Calprotectin protects Staphylococcus aureus in coculture with Pseudomonas aeruginosa by attenuating quorum sensing and decreasing the production of pseudomonal antimicrobials

Abstract

The innate immune protein calprotectin (CP) defends the host against bacterial pathogens by sequestering multiple essential nutrient metal ions at infection sites. In addition to this role in nutritional immunity, CP promotes the survival of Staphylococcus aureus in coculture with Pseudomonas aeruginosa , an effect that is independent of its metal-sequestering function. In this work, we sought to understand how CP modulates this interspecies interaction by evaluating the transcriptional responses of P. aeruginosa and S. aureus to CP and metal limitation in cocultures. Our study revealed that CP attenuates the ability of P. aeruginosa to attack S. aureus with anti-staphylococcal factors and enhances the capacity of S. aureus to withstand this assault, effects that are not recapitulated by metal limitation. This work provides a new understanding of how CP modulates microbial interactions that are relevant to human health.