Interleukin-22 level is negatively correlated with neutrophil recruitment in the lungs in a Pseudomonas aeruginosa pneumonia model.

Pseudomonas aeruginosa is a major threat for immune-compromised patients. Bacterial pneumonia can induce uncontrolled and massive neutrophil recruitment ultimately leading to acute respiratory distress syndrome and epithelium damage. Interleukin-22 plays a central role in the protection of the epithelium. In this study, we aimed to evaluate the role of interleukin-22 and its soluble receptor IL-22BP in an acute Pseudomonas aeruginosa pneumonia model in mice. In this model, we noted a transient increase of IL-22 during Pseudomonas aeruginosa challenge. Using an antibody-based approach, we demonstrated that IL-22 neutralisation led to increased susceptibility to infection and to lung damage correlated with an increase in neutrophil accumulation in the lungs. On the contrary, rIL-22 administration or IL-22BP neutralisation led to a decrease in mouse susceptibility and lung damage associated with a decrease in neutrophil accumulation. This study demonstrated that the IL-22/IL-22BP system plays a major role during Pseudomonas aeruginosa pneumonia by moderating neutrophil accumulation in the lungs that ultimately leads to epithelium protection.