Clinical Value of Neutrophil Gelatinase-Associated Lipocalin as a Non-Invasive Biomarker for Intestinal Ulcer in Behçet’s Syndrome: A Pilot Study

Intestinal Behçet’s syndrome (BS) is a severe phenotype associated with high morbidity and mortality. Early identification of intestinal involvement in BS remains clinically challenging due to the lack of reliable biomarkers. Neutrophil gelatinase-associated lipocalin (NGAL) is abundantly secreted during intestinal inflammation and has been recognized as a promising inflammatory biomarker. This study was designed to investigate the clinical value of NGAL for predicting intestinal involvement in BS patients. BS patients who underwent colonoscopy for suspected intestinal lesions were enrolled and classified into intestinal BS and non-intestinal BS groups. Immunohistochemistry was performed to compare colonic mucosal NGAL expression among intestinal BS, non-intestinal BS, inflammatory bowel disease (IBD) patients, and healthy controls. Serum and fecal NGAL levels were also measured in intestinal BS, non-intestinal BS, and healthy controls. Intestinal mucosal NGAL expression was significantly elevated in both intestinal BS and IBD patients, with no significant difference between the two groups. Serum and fecal NGAL levels were both higher in intestinal BS patients than in healthy controls. Notably, only fecal NGAL was significantly increased in intestinal BS compared to non-intestinal BS (p < 0.001). Multivariate logistic regression analysis identified fecal NGAL as an independent predictive factor for intestinal involvement in BS (OR = 1.093, 95% CI: 1.017–1.174, p = 0.015), with superior predictive performance over conventional inflammatory markers. In conclusion, fecal NGAL serves as a non-invasive and promising biomarker for risk stratification of intestinal involvement in BS patients. Further large-scale prospective studies are required to verify these preliminary results.