Smoking has become a major cause of chronic obstructive pulmonary disease through weakening of the respiratory mucus-ciliary transport system, impairing cough reflex sensitivity, and inducing inflammation. Recent researches have indicated that hydrogen sulfide is essential in the development of various lung diseases. However, the effect and mechanism of hydrogen sulfide on cigarette smoke-induced chronic obstructive pulmonary disease have not been reported. In this study, rats were treated with cigarette smoke to create a chronic obstructive pulmonary disease model followed by treatment with a low concentration of hydrogen sulfide. Pulmonary function, histopathological appearance, lung edema, permeability, airway remodeling indicators, oxidative products/antioxidases levels, inflammatory factors in lung, cell classification in bronchoalveolar lavage fluid were measured to examine the effect of hydrogen sulfide on chronic obstructive pulmonary disease model. The results showed that hydrogen sulfide effectively improved pulmonary function and reduced histopathological changes, lung edema, and permeability. Airway remodeling, oxidative stress, and inflammation were also reduced by hydrogen sulfide treatment. To understand the mechanisms, we measured the expression of TGF-β1, TGF-βIand TGF-βII receptors and Smad7 and phosphorylation of Smad2/Smad3. The results indicated that the TGF-β1 and Smad were activated in cigarette smoke-induced chronic obstructive pulmonary disease model, but inhibited by hydrogen sulfide. In conclusion, this study showed that hydrogen sulfide treatment alleviated cigarette smoke-induced chronic obstructive pulmonary disease through inhibition of the TGF-β1/Smad pathway.
Impact statement: COPD has become a severe public health issue in the world and smoking has become a major cause of COPD. As a result, it is a demandingly needed to explore new potential therapy for cigarette smoke-associated COPD. The present study suggested that H2S treatment improved pulmonary function and reduced histopathological changes, lung edema, permeability, inflammation, airway remodeling and oxidative injury in a COPD model induced by cigarette smoke. Although additional studies are required to elucidate the pharmacodynamics, pharmacokinetics, and pharmacology of H2S in the cigarette smoke-associated COPD, our findings provide an experimental basis for the potential clinical application of H2S in COPD treatment.
Keywords: Hydrogen sulfide; Smad; TGF-β1; chronic obstructive pulmonary disease; cigarette smoke.