Faecal chitinase 3-like-1: a novel biomarker of disease activity in paediatric inflammatory bowel disease

Background Chitinase 3-like-1 (CHI3L1) is up-regulated in the inflamed mucosa of inflammatory bowel disease (IBD). Aim To evaluate the usefulness of a faecal CHI3L1 assay, as a reliable marker for predicting the severity of paediatric IBD. Methods Faecal samples were obtained from ulcerative colitis (UC, n = 94), Crohn's disease (CD, n = 87), and healthy individuals (n = 56). The faecal CHI3L1 and calprotectin levels were determined by ELISA. For endoscopic evaluation, the sum of the Matts' score for UC and the simple endoscopic score for CD (SES-CD) were used. Ileal lesions were evaluated by ultrasonography. Results Faecal CHI3L1 levels were significantly elevated in active UC (median 366.6 ng/g, n = 44) and active CD (median 632.7 ng/g, n = 48) patients, as compared with healthy individuals (median 2.2 ng/g, n = 56). In UC patients, the faecal CHI3L1 levels were positively correlated with the sum of the Matts' score (r = 0.73, P < 0.01, n = 42). In CD patients, there was a significant correlation between faecal CHI3L1 levels and endoscopic activity as determined by the SES-CD scoring system (r = 0.61, P < 0.01, n = 25). The faecal CHI3L1 levels of patients with wall thickening of their small intestine were significantly higher than those of healthy controls or patients without wall thickening. The cutoff value of 13.7 ng/g for fecal CHI3L1(the 95th percentile of the control value) predicted active lesions in IBD patients with a sensitivity of 84.7% and a specificity of 88.9%. Conclusion Faecal CHI3L1 assays may be useful for predicting the severity and activity of mucosal inflammation in IBD. Aliment Pharmacol Ther 2011; 34: 941-948