Fig. 1

HE staining of lung tissue. Arrows: blue - leukomonocytes, red - neutrophils, black - macrophages. a Lung tissues from the control group. These tissues show a few RBCs from the trachea and bronchus in the interalveolar septa. Scale bar, 10 μm. b-f Lung tissues from the treatment groups. Scale bar, 10 μm. b Four hours after infection, interalveolar septa shows infiltration of inflammatory cells. c Six hours after infection, the interalveolar septa shows an increase of inflammatory cells, bleeding, and thickening. d Eight hours after infection, the interalveolar septa is filled with fibrin and cells, including leukomonocytes, neutrophils, macrophages and RBCs. e Ten hours after infection, a vein and interalveolar septa exhibit numerous neutrophils. f Twelve hours after infection, serious thickening of the interalveolar septa, with bleeding and infiltration of neutrophils and leukomonocytes, is observed