Background
The involvement of Mediterranean fever (MEFV) gene mutations in patients with inflammatory bowel disease unclassified (IBDU) remains unclear. This study aimed to determine the clinical characteristics and responsiveness to colchicine in Japanese patients with IBDU carrying MEFV mutations.
Methods
In this retrospective cohort study, we examined MEFV mutations using gene analysis, clinical information, and colchicine responsiveness. Furthermore, we examined cytokine production in exon 2-mutated THP-1 cells (a monocytic cell line) and microbiome analysis. Findings: Of the 396 patients diagnosed with IBDU, 60.1% had MEFV mutations. Exon 2 mutations were the most common (83.7%). Among patients with available clinical information, 43.3% of patients with IBDU had typical Familial Mediterranean fever (FMF). The efficacy of colchicine in patients with IBDU carrying MEFV mutations was 84.6%. Significant differences were noted in the production of inflammatory; cytokines between THP-1 cells with and without MEFV mutations. Microbial compositions differed between patients with IBDU carrying MEFV mutations and patients with IBD and healthy controls. Interpretation: Patients with IBDU carrying MEFV mutations responded well to colchicine treatment. A notable subset of patients met the criteria for typical FMF. Alterations in intestinal microbiota may contribute to disease pathogenesis. Funding: This work was supported by the Japan Agency for Medical Research and Development (21ek0410057h0003), a grant from the Uehara Memorial Foundation, and the Health and Labour Sciences Research Grants for research on intractable diseases from the Ministry of Health, Labour and Welfare (MHLW) of Japan (Investigation and Research for Intractable Inflammatory Bowel Disease; Grant Number 20316729).