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Background and Aims: Non-invasive cross-sectional imaging via magnetic resonance enterography [MRE] offers excellent accuracy for the diagnosis of stricturing complications in Crohn's disease [CD] but is limited in determining the degrees of fibrosis and inflammation within a stricture. We developed and validated a radiomics-based machine-learning model for separately characterizing the degree of histopathological inflammation and fibrosis in CD strictures and compared it to centrally read visual radiologist scoring of MRE., Methods: This single-centre, cross-sectional study included 51 CD patients [n = 34 for discovery; n = 17 for validation] with terminal ileal strictures confirmed on diagnostic MRE within 15 weeks of resection. Histopathological specimens were scored for inflammation and fibrosis and spatially linked with corresponding pre-surgical MRE sequences. Annotated stricture regions on MRE were scored visually by radiologists as well as underwent 3D radiomics-based machine learning analysis; both were evaluated against histopathology., Results: Two distinct sets of radiomic features capturing textural heterogeneity within strictures were linked with each of severe inflammation or severe fibrosis across both the discovery (area under the curve [AUC = 0.69, 0.83] and validation [AUC = 0.67, 0.78] cohorts. Radiologist visual scoring had an AUC = 0.67 for identifying severe inflammation and AUC = 0.35 for severe fibrosis. Use of combined radiomics and radiologist scoring robustly augmented identification of severe inflammation [AUC = 0.79] and modestly improved assessment of severe fibrosis [AUC = 0.79 for severe fibrosis] over individual approaches., Conclusions: Radiomic features of CD strictures on MRE can accurately identify severe histopathological inflammation and severe histopathological fibrosis, as well as augment performance of the radiologist visual scoring in stricture characterization., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Introduction: As hospitals strive to reduce their environmental footprint, there is an ongoing debate over the environmental implications of reusable versus disposable linens in operating rooms (ORs). This research aimed to compare the environmental impact of reusable versus single-use OR bed covers and lift sheets using life cycle assessment (LCA) methodology., Methods: LCA is an established tool with rigorous methodology that uses science-based processes to measure environmental impact. This study compared the impacts of three independent system scenarios at a single large academic hospital: reusable bed covers with 50 laundry cycles and subsequent landfill disposal (System 1), single-use bed covers with waste landfill disposal (System 2), and single-use bed covers with waste disposal using incineration (System 3)., Results: The total carbon footprint of System 1 for 50 uses was 19.83 ​kg carbon dioxide equivalents (CO 2 -eq). System 2 generated 64.99 ​kg CO 2 -eq. For System 3, the total carbon footprint was 108.98 ​kg CO 2 -eq. The raw material extraction for all the material to produce an equivalent 50 single-use OR bed cover kits was tenfold more carbon-intensive than the reusable bed cover. Laundering one reusable OR bed cover 50 times was more carbon intensive (12.12 ​kg CO2-eq) than landfill disposal of 50 single-use OR bed covers (2.52 ​kg CO2-eq)., Discussion: Our analysis demonstrates that one reusable fabric-based OR bed cover laundered 50 times, despite the carbon and water-intensive laundering process, exhibits a markedly lower carbon footprint than its single-use counterparts. The net difference is 45.16 ​kg CO2-eq, equivalent to driving 115 miles in an average gasoline-powered passenger vehicle. This stark contrast underscores the efficacy of adopting reusable solutions to mitigate environmental impact within healthcare facilities., Competing Interests: Declaration of competing interest The authors have no financial disclosures nor conflicts of interest to report., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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., (© 2024. Springer Nature Limited.)

Objective: Since the inception of Ken Lee Memorial Fellowship (KLMF) in 2013, our institution has achieved 10 years of trainee led sustainability projects. The ability of health care organizations to drive sustainability depends on organizational and human capacity. This qualitative study presents the first decade of sustainability fellows' projects, the challenges associated with implementing them, and the environmental and cost impact of these initiatives., Design, Setting, Participants: All residents in the General Surgery residency program at the Cleveland Clinic, a quaternary hospital, regardless of postgraduate year (PGY) level, are invited to apply for the KLMF program with a short project proposal. One fellow is selected per year. Each project since the program's inception was reviewed qualitatively, relying on data derived from observation, interview of prior fellows, and supervising staff, and analysis of documentation from the annual fellow presentation and abstract, Grand Rounds recording, and fellowship leadership., Results: A targeted approach by each sustainability fellow is encouraged, with the following action cycle for change implementation throughout the 1-year fellowship: identification and discovery of an issue, collaborative planning of an intervention, implementation of the intervention, and evaluation. Projects range from water and waste reduction to education of surgical staff, with positive implications for environmental stewardship in our hospital. However, multiple barriers to completing, scaling, and maintaining sustainability initiatives remain, as demonstrated by challenges faced by our Ken Lee Fellows., Conclusions: Our goal is that this intensive educational experience within the framework of a graduate medical education curriculum will ensure future generations of surgeons who are thoughtful leaders in environmental stewardship., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

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 αvβ5 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., Competing Interests: Competing interests: The Cleveland Clinic receives funds on her behalf from Celgene, Morphic, Pfizer, UCB, GB004 and Helmsley. SDH was consultant to Shionogi, Takeda and Guidepoint and receives research funding from the Crohn’s and Colitis Foundation and the American Society of Colon and Rectal Surgeons. CF receives speaker fees from UCB, Genentech, Sandoz and Janssen, and he is the consultant of Athos Therapeutics, Inc. FR is the consultant of Agomab, Allergan, AbbVie, Boehringer-Ingelheim, Celgene, Cowen, Genentech, Gilead, Gossamer, Guidepoint, Helmsley, Index Pharma, Jansen, Koutif, Metacrine, Morphic, Pfizer, Pliant, Prometheus Biosciences, Receptos, RedX, Roche, Samsung, Takeda, Techlab, Thetis, UCB and 89Bio., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Histological assessment of endoscopic biopsies in inflammatory bowel disease [IBD] plays an important role in clinical management, investigative studies, and clinical trials. Scoring schemes consisting of multiple histological items and offering considerable precision are widely available. However, definitions of histological abnormalities are often inconsistent. Furthermore, interobserver variability for their recognition and assessment may be high. The European Crohn's and Colitis Organisation [ECCO] formed an expert panel to explore definitions of histological abnormalities in IBD, with the aim of improving the quality of diagnosis and facilitating development of scoring schemes. The process confirmed that the current definitions often have no evidence base and vary between sources. Using available evidence and expert knowledge, the panel produced a series of ECCO consensus position statements on histological features in IBD., (© The Author(s) 2023. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation.)

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 ., Competing Interests: Declaration of interests I.O.G. received funding from UCB, Celgene, Gossamer, and Pliant. S.M.C. and K.M.K. are employees of Pfizer, Inc. and may hold stock equity. C.F. received speaker fees from UCB, Genentech, Sandoz, and Janssen and is a consultant for Athos Therapeutics, Inc. F.R. was a consultant to AbbVie, Adnovate, Agomab, Allergan, Arena, AstraZeneca, Boehringer-Ingelheim, Celgene/BMS, CDISC, Celsius, Cowen, Ferring, Galapagos, Galmed, Genentech, Gilead, Gossamer, Granite, Guidepoint, Helmsley, Horizon Therapeutics, Image Analysis Limited, Index Pharma, Landos, Jannsen, Koutif, Mestag, Metacrine, Mopac, Morphic, Organovo, Origo, Pfizer, Inc., Pliant, Prometheus Biosciences, Receptos, RedX, Roche, Samsung, Sanofi, Surmodics, Surrozen, Takeda, Techlab, Teva, Theravance, Thetis, UCB, Ysios, and 89bio., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Competing Interests: The authors report no conflicts of interest.

