Polysaccharides from Dendrobium officinale inhibit bleomycin-induced pulmonary fibrosis via the TGFβ1-Smad2/3 axis

Polysaccharides from Dendrobium officinale (PDO) have been found to elicit significant benefits for patients with fibrotic diseases. However, there are no reports on treatment of idiopathic pulmonary fibrosis (IPF) using PDO. The aim of this paper was to investigate the therapeutic effects of PDO on IPF and its underlying mechanisms. Our data showed that PDO significantly ameliorated indices for both pulmonary inflammation and fibrosis in a bleomycin (BLM)-induced pulmonary fibrosis model in rats, which was associated with inactivation of transforming growth factor β1 (TGFβ1)-Smad2/3 signaling pathway. Moreover, PDO effectively blocked TGFβ1-induced transformation of rat alveolar epithelial type II cells into myofibroblasts, with the inhibition of total Smad2/3, pSmad2/3, collagen I and fibronectin protein expression in a dose-dependent manner in vitro. Therefore, PDO may represent as a promising candidate biomacromolecule drug for the safe and effective therapy of IPF.