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The Gut Microbiome at the Onset of Inflammatory Bowel Disease: A Systematic Review and Unified Bioinformatic Synthesis

Peter Rimmer, Fan Zhang, G. Scott, N. Kaakoush, P. Lewindon, J. Ashton, S. Kansal, J. V. van Limbergen et al.

Gastroenterology, 2025

1,743 participants · 18 citations

Abstract

BACKGROUND & AIMS

Few studies describe gut microbiome signatures in treatment-naïve new-onset inflammatory bowel disease (IBD). We present a novel secondary bioinformatic reanalysis of sequence outputs mapped to the latest microbial taxonomy.

METHODS

MEDLINE and Embase searches were performed for microbiome studies in treatment-naïve IBD. Appraisal was completed with Risk Of Bias In Non-randomized Studies - of Exposures (ROBINS-E). Available 16S ribosomal RNA sequence data sets were downloaded and missing data sets requested. Integrated data were run through a unified QIIME2 bioinformatics pipeline. Multivariable models adjusting for methodologic differences were developed using MaAsLin2.

RESULTS

There were 36 eligible studies; 18 contributed to bioinformatic reanalysis and 24 to supplementary meta-analysis. Samples from 1743 patients were included, comprising 678 from individuals with Crohn's disease (CD), 399 with ulcerative colitis (UC), 130 healthy controls (HCs), and 405 symptomatic controls (SCs); 990 of which were biopsy samples. Alpha diversity was reduced: feces-pediatric UC vs SCs, adult CD and UC vs HCs, and pediatric SCs vs HCs; pediatric biopsy samples-CD vs SCs, CD vs UC, and UC vs SCs. Beta diversity demonstrated clear distinctions between fecal and mucosal biopsy communities, least evident in UC, in addition to community separation by geography. Multivariate modeling revealed depletion of anaerobic and enrichment of aerobic and facultative anaerobic bacteria,…

How strong is the evidence?

Evidence Hub reads this as a systematic review, done in computer models (in silico), not in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health. Reported size: 1,743 participants or records.

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