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., (Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Reducing low-value clinical care is an important strategy to mitigate environmental pollution caused by health care., Objective: To estimate the environmental impacts associated with prostate magnetic resonance imaging (MRI) and prostate biopsy., Design, Setting, and Participants: We performed a cradle-to-grave life cycle assessment of prostate biopsy. Data included materials and energy inventory, patient and staff travel contributed by prostate MRI, transrectal ultrasound guided prostate biopsy, and pathology analysis. We compared environmental emissions across five clinical scenarios: multiparametric MRI (mpMRI) of the prostate with targeted and systematic biopsies (baseline), mpMRI with targeted biopsy cores only, systematic biopsy without MRI, mpMRI with systematic biopsy, and biparametric MRI (bpMRI) with targeted and systematic biopsies. We estimated the environmental impacts associated with reducing the overall number and varying the approach of a prostate biopsy by using MRI as a triage strategy or by omitting MRI. The study involved academic medical centers in the USA, outpatient urology clinics, health care facilities, medical staff, and patients., Outcome Measurements and Statistical Analysis: Greenhouse gas emissions (CO 2 equivalents, CO 2 e), and equivalents of coal and gasoline burned were measured., Results and Limitations: In the USA, a single transrectal prostate biopsy procedure including prostate MRI, and targeted and systematic biopsies emits an estimated 80.7 kg CO 2 e. An approach of MRI targeted cores alone without a systematic biopsy generated 76.2 kg CO 2 e, a systematic 12-core biopsy without mpMRI generated 36.2 kg CO 2 e, and bpMRI with targeted and systematic biopsies generated 70.5 kg CO 2 e; mpMRI alone contributed 42.7 kg CO 2 e (54.3% of baseline scenario). Energy was the largest contributor, with an estimated 38.1 kg CO 2 e, followed by staff travel (20.7 kg CO 2 e) and supply production (11.4 kg CO 2 e). Performing 100 000 fewer unnecessary biopsies would avoid 8.1 million kg CO 2 e, the equivalent of 4.1 million liters of gasoline consumed. Per 100 000 patients, the use of prostate MRI to triage prostate biopsy and guide targeted biopsy cores would save the equivalent of 1.4 million kg of CO 2 emissions, the equivalent of 700 000 l of gasoline consumed. This analysis was limited to prostate MRI and biopsy, and does not account for downstream clinical management., Conclusions: A prostate biopsy contributes a calculable environmental footprint. Modifying or reducing the number of biopsies performed through existing evidence-based approaches would decrease health care pollution from the procedure., Patient Summary: We estimated that prostate magnetic resonance imaging (MRI) with a prostate biopsy procedure emits the equivalent of 80.7 kg of carbon dioxide. Performing fewer unnecessary prostate biopsies or using prostate MRI as a tool to decide which patients should have a prostate biopsy would reduce procedural greenhouse gas emissions and health care pollution., (Copyright © 2022 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Healthcare generates large amounts of waste, harming both environmental and human health. Waste audits are the standard method for measuring and characterizing waste. This is a systematic review of healthcare waste audits, describing their methods and informing more standardized auditing and reporting. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched MEDLINE, Embase, Inspec, Scopus and Web of Science Core Collection databases for published studies involving direct measurement of waste in medical facilities. We screened 2398 studies, identifying 156 studies for inclusion from 37 countries. Most were conducted to improve local waste sorting policies or practices, with fewer to inform policy development, increase waste diversion or reduce costs. Measurement was quantified mostly by weighing waste, with many also counting items or using interviews or surveys to compile data. Studies spanned single procedures, departments and hospitals, and multiple hospitals or health systems. Waste categories varied, with most including municipal solid waste or biohazardous waste, and others including sharps, recycling and other wastes. There were significant differences in methods and results between high- and low-income countries. The number of healthcare waste audits published has been increasing, with variable quality and general methodologic inconsistency. A greater emphasis on consistent performance and reporting standards would improve the quality, comparability and usefulness of healthcare waste audits.

Strictures in Crohn's disease (CD) are a hallmark of long-standing intestinal damage, brought about by inflammatory and non-inflammatory pathways. Understanding the complex pathophysiology related to inflammatory infiltrates, extracellular matrix deposition, as well as muscular hyperplasia is crucial to produce high-quality scoring indices for assessing CD strictures. In addition, cross-sectional imaging modalities are the primary tool for diagnosis and follow-up of strictures, especially with the initiation of anti-fibrotic therapy clinical trials. This in turn requires such modalities to both diagnose strictures with high accuracy, as well as be able to delineate the impact of each histomorphologic component on the individual stricture. We discuss the current knowledge on cross-sectional imaging modalities used for stricturing CD, with an emphasis on histomorphologic correlates, novel imaging parameters which may improve segregation between inflammatory, muscular, and fibrotic stricture components, as well as a future outlook on the role of artificial intelligence in this field of gastroenterology., (© 2022 The Authors. United European Gastroenterology Journal published by Wiley Periodicals LLC. on behalf of United European Gastroenterology.)

In inflammatory bowel disease [IBD], mucosal healing is a major therapeutic target and a reliable predictor of clinical course. However, endoscopic mucosal healing is not synonymous with histological healing, and the additional benefits of including histological remission as a target are unclear. In Crohn´s disease [CD], there are few studies highlighting the value of histological remission as a therapeutic target. Histological activity can persist in CD patients who are in endoscopic remission, and the absence of histological activity may be associated with lower relapse rates. Therefore, standardisation of procedures to evaluate CD histological activity is desirable. Topics that would benefit from standardisation and harmonisation include biopsy procedures, biopsy processing techniques, the content of histological scores, and the definitions of histological remission, histological response, and histological activity. In line with these needs, the European Crohn's and Colitis Organisation [ECCO] assembled a consensus group with the objective of developing position statements on CD histology based on published evidence and expert consensus. There was agreement that definitions of histological remission should include absence of erosion, ulceration, and mucosal neutrophils; that the absence of neutrophilic inflammation is an appropriate histological target in CD; that CD histological scores, such as the Global Histological Disease Activity Score, lack formal validation; and that histological scoring systems for ulcerative colitis, including the Geboes Score, Robarts Histopathology Index, and Nancy Histological Index, can be used for scoring intestinal biopsies in CD patients., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background and Aims: Intestinal fibrosis has recently been characterised in adult ulcerative colitis and may affect motility, diarrhoea, and the symptom of urgency. We aimed to charactersze the presence of fibrosis in paediatric patients with ulcerative colitis, and its link to severity and chronicity of mucosal inflammation, as well as clinical factors of severity., Methods: We performed a single-centre cross-sectional study in children ages 1-18 years with ulcerative colitis, undergoing colectomy or proctocolectomy. Tissue cross-sections were derived from proximal, mid, and distal colon and rectum, and inflammation and fibrosis were graded based on previously developed scores. Clinical data were collected prospectively., Results: From 62 patients, 205 intestinal sections were evaluated. Median age at diagnosis was 13 years, 100% had extensive colitis, and all resections were done for refractory disease. The presence, chronicity, and degree of inflammation were linked with the presence of fibrosis. Thickness of the muscularis mucosa was also linked with presence and chronicity of inflammation. The overall submucosal fibrosis burden was associated with prior anti-tumour necrosis factor use., Conclusions: Paediatric patients with ulcerative colitis exhibit colorectal submucosal fibrosis and muscularis mucosa thickening, which correlate with the presence, chronicity, and degree of mucosal inflammation. Fibrosis should be recognised as a complication of paediatric ulcerative colitis, and ulcerative colitis should be considered a progressive disease., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Recurrent chronic mucosal inflammation, a characteristic of inflammatory bowel diseases (IBD), perturbs the intestinal epithelial homeostasis resulting in formation of mucosal wounds and, in most severe cases, leads to colitis-associated colon cancer (CAC). The altered structure of epithelial cell-cell adhesions is a hallmark of intestinal inflammation contributing to epithelial injury, repair, and tumorigenesis. P-cadherin is an important adhesion protein, poorly expressed in normal intestinal epithelial cells (IEC) but upregulated in inflamed and injured mucosa. The goal of this study was to investigate the roles of P-cadherin in regulating intestinal inflammation and CAC. P-cadherin expression was markedly induced in the colonic epithelium of human IBD patients and CAC tissues. The roles of P-cadherin were investigated in P-cadherin null mice using dextran sulfate sodium (DSS)-induced colitis and an azoxymethane (AOM)/DSS induced CAC. Although P-cadherin knockout did not affect the severity of acute DSS colitis, P-cadherin null mice exhibited faster recovery after colitis. No significant differences in the number of colonic tumors were observed in P-cadherin null and control mice. Consistently, the CRISPR/Cas9-mediated knockout of P-cadherin in human IEC accelerated epithelial wound healing without affecting cell proliferation. The accelerated migration of P-cadherin depleted IEC was driven by activation of Src kinases, Rac1 GTPase and myosin II motors and was accompanied by transcriptional reprogramming of the cells. Our findings highlight P-cadherin as a negative regulator of IEC motility in vitro and mucosal repair in vivo. In contrast, this protein is dispensable for IEC proliferation and CAC development.

