Lung injury scoring of histology

Blinded histological scoring was implemented to assess of the severity of airway inflammation and hemorrhage in WT (n=5) and Timp1^−/− (n=5) lungs as previously described [16]. Sections of each of the lobes from the right lung were randomly selected for pathological assessment. Scores were determined by the estimated percentage of the section of lung affected by inflammation determined by the collection of inflammatory cells, destruction to the parenchyma, such as the alveolar space, and loss of integrity of the epithelial cell barrier of the airway. Hemorrhage was scored based upon the presence and degree of red blood cell infiltration. Scores from each of the lobes of each lung was averaged resulting in the final histological score for each animal. The degree of inflammation and hemorrhage were determined based on the following numerical scale; 1= minimal/mild, 2= moderate, 3= marked, 4=severe.