3-Dimensional Pouchography: A Proof-of-Concept Study of a Novel Technique for Visualizing Ileoanal Pouch Anatomy & Morphology in Normal and Mechanical Pouch Complication Patients.

BACKGROUND: Herein, we present a proof-of-concept study of 3-dimensional (3D) pouchography using virtual and printed 3D models of ileal pouch-anal anastomosis (IPAA) in patients with normal pouches and in cases of mechanical pouch complications. MATERIALS & METHODS: We performed a retrospective, descriptive case series of a convenience sample of 10 pouch patients with or without pouch dysfunction who had CT scans appropriate for segmentation were identified from our pouch registry. The steps involved in clinician-driven automated 3D reconstruction are presented. RESULTS: Three patients who underwent CT imaging and were found to have no primary pouch pathology, and seven patients with known pouch pathology identifiable with 3D reconstruction including pouch strictures, megapouch, pouch volvulus, and twisted pouches underwent 3D virtual modeling; one normal and one twisted pouch were 3D printed. We discovered that 3D pouchography reliably identified staple lines (pouch body, anorectal circular and transverse, and tip of J), the relationship between staple lines, and variations in pouch morphology, and pouch pathology. CONCLUSIONS: Three-dimensional reconstruction of IPAA morphology is highly feasible using readily available technology. In our practice, we have found 3D pouchography to be an extremely useful adjunct to diagnose various mechanical pouch complications and improve planning for pouch salvage strategies. Given its ease of use and helpfulness in understanding the pouch structure and function, we have started to routinely integrate 3D pouchography into our clinical pouch referral practice. Further study is needed to formally assess to value of this technique to aid in the diagnosis of pouch pathology.

Systematic review: Defining, diagnosing and monitoring small bowel strictures in Crohn's disease on intestinal ultrasound.

BACKGROUND: Stricturing Crohn's disease (CD) occurs most commonly in the terminal ileum and poses a clinical problem. Cross-sectional imaging modalities such as intestinal ultrasound (IUS), computed tomography enterography (CTE), and magnetic resonance enterography (MRE) allow for assessment of the entire bowel wall and associated peri-enteric findings. Radiologic definitions of strictures have been developed for CTE and MRE; their reliability and responsiveness are being evaluated in index development programs. A comprehensive assessment strategy for strictures using IUS is needed. AIMS: To provide a detailed summary of definitions, diagnosis and monitoring of strictures on IUS as well as technical aspects of image acquisition. METHODS: We searched four databases up to 6 January 2024. Two-stage screening was done in duplicate. We assessed risk of bias using QUADAS-2. RESULTS: There were 56 studies eligible for inclusion. Definitions for strictures on IUS are heterogeneous, but the overall accuracy for diagnosis of strictures is high. The capability of IUS for characterising inflammation versus fibrosis in strictures is not accurate enough to be used in clinical practice or trials. We summarise definitions for improvement of strictures on IUS, and discuss parameters for image acquisition and standardisation. CONCLUSIONS: This systematic review is the first step for a structured program to develop a stricture IUS index for CD.

Preventing fibrosis in IBD: update on immune pathways and clinical strategies.

INTRODUCTION: Intestinal fibrosis is a common and serious complication of inflammatory bowel diseases (IBD) driving stricture formation in Crohn's disease patients and leading to submucosal damage in ulcerative colitis. Recent studies provided novel insights into the role of immune and nonimmune components in the pathogenesis of intestinal fibrosis. Those new findings may accelerate the development of anti-fibrotic treatment in IBD patients. AREAS COVERED: This review is designed to cover the recent progress in mechanistic research and therapeutic developments on intestinal fibrosis in IBD patients, including new cell clusters, cytokines, proteins, microbiota, creeping fat, and anti-fibrotic therapies. EXPERT OPINION: Due to the previously existing major obstacle of missing consensus on stricture definitions and the absence of clinical trial endpoints, testing of drugs with an anti-fibrotic mechanism is just starting in stricturing Crohn's disease (CD). A biomarker to stratify CD patients at diagnosis without any complications into at-risk populations for future strictures would be highly desirable. Further investigations are needed to identify novel mechanisms of fibrogenesis in the intestine that are targetable and ideally gut specific.