Artificial intelligence [AI] techniques are quickly spreading across medicine as an analytical method to tackle challenging clinical questions. What were previously thought of as highly complex data sources, such as images or free text, are now becoming manageable. Novel analytical methods merge the latest developments in information technology infrastructure with advances in computer science. Once primarily associated with Silicon Valley, AI techniques are now making their way into medicine, including in the field of inflammatory bowel diseases [IBD]. Understanding potential applications and limitations of these techniques can be difficult, in particular for busy clinicians. In this article, we explain the basic terminologies and provide a particular focus on the foundations behind state-of-the-art AI methodologies in both imaging and text. We explore the growing applications of AI in medicine, with a specific focus on IBD to inform the practising gastroenterologist and IBD specialist. Finally, we outline possible future uses of these technologies in daily clinical practice., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Effective medical therapy and validated trial outcomes are lacking for small bowel Crohn's disease (CD) strictures. Histopathology of surgically resected specimens is the gold standard for correlation with imaging techniques. However, no validated histopathological scoring systems are currently available for small bowel stricturing disease. We convened an expert panel to evaluate the appropriateness of histopathology scoring systems and items generated based on panel opinion., Design: Modified RAND/University of California Los Angeles methodology was used to determine the appropriateness of 313 candidate items related to assessment of CD small bowel strictures., Results: In this exercise, diagnosis of naïve and anastomotic strictures required increased bowel wall thickness, decreased luminal diameter or internal circumference, and fibrosis of the submucosa. Specific definitions for stricture features and technical sampling parameters were also identified. Histopathologically, a stricture was defined as increased thickness of all layers of the bowel wall, fibrosis of the submucosa and bowel wall, and muscularisation of the submucosa. Active mucosal inflammatory disease was defined as neutrophilic inflammation in the lamina propria and any crypt or intact surface epithelium, erosion, ulcer and fistula. Chronic mucosal inflammatory disease was defined as crypt architectural distortion and loss, pyloric gland metaplasia, Paneth cell hyperplasia, basal lymphoplasmacytosis, plasmacytosis and fibrosis, or prominent lymphoid aggregates at the mucosa/submucosa interface. None of the scoring systems used to assess CD strictures were considered appropriate for clinical trials., Conclusion: Standardised assessment of gross pathology and histopathology of CD small bowel strictures will improve clinical trial efficiency and aid drug development., Competing Interests: Competing interests: IOG receives grant support from UCB, Celgene, Morphic and Pliant Therapeutics. DB is on the advisory board or consultant for Amgen, AbbVie, Celltrion, Dr Falk Foundation, Ferring, MSD, Pfizer, Pharmacosmos, Roche, Takeda, Tillotts Pharma and Vifor. GdH reports fees to his institution (KULeuven) for his participation as a central pathology reviewer in clinical trials sponsored by GlaxoSmithKline, Shire Pharmaceuticals, Teva Pharma, Galapagos, Genentech, Novartis Pharma, Fast Forward Pharmaceuticals, Takeda and Janssen R&D. MR reports Merck, speaker panel; Bayer, pathologist on a clinical trial; Chief Scientific Officer of Beyond Celiac, a non-profit patient support organisation, outside of the submitted work. NH is a consultant for AbbVie, BMS, Celgene and Lilly USA. PB reports personal fees from MSD, personal fees from Roche and personal fees from AstraZeneca, outside the submitted work. RiKP has received consulting fees from Genentech, Eli Lilly, Allergan, AbbVie and Alimentiv. RF is a central reader for Alimentiv (formerly Robarts Clinical Trials) and received speaker’s fees in 2020 from Takeda. CEP, LG, LMS and TN are employees of Alimentiv. WJS reports research grants from AbbVie, Abivax, Arena Pharmaceuticals, Boehringer Ingelheim, Celgene, Genentech, Gilead Sciences, GlaxoSmithKline, Janssen, Lilly, Pfizer, Prometheus Biosciences, Seres Therapeutics, Shire, Takeda, Theravance Biopharma; consulting fees from AbbVie, Abivax, Admirx, Alfasigma, Alimentiv (formerly Robarts Clinical Trials), Alivio Therapeutics, Allakos, Amgen, Applied Molecular Transport, Arena Pharmaceuticals, Bausch Health (Salix), Beigene, Bellatrix Pharmaceuticals, Boehringer Ingelheim, Boston Pharmaceuticals, Bristol Meyers Squibb, Celgene, Celltrion, Cellularity, Cosmo Pharmaceuticals, Escalier Biosciences, Equillium, Forbion, Genentech/Roche, Gilead Sciences, Glenmark Pharmaceuticals, Gossamer Bio, Immunic (Vital Therapies), Index Pharmaceuticals, Intact Therapeutics, Janssen, Kyverna Therapeutics, Landos Biopharma, Lilly, Oppilan Pharma, Otsuka, Pandion Therapeutics, Pfizer, Progenity, Prometheus Biosciences, Protagonists Therapeutics, Provention Bio, Reistone Biopharma, Seres Therapeutics, Shanghai Pharma Biotherapeutics, Shire, Shoreline Biosciences, Sublimity Therapeutics, Surrozen, Takeda, Theravance Biopharma, Thetis Pharmaceuticals, Tillotts Pharma, UCB, Vendata Biosciences, Ventyx Biosciences, Vimalan Biosciences, Vivelix Pharmaceuticals, Vivreon Biosciences, Zealand Pharma; and stock or stock options from Allakos, BeiGene, Gossamer Bio, Oppilan Pharma, Prometheus Biosciences, Progenity, Shoreline Biosciences, Ventyx Biosciences, Vimalan Biosciences, Vivreon Biosciences. Spouse: Iveric Bio—consultant, stock options; Progenity—stock; Oppilan Pharma—consultant, stock options; Prometheus Biosciences—employee, stock, stock options; Ventyx Biosciences—stock, stock options; Vimalan Biosciences—stock, stock options. VJ receives salary support from the John and Susan McDonald Endowed IBD Chair at Western University, London, Ontario, Canada; has received has received consulting fees from AbbVie, Eli Lilly, GlaxoSmithKline, Arena Pharmaceuticals, Genetech, Pendopharm, Pfizer, Fresenius Kabi, Bristol Myers Squibb, Roche, Ferring, Sandoz, Merck, Takeda, Janssen, Alimentiv (formerly Robarts Clinical Trials), Topivert, Celltrion, Mylan, Gilead; speaker’s fees from Takeda, Janssen, Shire, Ferring, AbbVie, Pfizer. MB receives no direct support. Cleveland Clinic receives support for him from Siemens Healthineers in the form of salary, software and hardware for the investigation of reduced exposure in CT Enterography, as well as from The Leona and Harry Helmsley Charitable Trust and from Pfizer grants through the Stenosis Therapy and Anti-Fibrotic Research (STAR) Consortium in the form of salary. DHB is a consultant for and receives research support from Medtronics, and receives research support from Takeda. JGF receives research funding support from grants from Siemens Healthineers, Helmsley Charitable Trust through the Stenosis Therapy and Anti-Fibrotic Research (STAR) Consortium, Takeda Pharmaceuticals and National Institutes of Health (R01 EB017095, U24 EB28936, R01 DK120559). Funds from all grants are paid to Mayo Clinic. He is a consultant for Takeda Pharmaceuticals, Medtronic, Janssen, Pfizer, GlaxoSmithKline and Boheringer-Ingelheim, with fees paid to institution. BGF has received grant/research support from Millennium Pharmaceuticals, Merck, Tillotts Pharma AG, AbbVie, Novartis Pharmaceuticals, Centocor, Elan/Biogen, UCB Pharma, Bristol-Myers Squibb, Genentech, ActoGenix and Wyeth Pharmaceuticals; consulting fees from Millennium Pharmaceuticals, Merck, Centocor, Elan/Biogen, Janssen-Ortho, Teva Pharmaceuticals, Bristol-Myers Squibb, Celgene, UCB Pharma, AbbVie, AstraZeneca, Serono, Genentech, Tillotts Pharma AG, Unity Pharmaceuticals, Albireo Pharma, Given Imaging, Salix Pharmaceuticals, Novonordisk, GSK, Actogenix, Prometheus Therapeutics and Diagnostics, Athersys, Axcan, Gilead, Pfizer, Shire, Wyeth, Zealand Pharma, Zyngenia, GiCare Pharma and Sigmoid Pharma; and speakers bureaux fees from UCB, AbbVie and J&J/Janssen. FR is on the advisory board or consultant for Agomab, Allergan, AbbVie, Boehringer-Ingelheim, Celgene/BMS, CDISC, Cowen, Genentech, Gilead, Gossamer, Guidepoint, Helmsley, Index Pharma, Janssen, Koutif, Mestag, Metacrine, Morphic, Origo, Pfizer, Pliant, Prometheus Biosciences, Receptos, RedX, Roche, Samsung, Surrozen, Takeda, Techlab, Theravance, Thetis, UCB. AB, CR, JI, ReKP, LMS, MAV, RF, RO and RM report no conflicts of interest., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Medical schools face a challenge when trying to include new topics, such as climate change and health (CCH), in their curricula because of competing demands from more traditional biomedical content. At the same time, an understanding of CCH topics is crucial for physicians as they have clear implications for clinical practice and health care delivery. Although some medical schools have begun to incorporate CCH into curricula, the inclusion usually lacks a comprehensive framework for content and implementation. The authors propose a model for integrating CCH into medical school curricula using a practical, multistakeholder approach designed to mitigate competition for time with existing content by weaving meaningful CCH examples into current curricular activities. After the authors identified stakeholders to include in their curricular development working group, this working group determined the goals and desired outcomes of the curriculum; aligned those outcomes with the school's framework of educational objectives, competencies, and milestones; and strove to integrate CCH goals into as many existing curricular settings as possible. This article includes an illustration of the proposed model for one of the curricular goals (understanding the impacts of climate change on communities), with examples from the CCH curriculum integration that began in the fall of 2020 at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. The authors have found that this approach does minimize competition for time with existing content and allows mapping of content to existing curricular competencies and milestones, while encouraging a broad understanding of CCH in the context of individual patients, populations, and communities. This model for curricular integration can be applied to other topics such as social determinants of health, health equity, disability studies, and structural racism., (Copyright © 2021 by the Association of American Medical Colleges.)

