Forsythin (60), a novel PDE4 inhibitor, inhibited the expression of PDE4 and production of NO, inducible nitric oxide synthase (iNOs), Toll-like receptor 4 (TRL4), TNF-α, IL-1β in LPS-induced lung injury mice, LPS-stimulated BV2 microglial cells and Staphylococcus aureus-induced monocyte-macrophages [94,95,99,111]. Here, PDE4A is linked to injury.