Redo IPAA for long rectal cuff syndrome after ileoanal pouch for inflammatory bowel disease.

ABTRACT: BACKGROUND: When constructing an ileal pouch-anal anastomosis (IPAA), the rectal cuff should ideally be 1-2 cm long to avoid subsequent complications. METHODS: We identified patients from our IBD center who underwent redo IPAA for a long rectal cuff. Long rectal cuff syndrome (LRCS) was defined as a symptomatic rectal cuff ≥ 4 cm. RESULTS: Forty patients met the inclusion criteria: 42.5% female, median age at redo surgery 42.5 years. The presentation was ulcerative proctitis in 77.5% of the cases and outlet obstruction in 22.5%. The index pouch was laparoscopically performed in 18 patients (45%). The median rectal cuff length was 6 cm. The pouch was repaired in 16 (40%) cases, whereas 24 (60%) required the creation of a neo-pouch. At the final pathology, the rectal cuff showed chronic active colitis in 38 (90%) cases. After a median follow-up of 34.5 (IQR 12-109) months, pouch failure occurred in 9 (22.5%) cases. The pouch survival rate was 78% at 3 years. Data on the quality of life were available for 11 (27.5%) patients at a median of 75 months after redo surgery. The median QoL score (0-1) was 0.7 (0.4-0.9). CONCLUSION: LRCS, a potentially avoidable complication, presents uniformly with symptoms of ulcerative proctitis or stricture. Redo IPAA was restorative for the majority.

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.

Fibrosis in IBD: from pathogenesis to therapeutic targets.

BACKGROUND: Intestinal fibrosis resulting in stricture formation and obstruction in Crohn's disease (CD) and increased wall stiffness leading to symptoms in ulcerative colitis (UC) is among the largest unmet needs in inflammatory bowel disease (IBD). Fibrosis is caused by a multifactorial and complex process involving immune and non-immune cells, their soluble mediators and exposure to luminal contents, such as microbiota and environmental factors. To date, no antifibrotic therapy is available. Some progress has been made in creating consensus definitions and measurements to quantify stricture morphology for clinical practice and trials, but approaches to determine the degree of fibrosis within a stricture are still lacking. OBJECTIVE: We herein describe the current state of stricture pathogenesis, measuring tools and clinical trial endpoints development. DESIGN: Data presented and discussed in this review derive from the past and recent literature and the authors' own research and experience. RESULTS AND CONCLUSIONS: Significant progress has been made in better understanding the pathogenesis of fibrosis, but additional studies and preclinical developments are needed to define specific therapeutic targets.

Preoperative Use of Multiple Advanced Therapies Is Not Associated With Endoscopic Inflammatory Pouch Diseases.

BACKGROUND: Patients with an ileal pouch-anal anastomosis (IPAA) can experience pouch inflammation postoperatively. The use of antitumor necrosis factor (anti-TNF) biologics may be associated with pouch inflammation, but limited data exist on the impact of multiple advanced therapies on development of subsequent pouch inflammation. The aim of this study was to assess for an association between preoperative use of multiple advanced therapies and risk of endoscopically detected inflammatory pouch diseases (EIPDs). METHODS: We performed a retrospective analysis of ulcerative colitis (UC) and indeterminate colitis (IBDU) patients who underwent an IPAA at a quaternary care center from January 2015 to December 2019. Patients were grouped based on number and type of preoperative drug exposures. The primary outcome was EIPD within 5 years of IPAA. RESULTS: Two hundred ninety-eight patients were included in this analysis. Most of these patients had UC (95.0%) and demonstrated pancolonic disease distribution (86.1%). The majority of patients were male (57.4%) and underwent surgery for medically refractory disease (79.2%). The overall median age at surgery was 38.6 years. Preoperatively, 68 patients were biologic/small molecule-naïve, 125 received anti-TNF agents only, and 105 received non-anti-TNF agents only or multiple classes. Ninety-one patients developed EIPD. There was no significant association between type (P = .38) or number (P = .58) of exposures and EIPD, but older individuals had a lower risk of EIPD (P = .001; hazard ratio, 0.972; 95% confidence interval, 0.956-0.989). CONCLUSION: Development of EIPD was not associated with number or type of preoperative advanced therapies.

