Hydrogen sulfide protects against bleomycin-induced pulmonary fibrosis in rats by inhibiting NF-κB expression and regulating Th1/Th2 balance.

Hydrogen sulfide (H2S) displays vasodilative, anti-oxidative, anti-inflammatory and cytoprotective activities. The objective of this study was to evaluate the inhibitory effect of H2S on bleomycin (BLM)-induced pulmonary fibrosis in rats and its possible mechanisms. Fifty-four pathogen-free Male Wistar rats were randomly divided into three groups: control, BLM and H2S treated groups with 18 rats in each group. Each group was then divided into three subgroups based on time of study (7, 14 and 28 day). Pulmonary fibrosis model was established by a single intratracheal instillation of BLM A5 (5 mg/kg). While control rats received saline, rats of the treated group simultaneously were administered intraperitoneal injections of NaHS (the H2S donor, 28 μmol/kg) once daily. BLM induced pulmonary inflammation and fibrosis, increased lung hydroxyproline levels, lung index, total cell counts, neutrophils and eosinophils counts and expression of NF-κB p65 in lung tissue, decreased lymphocytes and macrophages counts. In addition, Th1 response is suppressed as shown by diminished IFN-γ in bronchoalveolar lavage fluid (BALF) after BLM exposure, and enhancement of Th2 response is marked by increased IL-4 in BALF. H2S administration significantly attenuated these effects. The findings reveal the therapeutic potential of H2S for BLM-induced pulmonary fibrosis in male rats, which were at least partly due to inhibition NF-κB p65 expression and regulation of Th1/Th2 balance.