Objective: Creeping fat, the wrapping of mesenteric fat around the bowel wall, is a typical feature of Crohn's disease, and is associated with stricture formation and bowel obstruction. How creeping fat forms is unknown, and we interrogated potential mechanisms using novel intestinal tissue and cell interaction systems., Design: Tissues from normal, UC, non-strictured and strictured Crohn's disease intestinal specimens were obtained. The muscularis propria matrisome was determined via proteomics. Mesenteric fat explants, primary human preadipocytes and adipocytes were used in multiple ex vivo and in vitro cell migration systems on muscularis propria muscle cell derived or native extracellular matrix. Functional experiments included integrin characterisation via flow cytometry and their inhibition with specific blocking antibodies and chemicals., Results: Crohn's disease muscularis propria cells produced an extracellular matrix scaffold which is in direct spatial and functional contact with the immediately overlaid creeping fat. The scaffold contained multiple proteins, but only fibronectin production was singularly upregulated by transforming growth factor-β1. The muscle cell-derived matrix triggered migration of preadipocytes out of mesenteric fat, fibronectin being the dominant factor responsible for their migration. Blockade of α5β1 on the preadipocyte surface inhibited their migration out of mesenteric fat and on 3D decellularised intestinal tissue extracellular matrix., Conclusion: Crohn's disease creeping fat appears to result from the migration of preadipocytes out of mesenteric fat and differentiation into adipocytes in response to an increased production of fibronectin by activated muscularis propria cells. These new mechanistic insights may lead to novel approaches for prevention of creeping fat-associated stricture formation., Competing Interests: Competing interests: FR is consultant to Agomab, Allergan, AbbVie, Boehringer-Ingelheim, Celgene, Cowen, Genentech, Gilead, Gossamer, Guidepoint, Helmsley, Index Pharma, Jannsen, Koutif, Metacrine, Morphic, Pfizer, Pliant, Prometheus Biosciences, Receptos, RedX, Roche, Samsung, Takeda, Techlab, Thetis, UCB and receives funding from the Crohn’s and Colitis Foundation of America, the Helmsley Charitable Trust, Kenneth Rainin Foundation and the National Institute of Health. CF received speaker fees from UCB, Genentech, Sandoz, Janssen and he is consultant for Athos Therapeutics., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Given adverse health effects of climate change and contributions of the US health care sector to greenhouse gas (GHG) emissions, environmentally sustainable delivery of care is needed. We applied life cycle assessment to quantify GHGs associated with processing a gastrointestinal biopsy in order to identify emissions hotspots and guide mitigation strategies., Methods: The biopsy process at a large academic pathology laboratory was grouped into steps. Each supply and reagent was catalogued and postuse treatment noted. Energy consumption was estimated for capital equipment. Two common scenarios were considered: 1 case with 1 specimen jar (scenario 1) and 1 case with 3 specimen jars (scenario 2)., Results: Scenario 1 generated 0.29 kg of carbon dioxide equivalents (kg CO2e), whereas scenario 2 resulted in 0.79 kg CO2e-equivalent to 0.7 and 2.0 miles driven, respectively. The largest proportion of GHGs (36%) in either scenario came from the tissue processor step. The second largest contributor (19%) was case accessioning, mostly attributable to production of single-use disposable jars., Conclusions: Applied to more than 20 million biopsies performed in the US annually, emissions from biopsy processing is equivalent to yearly GHG emissions from 1,200 passenger cars. Mitigation strategies may include modification of surveillance guidelines to include the number of specimen jars., (© American Society for Clinical Pathology, 2021. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Endoscopic eradication therapy (EET) with maximal acid suppression is the cornerstone for the management of patients with Barrett's esophagus (BE) associated dysplasia. The occurrence of buried dysplastic glands after re-epithelialization of a neo-squamous epithelium is of concern for endoscopists. Here, we present a patient with BE and high-grade dysplasia successfully treated by EET who developed buried dysplastic BE during surveillance. A review of literature on buried dysplasia after successful endoscopic therapy of BE is also discussed.

Background: Pouchitis is a condition with large unmet medical needs and no approved therapies. Lack of validated instruments to measure disease activity and treatment response is a major barrier to drug development., Aim: To conduct a modified RAND/University of California Los Angeles appropriateness process to produce a standardised assessment of pouchitis disease activity in clinical trials., Methods: A list of 164 items generated upon a systematic review and expert opinion were rated based on a 9-point scale (appropriate, uncertain and inappropriate), by a panel including 16 gastroenterologists, surgeons and histopathologists., Results: Items rated as appropriate to evaluate in pouchitis clinical trials were: (a) clinical: stool frequency and faecal urgency; (b) endoscopic: primary assessment in the pouch body according to the percentage of affected area (<50%, 50%-75% and >75%), evaluation of the presence of ulcers/erosions according to size (erosions <5 mm, ulcers ≥5 mm to 2 cm and large ulcers >2 cm) and ulcerated area (<10%, 10%-30% and >30%); (c) histologic: two biopsies from each segment, from the ulcer's edge when present, or endoscopically normal areas, assessment of lamina propria chronic inflammation, epithelial and lamina propria neutrophils, epithelial damage, erosions and ulcers; and (d) clinical trial inclusion/outcome criteria: minimum histologic disease activity for inclusion, a primary endpoint based on stool frequency and assessment of clinical, endoscopic and histologic response and remission. The overall majority of items surveyed (100/164) were rated 'uncertain'., Conclusion: We conducted a RAND/UCLA appropriateness process to help inform measurement of pouchitis disease activity within clinical trials and foster the development of novel therapies., (© 2021 John Wiley & Sons Ltd.)

