Diagnostic value of interleukins 23 and 17 in the assessment of ulcerative colitis severity

Background. Ulcerative colitis (UC) is a chronic bowel disease with a complex aetiology that includes immune, genetic and environmental factors. Its progression and severity vary greatly, suggesting that different cytokine pathways may be responsible for the heterogeneity of clinical outcomes. The purpose of the study was to investigate the state of cytokine regulation of inflammation depending on the severity of UC. Materials and methods. We examined 32 patients with UC who were treated at the Department of Intestinal Diseases of the State Institution “Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine”. Patients were divided into groups depending on disease severity determined by the Mayo index: moderate UC — 24 individuals, severe UC — 8 patients. Serum levels of interleukin (IL) 17 and IL-23 were determined by enzyme-linked immunosorbent assay. The study was performed according to the instructions for each test kit. Statistical processing of the results was done using the Statistica 6.1 software package. Results. The content of proinflammatory cytokines in the examined patients with UC was significantly higher than in the control group: IL-17 — by 9.0 times (р < 0.05), the median level of IL-23 — 8.6-fold (р < 0.05). When analysing the data depending on the disease severity, it was found that IL-17 was significantly higher in patients with moderate (by 9.9 times, р < 0.05) and severe UC (by 9.1 times, р < 0.05) than in controls. The median level of IL-23 was significantly higher in moderate (by 8.3 times, р < 0.05) and severe UC (by 13.2 times, р < 0.05) compared to that of the control group. In addition, with severe UC, the concentration of IL-23 was 1.6 times than in moderate UC. A correlation was found between the levels of IL-17 and IL-23 in patients with UC (r = +0.361; p = 0.042). Conclusions. The content of proinflammatory cytokines in UC has reliable differences vs. control group: IL-17 is significantly higher, by 9.0 times (р < 0.05), and IL-23 — by 8.6 times (р < 0.05). It was found that among patients with UC, the level of IL-23 was higher in those with severe course. Thus, quantitative determination of IL-17 and IL-23 levels in the blood serum of patients with UC can be a useful clinical tool for stratification by disease severity and help choose therapy.