Risankizumab Induction Therapy Achieves Early Symptom Improvements That Are Associated With Future Clinical and Endoscopic Outcomes in Crohn's Disease: Post Hoc Analysis of the ADVANCE, MOTIVATE, and FORTIFY Phase 3 Studies.

BACKGROUND AND AIMS: Crohn's disease (CD) symptoms are a main driver for impaired quality of life and fast relief is important for patient care. Stool frequency (SF) and abdominal pain score (APS) are patient reported outcomes (PROs) measuring symptom severity, which are supported as treatment targets by the STRIDE-II consensus. This post hoc analysis examined the efficacy of risankizumab (RZB), a humanised monoclonal antibody with high specificity for interleukin-23 p19, for providing early symptom relief, along with the prognostic value of early symptom relief for achieving future clinical and endoscopic endpoints. METHODS: Individual and combined measures of SF and AP at weeks 1, 2, and 3 were assessed in patients with moderate to severe CD who received 600 mg intravenous RZB or placebo (PBO) in the ADVANCE or MOTIVATE induction studies. Multivariate logistic regression was used to examine the predictiveness of early symptom improvement for clinical and endoscopic outcomes following RZB induction and maintenance. RESULTS: Higher rates of SF/APS clinical remission and enhanced clinical response were observed as early as week 1 with RZB versus PBO. A larger proportion of patients achieved clinical endpoints with RZB versus PBO, irrespective of prior bio-failure status. Early PRO improvement was associated with a greater likelihood of achieving clinical and endoscopic improvement following 12-weeks induction and 52-weeks maintenance RZB dosing. CONCLUSIONS: After the first intravenous RZB induction dose, significantly greater rates of symptom improvement versus PBO were achieved. Improvements could be observed as early as week 1 and were predictive of week 12 and 52 clinical and endoscopic improvement.

Characteristics of Interventional Trials for Patients Living With Intestinal Stoma Registered in ClinicalTrials.gov With a Focus on Inflammatory Bowel Disease.

BACKGROUND: This systematic review was performed to characterize the landscape of research conducted in patients with intestinal stoma (IS) and highlight unmet needs for clinical research in Crohn's disease (CD) and IS. METHODS: We searched ClinicalTrials.gov from inception to May 25, 2022, to identify clinical trials assessing interventions in patients with an IS, as well as those with an IS and CD. Studies were grouped according to type of intervention. We excluded observational studies with no treatment arm. RESULTS: A total of 253 studies were included in the final analysis. Most studies investigated devices (n = 122 [48.2%]), or surgical procedures (n = 63 [24.9%]), followed by behavioral interventions (n = 30 [11.8%]), drugs (n = 20 [7.9%]), dietary interventions (n = 2 [0.8%]), skin care products (n = 2 0.8%]), and others (n = 14 [5.5%]). A total of 50.9% (n = 129) of studies had completed recruitment, enrolling 11 116 participants. Only 6 studies (surgery: n = 3; physiological studies: n = 2; drugs: n = 1) exclusively included patients with inflammatory bowel disease (IBD), and 16 studies commented that patients with IBD were excluded in their eligibility criteria. No study assessed efficacy of drugs in patients with CD and IS. Approximately one-quarter of studies (n = 65 of 253) included quality of life as an outcome measure. CONCLUSION: There is a paucity of research in IBD patients with IS, with the majority focusing on devices and surgical procedures. There have been no drug trials evaluating efficacy in patients with CD and IS. There is an urgent need to identify barriers to enrollment and develop eligibility and outcome measures that enable the inclusion of patients with CD with stoma into clinical trials.

We analyzed registered trials for patients with intestinal stoma with special focus on Crohn's disease patients to explore research and unmet needs. Our results indicate a scarcity of studies in this area with most studies limited to surgical procedures and devices.