Background: Therapeutic efficacy of biologics has remained at about 50% for 2 decades. In Crohn's disease (CD) patients, we examined the predictive value of an epithelial cell biomarker, ileal microvillar length (MVL), for clinical response to ustekinumab (UST) and vedolizumab (VDZ) and its relationship to another biomarker, intestinal epithelial cell (IEC) pyroptosis, with respect to response to VDZ., Method: Ileal biopsies from the UNITI-2 randomized controlled trial were analyzed for MVL as a predictor of clinical response to UST. In a 5-center academic retrospective cohort of CD patients, ileal MVL was analyzed to determine its predictive value for response to VDZ. Correlation between ileal MVL and IEC pyroptosis was determined, and the discriminant ability of the combination of 2 biomarkers to VDZ was examined., Results: Clinical response in UST was significantly higher than placebo (65% vs 39%; P = 0.03), with patients with normal MVL (>1.7 µm) having the greatest therapeutic effect: 85% vs 20% (P = 0.02). For VDZ, clinical response with MVL of 1.35 to 1.55 µm was 82% vs 44% (<1.35 µm) and 40% (>1.55 µm; P = 0.038). There was no correlation between ileal MVL and IEC pyroptosis. The combination criteria of ileal pyroptosis <14 positive cells/1000 IECs or MVL of 1.35 to 1.55 µm could identify 84% of responders and 67% of nonresponders (P = 0.001)., Conclusion: Ileal MVL was predictive of response to UST and VDZ in prospective and retrospective CD cohorts. It was independent of ileal IEC pyroptosis, and combination of the 2 biomarkers enhanced the discriminate ability of responders from nonresponders to VDZ., (© 2020 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Subsquamous intestinal metaplasia (SSIM) in the setting of Barrett's esophagus (BE) is a technically challenging diagnosis. While the risk for progression of BE involving the surface mucosa is well documented, the potential risk for development of advanced neoplasia associated with SSIM has been controversial. This study aimed to determine the effects of specimen adequacy, presence of dysplasia, and interobserver agreement for SSIM interpretation. Adult patients (n = 28) who underwent endoscopic therapy for BE with high-grade dysplasia or intramucosal carcinoma (HGD/IMC) between October 2005 and June 2013 were included. Initial evaluation (n = 140 slides) by an experienced gastrointestinal pathologist was followed by an interobserver study by 8 pathologists. Forty-seven (34%) slides had insufficient subsquamous tissue to assess for SSIM. SSIM was found in 19% of all slides and 29% of slides with sufficient subsquamous tissue. At least one slide had SSIM in 54% to 64% of patients. Subsquamous low grade dysplasia (LGD) was found in 4 (15%) slides with SSIM and subsquamous HGD/IMC was found in 5 (19%) slides with SSIM. At the patient level, 8 (53%) had no dysplasia, 4 (27%) had LGD and 3 (20%) had HGD/IMC. Overall agreement for SSIM by slide was 92% to 94% (κ = 0.73 to κ = 0.82, moderate to strong agreement), and by patient was 82% to 94% (κ = 0.65 to κ = 0.87, moderate to strong agreement). This study confirms the need for assessing specimen adequacy and assessing the prevalence of SSIM and is the first to assess interobserver agreement for SSIM and dysplasia within SSIM., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objectives.: With targeted agents, characterizing carcinomas of the gastrointestinal (GI) tract has become more important. We aim to determine the usefulness of p40 in classifying GI tract carcinomas., Methods.: Seventy-five GI carcinomas including 28 squamous cell carcinomas (SCC), 2 adenosquamous carcinomas (ASCA), 21 poorly differentiated carcinomas (PDCA), and 24 adenocarcinomas (AdCA; control group) were stained for p40, p63, and CK5/6. Tumors were scored from 0 to 5 based on extent of staining and marked as positive (score >2) or negative., Results.: p63 was positive in 100% of SCC/ASCA and 12.5% of AdCA. p40 was positive in 92.5% of SCC/ASCA and 4.1% of AdCA. In the PDCA subset, a panel including p63, p40, and MOC31 was the best way to accurately classify most cases., Conclusions.: p63 and CK5/6 are more sensitive but less specific than p40 for SCC/ASCA in GI carcinomas. In PDCA, a panel approach including p63, CK5/6, and p40 may be best in classifying these cases.

Objective: Mucosal barrier dysfunction plays a crucial role in intestinal inflammation in Crohn's disease (CD). Intestinal epithelial cell (IEC) death resulting from innate immune activation, termed pyroptosis, was recently found to be a cause of this barrier defect. The aim of this study was to determine the predictive value of pretreatment ileal biopsy pyroptosis as a biomarker for clinical response to vedolizumab in CD., Design: Crohn's disease patients ranging 18 to 80 years old from 5 IBD centers with pre-vedolizumab ileal biopsies during colonoscopy were enrolled. Biopsies were stained for activated caspases, and levels of ileal IEC pyroptosis levels were quantified. The primary outcome was clinical response 6 months after therapy, defined as a reduction of Harvey-Bradshaw Index (HBI) of ≥5 points from baseline. Secondary outcomes included clinical remission, defined as HBI <5, and endoscopic improvement, as measured by the Simple Endoscopic Score for Crohn's Disease (SES-CD)., Results: One hundred CD patients (45 male, 55 female), median age 47 (19, 78) years, were included; clinical response rate was 60%, and clinical remission was 36%. The response rate in patients with ileal pyroptosis <14 positive cells per 1000 IECs was significantly higher than those above the threshold: 89% (25 of 28) vs 49% (35 of 72), odds ratio (OR) 8.8 (95% CI, 2.3-48.6; P < 0.001). Corresponding remission rates were 54% (15 of 28) vs 29% (21 of 72; OR 2.8 [1.03-7.59; P = 0.036]). For endoscopic improvement, ileal pyroptosis of 22 positive cells per 1000 IECs was the optimal threshold that determines the magnitude SES-CD change., Conclusions: Ileal biopsy IEC pyroptosis was predictive of clinical response and endoscopic improvement to vedolizmab in CD patients., (© 2019 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background & Aims: Collagenous colitis (CC) is an inflammatory bowel disorder with unknown etiopathogenesis involving HLA-related immune-mediated responses and environmental and genetic risk factors. We carried out an array-based genetic association study in a cohort of patients with CC and investigated the common genetic basis between CC and Crohn's disease (CD), ulcerative colitis (UC), and celiac disease., Methods: DNA from 804 CC formalin-fixed, paraffin-embedded tissue samples was genotyped with Illumina Immunochip. Matching genotype data on control samples and CD, UC, and celiac disease cases were provided by the respective consortia. A discovery association study followed by meta-analysis with an independent cohort, polygenic risk score calculation, and cross-phenotype analyses were performed. Enrichment of regulatory expression quantitative trait loci among the CC variants was assessed in hemopoietic and intestinal cells., Results: Three HLA alleles (HLA-B∗08:01, HLA-DRB1∗03:01, and HLA-DQB1∗02:01), related to the ancestral haplotype 8.1, were significantly associated with increased CC risk. We also identified an independent protective effect of HLA-DRB1∗04:01 on CC risk. Polygenic risk score quantifying the risk across multiple susceptibility loci was strongly associated with CC risk. An enrichment of expression quantitative trait loci was detected among the CC-susceptibility variants in various cell types. The cross-phenotype analysis identified a complex pattern of polygenic pleiotropy between CC and other immune-mediated diseases., Conclusions: In this largest genetic study of CC to date with histologically confirmed diagnosis, we strongly implicated the HLA locus and proposed potential non-HLA mechanisms in disease pathogenesis. We also detected a shared genetic risk between CC, celiac disease, CD, and UC, which supports clinical observations of comorbidity., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Stenosis is a common complication of Crohn's disease (CD) that has no effective medical therapy. Development of antifibrotic agents will require testing in randomized controlled trials. Computed tomography enterography- and magnetic resonance enterography-based technologies might be used to measure outcomes in these trials. These approaches have been validated in studies of patients with symptomatic strictures who underwent imaging evaluations followed by resection with histopathologic grading of the intestinal tissue for inflammation and/or fibrosis (the reference standard). Imaging findings have correlated with findings from quantitative or semiquantitative histologic evaluation of the degree of fibromuscular stenosis and/or inflammation on the resection specimen. However, it is not clear whether histologic findings are an accurate reference standard. We performed a systematic review of all published histologic scoring systems used to assess stenosing CD., Methods: We performed a comprehensive search of Embase and MEDLINE of studies through March 13, 2019, that used a histologic scoring system to characterize small bowel CD and assessed inflammatory and fibrotic alterations within the same adult individual. All scores fitting the criteria were included in our analysis, independent of the presence of stricturing disease, as long as inflammation and fibrosis were evaluated separately but in the same scoring system., Results: We observed substantial heterogeneity among the scoring systems, which were not derived from modern principles for evaluative index development. None had undergone formal validity or reliability testing. None of the existing indices had been constructed according to accepted methods for the development of evaluative indices. Basic knowledge regarding their operating properties were lacking. Specific indices for evaluating the important pathologic component of myofibroblast hypertrophy or hyperplasia have not been proposed., Conclusions: In a systematic review of publications, we found a lack of validated histopathologic scoring systems for assessment of fibromuscular stenosis. Data that describe the operating properties of existing cross-sectional imaging techniques for stenosing CD should be questioned. Development and validation of a histopathology index is an important research priority., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Fibrosis is a significant complication of intestinal disorders associated with microbial dysbiosis and pathobiont expansion, notably Crohn's disease (CD). Mechanisms that favor fibrosis are not well understood, and therapeutic strategies are limited. Here we demonstrate that colitis-susceptible Il10 -deficient mice develop inflammation-associated fibrosis when monoassociated with adherent/invasive Escherichia coli (AIEC) that harbors the yersiniabactin (Ybt) pathogenicity island. Inactivation of Ybt siderophore production in AIEC nearly abrogated fibrosis development in inflamed mice. In contrast, inactivation of Ybt import through its cognate receptor FyuA enhanced fibrosis severity. This corresponded with increased colonic expression of profibrogenic genes prior to the development of histological disease, therefore suggesting causality. fyuA -deficient AIEC also exhibited greater localization within subepithelial tissues and fibrotic lesions that was dependent on Ybt biosynthesis and corresponded with increased fibroblast activation in vitro Together, these findings suggest that Ybt establishes a profibrotic environment in the host in the absence of binding to its cognate receptor and indicate a direct link between intestinal AIEC and the induction of inflammation-associated fibrosis., (Copyright © 2019 Ellermann et al.)

