P136 Serum IL-17 and IL-23 levels can distinguish between severe and non-severe inflammatory bowel disease

Abstract

Background: Interleukin-17 (IL-17) and Interleukin-23 (IL-23) are both involved in the regulation of the immune response and inflammation in inflammatory bowel disease (IBD) patients. IL-17 is produced upon IL-23 stimulation of Th17 cells in a proinflammatory context. Il-23 is also highly expressed in colonic tissue, therefore being a therapeutic target in many clinical trials. High serum levels of IL-17 and IL-23 in IBD patients with active disease has been reported before, but the relationship between these cytokines and disease severity has not been thoroughly assessed. We aimed to investigate whether the levels of IL-17 and IL23 in the serum of patients with Crohn's disease (CD) and ulcerative colitis (UC) reflect disease severity and whether they correlate with standard inflammatory biomarkers, such as C-reactive protein (CRP) and faecal calprotectin (FC). Method(s): 77 participants were prospectively included in the study: 31 patients with CD, 31 patients with UC and 15 healthy controls (HC). Blood was collected at the clinic in tubes containing serum separator clot activator, and serum was obtained and stored at -80degreeC until analysis. Using disease activity scores such as Mayo and CDAI, serum and faecal inflammatory biomarkers (albumin, ESR, CRP, faecal calprotectin), disease pattern (stricturing and/or fistulising disease for CD), history of IBD-related surgery, we further classified the patients into severe (s) and non-severe (ns) disease. As such, the study consisted of five groups 15 HC, 16 CDns, 15 CDs, 14 UCns and 17 UCs. Serum levels of IL-17 and IL-23 were determined using sandwich enzyme-linked immunosorbent assays (ELISA). Data are presented as mean and differences among the groups were analysed by employing Student t-test and significance was set at p < 0.05. Result(s): Serum levels of IL-17 were 454.3 pg/ml in the HC group, 926.6 pg/ml in the UCns group, 1914 pg/ml in the Ucs group, 855.9pg/ml in the CDns group and 1484pg/ml in the CDs group. Serum levels of IL-23 were 371.4 pg/ml in the HC group, 748.1pg/ml in the UCns group, 1535 pg/ml in the UCs group, 784.8 pg/ml in the CDns group and 1488 +/- 101.8 pg/ml in the CDs group respectively. T-test result showed significantly differences among the IL-23 and IL-17 serum levels in the s and ns patients among the IBD groups IL-17 and IL-23 serum levels could not distinguish between Ucs and CDs patients. These results were consistent with standard inflammatory biomarkers levels (CRP and FC). Conclusion(s): IL-17 and IL-23 serum level can differentiate between IBD patients with severe and non-severe disease and can assess disease severity in the clinical practice. Further monitorization of these cytokines in larger IBD groups might be a promising tool in assessing disease progression.