Plantamajoside ameliorates lipopolysaccharide-induced acute lung injury via suppressing NF-κB and MAPK activation

Despite developments in the knowledge and therapy of acute lung injury in recent decades, mortality remains high, and there is usually a lack of effective therapy. Plantamajoside, a major ingredient isolated from Plantago asiatica L. (Plantaginaceae), has been reported to have potent anti-inflammatory properties. However, the effect of plantamajoside on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice has not been investigated. The present study aimed to reveal the potential mechanism responsible for the anti-inflammatory effects of plantamajoside on LPS-induced acute lung injury in mice and in RAW264.7 cells. The results of histopathological changes as well as the lung wet-to-dry ratio and myeloperoxidase (MPO) activity showed that plantamajoside ameliorated the lung injury that was induced by LPS. qPCR and ELISA assays demonstrated that plantamajoside suppressed the production of IL-1β, IL-6 and TNF-α in a dose-dependent manner. TLR4 is an important sensor in LPS Infection. Molecular studies showed that the expression of TLR4 was inhibited by plantamajoside administration. Further study was conducted on nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) using pathways using western blots. The results showed that plantamajoside inhibited the phosphorylation of IκBα, p65, p38, JNK and ERK. All results indicated that plantamajoside has protective effect on LPS-induced ALI in mice and in RAW264.7 cells. Thus, plantamajoside may be a potential therapy for the treatment of pulmonary inflammation.