Background: Intestinal fibrosis is a common and serious complication of Crohn's disease characterized by the accumulation of fibroblasts, deposition of extracellular matrix, and formation of scar tissue. Although many factors including cytokines and proteases contribute to the development of intestinal fibrosis, the initiating mechanisms and the complex interplay between these factors remain unclear., Methods: Chronic infection of mice with Salmonella enterica serovar Typhimurium was used to induce intestinal fibrosis. A murine protease-specific CLIP-CHIP microarray analysis was employed to assess regulation of proteases and protease inhibitors. To confirm up- or downregulation during fibrosis, we performed quantitative real-time polymerase chain reaction (PCR) and immunohistochemical stainings in mouse tissue and tissue from patients with inflammatory bowel disease. In vitro infections were used to demonstrate a direct effect of bacterial infection in the regulation of proteases., Results: Mice develop severe and persistent intestinal fibrosis upon chronic infection with Salmonella enterica serovar Typhimurium, mimicking the pathology of human disease. Microarray analyses revealed 56 up- and 40 downregulated proteases and protease inhibitors in fibrotic cecal tissue. Various matrix metalloproteases, serine proteases, cysteine proteases, and protease inhibitors were regulated in the fibrotic tissue, 22 of which were confirmed by quantitative real-time PCR. Proteases demonstrated site-specific staining patterns in intestinal fibrotic tissue from mice and in tissue from human inflammatory bowel disease patients. Finally, we show in vitro that Salmonella infection directly induces protease expression in macrophages and epithelial cells but not in fibroblasts., Conclusions: In summary, we show that chronic Salmonella infection regulates proteases and protease inhibitors during tissue fibrosis in vivo and in vitro, and therefore this model is well suited to investigating the role of proteases in intestinal fibrosis., (© 2019 Crohn’s & Colitis Foundation. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation.)

Adipose tissue is present in close proximity to various organs in the human body. One prominent example is fat contained in the mesentery that is contiguous with all abdominal digestive organs including the intestine. Despite the fact that mesenteric fat-wrapping around the inflamed gut (so called "creeping fat") was described as a characteristic feature of Crohn's disease (CD) in the early 1930s, the functional implications of creeping fat have received only recent attention. As a potent producer of fatty acids, cytokines, growth factors, and adipokines, creeping fat plays an important role in regulation of immunity and inflammation. Increasing evidence points to a link between creeping fat and intestinal inflammation in CD, where histopathologic evaluation shows a significant association between creeping fat and connective tissue changes in the bowel wall, such as muscular hypertrophy, fibrosis, and stricture formation. In addition, emerging mechanistic data indicate a link between creeping fat, muscularis propria hyperplasia, and stricturing disease. Information on fat-mesenchymal interactions in other organs could provide clues to fill the fundamental knowledge gap on the role of distinct components of creeping fat in intestinal fibrosis and stricture formation. Future studies will provide important new information that in turn could lead to novel therapeutic agents aimed at prevention or treatment of CD-associated fibrosis and stricture formation., (© 2018 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Fibrosis in ulcerative colitis has remained largely unexplored despite its clinical implications., Aims: This cross-sectional study was aimed at characterising the presence, anatomical location and degree of ulcerative colitis-associated fibrosis and its possible link to clinical parameters., Methods: Seven hundred and six individual tissue cross-sections derived every 10 cm along the length of 89 consecutive Ulcerative colitis colectomy specimens were examined and compared to Crohn's disease colitis, diverticular disease and uninvolved areas from colorectal cancer patients. Degree of inflammation, fibrosis and morphometric measurements of all layers of the intestinal wall were evaluated. Three gastrointestinal pathologists independently assessed colon sections stained with haematoxylin and eosin, Masson trichrome and Sirius red. Clinical data were collected prospectively., Results: Submucosal fibrosis was detected in 100% of ulcerative colitis colectomy specimens, but only in areas affected by inflammation. Submucosal fibrosis was associated with the severity of intestinal inflammation (Spearman correlations rho (95% confidence interval): 0.58 (P < 0.001) and histopathological changes of chronic mucosal injury, but not active inflammation. Colectomy for refractory disease rather than presence of dysplasia was associated with increased fibrosis and a thicker muscularis mucosae, whereas a thinner muscularis mucosae was associated with anti-tumour necrosis factor therapy. No feature on endoscopic mucosal biopsies could predict the underlying amount of fibrosis or the thickness of the muscularis mucosae., Conclusions: A significant degree of fibrosis and muscularis mucosae thickening should be considered as common complications of chronic progressive ulcerative colitis. These features may have clinical consequences such as motility abnormalities and increased wall stiffness., (© 2018 John Wiley & Sons Ltd.)

Lymphocytic esophagitis (LE) is a clinicopathologic entity first described by Rubio et al in 2006. It is defined as peripapillary intraepithelial lymphocytosis with spongiosis and few or no granulocytes on esophageal biopsy. This definition is not widely accepted and the number of lymphocytes needed to make the diagnosis varied in different studies. Multiple studies have described potential clinical associations and risk factors for LE, such as old age, female gender and smoking history. This entity was reported in inflammatory bowel disease in the pediatric population but not in adults. Other associations include gastroesophageal reflux disease and primary esophageal motility disorders. The most common symptom is dysphagia, with a normal appearing esophagus on endoscopy, though esophageal rings, webs, nodularities, furrows and strictures have been described. Multiple treatment modalities have been used such as proton pump inhibitors and topical steroids. Esophageal dilation seems to be therapeutic when dysphagia is present along with esophageal narrowing secondary to webs, rings or strictures. The natural history of the disease remains unclear and needs to be better delineated. Overall, lymphocytic esophagitis seems to have a chronic and benign course, except for two cases of esophageal perforation in the literature, thought to be secondary to this entity., Competing Interests: Conflict-of-interest statement: All authors have no conflict of interest.

In patients who have undergone ablation therapy for treatment of Barrett's esophagus with dysplasia, histologic features of eosinophilic esophagitis, but not lymphocytic esophagitis, have been described. We evaluated for histologic evidence of eosinophilic esophagitis and lymphocytic esophagitis and correlated with endoscopic findings in this population. A single-institution Barrett's esophagus registry was searched for patients who had received radiofrequency ablation, cryotherapy, or both for treatment of Barrett's esophagus with dysplasia. Clinical and endoscopic data were collected and biopsies were reviewed for inflammation and reactive changes at three time points: pre-intervention, first surveillance after ablation therapy, and most recent surveillance. Of the 173 patients initially identified, 102 met the inclusion criteria. Intraepithelial eosinophils were increased at first surveillance (60%, P=0.096) and last surveillance (69%, P=0.048) compared with pre-intervention (50%), although histologic evidence of post-ablation eosinophilic esophagitis was not significant. Prevalence of lymphocytic esophagitis was significantly higher at first surveillance (17%, P=0.02) and at last surveillance (43%, P<0.001), compared with pre-intervention (7%). Smoking, hyperlipidemia, and cryotherapy were identified as independent risk factors for developing histologic lymphocytic esophagitis. This is the first report that histologic evidence of lymphocytic esophagitis increased over time in patients undergoing ablation for Barrett's esophagus with dysplasia. Though the pathophysiology of lymphocytic esophagitis remains unknown, patients in our study with a history of smoking, hyperlipidemia, or cryotherapy were more likely to develop post-ablation lymphocytic esophagitis.

Background: The management of colonic epithelial changes indefinite for dysplasia (IND) in patients with inflammatory bowel disease (IBD) remains controversial because of a paucity of published outcome data., Methods: We analyzed data from 93 patients with IBD who were IND and 52 IBD patients without dysplasia (controls) from the Department of Anatomic Pathology database at the Cleveland Clinic from 1989 to 2004. Pathology reports, histologic slides, clinical features, and outcomes were reviewed., Results: Twenty-two patients (23.7%) had surgical resections within 6 months of the IND assignment; of these, 6 had dysplasia (27.3%; 1 low-grade dysplasia and 5 high-grade dysplasia [HGD]). The remaining 71 patients received regular colonoscopy examinations for a mean period of 98.6 months; 18 patients developed dysplasia or carcinoma (25.2%; 10 low-grade dysplasia, 5 HGD, and 3 colorectal cancer). There was a mean interval of 53.9 months between an IND assignment and identification of dysplasia or carcinoma. Histology review of 59 cases revealed 3.2 cases per 100 person-years for neoplasia (low-grade dysplasia, HGD, or colorectal cancer) and 1.5 cases per 100 person-years for advanced neoplasia (HGD or colorectal cancer); these values were higher than those for controls (1.9 cases per 100 person-years for neoplasia and 0.7 cases per 100 person-years for advance neoplasia; P = 0.1 and P = 0.2, respectively, for IND versus controls). Patients aged more than 44 years when they were found to be IND were more likely than younger patients to develop neoplasia (hazard ratio, 6.7; P = 0.01)., Conclusions: Patients with IBD and IND are at significant risk for colorectal dysplasia and cancer. These patients should be closely followed.

