Exploring the Fecal miRNA Profile in FMF Patients and the Role of miR-21-5p in Inflammatory Pathways Associated with FMF Pathogenesis

Abstract

Introduction: Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disease caused by mutations in the MEFV gene encoding pyrin, a key inflammatory regulator. In addition to genetic factors, epigenetics seems to play an important role in the manifestation of FMF. Objectives: This study aims to evaluate the differential expression of selected miRNAs in stool samples of FMF patients, and to investigate the functional role of mir-21-5p in FMF-related inflammatory pathways. Methods: Twenty-four FMF patients, five patients with Clostridioides difficile infection (CDI), and 25 controls were recruited for this study. MEFV genotyping of FMF patients was performed by Sanger sequencing and disease severity was evaluated using the International Severity Score for FMF (ISSF). The fecal levels of 27 selected miRNAs implicated in inflammation, apoptosis, and autophagy were quantified by qRT-PCR. The functional role of mir-21-5p in regulating NF- κB and pyrin inflammasome pathways was investigated in LPS-stimulated THP-1 derived macrophages transfected with an anti-mir-21-5p inhibitor via western blot. Results: Among the 27 analyzed miRNAs, eight miRNAs were significantly higher in FMF patients compared to controls, with mir-21-5p, mir-30e-3p, and mir-148a-3p being specific to FMF patients. Correlation studies revealed that three anti-inflammatory miRNAs, mir-144-3p, mir-29b- 3p, and mir-374b-5p, were downregulated in M694V homozygous patients compared to those with other genotypes and six miRNAs were higher in patients with greater disease severity. The inhibition of mir-21-5p in LPS-stimulated THP-1 derived macrophages reduced the activation of NF-κB and inflammasome pathways. Conclusion: Our findings highlight the role of miRNAs in intestinal inflammation and their potential as diagnostic and prognostic markers in FMF. Furthermore, our functional data underscores the therapeutic potential of targeting mir-21-5p to treat FMF patients refractory to colchicine.