The inhibitory role of hydrogen sulfide in airway hyperresponsiveness and inflammation in a mouse model of asthma.

Cystathionine γ-lyase (CSE) is one of the major enzymes producing hydrogen sulfide (H2S) in lungs, participating in the regulation of respiratory functions. The role of CSE-derived H2S in eosinophil-dominant inflammation in allergic diseases has been unclear. The objective of this study was to explore the protective role of H2S against allergen-induced airway hyperresponsiveness (AHR) and inflammation. CSE expression and H2S production rate were assessed in mouse lung tissues with ovalbumin (OVA)-induced acute asthma. AHR, airway inflammation, and Th2 response in wild-type (WT) mice were compared with those in CSE gene knockout (KO) mice. The effect of NaHS, an exogenous H2S donor, was also evaluated on these parameters. CSE expression was absent and H2S production rate was significantly lower in the lungs of CSE KO mice when compared with WT littermates. OVA challenge decreased lung CSE expression and H2S production in WT mice. CSE deficiency resulted in aggravated AHR, increased airway inflammation, and elevated levels of Th2 cytokines such as IL-5, IL-13, and eotaxin-1 in bronchoalveolar lavage fluid after OVA challenge. The aforementioned alterations were reversed by exogenous H2S treatment. More importantly, NaHS supplement rescued CSE KO mice from the aggravated pathological process of asthma. The CSE/H2S system plays a critical protective role in the development of asthma. A new therapeutic potential for asthma via targeting CSE/H2S metabolism is indicated.