Wedelolactone protects human bronchial epithelial cell injury against cigarette smoke extract-induced oxidant stress and inflammation responses through Nrf2 pathway

Cigarette smoke is the leading cause of the development of various lung diseases including lung cancer through triggering oxidant stress and inflammatory responses which contributed to the lesions of normal human bronchial epithelial (NHBE) cell. Wedelolactone (WEL), a natural compound from Eclipta prostrata L., has been found to possess the inhibitive effects on the proliferation and growth of cancers. In the present study, we investigated the effects of WEL on NHBE cell injury induced by cigarette smoke extract (CSE) in vitro. It showed that the pretreatment WEL (2.5-20 μM) resulted in a significant protective effect on 10% CSE-induced cell death in NHBE cells. The pretreatment with WEL dose-dependently and significantly reversed the activities of SOD, CAT, GSH and the level of MDA to normal level. We also found that the protein expression levels of COX-2 and ICAM-1 which are related to inflammatory response were remarkably reduced by WEL compared with 10% CSE treatment. Additionally, WEL also reduced the expressions of antioxidases including NAD(P)H dehydrogenase:Quinone 1 (NQO1) and heme oxygenase-1 (HO-1). Moreover, Nrf2 inhibitor all-trans-retinoic acid (ATRA) decreased remarkably their expressions. These results suggest that WEL protects NHBE cell against CSE-induced injury through modulating Nrf2 pathway. Our study indicates that WEL may be a new potential protective agent against CSE-induced lung injury.