HMOX1 and acute respiratory distress syndrome: Studies show that 5-methoxyflavone and hydnocarpin D can significantly regulate the inflammatory response in ALI by reducing the expression of Keap1 in macrophages and promoting the expression of antioxidant factors Nrf2 and HO-1, in which 5-methoxyflavone can inhibit M1 polarization of macrophages in ALI and M1 repolarization of M2 macrophages (Figure 2A,B) [45,54].