The Safety, Tolerability, Pharmacokinetics and Clinical Efficacy of the NLRX1 agonist NX-13 in Active Ulcerative Colitis: Results of a Phase 1b Study.

BACKGROUND AND AIMS: NX-13 activation of NLRX1 reduces intracellular reactive oxygen species and decreases inflammation in animal models of colitis. A phase 1a trial demonstrated a gut-selective pharmacokinetic (PK) profile with good tolerability. This phase Ib study aimed to evaluate the safety, tolerability, and PK of NX-13 in patients with active ulcerative colitis (UC). METHODS: We conducted a multicenter, randomized, double-blinded, placebo-controlled trial of NX-13 in patients with active UC. Patients with a Mayo Clinic Score of 4-10 were randomly assigned (3:3:3:1 ratio) to three NX-13 oral dose groups (250mg Immediate Release (IR), 500mg IR, or 500mg Delayed Release (DR) or placebo) once daily for 4 weeks. Safety and PK were the primary and secondary objectives, respectively. RESULTS: Thirty-eight patients (11 females) were recruited and randomized to placebo (5), NX-13 250mg IR (11), NX-13 500mg IR (11), or NX-13 500mg DR (11) and received at least one dose. There were no Serious Adverse Events (SAEs) or deaths during the trial. One patient (500mg DR, 1/11) withdrew for worsening of UC and a second (500mg IR, 1/11) on the last day of treatment after a panic attack associated with atrial fibrillation. In the efficacy population (36 patients), clinical improvement in rectal bleeding and stool frequency scores relative to placebo were seen as early as week 2 and endoscopic response was seen at week 4. CONCLUSIONS: NX-13 was generally safe and well tolerated with early signs of rapid symptom and endoscopic improvement. This novel mechanism of action warrants further investigation. ClinicalTrials.gov: NCT04862741.

Change in Biologic Class Promotes Endoscopic Remission Following Endoscopic Postoperative Crohn's Disease Recurrence.

GOALS: Assess the outcomes of various therapeutic regimens to treat initial endoscopic postoperative recurrence despite biologic prophylaxis. BACKGROUND: Postoperative biologic prophylaxis reduces postoperative Crohn's disease (CD) recurrence rates. Optimal treatment strategies for endoscopic recurrence have not been elucidated. STUDY: Retrospective cohort study of adult CD patients who underwent ileocolonic resection between 2009 and 2020. Patients with endoscopic postoperative recurrence despite prophylactic biologic therapy and ≥1 subsequent colonoscopy were included. Treatment changes after recurrence were categorized as (1) therapy optimization or continuation or (2) new biologic class. The primary outcome was composite endoscopic or surgical recurrence at the time of or prior to subsequent follow-up colonoscopy. RESULTS: Eighty-one CD patients with endoscopic recurrence (54.3% i2b, 22.2% i3, and 23.5% i4) despite biologic prophylaxis (86.4% anti-tumor necrosis factor, 8.6% vedolizumab, 4.9% ustekinumab) were included. Most patients received therapy optimization or continuation (76.3%, n=61) following recurrence compared to being started on a new biologic class. Sixty patients (N=48 therapy optimization; N=12 new biologic class) experienced composite recurrence (78.3% endoscopic, 21.7% surgical). On multivariable modeling, initiation of a new biologic class was associated with reduced risk for composite recurrence compared to therapy optimization or continuation (aOR: 0.26; P=0.04). Additionally, initiation of a new biologic class was associated with endoscopic improvement when adjusting for endoscopic severity at the time of recurrence (aOR: 3.4; P=0.05). On sensitivity analysis, a new biologic class was associated or trended with improved rates of endoscopic healing and composite recurrence when directly compared to therapy optimization or continuation. CONCLUSION: In patients with CD who experience endoscopic recurrence despite biologic prophylaxis, changing the mechanism of biologic action may promote endoscopic improvement.

Single-cell isolation from full-thickness human intestinal tissue resections for single-cell RNA sequencing.

