Non-invasive determination of disease activity in Crohn's disease by serum luminex profiling

Crohn’s disease (CD) is a type of inflammatory bowel disease (IBD), and treatment depends on disease activity assessment requiring invasive procedures. We aimed to identify serum cytokines/chemokines that differ between CD and controls, and by clinical, endoscopic, and histologic disease activity. Serum samples were obtained from 103 CD to 40 non-IBD controls undergoing colonoscopy. Clinical information was obtained by questionnaire and chart review. Disease activity was determined: clinically (Crohn’s Disease Activity Index), endoscopically (Simple Endoscopic Score for Crohn’s Disease), and histologically from colonoscopic biopsies. Cytokines/chemokines were measured by Luminex assay and compared by disease activity assessments (control vs. inactive vs. active), with adjustment for multiple comparisons. Correlation between activity indices and versus analytes were performed. Multiple analytes were significantly altered between clinically, endoscopically, and histologically inactive and active CD vs. control. One analyte, CXCL9, was significantly increased in active vs. inactive CD in endoscopic and histologic activity assessments. CXCL9 was the only analyte with a significant correlation to both SES (r = 0.57, q < 0.001) and histologic severity (r = 0.42, q < 0.001). CXCL9 had the highest discriminatory capacity for active vs. inactive disease both endoscopically (AUC = 0.76, 95% CI 0.65–0.87) and histologically (AUC = 0.79, 95% CI 0.70–0.88). Cytokine/chemokine profiling differentiated CD vs. controls and by disease activity, with CXCL9 as a potential marker distinguishing activity in endoscopic and histologic assessments. Serum cytokine/chemokine profiling may be a non-invasive strategy to assess disease activity in CD.