When we subconjunctivally injected IL-17A– and RBP4-recombinant protein simultaneously in COPD mouse models 4 h prior to inoculation, the RBP4 protein dampened the severity of rm–IL-17A–induced airway inflammation at one day post inoculation, including a decreased infiltrate score and MPO activity compared with rm–IL-17A–only-treated PA-COPD mice as the control (Figures 6C, D). Here, MPO is linked to chronic obstructive pulmonary disease.