Pf Bacteriophage Inhibits Neutrophil Migration in the Lung

Bacteriophages are abundant in the human body, including at sites of infection. We report that Pf4 phage, a filamentous bacteriophage produced by Pseudomonas aeruginosa , dampens inflammatory responses in response to either P. aeruginosa airway infection in a mouse model of acute pneumonia or bacterial endotoxin treatment. Pf4 triggers TLR3-dependent type I interferon production and antagonize production of anti-bacterial cytokines and chemokines. In particular, Pf4 phages inhibit CXCL5, preventing efficient neutrophil chemotaxis in response to endotoxin. These results suggest that Pf4 phages alter innate immunity to bacteria potentially dampening inflammation and neutrophil migration at sites of bacterial colonization or infection. ### Competing Interest Statement The authors have declared no competing interest.