Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (622 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
A chronic transmural inflammation that may involve any part of the digestive tract from mouth to ANUS, mostly found in the ileum, the cecum, and the colon. In Crohn disease, the inflammation, extending through the intestinal wall from the mucosa to the serosa, is characteristically asymmetric and segmental. Epithelioid granulomas may be seen in some patients.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Crohn's Disease; Crohns Disease; Crohn's Enteritis; Inflammatory Bowel Disease 1; Regional Enteritis; Ileocolitis; Ileitis, Terminal; Terminal Ileitis.
Where it fits in the MeSH classification
- Broader topics
- Inflammatory Bowel Diseases
Related concepts
Research landscape
PubMed indexes 49,598 records tagged with the MeSH heading “Crohn Disease” (counts retrieved 2026-11-04). 10,732 of them (21.6%) were published from 2020 onward, and the busiest period so far is through 1999 with 15,300 records.
Reviews account for 7,974 records (16.1%) and meta-analyses for 917. Randomized controlled trials number 1,132 (2.3%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 15,300 |
| 2000-2009 | 9,391 |
| 2010-2019 | 14,175 |
| 2020 onward | 10,732 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 7,974 | 16.1% |
| Meta-analyses | 917 | 1.8% |
| Randomized controlled trials | 1,132 | 2.3% |
Method: PubMed query "Crohn Disease"[MeSH Terms] with publication-type and date filters, retrieved 2026-11-04.
Reading the evidence in digestive system and liver
Gut and liver research ranges from laboratory studies of the microbiome to large trials of drugs and surgery. Symptoms such as pain, reflux or bowel change are reported by patients and overlap between conditions, and diet and microbiome studies are mostly observational. Check whether the study measured symptoms, tissue findings or long-term outcomes, how the diagnosis was made and how long people were followed. Nothing here replaces advice from a qualified clinician.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Single-cell RNA sequencing of terminal ileal biopsies identifies signatures of Crohn's disease pathogenesis | 2026 | Research article Design not recorded in structured metadata | 11 | cc by PMID 42298187 · DOI · PMC13364666 |
| Concerted changes in the pediatric single-cell intestinal ecosystem before and after anti-TNF blockade | 2026 | Research article Design not recorded in structured metadata | 10 | cc by PMID 42678060 · DOI · PMC13533482 |
| Associations between demographic, clinical and dietary factors and flares in inflammatory bowel disease: the PRognostic effect of Environmental factors in Crohn's and Colitis (PREdiCCt) prospective cohort study | 2026 | Research article Design not recorded in structured metadata | 9 | cc by PMID 41554630 · DOI · PMC13479245 |
Single-cell RNA sequencing of terminal ileal biopsies identifies signatures of Crohn's disease pathogenesis [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Crohn's disease (CD) is a chronic inflammatory bowel disease exhibiting substantial heterogeneity in clinical presentation and response to therapy.
- Closing excerpt
- These findings establish a comprehensive cellular and molecular framework for CD, offering insights into disease mechanisms and therapeutic opportunities.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (151 words)
Crohn's disease (CD) is a chronic inflammatory bowel disease exhibiting substantial heterogeneity in clinical presentation and response to therapy. To explore its molecular basis, we developed IBDverse, a large single-cell RNA sequencing (scRNA-seq) dataset of terminal ileal biopsies, profiling over 1.1 million cells from 111 patients with CD and 232 healthy controls. This resource integrates discovery and replication cohorts for the robust identification of CD-associated cell types, genes and pathways. We uncovered epithelial changes marked by interferon-driven upregulation of major histocompatibility complex class I molecules that persisted in progenitor cells after macroscopic inflammation resolution. ITGA4+ macrophages were identified as key inflammatory drivers, showing enriched JAK-STAT signaling and cytokine expression (interleukin-6 (IL-6), IL-12 and IL-23). Heritability analysis linked inflammatory monocytes and macrophages to CD susceptibility, implicating resident and recruited immune cells in pathogenesis. These findings establish a comprehensive cellular and molecular framework for CD, offering insights into disease mechanisms and therapeutic opportunities.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42298187 · DOI · PMC13364666
Concerted changes in the pediatric single-cell intestinal ecosystem before and after anti-TNF blockade [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Crohn's disease is an inflammatory bowel disease (IBD) commonly treated through anti-TNF blockade.
