Quzhou Aurantii Fructus Extract Attenuates Idiopathic Pulmonary Fibrosis by Regulating Nrf2/HO-1 Axis

Recently, Quzhou Aurantii Fructus Extract (QAFE) was reported to exert anti-inflammatory effects on different types of respiratory diseases; however, it is yet to be determined whether it is effective in patients with idiopathic pulmonary fibrosis (IPF). The purpose of this study is to explore the capacity of QAFE to fight fibrotic disease, in particular how it works in relation to the regulation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway. QAFE was made with Quzhou Fructus Aurantii (QAF), and the content of four flavonoids in the samples prepared was analyzed by high-performance liquid chromatography (HPLC). The therapeutic effect of QAFE was experimented by establishing IPF models in mice and in cells. Identification of the mechanism of QAFE in IPF through knockout or knockdown of the Nrf2 gene. The experiments suggest that QAFE has the potential to prevent IPF-induced inflammation, collagen deposition, oxidative stress, and apoptosis of cells. Silencing Nrf2 by knockdown or knockout is enough to prevent the capacity of QAFE to inhibit the process of inflammation, oxidative stress, and collagen deposition to cause more serious lung injury and HO-1 expression downregulation. QAFE is a potential new antifibrotic drug in IPF with an effect on the Nrf2/HO-1 pathway that reduces inflammation and oxidative stress.