Exploring novel biomarkers in pediatric ulcerative colitis. The role of Lipocalin-2, MMP-9, and MMP-9/LCN-2 complex

Background and aims: Lipocalin-2 (LCN-2), Matrix Metalloproteinase-9 (MMP-9), and the MMP-9/LCN-2 complex are emerging biomarkers for ulcerative colitis (UC). While extensively studied in adults, data in children are limited. This study aimed to evaluate their serum levels in children with newly diagnosed UC, compare them with healthy controls, and assess correlations with disease severity and extent. Methods: In this prospective case-control study, 32 children with UC (6–18 years) and 38 healthy controls were enrolled. Baseline clinical (Pediatric Ulcerative Colitis Activity Index/ PUCAI), laboratory (albumin, hemoglobin, Erythrocyte Sedimentation Rate, C-reactive protein/CRP, fecal calprotectin), and endoscopic (extent, Ulcerative Colitis Endoscopic Index of Severity/UCEIS) data were collected. Serum LCN-2, MMP-9, and MMP-9/LCN-2 complex levels were measured by ELISA. Results: Serum LCN-2, MMP-9, and MMP-9/LCN-2 levels were significantly higher in UC patients than controls. ROC analysis indicated LCN-2 had the best diagnostic performance. Higher LCN-2 and MMP-9 levels were observed in children with more severe endoscopic disease (UCEIS > 4) or pancolitis. LCN-2 levels inversely correlated with albumin, whereas MMP-9 positively correlated with CRP and UCEIS. Conclusions: LCN-2 and MMP-9 are promising biomarkers in pediatric UC, reflecting disease severity and extent. Their measurement may have clinical utility in monitoring disease progression and guiding management in children.