Single-cell isolation techniques allow the investigation of physical and functional relationships between individual cells within a complex cell population. Here, we present a protocol for single-cell isolation from full-thickness intestinal tissue resections. We describe steps for pre-processing specimens, isolation of lamina propria and muscular layers, and red blood cell lysis. We then detail fixation of isolated cells and assessment of cell quality. The resulting cell suspension can be subjected to RNA sequencing on the 10× Chromium platform. For complete details on the use and execution of this protocol, please refer to Mukherjee et al.1.

Defining the Roles of Inflammatory Bowel Disease Clinical Pharmacists in the United States: A Systematic Review and National RAND/UCLA Consensus.

BACKGROUND: Given the complexity of inflammatory bowel disease (IBD) care, utilization of multidisciplinary teams is recommended to optimize outcomes. There is a growing recognition that clinical pharmacists should be an integral part of this care model. We sought to define the roles of IBD clinical pharmacists in the United States. METHODS: A national multidisciplinary expert panel of 12 gastroenterologists and clinical pharmacists practicing in IBD clinics was assembled. We used the RAND/University of California, Los Angeles appropriateness method, with a total of 281 statements generated based on a systematic literature review and expert opinion. Each statement was anonymously rated as appropriate, uncertain, or inappropriate in 2 rounds of voting. RESULTS: The number of publications evaluating the clinical pharmacists' roles in IBD is limited, primarily focusing on thiopurine initiation and monitoring, medication adherence, and switching to biosimilars. Medication education; medication initiation and monitoring; therapeutic drug monitoring; biosimilar management; health maintenance review; and transitions of care were deemed by the panel to be appropriate roles for IBD clinical pharmacists. In considering real-world settings, IBD clinical pharmacists should practice clinically under a predefined scope and primarily focus on complex treatments (eg, immunomodulators, biologics, and small molecules). Clinical pharmacists should also be included in practice settings with IBD specialized physicians. Additionally, clinical pharmacists caring for patients with IBD should be residency trained and board certified. CONCLUSIONS: This consensus defines IBD clinical pharmacists' roles and provides a framework for embedded clinical pharmacists in IBD care.

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

INTRODUCTION: Surgical management of Crohn's disease (CD) is common. Postoperative complications include anastomotic stricturing (AS). The natural history and risk factors for AS have not been elucidated. METHODS: A retrospective cohort study of patients with CD who underwent ileocolonic resection (ICR) with ≥1 postoperative ileocolonoscopy between 2009 and 2020. Postoperative ileocolonoscopies with corresponding cross-sectional imaging were evaluated for evidence of AS without neoterminal ileal extension. Severity of AS and endoscopic intervention at time of detection were collected. Primary outcome was development of AS. Secondary outcome was time to AS detection. RESULTS: A total of 602 adult patients with CD underwent ICR with postoperative ileocolonoscopy. Of these, 426 had primary anastomosis, and 136 had temporary diversion at time of ICR. Anastomotic configuration consisted of 308 side-to-side, 148 end-to-side, and 136 end-to-end. One hundred ten (18.3%) patients developed AS with median time of 3.2 years to AS detection. AS severity at time of detection was associated with need for repeat surgical resection for AS. On multivariable Cox proportional hazard regression, anastomotic configuration and temporary diversion were not associated with risk of or time to AS. Preoperative stricturing disease was associated with decreased time to AS (adjusted hazard ratio 1.8; P = 0.049). Endoscopic ileal recurrence before AS was not associated with subsequent AS detection. DISCUSSION: AS is a relatively common postoperative CD complication. Patients with previous stricturing disease behavior are at increased risk of AS. Anastomotic configuration, temporary diversion, and ileal CD recurrence do not increase risk of AS. Early detection and intervention for AS may help prevent progression to repeat ICR.

Sweet Syndrome Associated with Active Inflammatory Bowel Disease: A Case Series of a Rare Extra-intestinal Manifestation.