- Closing excerpt
- Our study jointly leverages a treatment-naive cohort, high-resolution principled scRNA-seq data analysis, and clinical outcomes to understand which baseline cell states may predict Crohn's disease trajectory.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (273 words)
Crohn's disease is an inflammatory bowel disease (IBD) commonly treated through anti-TNF blockade. However, most patients still relapse and inevitably progress. Comprehensive single-cell RNA-sequencing (scRNA-seq) atlases have largely sampled patients with established treatment-refractory IBD, limiting our understanding of which cell types, subsets, and states at diagnosis anticipate disease severity and response to treatment. Here, through combining clinical, flow cytometry, histology, and scRNA-seq methods, we profile diagnostic human biopsies from the terminal ileum of treatment-naive pediatric patients with Crohn's disease (pediCD; n = 14), matched repeat biopsies (pediCD-treated; n = 8) and from non-inflamed pediatric controls with functional gastrointestinal disorders (FGIDs; n = 13). To resolve and annotate epithelial, stromal, and immune cell states among the 201,883 baseline single-cell transcriptomes, we develop a principled and unbiased tiered clustering approach, ARBOL. Through flow cytometry and scRNA-seq, we observe that treatment-naive pediCD and FGID have similar broad cell type composition. However, through high-resolution scRNA-seq analysis and microscopy, we identify significant differences in cell subsets and states that arise during pediCD relative to FGID. By closely linking our scRNA-seq analysis with clinical meta-data, we resolve a vector of T cell, innate lymphocyte, myeloid, and epithelial cell states in treatment-naive pediCD (pediCD-TIME) samples, which can distinguish patients along the trajectory of disease severity and anti-TNF response. By using ARBOL with integration, we position repeat on-treatment biopsies from our patients between treatment-naive pediCD and on-treatment adult CD. We identify that anti-TNF treatment pushes the pediatric cellular ecosystem toward an adult, more treatment-refractory state. Our study jointly leverages a treatment-naive cohort, high-resolution principled scRNA-seq data analysis, and clinical outcomes to understand which baseline cell states may predict Crohn's disease trajectory.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42678060 · DOI · PMC13533482
Associations between demographic, clinical and dietary factors and flares in inflammatory bowel disease: the PRognostic effect of Environmental factors in Crohn's and Colitis (PREdiCCt) prospective cohort study [3]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundIBD is characterised by recurrent flares, but evidence on whether modifiable dietary factors influence flare risk is limited.
