas of strictured bowel and providing proof of principle for therapeutic target validation. METHODS: We performed scRNAseq of 13 fresh full-thickness CD resections containing noninvolved, inflamed nonstrictured, and strictured segments as well as 7 normal non-CD bowel segments. Each segment was separated into mucosa/submucosa or muscularis propria and analyzed separately for a total of 99 tissue samples and 409,001 cells. We validated cadherin-11 (CDH11) as a potential therapeutic target by using whole tissues, isolated intestinal cells, NanoString nCounter, next-generation sequencing, proteomics, and animal models. RESULTS: Our integrated dataset revealed fibroblast heterogeneity in strictured CD with the majority of stricture-selective changes detected in the mucosa/submucosa, but not the muscle layer. Cell-cell interaction modeling revealed CXCL14+ as well as MMP/WNT5A+ fibroblasts displaying a central signaling role in CD strictures. CDH11, a fibroblast cell-cell adhesion molecule, was broadly expressed and up-regulated, and its profibrotic function was validated using NanoString nCounter, RNA sequencing, tissue target expression, in vitro gain- and loss-of-function experiments, proteomics, and knock-out and antibody-mediated CDH11 blockade in experimental colitis. CONCLUSIONS: A full-thickness bowel scRNAseq atlas revealed previously unrecognized fibroblast heterogeneity and interactions in CD strictures and CDH11 was validated as a potential therapeutic target. These results provide a new resource for a better understanding of CD stricture formation and open potential therapeutic developments. This work has been posted as a preprint on Biorxiv under doi: 10.1101/2023.04.03.534781.

Gut Microbiome-Generated Phenylacetylglutamine from Dietary Protein is Associated with Crohn's Disease and Exacerbates Colitis in Mouse Model Possibly via Platelet Activation.

OBJECTIVES: Our aims were to better understand the interplay of diet and gut microbiota in Crohn's disease [CD], taking advantage of a new-onset treatment-naïve CD cohort. We focus on phenylacetylglutamine [PAGln], a diet-derived meta-organismal prothrombotic metabolite. DESIGN: We collected faecal and serum samples from a CD cohort [n = 136] and healthy controls [n = 126] prior to treatment, and quantified serum PAGln using LC-MS/MS. Diet was assessed using food-frequency questionnaires. Mice [C57BL/6] were fed high/low-protein diets and administered dextran sodium sulphate [DSS] to examine plasma PAGly, thrombosis potential, and colitis severity. PAGly or saline was administered to DSS-induced colitis mice, and colitis severity and colonic tissue gene expression were examined. P-selectin and CD40L expression were determined in human platelet-rich plasma [n = 5-6] after exposure to platelet agonists following PAGln priming. Bioinformatic analysis and bacterial culturing identified the main contributor of PAGln in CD. RESULTS: PAGln, a meta-organismal prothrombotic metabolite, is associated with CD. Administration of PAGly exacerbated colitis in a mouse model and upregulated coagulation-related biological processes. Antiplatelet medicine, dipyridamole, attenuated PAGly-enhanced colitis susceptibility. PAGln enhanced platelet activation and CD40L expression in platelet-rich plasma ex vivo. Further study revealed that high dietary protein intake and increased abundance of phenylacetic acid [PAA]-producing Proteobacteria mediated by phenylpyruvate decarboxylase act in concert to cause the elevated PAGln levels in CD patients. CONCLUSION: Taken together, ppdc-carrying Proteobacteria-generated PAGln from dietary protein is associated with CD and exacerbates colitis possibly via platelet-induced coagulation and inflammation These results suggest that PAGln is a potential early diagnostic marker and therapeutic target of CD.

Early transmural healing and its predictors assessed by magnetic resonance enterography in patients with Crohn's disease receiving ustekinumab.

Background: Transmural healing (TH) is a potential therapeutic goal of Crohn's disease (CD) and is associated with better clinical outcomes. However, few studies have described early TH and its predictors. Objectives: We aimed to evaluate early TH and its predictors using magnetic resonance enterography (MRE) in patients with CD receiving ustekinumab (UST). Design: This was a retrospective observational study. Methods: Patients with active CD treated with UST and their intestinal segments with bowel wall thickness (BWT) ⩽ 3 mm at baseline were included. Clinical characteristics, laboratory indicators, endoscopic manifestations, and MRE indices were evaluated at baseline and week 26 (W26) of the therapy. The following MRE parameters were assessed: BWT, edema, apparent diffusion coefficient (ADC), Clermont score, Magnetic Resonance Index of Activity score, fat stranding, comb sign, and stricture. TH was defined as BWT ⩽ 3 mm without any signs of inflammation (i.e., ulceration, edema, diffusion-weighted hyperintensity, and increased contrast enhancement) at W26. Results: The study included 37 patients with 106 intestinal segments (including 15 proximal small intestines, 33 terminal ilea, and 58 colons). Clinical features, laboratory indicators, endoscopic results, and MRE parameters at W26 were significantly improved after UST treatment in both patient-based and intestinal segment-based analysis. Seven (18.9%) patients and 26 (24.5%) intestinal segments achieved TH at W26. Baseline BWT [odds ratio (OR) = 0.287, 95% confidence interval (CI), 0.090-0.918, p = 0.035] and ADC (OR = 2.997, 95% CI, 1.009-8.908, p = 0.048) predict TH of patients at W26. Baseline ADC (OR = 2.857, 95% CI, 1.285-6.349, p = 0.010) and presence of stenosis (OR = 0.196, 95% CI, 0.052-0.735, p = 0.016) were associated with TH of segments at W26. Conclusion: Early TH assessed by MRE was observed in nearly one-fifth of patients with CD and intestinal segments after UST treatment for 26 weeks. Baseline MRE indices such as BWT and presence of stenosis might negatively predict TH, while ADC might positively predict early TH.

