Staphylococcal superantigen-like 5 activates platelets and supports platelet adhesion under flow conditions, which involves glycoprotein Iba and aIIbb3

• Published in: Journal of thrombosis and haemostasis Vol. 7; no. 11; pp. 1867 - 1874
• Main Authors: DE HAAS, CJC, WEETERINGS, C, VUGHS, M M, DE GROOT, PG, Van Strijp, Ja, Lisman, T
• Format: Journal Article
• Language: English
• Published: 01.11.2009
• Subjects: Staphylococcus aureus
• ISSN: 1538-7933
• DOI: 10.1111/j.1538-7836.2009.03564.x

See also Cox D. Bacteria-platelet interactions. This issue, pp 1865-6.Summary. Objectives: Staphylococcal superantigen-like 5 (SSL5) is an exoprotein secreted by Staphylococcus aureus that has been shown to inhibit neutrophil rolling over activated endothelial cells via a direct interaction with P-selectin glycoprotein ligand 1 (PSGL-1). Methods and Results: When purified recombinant SSL5 was added to washed platelets in an aggregometry set-up, complete and irreversible aggregation was observed. Proteolysis of the extracellular part of GPIba or the addition of dRGDW abrogated platelet aggregation. When a mixture of isolated platelets and red cells was perfused over immobilized SSL5 at a shear rate of 300 s-1, stable platelet aggregates were observed, and platelet deposition was substantially reduced after proteolysis of GPIb or after addition of dRGDW. SSL5 was shown to interact with glycocalicin, a soluble GPIba fragment, and binding of SSL5 to platelets resulted in GPIb-mediated signal transduction as evidenced by translocation of 14-3-3. In addition, SSL5 was shown to interact with endothelial cell matrix (ECM) and this interaction enhanced aggregation of platelets from whole blood to this ECM. Conclusions: SSL5 activates and aggregates platelets in a GPIba-dependent manner, which could be important in colonization of the vascular bed and evasion of the immune system by S. aureus.