Objective: To investigate the changes of interleukin-17 (IL-17) both in rat models of chronic obstructive pulmonary disease (COPD) and in asthma.
Methods: Male SD rats were randomly divided into COPD group, asthma group, smoking group and control group. The concentrations of IL-17 in lung tissues and in bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay (ELISA). The expression of IL-17 in lung tissue was determined by immunohistochemical staining and photographic analysis.
Results: The concentrations of IL-17 both in the lung tissue and in the BALF were significantly higher in the COPD group and the asthma group than in the controls and the smoking group (all P <0. 01). IL-17 was mainly expressed in airway epithelial cells of COPD rats and in T lymphocytes around the airway in rats with asthma. The levels of IL-17 were also higher both in the COPD group and in the asthma group than in the smoking group and the controls (all P < 0. 01) evaluated by immunohistochemical staining and photographic analysis. In the COPD group,IL-17 concentration of lung tissue was positively correlated with percentage of neutrophils in BALF; it also tended to be positively correlated with the level of intercellular adhesion molecule-1 (ICAM-1) in airway epithelial cells, and the concentration of IL-17 in BALF was positively correlated with the degree of smooth muscle proliferation as well. The concentration of IL-17 in the lung tissue of the asthma group was positively correlated with the number of eosinophils in BALF and with the number of CD3 T lymphocytes in lung tissues respectively.
Conclusions: The production of IL-17 in COPD and in asthma might be distinct. IL-17 probably recruits neutrophils into airways by enhancing the expression of ICAM-1 in airway epithelial cells, and it might play a role in pathological changes of small airways in COPD. The role of IL-17 in asthma maybe associated with the recruitment of eosinophils into airways.