Mucosal Interleukin-10 depletion in steroid-refractory Crohn's disease patients

Background: Previous studies suggested that Interleukin-10 (IL-10) depletion in Crohn's disease (CD) could predict outcome. Aim: To determine IL-10 in blood and at different intestinal locations in patients with active CD and to assess its potential prognostic capacity to identify aggressive CD. Methods: Twenty-three patients with CD were included. Ulcerative colitis (UC), infectious colitis and healthy individuals acted as controls. Serum and mucosal samples were taken at baseline and 1 month after steroid initiation in CD patients. Patients were classified according to steroid response. Control samples were obtained from different intestinal locations. IL-10 expression was measured with real-time polymerase chain reaction, immunofluorescence (intestine) and ELISA (serum, biopsy cultures' supernatants and tissue homogenates). Results: CD and UC showed an increase in IL-10 messenger RNA (mRNA) versus controls (p < .0001) in mucosa, whereas IL-10 protein secretion was increased in all types of intestinal inflammation (p < .001). No differences in IL-10 mRNA were found in CD at baseline regarding steroid response, but levels decreased in non-responders versus responders (p = .027) and were restored with rescue therapy. Serum IL-10 was increased in steroid-refractory CD at baseline and after treatment. Conclusions: Abnormal IL-10 levels in refractory patients in both mucosa and blood have physiopathological relevance and may have potential clinical applications.