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Background and Aims: During early phases of inflammation, activated neutrophils extrude neutrophil extracellular traps (NETs) in a peptidyl arginine deiminase 4 (PAD4)-dependent manner, aggravating tissue injury and remodeling. In this study, we investigated the potential pro-fibrotic properties and signaling of NETs in Crohn's disease (CD)., Methods: NETs and activated fibroblasts were labeled on resected ileum from CD patients by multiplex immunofluorescence staining. NETs-treated human primary intestinal fibroblasts were analyzed by bulk RNA sequencing to uncover cell signaling pathways, and by high-throughput imaging to assess collagen production and migratory activity. Consequentially, TLR2/NF-κB pathway was evaluated by transfection of CCD-18Co fibroblasts with an NF-κB-luciferase reporter plasmid, incorporating C29 to block TLR2 signaling. A chronic dextran sulfate sodium (DSS) mouse model was used to define the specific role of PAD4 deletion in neutrophils (MRP8-Cre, Pad4fl/fl)., Results: Immunofluorescence showed spatial colocalization of NETs and activated fibroblasts in ileal ulcerations of CD patients. Transcriptomic analysis revealed upregulation of pro-fibrotic genes and activation of Toll-like receptor signaling pathways in NETs-treated fibroblasts. NETs treatment induced fibroblast proliferation, diminished migratory capability, and increased collagen release. Transfection experiments indicated a substantial increase in an NF-κB expression with NETs, whereas C29 led to decreased expression and release of collagen. In line, a significant reduction in collagen content was observed in the colon of MRP8-Cre, Pad4fl/fl mice subjected to chronic DSS colitis., Conclusions: NETs potentially serve as an initial stimulus for pathological activation of fibroblasts within the intestine via the TLR2/NF-κB pathway. Given their early involvement in inflammation, inhibition of PAD4 might offer a strategy to modulate both inflammation and fibrogenesis in CD., (© 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.)

Inflammatory bowel disease [IBD] is associated with various immune-mediated disorders including spondylarthritis, pyoderma gangrenosum, primary sclerosing cholangitis, and uveitis. Chronic kidney disease [CKD] is defined by a reduction in kidney function (estimated glomerular filtration rate [eGFR] less than 60 ml/min/1.73m2] and/or damage markers that are present for at least 3 months, regardless of the aetiology. Case reports and cohort studies suggest that IBD is associated with CKD. The extent and magnitude of a potential association is unknown. A comprehensive search was conducted in EMBASE, MEDLINE, Web of Science, the Cochrane database, and SCOPUS. Two separate reviewers were involved in the process of article selection and evaluation. Odds ratios were calculated in those papers with a comparison between an IBD population and a non-IBD control population, the Mantel Haenszel test was employed, using a random effect model. The systematic review was registered in PROSPERO [RD42023381927]. A total of 54 articles was included in the systematic review. Of these, eight articles included data on prevalence of CKD in IBD patients [n = 102 230] vs healthy populations [n = 762 430]. Of these, diagnosis of CKD was based on International Classification of Diseases [ICD] codes in five studies vs on eGFR in three studies. The overall odds ratio of developing CKD in the IBD population is 1.59, [95% CI 1.31-1.93], without any difference between studies using diagnostic coding (odds ratio [OR] 1.70, 95% CI 1.33-2.19] vs diagnosis based on eGFR [OR 1.36, 95% CI 1.33-1.64]. IBD is associated with a clinically meaningful increased CKD prevalence. We provide recommendations on diagnostic evaluation, as well as suggestions for future research., (© 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.)

Background and Aims: Intestinal ultrasound [IUS] is widely accepted as a reliable tool to monitor Crohn's disease [CD]. Several IUS scores have been proposed, but none has been formally accepted by international organizations. Our aim here was to compare the available scores regarding their correlation with endoscopic activity., Methods: Consenting CD patients undergoing ileocolonoscopy at our Unit between September 2021 and February 2023 were included. Endoscopic activity was defined as SES-CD ≥ 3 or Rutgeerts score ≥ i2b for operated patients. IUS was performed within 6 weeks of endoscopy and scored with IBUS-SAS, BUSS, Simple-US and SUS-CD scores. All correlations were performed using Spearman's rank coefficient [rho = ρ]. Receiver operating characteristic [ROC] curves were compared with the Hanley and McNeil method., Results: Of 73 CD patients, 45 [61.6%] presented endoscopic activity, of whom 22 were severe [30.1%]. All IUS scores showed a significant positive correlation with endoscopy [p < 0.0001], with IBUS-SAS ranking the highest [ρ = 0.87]. Similarly, IBUS-SAS was the most highly correlated with clinical activity [ρ = 0.58]. ROC analysis of IBUS-SAS for any endoscopic activity showed the highest area under the curve (0.95 [95% confidence interval 0.87-0.99]), with sensitivity of 82.2% and specificity of 100% for a cut-off value of 25.2. IBUS-SAS was statistically superior to all the other scores in detecting severe endoscopic activity [SES-CD ≥ 9 or Rutgeerts i4]., Conclusions: All IUS scores provided solid correlation with endoscopy and clinical symptoms. IBUS-SAS outperformed the others due to a more granular description that might help in stratifying different levels of disease activity. Therefore, the use of IBUS-SAS in centres with well-founded expertise in IUS can be suggested., (© The Author(s) 2023. 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.)

Micro-RNAs (miRNAs) are noncoding RNAs usually 24-30 nucleotides long that play a central role in epigenetic mechanisms of inflammatory diseases and cancers. Recently, several studies have assessed the involvement of miRNAs in the pathogenesis of inflammatory bowel disease (IBD) and colitis-associated neoplasia. Particularly, it has been shown that many members of miRNAs family are involved in the pathways of inflammation and fibrogenesis of IBD; therefore, their use as inflammatory and fibrosis biomarkers has been postulated. In light of these results, the role of miRNAs in IBD therapy has been proposed and is currently under investigation with many in vitro and in vivo studies, murine models, and a phase 2a trial. The accumulating data have pushed miRNA-based therapy closer to clinical practice, although many open questions remain. With this systematic review, we discuss the current knowledge about the therapeutic effects of miRNAs mimicking and inhibition, and we explore the new potential targets of miRNA family for the treatment of inflammation and fibrosis in IBD., (© The Author(s) 2022. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)