Abstract Background Both gut microbiota and microRNAs (miRNAs) are key regulators in the pathogenesis of inflammatory bowel disease. This study aimed to investigate longitudinal changes in gut microbiota composition and miRNA expression across the active and quiescent phases of patients with ulcerative colitis (UC). Methods Eleven patients with UC who underwent colonoscopy for diagnosis or monitoring were enrolled. Colonic tissue samples were collected during both the active and quiescent phases for microbiota and miRNA analysis. Additionally, colonic tissues from seven healthy controls were obtained. Gut microbial composition was analyzed via 16S rRNA sequencing, and miRNA expression profiles were determined using microarray analysis. Alpha and beta diversity, taxonomic composition, and differential abundance were assessed. LEfSe analysis and fold-change filtering were used to identify significantly altered taxa and miRNAs. Results Patients with UC exhibited distinct gut microbiota compositions and miRNA expression profiles compared to healthy controls. However, differences in gut microbiota composition between the active and quiescent phases were less pronounced than those between patients with UC and controls. LefSe analysis revealed the genera Shigella, Klebsiella, Roseburia, and Intestinimonas were significantly enriched in the active UC group compared to controls. When comparing active and quiescent UC, only three genera (Staphylococcus, Cutibacterium, and Romboutsia) were significantly altered. In contrast to microbial shifts across groups, miRNA expression exhibited distinct clustering by disease phase. Between active UC and controls, a wide range of miRNA changes was observed, including upregulation of miR-126-3p and miR-199b-3p, and downregulation of miR-7641 and miR-5100 in active UC group. Between active and quiescent UC, multiple differentially expressed miRNAs were also identified, including upregulation of miR-31-5p and miR-708-5p, and downregulation of miR-422a and miR-378i in the quiescent UC group. Conclusion While gut microbial alterations distinguished patients with UC from healthy controls, differences between active and quiescent phases were limited. In contrast, miRNA expression profiles showed phase-specific signatures, suggesting that colonic miRNA expression may serve as sensitive indicators for disease activity in UC. Conflict of interest: Prof. Dr. Eun, Chang Soo: No conflict of interest Lee, Jae Gon: No conflict of interest Lee, A. Reum: No conflict of interest Han, Dong Soo: No conflict of interest
Eun et al. (Thu,) studied this question.