Chronic intestinal inflammation and impaired tissue repair leading to intestinal fibrosis are a commonly observed complication in inflammatory bowel disease. This is particularly true for small bowel Crohn's disease. However, the development of fibrosis in ulcerative colitis has remained largely unexplored. This is surprising, given knowledge about its prevalence for decades, well described histopathologic features of fibrotic and stricturing ulcerative colitis, the relevance of the extracellular matrix for intestinal inflammation and fibrosis, and the clinical impact of fibrosis on stricture formation, motility, and the necessary discrimination from colonic malignancy. This systematic review summarizes the current knowledge of ulcerative colitis-related fibrosis, including epidemiology, basic mechanisms, histopathology, and clinical implications.

In the latter half of the 20th century, societal and technological changes led to a shift in the composition of the American diet to include a greater proportion of processed, pre-packaged foods high in fat and carbohydrates, and low in dietary fiber (a "Western diet"). Over the same time period, there have been parallel increases in Salmonella gastroenteritis cases and a broad range of chronic inflammatory diseases associated with intestinal dysbiosis. Several polysaccharide food additives are linked to bacterially-driven intestinal inflammation and may contribute to the pathogenic effects of a Western diet. Therefore, we examined the effect of a ubiquitous polysaccharide food additive, maltodextrin (MDX), on clearance of the enteric pathogen Salmonella using both in vitro and in vivo infection models. When examined in vitro, murine bone marrow-derived macrophages exposed to MDX had altered vesicular trafficking, suppressed NAPDH oxidase expression, and reduced recruitment of NADPH oxidase to Salmonella-containing vesicles, which resulted in persistence of Salmonella in enlarged Rab7+ late endosomal vesicles. In vivo, mice consuming MDX-supplemented water had a breakdown of the anti-microbial mucous layer separating gut bacteria from the intestinal epithelium surface. Additionally, oral infection of these mice with Salmonella resulted in increased cecal bacterial loads and enrichment of lamina propria cells harboring large Rab7+ vesicles. These findings indicate that consumption of processed foods containing the polysaccharide MDX contributes to suppression of intestinal anti-microbial defense mechanisms and may be an environmental priming factor for the development of chronic inflammatory disease.

Background: Candidate predictive biomarkers for epidermal growth factor receptor inhibitors (EGFRi), skin rash and serum proteomic assays, require further qualification to improve EGFRi therapy in non-small cell lung cancer (NSCLC). In a phase II trial that was closed to accrual because of changes in clinical practice we examined the relationships among candidate biomarkers, quantitative changes in tumor size, progression-free and overall survival., Methods: 55 patients with progressive NSCLC after platinum therapy were randomized to receive (Arm A) cetuximab, followed by pemetrexed at progression, or (Arm B) concurrent cetuximab and pemetrexed. All received cetuximab monotherapy for the first 14 days. Pre-treatment serum and weekly rash assessments by standard and EGFRi-induced rash (EIR) scales were collected., Results: 43 patients (20-Arm A, 23-Arm B) completed the 14-day run-in. Median survival was 9.1 months. Arm B had better median overall (Arm B = 10.3 [95% CI 7.5, 16.8]; Arm A = 3.5 [2.8, 11.7] months P = 0.046) and progression-free survival (Arm B = 2.3 [1.6, 3.1]; Arm A = 1.6 [0.9, 1.9] months P = 0.11). The EIR scale distributed ratings among 6 rather than 3 categories but ordinal scale rash severity did not predict outcomes. The serum proteomic classifier and absence of rash after 21 days of cetuximab did., Conclusions: Absence of rash after 21 days of cetuximab therapy and the serum proteomic classifier, but not ordinal rash severity, were associated with NSCLC outcomes. Although in a small study, these observations were consistent with results from larger retrospective analyses.

We present the case of a 64-year old male with Crohn's disease, who has intriguing endoscopic findings. Upon initial diagnosis at age 20, he received steroid therapy, but has not required any further medical intervention. He has remained relatively asymptomatic and keeps a healthy lifestyle. At routine colonoscopy, we identified pseudopolyps as well as tissue bridges within the colon, giving an unusual "swiss cheese" appearance. This case exemplifies the heterogeneity of Crohn's disease, emphasizing the possibility of finding evidence of ongoing disease despite lack of symptoms.

Objective: Bronchial thermoplasty (BT) reduces airway smooth muscle in patients with severe asthma. We developed a novel standardized histologic grading system assessing inflammation and structural remodeling on endobronchial biopsy (EBBx) in severe persistent asthma and evaluated airway structure before and after BT. In addition, we correlated invasive and non-invasive inflammatory markers in severe persistent asthma., Methods: Thirty-three patients with severe persistent asthma underwent bronchoscopy, including bronchoalveolar lavage (BAL) and diagnostic EBBx. The control group (N = 41) underwent EBBx for other clinical indications. Biopsies were graded for airway inflammation and epithelial and submucosal structural features. We also evaluated airway histology in three patients before and after BT., Results: Compared to the control group, patients with severe persistent asthma more often had intraepithelial eosinophils and lymphocytes (67% vs. 17% and 61% vs. 27%; p < .001 and p = .005, respectively) and prominent smooth muscle and goblet cell hyperplasia (88% vs. 29% and 47% vs. 22%, p < .001 and p = .004, respectively). Other features including epithelial denudation and basement membrane thickening were not significantly different. Following BT, airway smooth muscle was no longer prominent due to partial replacement by fibrosis. Increased submucosal eosinophilic inflammation and BAL eosinophilia correlated with exhaled nitric oxide (eNO, p = .05 for both)., Conclusions: We developed a clinically applicable standardized histologic grading system which identified structural but not inflammatory changes before and after BT in severe persistent asthmatics. Additionally, we demonstrated that eNO is representative of submucosal eosinophilia in this population. This semi-quantitative assessment will be useful for practicing pathologists assessing EBBx from severe persistent asthma patients for diagnostic and clinical research purposes.

A 56-year-old woman presented to our clinic for recurrent hypoglycemia after undergoing resection of an incidentally discovered nonfunctional pancreatic endocrine tumor 6 years ago. She underwent a distal pancreatectomy and splenectomy, after which she developed diabetes and was placed on an insulin pump. Pathology showed a pancreatic endocrine neoplasm with negative islet hormone immunostains. Two years later, computed tomography scan of the abdomen showed multiple liver lesions. Biopsy of a liver lesion showed a well-differentiated neuroendocrine neoplasm, consistent with pancreatic origin. Six years later, she presented to clinic with 1.5 years of recurrent hypoglycemia. Laboratory results showed elevated proinsulin, insulin levels, and c-peptide levels during a hypoglycemic episode. Computed tomography scan of the abdomen redemonstrated multiple liver lesions. Repeated transarterial catheter chemoembolization and microwave thermal ablation controlled hypoglycemia. The unusual features of interest of this case include the transformation of nonfunctioning pancreatic endocrine tumor to a metastatic insulinoma and the occurrence of atrial flutter after octreotide for treatment.

Angiogenesis has an important role in the carcinogenesis of esophageal adenocarcinoma, however, the diagnostic and prognostic utility of microvascular density counts have not been clinically established. The aim of this study is to assess the correlation between microvascular density and disease progression of non-dysplastic Barrett's esophagus, low-grade dysplasia, high-grade dysplasia and invasive carcinoma in the superficial aspects of the tissue. Archival histological specimens from two referral centers for Barrett's esophagus and esophageal cancer were selected for review. A total of 160 regions marked according to histological grade were assessed with digitally interactive software to measure microvascular density. This was quantified in three levels: 0-50, 50-100 and 100-150 μm. In the areas of gastric cardia, Barrett's esophagus, low-grade dysplasia, high-grade dysplasia and cancer, microvascular density was significantly different (P<0.0001) among the five groups in the most superficial 150 μm of the mucosa. Furthermore, when examining the pairwise difference between the groups, there was a significant difference between cancer and each of the lower grades of histology (P<0.05) and between high-grade dysplasia and each of the lower grades of histology (P<0.05). These statistically significant differences were preserved in examining the depth at the most superficial 50 μm. We have used digital pathology to demonstrate a significant and stepwise increase in microvascular density, which supports the hypothesis that angiogenesis has a key role in Barrett's carcinogenesis. Furthermore, the differences in the most superficial mucosal layers are consistent with findings of increased vascularity by depth-restricted imaging modalities.

