Punicalin attenuates LPS-induced acute lung injury by inhibiting inflammatory cytokine production and MAPK/NF-κB signaling in mice

Abstract

BackgroundAcute lung injury (ALI) remains a significant cause of morbidity and mortality in critically ill patients. Novel therapies interfering with the inflammatory response has been an area of focus for infectious disease treatment. Punicalin has shown strong anti-inflammatory and antioxidative properties; however, its effect in ALI has not been previously explored. PurposeTo investigate the effects of punicalin in lipopolysaccharide (LPS)-induced ALI and explore the underlying mechanisms. MethodsLPS (10 mg/kg) was administered intratracheally to create the ALI model in mice. Punicalin (10 mg/kg) was administered intraperitoneally shortly after LPS to investigate survival rate, lung tissue pathological injury, oxidative stress, levels of inflammatory cytokines in BALF and lung tissue, neutrophil extracellular trap (NET) formation and its effects on NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. In vitro studies were performed to evaluate the inflammatory cytokine release and NET formation in LPS-induced (1 μg/ml) and punicalin-treated mouse neutrophils derived from the bone marrow. ResultsIn vivo, punicalin reduced mortality, lung injury score, lung wet-to-dry (W/D) weight ratio, protein concentrations in BALF and malondialdehyde (MDA) levels in lung tissues, and increased superoxide dismutase (SOD) levels in lung tissues of LPS-induced ALI mice. Increased secretion of TNF-α, IL-1β, and IL-6 in the BALF and the lungs of ALI mice was reversed by punicalin, whereas IL-10 was upregulated. Neutrophil recruitment and NET formation were also decreased by punicalin. Inhibition of NF-κB and MAPK signaling pathways was observed in punicalin-treated ALI mice. In vitro co-incubation with punicalin (50 μg/ml) inhibited the production of inflammatory cytokines and NET formation in LPS-treated neutrophils derived from mouse bone marrow. ConclusionPunicalin reduces inflammatory cytokine production, prevents neutrophil recruitment and NET formation, and inhibits the activation of NF-κB and MAPK signaling pathways in LPS-induced ALI.