2.8. Histological analysis

Mouse lung specimens were fixed in 10% paraformaldehyde, embedded in paraffin, cut into 4 μm‐thick sections and stained with haematoxylin‐eosin (H&E). The stained sections were reviewed for morphology under a photomicroscope (Leica, Heidelberg, Germany). The neutrophil infiltration and inflammatory scores of the lung samples were determined as described previously.25, 26 In brief, for evaluation of lung neutrophils, three lung sections from each mouse were analysed and three randomly selected high‐power fields (HPF) were examined for each lung section, the average value of cells/HPF for each mouse was determined by summation of all numbers divided by 9. The inflammatory levels were semi‐quantitatively determined as below: peribronchial/peribronchiolar inflammation 0‐4, perivascular inflammation 0‐4 and alveolar inflammation 0‐2. Each lung section was given a total inflammatory score (maximum score of 10).