IL-33 induced inflammation exacerbated the development of chronic obstructive pulmonary disease through oxidative stress.

OBJECTIVE: We aimed at exploring the role of IL-33 in mouse chronic obstructive pulmonary disease and its potential molecular mechanism. MATERIALS AND METHODS: The chronic obstructive pulmonary disease (COPD) mice model was established by cigarette smoking (CS). COPD mice were randomly assigned into PBS group and IL-33 antibody group. The peripheral blood and lung tissues of mice from two groups were collected for the following experiments. Pathological changes of the lung tissues in both groups were analyzed by hematoxylin and eosin (HE) staining. IL-33 positive cells in lung tissues were detected by immunohistochemistry. Then, the mRNA and protein levels of IL-33, sST2, ERK and TNF-α in the mice peripheral blood of the two groups were accessed by Real-time polymerase chain reaction (RT-PCR) and Western blot. Finally, the indicators related to oxidative stress, including superoxide dismutase (SOD), malondialdehyde (MDA) and reactive oxygen species (ROS) in the mice serum of two groups were measured. RESULTS: After successful construction of COPD mouse model by CS, HE staining illustrated that the structure of airway wall of lung tissue in mice from PBS group was irregular. The ciliated columnar epithelium presented significant degeneration, necrosis and shedding. A large amount of inflammation cell infiltration was observed in vascular tissues. The alveolar epithelial structure was severely damaged and alveolar septum was narrowed and ruptured. Adjacent alveoli were found to be fused into larger cysts. The above pathological changes were relatively better in mice from IL-33 antibody group. Immunohistochemical results demonstrated that IL-33 was remarkably deposited in the lung tissue of PBS group. The mRNA and protein levels of IL-33, sST2, ERK and TNF-α in peripheral blood of PBS group were much higher than those of IL-33 antibody group. At the same time, SOD level in PBS group decreased, while MDA level and ROS production increased. CONCLUSIONS: IL-33 aggravates lung injury in COPD mice by increasing inflammation response and oxidative stress, which may serve as a target for predicting and treating COPD.