The efficacy of Esc(1–21)-1c in alleviating respiratory Pseudomonal infection was further assessed by mouse lung histopathological evaluation. We observed the increased number of inflammatory cells after Pseudomonas infection in both airways and alveolar regions, but the increase was more prominent in the alveolar region (Fig. 7). There was clearly more neutrophilic infiltration in the alveoli of PBS-treated mice than in AMP-treated mice at 24 hours after infection (Fig. 7).Figure 7Histologic analysis of lung tissues with PAO1 challenge at 24 hours after bacterial infection. Mouse lung tissues were harvested, fixed and stained for histological evaluation without peptide treatment (B) or with a single (C) and double (D) administration of Esc(1–21)-1c at 0.1 mg/kg in comparison with non-infected and untreated samples. (A) Infected but untreated mice (B) exhibited more inflammation, airway lumen leukocyte accumulation (black arrow).