The Platelet Specific Chemokine Platelet Factor 4 Induces Expression of E-Selectin in an NF-κ B Dependent Manner.

The involvement of platelets in the pathogenesis of atherosclerosis has recently gained much attention. Platelet factor 4 (PF4) is a platelet specific chemokine released upon platelet activation. PF4 has been localized to atherosclerotic lesions, including macrophages and endothelium. In this report, we demonstrate that E-selectin, an adhesion molecule involved in atherogenesis, is up-regulated in human umbilical vein endothelial cells exposed to PF4. Induction of E-selectin mRNA is time and dose dependent, and requires the presence of cell surface glycosaminoglycans. Surface expression of E-selectin, as measured by flow cytometry, is also increased by PF4. Activation of NF-κB is critical for PF4 induced E-selectin expression, as demonstrated by promoter activation studies and electrophoretic mobility shift assays. In summary, our data demonstrate that PF4 can increase expression of E-selectin by endothelial cells by activation of NF-κB. PF4 induction of endothelial E-selectin expression represents another mechanism by which platelets may participate in atherosclerotic lesion progression. These data also suggest that PF4 may participate in the proinflammatory functions of activated platelets.