Interaction of PF4 (CXCL4) with the vasculature: A role in atherosclerosis and angiogenesis

Platelet factor 4 (PF4), a platelet derived chemokine has two important functions in the vasculature It has a pro atherogenic role while also having anti angiogenic effects The activity of platelet factor 4 (PF4), unlike other chemokines that bind to specific receptors depends on its unusually high affinity for proteoglycans and other negatively charged molecules High affinity for heparan sulfates was thought to be central to all of PF4 s biological functions However other mechanisms have been described such as direct growth factor binding activation of the CXCR3B chemokine receptor isoform that is present in some vascular cells or binding to lipoprotein related protein 1 (LRP1) Furthermore, PF4 also binds to integrins with affinities similar to matrix molecules These interactions may explain the effects of PF4 in healthy and path logical tissues However the mechanisms involved in PF4's activity are complex and may depend on a given tissue or localisation Overall, while much is already known about PF4, its specific role in atherosclerosis and angiogenesis remains still to be clarified