PDE4 inhibitors reduce H1N1 influenza-induced lung injury.

<p>C57/BL6 mice were challenged with H1N1 (10⁵ pfu/mouse, i.t.) for up to 6 days. For compound treatment, a stock solution (5 mg/ml) was added to the drinking water (containing 2% sucrose) to a final concentration of 30 µg/ml. <b>A.</b> Survival studies of mice administered i.t. with H1N1 (10⁵ pfu/mouse, <i>n</i> = 6 mice/group). Mice were then euthanized using pentobarbital and lungs were lavaged with saline, harvested, and then homogenized. Cell counts and lavage protein were measured (<b>B, C</b>). Lavage cytokine secretions were measured (<b>D, E</b>). Serum samples were also collected and cytokine levels were measured (<b>F, G</b>). <b>H.</b> H&E staining was performed on lung samples. Original magnification, ×60. The data represent <i>n</i> = 4–6 mice/group, *<i>P</i><0.05 versus vehicle.