Prognostic significance of faecal eosinophil granule proteins in inflammatory bowel disease

Background: Non-invasive markers for predicting relapse would be a useful tool for the management of patients with inflammatory bowel disease. Eosinophil granulocytes and their granule proteins eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) have previously been shown to reflect disease activity in Crohn’s disease and ulcerative colitis. Aim: To examine the capacity of faecal ECP and EDN to predict relapse in ulcerative colitis and Crohn's disease, and to compare these proteins with faecal calprotectin. Methods: Patients with Crohn's disease (n = 49) and ulcerative colitis (n = 55) were followed prospectively until relapse or end of the two-year study period. Faecal samples were obtained every third month. The predictive value of ECP and EDN was assessed in Cox regression models. Results: In ulcerative colitis, a doubled EDN or ECP concentration was associated with a 31% and 27% increased risk of relapse, respectively. EDN levels were increased both at relapse and three months prior. By contrast, in Crohn's disease, the concentration of EDN was higher among patients in remission than in those who relapsed. Correlations between faecal calprotectin, ECP and EDN were observed in both diseases. Conclusions: We demonstrate that the risk of relapse in ulcerative colitis can be predicted by consecutively measuring faecal EDN every third month, and suggest EDN as a complementary faecal marker to calprotectin to predict future relapse in ulcerative colitis. Our finding of higher EDN in Crohn’s disease-patients staying in remission than in those who relapsed indicates different functions of the protein in ulcerative colitis and Crohn’s disease.