Abstract/Summary

Staphylococcus aureus is an opportunistic pathogenic bacterium known for its ability to interact with platelets and modulate their function. S. aureus lipoproteins are one of the major groups of bacterial surface molecules and are released into the extracellular milieu where they are recognized by host immune cells. The aim of this study was to determine the role of S. aureus lipoproteins in S. aureus-platelet interactions. Platelet aggregation and binding assays using S. aureus wild type and lgt strains showed that, S. aureus lipoproteins contribute towards binding of the pathogen to platelets. Lipoproteins present in extracellular milieu also bind platelets. Platelet spreading, thrombus formation, agonist induced platelet aggregation and αIIbβ3 activation were inhibited by cell-free lipoproteins. CD36 was identified as the major platelet surface molecule interacting with S. aureus lipoproteins. Antibody neutralization demonstrated that functional inhibition of platelet activation caused by lipoproteins was via CD36. Pre-incubation of platelets with S. aureus lipoproteins significantly increased the association of CD36 with integrin β3. Thus CD36-β3 association is proposed to be important in inhibiting activation of αIIbβ3 and consequent S. aureus lipoprotein mediated inhibition of platelet activation.