Resveratrol ameliorates lipopolysaccharide-induced epithelial mesenchymal transition and pulmonary fibrosis through suppression of oxidative stress and transforming growth factor-β1 signaling

Abstract

Fibrotic changes seem to be responsible for the high mortality rate observed in patients with acute respiratory distress syndrome (ARDS). The present study aimed to determine whether resveratrol, a natural antioxidant polyphenol, had anti-fibrotic effects in the murine model of lipopolysaccharide (LPS)-induced pulmonary fibrosis. Fibrosis was assessed by determination of collagen deposition, hydroxyproline and type I collagen levels in lung tissues. Development of epithelial-mesenchymal transition (EMT) was identified by the loss of E-cadherin accompanying by the acquisition of α-smooth muscle actin (α-SMA). Transforming growth factor (TGF)-β1 content, levels of phosphorylated Smad2/Smad3 and Smad4, malondialdehyde (MDA) content, total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, and catalase (CAT) activity in lung tissues were determined. LPS increased collagen deposition, hydroxyproline and type I collagen contents, and meanwhile induced EMT process, stimulated TGF-β1 production and Smad activation in lung tissues on day 21 to day 28 after LPS administration. In addition, LPS treatment resulted in a rapid induction of oxidative stress as evidenced by increase of MDA and decreases of T-AOC, CAT and SOD activities as early as 7 days after LPS treatment, which was persistent for at least 4 weeks. In contrast, resveratrol treatment attenuated LPS-induced EMT and pulmonary fibrosis, meanwhile it suppressed LPS-induced oxidative stress, TGF-β1 production and activation of Smad signaling pathway. Resveratrol may ameliorate LPS-induced EMT and pulmonary fibrosis through suppression of oxidative stress and TGF-β1/Smad signaling pathway. Application of antioxidants may represent a useful adjuvant pharmacologic approach to reduce ARDS-associated pulmonary fibrosis.