Nicotine suppressed the inflammatory response induced by pdmH1N1 infection <i>in vitro</i> and <i>in vivo</i>.

<p>A) Nicotine inhibited the pdmH1N1-induced production of cytokines and chemokines in primary human macrophages. Primary human macrophages were pre-treated with 10 µM nicotine for 72 h, and then infected with pdmH1N1 virus. Data represent 4–5 independent experiments. ^##<i>p</i><0.01 and ^###<i>p</i><0.001 were tested by ANOVA of three groups; *<i>p</i><0.05 and ***<i>p</i><0.001 were determined by Tukey post hoc test. B) Body weight changes of nicotine treated mice after pdmH1N1 virus infection. The mice were pre-treated with nicotine subcutaneously for 21 days and then infected by pdmH1N1 virus. There were 5 mice per group. Data are representative of two independent experiments. *<i>p</i><0.05 was examined by multiple regression analysis adjusted for time. C) Lung virus titers of nicotine treated mice at indicated time points after pdmH1N1 infection. There were 4 mice per group. D) Production of cytokines and chemokines in the lung homogenates from nicotine treated mice after pdmH1N1 virus infection. There were 4–5 mice per group. *<i>p</i><0.05 and **<i>p</i><0.01 were performed by unpaired two-tailed Student's <i>t test</i>. Results represent mean ± SEM.