Staphylococcal Protein A Is a Key Factor in Neutrophil Extracellular Traps Formation

Abstract

<i>Staphylococcus aureus</i> are strong inducers of neutrophil extracellular traps (NETs), a defense mechanism of neutrophils against pathogens. Our aim was to explore the role of Protein A in <i>S. aureus</i>-induced NETosis. We determined the Protein A production of four different <i>S. aureus</i> strains and found a direct relationship between the degree of NETosis induction and Protein A production: strains producing higher concentrations of Protein A evoke significantly more NETs. A <i>S. aureus</i> strain in which Protein A as well as a second binding protein for immunoglobulins (<i>Sbi</i>) have been knocked-out (Δ<i>SpA</i> Δ<i>Sbi</i>) induced significantly less NETosis than the wild-type strain. NETosis induction by this knockout strain can be rescued by the addition of purified Protein A. Dead <i>S. aureus</i> did not induce NETosis. In conclusion, Protein A is a determinant for NETosis induction by <i>S. aureus</i>.