S100A9 and bronchopneumonia: Following S. pneumoniae infection, lungs of S100A9 KO mice developed severe lobar bronchopneumonia characterized by consolidated infiltrates of interstitial and alveolar neutrophils and interstitial and alveolar edema, while lungs of S. pneumoniae-infected WT mice showed much less severe signs of bronchopneumonia (Fig 2C and 2D).