Background: An offsite satellite clinic of the University of Chicago Medical Center (UCMC) requested an investigation by the Clinical Chemistry Laboratory (CCL) into several cases of possible falsely elevated potassium (K⁺) values in their patients. Bloods for K⁺ and chemistry profiles are routinely collected in mint-green, heparinized plasma separator tubes (PST), centrifuged, and transported by courier from satellite clinic to CCL within several hours. Samples from on-site phlebotomy areas are similarly collected but sent uncentrifuged to CCL via a pneumatic tube system within minutes of collection., Methods: Our investigations included extensive QC and QA review of UCMC onsite and offsite outpatient clinics, reference range studies using PST and serum separator tubes (SST), assessment of pre-analytic handling of specimens, including transportation simulation study, and comparison of K⁺ results for samples collected simultaneously using PST and SST tubes at an offsite clinic., Results: Our transportation simulation demonstrated elevations in K⁺ concentrations following sample jostling and perturbations. We also observed RBC escape across the gel barrier further contributing to K⁺ elevations., Conclusion: Serum is preferred sample type for an offsite clinic., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Context: Usual interstitial pneumonia (UIP) is a common chronic interstitial pneumonitis. It can occur idiopathically (I-UIP) or in the setting of systemic connective tissue disease (CTD-UIP). Some studies suggest that CTD-UIP has a better prognosis than I-UIP. The histologic differences between CTD-UIP and I-UIP are not clearly defined., Objective: The purpose of this study was to evaluate histologic criteria that may differentiate CTD-UIP from I-UIP, including fibroblastic foci (FFs), lymphoid aggregates (LAs), and the presence of nonspecific interstitial pneumonia pattern., Design: Thirty-five patients with histologic diagnoses of UIP were identified (27 biopsies [77%]; 8 explants [23%]). Biopsy slides were scanned and analyzed quantitatively for FF size, FF area, LA size, and LA area. Biopsy and explant slides were examined qualitatively for the presence of a nonspecific interstitial pneumonia pattern in areas away from UIP fibrosis. Results.-Of 27 biopsies, the number and size of FFs in CTD-UIP were smaller than they were in I-UIP. The number and size of LAs were larger in patients with rheumatoid arthritis than they were in patients with I-UIP. There was no interobserver variability among 3 pathologists using this quantitative system. Of 35 biopsies and explants, there was a higher prevalence of the nonspecific interstitial pneumonia pattern among patients with CTD-UIP than there was among patients with I-UIP (P = .005)., Conclusions: Patients with CTD-UIP had fewer, smaller FFs than did patients with I-UIP, and patients with rheumatoid arthritis-UIP had more, larger LAs than did patients with I-UIP. Of importance, the coexistence of UIP and the nonspecific interstitial pneumonia patterns was one of the most salient features in distinguishing CTD-UIP from I-UIP because CTD-UIP demonstrated an increased prevalence of multilobar, cellular, nonspecific interstitial pneumonia patterns in areas away from the UIP fibrosis.

Background: The International Society for Heart and Lung Transplantation (ISHLT) guidelines on the interpretation of lung rejection in pulmonary allograft biopsy specimens were revised most recently in 2007. The goal of our study was to determine how these revisions, along with nuances in the interpretation and application of the guidelines, affect patient care., Methods: A Web-based survey was e-mailed to pathologists and pulmonologists identified as being part of the lung transplant team at institutions in the United States with active lung transplant programs as determined from the Organ Procurement and Transplantation Network Web site (http://optn.transplant.hrsa.gov/members/directory.asp)., Results: Grades B1 and B2 in asymptomatic patients would fall into the same treatment group under the 2007 classification, which combines B1 and B2 into B1R. Also, some pulmonologists would not interpret a pathologic diagnosis of lymphocytic bronchiolitis as grade B rejection, resulting in under-treatment of these patients. Regarding bronchiolitis obliterans, most pulmonologists would treat the patient differently if there were an active mononuclear inflammatory infiltrate, and most pathologists would comment on the presence of such an infiltrate, contrary to the 2007 guidelines, which discourage reporting this infiltrate. We also found discrepancies among pathologists in their interpretation of airway lymphocytic infiltrates, whether eosinophils can be present in bronchial-associated lymphoid tissue, and whether airway inflammation represents rejection or bacterial infection., Conclusions: The issue of grading and treating airway inflammation in pulmonary allograft biopsy specimens continues to be problematic, despite revised ISHLT guidelines. Clarification of guidelines for pathologists and pulmonologists using evidence-based criteria could lead to improved communication and patient care., (Copyright © 2012 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Objective: To test if estrogen promotes carcinogenesis in vitro and in a genetic mouse model of ovarian cancer and whether its effects can be inhibited by a novel selective estrogen receptor modulator (SERM), bazedoxifene., Methods: Bazedoxifene was synthesized and it was confirmed that the drug abrogated the uterine stimulatory effect of 17β-estradiol in mice. To determine if hormones alter tumorigenesis in vivo LSL-K-ras(G12D/+)Pten(loxP/loxP) mice were treated with vehicle control, 17β-estradiol or bazedoxifene. Hormone receptor status of a cell line established from LSL-K-ras(G12D/+)Pten(loxP/loxP) mouse ovarian tumors was characterized using Western blotting and immunohistochemistry. The cell line was treated with hormones and invasion assays were performed using Boyden chambers and proliferation was assessed using MTT assays., Results: In vitro 17β-estradiol increased both the invasion and proliferation of ovarian cancer cells and bazedoxifene reversed these effects. However, in the genetic mouse model neither treatment with 17β-estradiol nor bazedoxifene changed mean tumor burden when compared to treatment with placebo. The mice in all treatment groups had similar tumor incidence, metastatic nodules and ascites., Conclusion: While 17β-estradiol increases the invasion and proliferation of ovarian cancer cells, these effects do not translate into increased tumor burden in a genetic mouse model of endometrioid ovarian cancer. Likewise, while the SERM reversed the detrimental effects of estrogen in vitro, there was no change in tumor burden in mice treated with bazedoxifene. These findings demonstrate the complex interplay between hormones and ovarian carcinogenesis., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The effects of drugs on the gastrointestinal tract are diverse and depend on numerous factors. Diagnosis is centered on histologic findings, with mostly nonspecific patterns of injury that must be interpreted in the correct clinical context. Nonsteroidal antiinflammatory drugs are a common cause of drug-induced gastrointestinal injury, with effects primarily in the gastric mucosa but also throughout the gastrointestinal tract. Another common class of drugs causing a variety of pathologic findings in the gut is chemotherapeutic agents. This article discusses the differential diagnosis of the various patterns of injury, including ischemic damage, and the histologic findings specific for certain drugs., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Although epidemiologic evidence for the ability of combined oral contraception (OC) to reduce the risk of ovarian cancer (OvCa) is convincing, the biological mechanisms underlying this effect are largely unknown. We conducted the present study to determine if OC also influences ovarian carcinogenesis in a genetic mouse model and, if so, to investigate the mechanism underlying the protective effect. LSL-K-ras(G12D/+)Pten(loxP/loxP) mice were treated with ethinyl estradiol plus norethindrone, contraceptive hormones commonly used in combined OC, or norethindrone alone, or a gonadotropin-releasing hormone agonist. The combined OC had a 29% reduction in mean total tumor weight compared with placebo (epithelial tumor weight, -80%). Norethindrone alone reduced mean total tumor weight by 42% (epithelial tumor weight, -46%), and the gonadotropin-releasing hormone agonist increased mean total tumor weight by 71% (epithelial tumor weight, +150%). Large variations in tumor size affected the P values for these changes, which were not statistically significant. Nonetheless, the OC reductions are consistent with the epidemiologic data indicating a protective effect of OC. Matrix metalloproteinase-2 activity was decreased in association with OC, indicating that OC may affect ovarian carcinogenesis by decreasing proteolytic activity, an important early event in the pathogenesis of OvCa. In contrast, OC increased invasion in a K-ras/Pten OvCa cell line established from the mouse tumors, suggesting that OC hormones, particularly estrogen, may have a detrimental effect after the disease process is under way. Our study results support further investigation of OC effects and mechanisms for OvCa prevention.