Forsythiaside Inhibits Cigarette Smoke-induced Lung Inflammation by Activation of Nrf2 and Inhibition of NF-κB

Cigarette smoke has been reported to be the major cause of chronic obstructive pulmonary disease (COPD). It causes persistent inflammation by regulating the redox-sensitive pathways. Forsythiaside, an active constituent isolated from the Chinese medicinal herb Forsythia suspensa, has been reported to have anti-inflammatory and anti-oxidant effects. Thus, in this study, we investigated the protective effects of forsythiaside against cigarette smoke-induced lung inflammation in mice. COPD mice model was established by cigarette smoke. Forsythiaside was given 2h before cigarette smoke exposure for five consecutive days. Bronchoalveolar lavage fluid and lung tissues were collected to assess pathological changes, lipid peroxidation, inflammatory cytokine production, Nrf-2, and NF-κB expression. Our results showed that forsythiaside attenuated the infiltration of inflammatory cells, NO and inflammatory cytokines TNF-α, IL-6 and IL-1β production, and reversed the CS-induced decrease of glutathione/glutathione disulfide (GSH/GSSG) ratio. Western blot analysis showed that forsythiaside inhibited cigarette smoke-induced NF-κB activation. In addition, forsythiaside dose-dependently up-regulated the expression of Nrf2 and HO-1. In conclusion, forsythiaside protected against cigarette smoke-induced lung injury through activating Nrf2 and inhibiting NF-κB signaling pathway.