N-phenethyl-5-phenylpicolinamide alleviates inflammation in acute lung injury by inhibiting HIF-1α/glycolysis/ASIC1a pathway

Acute lung injury (ALI) is triggered by an acute inflammatory response. Lipopolysaccharide (LPS) is recognized as an important participant in the pathogenesis of sepsis, which may induce ALI. N-phenethyl-5-phenylpicolinamide (N5P) is a newly synthesized HIF-1α inhibitor. The purpose of the present study was to investigate the potential protective effects of N5P on LPS-induced ALI and the underlying mechanisms. In vivo experiment, the ALI rat model was induced by intratracheal injection of LPS, and various concentrations of N5P were injected intraperitoneally before LPS administration. In vitro experiment, RAW264.7 macrophages were administrated LPS and N5P to detect inflammatory cytokine changes. HIF-1α overexpression plasmid (HIF1α-OE) and granulocyte-macrophage colony-stimulating factor (GM-CSF), a glycolysis agonist, were used to examine the relationship between the HIF-1α/glycolysis/ASIC1a pathway. Pretreatment with N5P inhibited not only the histopathological changes that occurred in the lungs but also lung dysfunction in LPS-induced ALI. N5P also decreased the levels of lactic acid in lung tissue and arterial blood, and inflammatory factors IL-1β and IL-6 levels in serum. LPS increased HIF-1α, glycolysis proteins GLUT1, HK2, ASIC1a, IL-1β, IL-6, and these changes were reversed by N5P in primary alveolar macrophages and RAW264.7 macrophages. Overexpression of HIF-1α significantly increased glycolysis genes and ASIC1a as well as inflammatory cytokines. Excessive glycolysis levels weaken the ability of N5P to inhibit inflammation. N5P may alleviate inflammation in ALI through the HIF-1α/glycolysis/ASIC1a signaling pathway. The present findings have provided pertinent information in the assessment of N5P as a potential, future therapeutic drug for ALI.