Lapiferin protects against H1N1 virus-induced pulmonary inflammation by negatively regulating NF-kB signaling

H1N1 virus-induced excessive inflammatory response contributes to severe disease and high mortality rates. There is currently no effective strategy against virus infection in lung. The present study evaluated the protective roles of a natural compound, lapiferin, in H1N1 virus-induced pulmonary inflammation in mice and in cultured human bronchial epithelial cells. Initially, Balb/C mice were grouped as Control, H1N1 infection (intranasally infected with 500 plaque-forming units of H1N1 virus), lapiferin (10 mg/kg), and H1N1+lapiferin (n=10/group). Lung histology, expression of inflammatory factors, and survival rates were assessed after 14 days of exposure. Administration of lapiferin significantly alleviated the virus-induced inflammatory infiltrate in lung tissues. Major pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, were decreased at both mRNA and protein levels by lapiferin administration in the lung homogenate. Lapiferin also reduced inflammatory cell numbers in bronchoalveolar fluid. Mechanistically, lapiferin suppressed the transcriptional activity and protein expression of NF-κB p65, causing inhibition on NF-κB signaling. Pre-incubation of human bronchial epithelial cells with an NF-κB signaling specific activator, ceruletide, significantly blunted lapiferin-mediated inhibition of pro-inflammatory cytokines secretion in an air-liquid-interface cell culture experiment. Activation of NF-κB signaling also blunted lapiferin-ameliorated inflammatory infiltrate in lungs. These results suggested that lapiferin was a potent natural compound that served as a therapeutic agent for virus infection in the lung.