Serum X-C Motif Chemokine Ligand 1 Is Associated with Endoscopic Activity in Crohn's Disease: A Clinical Biomarker Study.

BACKGROUND/AIMS: Monitoring endoscopic inflammation in Crohn's disease (CD) is difficult. This study examined whether X-C motif chemokine ligand 1 (XCL1) is associated with endoscopic activity, as defined by the Simple Endoscopic Score for Crohn's Disease (SES-CD).

MATERIALS AND

METHODS

This was a single-center observational biomarker study. Peripheral blood mononuclear cell (PBMC) transcriptome sequencing was performed in 6 patients with newly diagnosed CD and 6 controls without inflammatory bowel disease. XCL1 protein expression was evaluated using immunohistochemistry and western blotting in 12 intestinal biopsy samples. Serum XCL1 levels were measured using enzyme-linked immunosorbent assay in 125 patients with CD and 40 controls. Patients with CD were classified according to the SES-CD. Correlation, logistic regression, receiver operating characteristic, bootstrap validation, and treatmentadjusted analyses were performed.

RESULTS

XCL1 was upregulated in PBMCs and increased in the intestinal mucosa of patients with active disease. Serum XCL1 levels differed among controls and SES-CD groups (P < .001). In patients with CD, serum XCL1 correlated with SES-CD (r = 0.692), fecal calprotectin (FC) (r = 0.573), Crohn's Disease Activity Index (r = 0.420), and C-reactive protein (CRP) (r = 0.433; all P < .001). XCL1 remained associated with endoscopic activity after adjustment (odds ratio = 1.005, 95% CI= 1.001-1.008, P = .012). The areas under the curve were 0.76 for XCL1, 0.81 for FC, and 0.85 for the XCL1+FC+CRP model.

CONCLUSION

Although serum XCL1 was associated with SES-CD-defined endoscopic activity, its performance was lower than that of FC. XCL1 may serve as an exploratory adjunctive serum marker but requires further validation.