Tobacco smoking aggravates airway inflammation by upregulating endothelin-2 and activating the c-Jun amino terminal kinase pathway in asthma

Abstract

BackgroundAsthma is closely associated with tobacco smoking (TS) and is more difficult to effectively treat after exposure to TS. ObjectiveTo observe the effects of TS on the expression of endothelin-2 (ET-2) and airway inflammation in asthmatic rats and to explore the related mechanisms. MethodsWe established an animal model of asthma with ovalbumin (OVA)/Al(OH)3 and subjected different animal groups to TS and/or dexamethasone/bosentan. The differences in the inflammatory cell infiltration, the pathological changes to the bronchial wall and the bronchial smooth muscle thickness, and the expression of ET-2, c-Jun amino terminal kinase (JNK1/2), malondialdehyde (MDA), and glutathione peroxidase (GSH) in the lung tissue and of interleukin (IL)-7 in bronchoalveolar lavage fluid (BALF) were assessed. ResultsExposure to TS or OVA caused an obvious increase in the inflammatory cells in the BALF over what was observed in the control group. In asthma models, the expression of ET-1, JNK1/2, MDA, and GSH in the lung tissues, as well as that of IL-17 in the BALF, was increased. After treatment with dexamethasone/bosentan, the expression of IL-17, JNK1/2, MDA, and GSH decreased compared to the smoking group; airway inflammation and the staining intensity in the lung tissue were also reduced. ConclusionTS exposure can clearly exacerbate airway inflammation in asthmatic rats, while bosentan can alleviate airway inflammation through regulation of the ET-2/JNK1/2 signalling pathway.