Increased expression of interleukin-23 induces proinflammatory cytokine secretion in inflammatory bowel disease

Objective To analyze expression of interleukin (IL)-23p19 and IL-23 receptor (IL-23R) in inflammatory bowel disease (IBD),and the role in the induction of peripheral blood T cell activation and proinflammatory cytokine secretion.Methods Peripheral blood (PB) and intestinal mueosal biopsies were collected from 12 patients with Crohn's disease (CD),25 patients with ulcerative colitis (UC) and 20 healthy controls.Expression of IL-23p19 was determined by immunohistochemistry and RT-PCR.IL-23R expression in CD4+,CD8+ T and NK cells from peripheral blood and lamina propria was analyzed by flow eytometry.Peripheral blood mononuclear ceils (PBMC) were isolated and cultured under stimulation with IL-23 and anti-CD3,and the levels of tumor necrosis factor α (TNFα) interferon (IFN)γ and IL-2 were determined by enzyme-linked immunosorbent assay (ELISA).Results The expression of II.-23p19 was significantly increased in inflamed mucosa of CD at both the transcriptional and translational levels compared with that in UC and healthy controls.IL-23R was mainly expressed in PB- and lamina propria-CD4+,CD8+T cells and NK cells from IBD patients,and markedly increased compared with controls (P＜0.05).IL-23 strongly triggered PBMC from IBD patients to produce significantly higher levels of IFN-γ,TNF-α and IL-2(P＜0.05).Conclusions IL-23p19 and IL-23R are highly expressed in IBD,particularly in CD,and may play an important role in the induction of T cell activation and proinflammatory cytokine secretion,suggesting that targeted therapy directed against IL-23 may have a therapeutic role in IBD. Key words: Inflammatory bowel disease; Interleukin-23; Receptor,cytokines