Some studies have reported that PI3K inhibition reduces Th2 cytokine production, pulmonary eosinophilia, airway inflammation, and bronchial hyperresponsiveness in a mouse asthma model 48, 49. In addition, PI3K is shown to be involved in HIF-1α activation induced by oxygen-dependent or oxygen-independent pathways 50, 51. Recently, p110δ and p110γ isoforms have sparked a great deal of interest, as there is increasing evidence that Decitabine cost these isoforms play key roles in immunity 52. We have also demonstrated that OVA-induced HIF-1α

activation is significantly reduced by administration of a PI3K-δ inhibitor and suggested that inhibition of the p110δ signaling pathway has therapeutic potential for allergic airway inflammation 33. Consistent with these observations, in the present study, levels of p-Akt protein and PI3K activity in lung tissues were increased after OVA inhalation. The increased levels of p-Akt and PI3K Nutlin-3 nmr activity were significantly reduced after administration of IC87114, a PI3K-δ inhibitor. Moreover, the increased levels of HIF-1α after OVA inhalation were significantly reduced by IC87114 in primary tracheal epithelial cells isolated from OVA-treated mice. These findings suggest

that PI3K-δ regulates HIF-1α activation therewith inducing VEGF expression in a murine model of allergic airway disease. In summary, we have examined the roles of HIF-1α in allergen-induced airway inflammation and bronchial hyperresponsiveness using an HIF-1α inhibitor,

2ME2, and siRNA targeting HIF-1α and evaluated the role of PI3K-δ signaling in HIF-1α activation in allergic airway disease. The administration of 2ME2 was effective in reversing all pathophysiological symptoms examined. Our data have also revealed that HIF-1α inhibition substantially reduces the increase in VEGF expression as well as the activity of VEGF in lungs, especially in bronchial epithelial cells, of our murine model of allergic Sorafenib mouse airway disease. In addition, administration of IC87114 reduced the increase in HIF-1α activity in OVA-treated airway epithelial cells. Therefore, one likely mechanism for the roles of HIF-1α in pathobiology of allergen-induced airway inflammation and hyperresponsiveness is induction of vascular leakage via up-regulation of VEGF expression in lungs as well as bronchial epithelium. Thus, these findings provide a crucial molecular mechanism for the potential of HIF-1α inhibition in preventing and/or treating asthma and other airway inflammatory disorders. Female C57BL/6 mice, aged 8–10 wk and free of murine specific pathogens, were obtained from the Orientbio (Seoungnam, Korea) were housed throughout the experiments in a laminar flow cabinet and were maintained on standard laboratory chow ad libitum.