Killing of Pseudomonas aeruginosa by chicken cathelicidin-2 is immunogenically silent, preventing lung inflammation in vivo

The development of antibiotic resistance by Pseudomonas aeruginosa is a major concern in the treatment of bacterial pneumonia. In the search of novel anti-infective therapies, the chicken-derived peptide cathelicidin-2 (CATH-2) has emerged as a potential candidate, with strong broad-spectrum antimicrobial activity and the ability to limit inflammation by inhibiting TLR2 and TLR4 activation. However, as it is unknown how CATH-2 affects inflammation in vivo, we investigated how CATH-2-mediated killing of P. aeruginosa affects lung inflammation in a murine model.First, murine macrophages were used to determine whether CATH-2-mediated killing of P. aeruginosa reduced pro-inflammatory cytokine production in vitro Next, a murine lung model was used to analyze how CATH-2-mediated killing of P. aeruginosa affects neutrophil and macrophage recruitment as well as cytokine/chemokine production in the lung.Our results show that CATH-2 kills P. aeruginosa in an immunogenically silent manner both in vitro and in vivo Treatment with CATH-2-killed P. aeruginosa showed reduced neutrophil recruitment to the lung as well as inhibition of cytokine and chemokine production, compared to treatment with heat- or gentamicin-killed bacteria.Together, these results show the potential for CATH-2 as a dual-activity antibiotic in bacterial pneumonia, which can both kill P. aeruginosa and prevent excessive inflammation