Endocytoscopic Classification Is Associated with Mucosal miR-192-5p Downregulation and CXCL2 Expression in Ulcerative Colitis: An Exploratory Study

Background/Objectives: Ultra-high-magnification endoscopy (Endocyto) visualizes microscopic mucosal structures and has been proposed as a tool for assessing mucosal inflammation. We previously developed an endocytoscopic classification system (EC-A to EC-D) for grading the severity of inflammation. In this study, we investigated the relationship between endocytoscopic classification and microRNA (miRNA) expression in 36 patients with ulcerative colitis (UC). Methods: This cross-sectional study was conducted in two phases at two institutions. In the first phase, microarray analysis was performed on biopsy samples from patients with UC and healthy controls enrolled at Nagasaki University Hospital. In the second phase, 36 patients with UC who underwent total colonoscopy via Endocyto at Tottori University Hospital were included, and selected miRNAs were analyzed via quantitative polymerase chain reaction. Results: Differentially expressed miRNAs were identified, and four (miR-141-5p, miR-192-5p, miR-194-5p, and miR-215-5p) were downregulated in inflammatory areas. Notably, miR-192-5p expression was markedly lower in the EC-B and EC-C+D groups than in the EC-A group. Furthermore, expression of CXC motif ligand 2 (CXCL2), a pro-inflammatory chemokine, was upregulated in inflammatory tissues and negatively correlated with miR-192-5p expression. Conclusions: These results indicate that reduced miR-192-5p expression is inversely associated with CXCL2 expression and that, among the miRNAs examined, miR-192-5p downregulation most consistently corresponded to the endocytoscopic classification. Our findings suggest that Endocyto may serve as a real-time, in vivo adjunct for a histology-like assessment of mucosal inflammation; its clinical utility requires prospective validation.