Attenuation of Bleomycin-Induced Pulmonary Fibrosis in Rats with S-Allyl Cysteine

Pulmonary fibrosis is a complex disease with high mortality and morbidity. As there are currently no effective treatments, development of new strategies is essential for improving therapeutic outcomes. S-allyl cysteine (SAC) is a constituent of aged garlic extract that has demonstrated efficacy as an antioxidant and anti-inflammatory agent. The current study examines the effects of SAC on pulmonary fibrosis induced by a single intratracheal instillation of bleomycin (2.5 mg/kg). SAC was administered to rats as 0.15% SAC-containing diet from seven days prior to instillation up until the conclusion of the experiment (14 days post-instillation). SAC significantly reduced collagen mRNA expression and protein deposition (33.3 ± 2.7 μg/mg and 28.2 ± 2.1 μg/mg tissue in vehicle- and SAC-treated rats, respectively), and decreased fibrotic area, as assessed histologically. In the rats’ lungs, SAC also attenuated the increased expression of transforming growth factor-β1 (TGF-β1), a central regulator of myofibroblast recruitment, activation, and differentiation. While bleomycin instillation increased the number of myofibroblasts within the lung mesenchymal area, this change was significantly reduced by SAC treatment. SAC may exert efficacy as an anti-fibrotic by attenuating myofibroblast differentiation through TGF-β1-mediated fibroproliferative processes. Thus, our results indicate SAC may be useful for the prevention or treatment of pulmonary fibrosis.