NON-INVASIVE DETERMINATION OF DISEASE ACTIVITY IN CROHN’S DISEASE BY SERUM LUMINEX PROFILING

Abstract

Abstract BACKGROUND & AIMS Crohn’s disease (CD) is a chronic inflammatory disease with a complex pathogenesis; treatment and management largely depend on disease activity assessment, which can be challenging and invasive. The aim of this study was to assess the ability of multiplex Luminex technology to identify serum cytokine and/or chemokine markers of disease activity. METHODS Serum samples were prospectively obtained from 103 CD and 40 healthy controls undergoing colonoscopy. CD activity was determined by histologic assessment of colonoscopic biopsies. The Simple Endoscopic Score for Crohn’s Disease (SES) was available for 94 CD patients. We determined if the SES score was predictive of histologic activity (normal, quiescent, mild, moderate, or severe). Patient demographics and clinical history were obtained by chart review. Serum cytokines and chemokines were measured by a 47-plex Luminex assay. Analytes that had more than 70% of values below the lower limit of detection were excluded (GMCSF, IL3, IL17A, IL22, and TNFβ). Analyte profiles in controls v. CD patients were compared using the Mann-Whitney U test with Benjamini-Hochberg (BH) adjustment given multiple comparisons, and by disease activity (control v. inactive v. active) using the Kruskal-Wallis test, with post-hoc Dunn’s test with BH adjustment. RESULTS 34 CD patients were inactive (normal, quiescent) and 69 CD patients had active disease (mild, moderate, severe) on histology. Use of steroids, immunomodulators, and biologics did not differ significantly between the active and inactive CD groups. There was a strong positive correlation between SES score and histologic disease severity (Spearman’s r = 0.58, p<0.001). After BH adjustment, 16 analytes were significantly increased in CD v. controls: Fractalkine, GROα, IFNα2, IL1β, IL4, IL6, IL10, IL13, IL25, IL17F, IL18, MCP3, MCSF, PDGFAA, PDGFABBB, and TGFα. As shown in Table 1, when categorized by disease activity, 4 analytes were significantly increased and one analyte was significantly decreased in inactive disease v. control; 18 analytes were significantly increased in active v. control; and one analyte, CXCL9, which attracts effector T cells to sites of inflammation, was significantly increased in active v. inactive disease. CONCLUSIONS In CD patients, 16 of 42 serum cytokines and chemokines detectable by Luminex assay were increased v. healthy controls. When stratified by histologic disease activity, multiple analytes were found to be increased in inactive or active CD v. controls. Thus, CD is associated with alterations in serum cytokines and chemokines, which was much more frequent in CD patients with histologically active disease. Serum cytokine/chemokine profiling may be a non-invasive strategy to reduce the need for frequent colonoscopy in CD to assess disease activity. Table 1 Serum analyte profiles compared by disease activity (control v. inactive v. active). Data are shown in pg/mL as mean ± SD. p-values are calculated using Kruskal-Wallis test with post-hoc Dunn’s test with BH adjustment for multiple comparisons where 0.05 was considered significant. *p