- Closing excerpt
- Trial registration numberNCT03282903.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (198 words)
BackgroundIBD is characterised by recurrent flares, but evidence on whether modifiable dietary factors influence flare risk is limited.ObjectiveThe PREdiCCt study was designed to examine demographic, clinical and dietary factors associated with disease flare among patients with IBD in self-reported remission.DesignMulticentre, prospective cohort study conducted across 47 UK centres. Patients with Crohn's disease (CD), ulcerative colitis (UC) or IBD unclassified (IBDU) in self-reported remission were prospectively followed up. The baseline diet was assessed using a validated food frequency questionnaire. The primary outcome was time to patient-reported flare (captured by monthly IBD-Control) and objective flare (clinical flare plus C-reactive protein >5 mg/L and/or faecal calprotectin (FC) >250 µg/g with treatment escalation). Associations were evaluated using Cox frailty models adjusted for demographic, clinical and biochemical variables, including baseline FC.ResultsBetween November 2016 and March 2020, 2629 participants (1370 CD; 1259 UC/IBDU) were enrolled and followed up for a median of 4.1 years (IQR 3.0-5.0). Baseline FC was strongly associated with patient-reported flares (FC ≥250 µg/g: adjusted HR (aHR) 2.22; FC 50-250 µg/g: aHR 1.52 (reference ConclusionHigher habitual meat intake was associated with increased risk of objective flare in UC, suggesting diet may contribute to flare susceptibility in specific patient groups.Trial registration numberNCT03282903.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41554630 · DOI · PMC13479245
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Environmental Risk Factors for Inflammatory Bowel Diseases: An Umbrella Review of Meta-analyses [4]
- Research article Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome [5]
- Research article Systematic review with meta-analysis: the efficacy of probiotics in inflammatory bowel disease [6]
- Research article Comparative efficacy and safety of biologic therapies for moderate-to-severe Crohn's disease: a systematic review and network meta-analysis [7]
- Research article Contemporary Risk of Surgery in Patients With Ulcerative Colitis and Crohn's Disease: A Meta-Analysis of Population-Based Cohorts [8]
- Research article Global Hospitalization Trends for Crohn's Disease and Ulcerative Colitis in the 21st Century: A Systematic Review With Temporal Analyses [9]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
Effects of Low and High FODMAP Diets on Human Gastrointestinal Microbiota Composition in Adults with Intestinal Diseases: A Systematic Review
Doris Vandeputte, Marie Joossens · Microorganisms 2020 · CC BY 4.0
References
- Krzak M, Alegbe T, Taylor DL, Jones GR, Ghouraba M, Strickland M, et al.. Single-cell RNA sequencing of terminal ileal biopsies identifies signatures of Crohn's disease pathogenesis. . 2026. PMID 42298187 · DOI · PMC13364666
- Zheng HB, Doran BA, Kimler K, Yu A, Tkachev V, Niederlova V, et al.. Concerted changes in the pediatric single-cell intestinal ecosystem before and after anti-TNF blockade. . 2026. PMID 42678060 · DOI · PMC13533482
- Constantine-Cooke N, Gros B, Plevris N, Williams LJ, Jones GR, Kyle J, et al.. Associations between demographic, clinical and dietary factors and flares in inflammatory bowel disease: the PRognostic effect of Environmental factors in Crohn's and Colitis (PREdiCCt) prospective cohort study. . 2026. PMID 41554630 · DOI · PMC13479245
- Piovani D, Danese S, Peyrin-Biroulet L, Nikolopoulos GK, Lytras T, Bonovas S. Environmental Risk Factors for Inflammatory Bowel Diseases: An Umbrella Review of Meta-analyses. Gastroenterology. 2019. PMID 31014995 · DOI
- Bolte LA, Vich Vila A, Imhann F, Collij V, Gacesa R, Peters V, et al.. Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome. Gut. 2021. PMID 33811041 · DOI · PMC8223641
- Derwa Y, Gracie DJ, Hamlin PJ, Ford AC. Systematic review with meta-analysis: the efficacy of probiotics in inflammatory bowel disease. Aliment Pharmacol Ther. 2017. PMID 28653751 · DOI
- Singh S, Murad MH, Fumery M, Sedano R, Jairath V, Panaccione R, et al.. Comparative efficacy and safety of biologic therapies for moderate-to-severe Crohn's disease: a systematic review and network meta-analysis. Lancet Gastroenterol Hepatol. 2021. PMID 34688373 · DOI · PMC8933137
- Tsai L, Ma C, Dulai PS, Prokop LJ, Eisenstein S, Ramamoorthy SL, et al.. Contemporary Risk of Surgery in Patients With Ulcerative Colitis and Crohn's Disease: A Meta-Analysis of Population-Based Cohorts. Clin Gastroenterol Hepatol. 2021. PMID 33127595 · DOI · PMC8934200
- Buie MJ, Quan J, Windsor JW, Coward S, Hansen TM, King JA, et al.. Global Hospitalization Trends for Crohn's Disease and Ulcerative Colitis in the 21st Century: A Systematic Review With Temporal Analyses. Clin Gastroenterol Hepatol. 2023. PMID 35863682 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.