Clinical outcome is distinct between radiological stricture and endoscopic stricture in ileal Crohn's disease.

OBJECTIVES: Differences in clinical adverse outcomes (CAO) based on different intestinal stricturing definitions in Crohn's disease (CD) are poorly documented. This study aims to compare CAO between radiological strictures (RS) and endoscopic strictures (ES) in ileal CD and explore the significance of upstream dilatation in RS. METHODS: This retrospective double-center study included 199 patients (derivation cohort, n = 157; validation cohort, n = 42) with bowel strictures who simultaneously underwent endoscopic and radiologic examinations. RS was defined as a luminal narrowing with wall thickening relative to the normal gut on cross-sectional imaging (group 1 (G1)), which further divided into G1a (without upstream dilatation) and G1b (with upstream dilatation). ES was defined as an endoscopic non-passable stricture (group 2 (G2)). Strictures met the definitions of RS (with or without upstream dilatation) and ES were categorized as group 3 (G3). CAO referred to stricture-related surgery or penetrating disease. RESULTS: In the derivation cohort, G1b (93.3%) had the highest CAO occurrence rate, followed by G3 (32.6%), G1a (3.2%), and G2 (0%) (p < 0.0001); the same order was found in the validation cohort. The CAO-free survival time was significantly different among the four groups (p < 0.0001). Upstream dilatation (hazard ratio, 1.126) was a risk factor for predicting CAO in RS. Furthermore, when upstream dilatation was added to diagnose RS, 17.6% of high-risk strictures were neglected. CONCLUSIONS: CAO differs significantly between RS and ES, and clinicians should pay more attention to strictures in G1b and G3. Upstream dilatation has an important impact on the clinical outcome of RS but may not be an essential factor for RS diagnosis. CLINICAL RELEVANCE STATEMENT: This study explored the definition of intestinal stricture with the greatest significance for the clinical diagnosis and prognosis of patients with CD, and consequently provided effective auxiliary information for clinicians to formulate strategies for the treatment of CD intestinal strictures. KEY POINTS: • The retrospective double-center study showed that clinical adverse outcome is different between radiological strictures and endoscopic strictures in CD. • Upstream dilatation has an important impact on the clinical outcome of radiological strictures but may not be an essential factor for diagnosis of radiological strictures. • Radiological stricture with upstream dilatation and simultaneous radiological and endoscopic stricture were at increased risk for clinical adverse outcomes; thus, closer monitoring should be considered.

Stricturing Crohn's disease single-cell RNA sequencing reveals fibroblast heterogeneity and intercellular interactions.

Background: Fibroblasts play a key role in stricture formation in Crohn's disease (CD) but understanding it's pathogenesis requires a systems-level investigation to uncover new treatment targets. We studied full thickness CD tissues to characterize fibroblast heterogeneity and function by generating the first single cell RNA sequencing (scRNAseq) atlas of strictured bowel and providing proof of principle for therapeutic target validation. Methods: We performed scRNAseq of 13 fresh full thickness CD resections containing non-involved, inflamed non-strictured, and strictured segments as well as 7 normal non-CD bowel segments. Each segment was separated into mucosa/submucosa or muscularis propria and analyzed separately for a total of 99 tissue samples and 409,001 cells. We validated cadherin-11 (CDH11) as a potential therapeutic target by using whole tissues, isolated intestinal cells, NanoString nCounter, next generation sequencing, proteomics and animal models. Results: Our integrated dataset revealed fibroblast heterogeneity in strictured CD with the majority of stricture-selective changes detected in the mucosa/submucosa, but not the muscle layer. Cell-cell interaction modeling revealed CXCL14+ as well as MMP/WNT5A+ fibroblasts displaying a central signaling role in CD strictures. CDH11, a fibroblast cell-cell adhesion molecule, was broadly expressed and upregulated, and its pro-fibrotic function was validated by NanoString nCounter, RNA sequencing, tissue target expression, in vitro gain- and loss-of-function experiments, proteomics, and two animal models of experimental colitis. Conclusion: A full-thickness bowel scRNAseq atlas revealed previously unrecognized fibroblast heterogeneity and interactions in CD strictures and CDH11 was validated as a potential therapeutic target. These results provide a new resource for a better understanding of CD stricture formation and opens potential therapeutic developments.