Th17-related cytokine expression is increased in the bronchial mucosa of stable COPD patients

Background: There is an increased number of activated Tl lymphocytes in the bronchial mucosa of stable COPD patients but are absent studies on Th17 cells and their effector cytokines.Objectives: To investigate the expression of retinoic orphan receptor(ROR)C2, interleukin(IL)-17A,IL-17F,IL-21,IL-22 and IL-23 in bronchial biopsies from patients with stable COPD of different severity(stage 2 to 4)compared with age-matched control subject(smokers with normal lung function and lifelong non-smokers).Methods: The expression of RORC2,IL-17A,IL-17F,IL-21,IL-22 and IL-23 was measured in the bronchial mucosa using immunohistochemistry and/or real time quantitative polymerase chain reaction. Results: The number of IL-22+ and IL23+ immunoreactive cells is increased in the bronchial epithelium of stable COPD compared with control groups. In addition, the number of IL-17A+ and IL22+ immunoreactive cells is increased in the bronchial submucosa of stable COPD compared with control non-smokers. In all smokers with and without disease and in patients with COPD alone the number of IL22+ cells is correlated significantly with the number of both CD4+ and CD8+ cells in the bronchial mucosa.The expression of the RORC2 mRNA in the bronchial mucosa was not significantly different between smokers with normal lung function and COPD. Conclusion: Thei ncreased expression of the Th17-related cytokines IL-17A,IL-22 and IL-23 maybe involved in the recruitment and activation of lymphocytes populating the bronchial mucosa and in the host defence developing in patients with stable COPD.