BACKGROUND: Cutaneous extra-intestinal manifestations (EIM) occur in up to 20% of patients with IBD. Information about Sweet syndrome (SS)'s clinical course as a rare cutaneous EIM in IBD is limited to case reports. We present the largest retrospective cohort on the occurrence and management of SS in IBD. STUDY: Electronic medical records and paper charts since 1980 were retrospectively reviewed at a large quaternary medical center to identify all adult IBD patients with histopathology-proven SS. Patient characteristics and clinical outcomes were evaluated. RESULTS: 25 IBD patients with SS were identified; 3 patients were assessed to have AZA-induced SS. The majority of SS patients were female. Median age at diagnosis was 47 years (IQR 33-54 years) and SS appeared at a median of 6.4 years after IBD diagnosis. IBD patients with SS had a high rate of complicated IBD phenotypes (75% extensive colitis in UC and 73% stricturing or penetrating disease in CD, with 100% colonic involvement), as well as frequent co-occurring EIMs (60%). SS correlated with global IBD disease activity. Corticosteroids were an effective therapy for SS in IBD. Recurrence rate of SS was 36%. CONCLUSION: Contrary to previous case reports, SS was a cutaneous EIM occurring late after diagnosis of IBD in our cohort, with occurrences paralleling global IBD disease activity. Although AZA-induced and IBD-associated SS were both effectively treated with corticosteroids, distinguishing them is relevant for future IBD treatment strategies.

Real-world effectiveness and safety of ustekinumab and vedolizumab in elderly patients with Crohn's disease.

Studies report favorable efficacy and safety profiles of ustekinumab (UST) and vedolizumab (VDZ) in Crohn's disease (CD), but effectiveness and safety data in elderly patients with CD is lacking. We retrospectively analyzed 78 elderly patients (39 each UST and VDZ) and found that patients on UST and VDZ experienced similar rates of clinical response, remission and mucosal healing despite high proportion of prior biologic exposure. Both UST and VDZ appear to be effective and safe in this at-risk CD population. Further large studies are needed to validate our findings.

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.

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.

Resolving Histological Inflammation in Ulcerative Colitis With Mirikizumab in the LUCENT Induction and Maintenance Trial Programmes.

BACKGROUND AND AIMS: To evaluate the effect of mirikizumab, a p19-targeted anti-interleukin-23, on histological and/or endoscopic outcomes in moderately-to-severely active ulcerative colitis [UC]. METHODS: Endoscopic remission [ER], histological improvement [HI], histological remission [HR], histological-endoscopic mucosal improvement [HEMI], and histological-endoscopic mucosal remission [HEMR] were assessed at Week [W]12 [LUCENT-1: N = 1162, induction] and W40 [LUCENT-2: N = 544, maintenance] for patients randomised to mirikizumab or placebo. Analyses were performed to evaluate predictors of: HEMI at W12 with mirikizumab and HEMR at W40 in patients re-randomised to subcutaneous [SC] mirikizumab; associations between W12 histological/endoscopic endpoints and W40 outcomes in mirikizumab responders re-randomised to mirikizumab SC; and associations between W40 endoscopic normalisation [EN] with/without HR. RESULTS: Significantly more patients treated with mirikizumab achieved HI, HR, ER, HEMI, and HEMR vs placebo [p <0.001], irrespective of prior biologic/tofacitinib failure [p <0.05]. Lower clinical baseline disease activity, female sex, no baseline immunomodulator use, and no prior biologic/tofacitinib failure were predictors of HEMI at W12 [p <0.05]. Corticosteroid use and longer disease duration were negative predictors of achieving HEMR at W40 [p <0.05]. W12 HI, HR, or ER was associated with W40 HEMI or HEMR [p <0.05]; ER at W12 was associated with clinical remission [CR] [p <0.05] and corticosteroid-free remission [CSFR] at W40 [p = 0.052]. HR and HEMR at W12 were associated with CSFR, CR, and symptomatic remission at W40. Alternate HEMR [EN + HR] at W40 was associated with bowel urgency remission at W40 [p <0.05]. CONCLUSIONS: Early resolution of endoscopic and histological inflammation with mirikizumab is associated with better UC outcomes. Clinicaltrials.gov: LUCENT-1, NCT03518086; LUCENT-2, NCT03524092.