Salvianolic acid B protects against paraquat-induced pulmonary injury by mediating Nrf2/Nox4 redox balance and TGF-β1/Smad3 signaling

The present study was aimed at exploring the protective effects of Salvianolic acid B (SalB) against paraquat (PQ) induced lung injury in mice. Lung fibrotic injuries were induced in mice by a single intragastrical administration of 300 mg/kg PQ then the mice were administrated with 200 mg/kg, 400 mg/kg SalB, 100 mg/kg vitamin C (Vit C) and dexamethasone (DXM) for 14 days. PQ-triggered structure distortion, collagen overproduction, excessive inflammatory infiltration, pro-inflammatory cytokine release, and oxidative stress damages in lung tissues and mortality of mice were attenuated by SalB in a dose-dependent manner. Furthermore, SalB was noted to enhance the expression and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and reduce expression of the reactive oxygen species-generating enzyme Nox4 [NADPH (reduced form of nicotinamide adenine di nucleotide phosphate) oxidase-4]. SalB also inhibited the increasing expression of transforming growth factor (TGF)-beta 1 and the phosphorylation of its downstream target Smad3 which were enhanced by PQ These results suggest that SalB may exert protective effects against PQ-induced lung injury and pulmonary fibrosis. Its mechanisms involve the mediation of Nrf2/Nox4 redox balance and TGF-beta 1/Smad3 signaling. (C) 2016 Published by Elsevier Inc.