Platelet effector functions in inflammation

A State of the Art lecture titled "Platelet effector functions in inflammation" was presented at the International Society on Thrombosis and Haemostasis congress in 2025. It is increasingly recognized that platelets are critical orchestrators of innate and adaptive immune responses. In this review, we highlighted how these cells partially engage distinct receptors, signaling pathways, and effector functions to fulfill their role in immunity. In the inflamed microenvironment, platelets migrate along substrate gradients to optimize positioning to sites of injury or pathogen entry in an actin-related protein 2/3 complex-dependent manner. This allows for pathogen collection and bundling, as well as prevention of inflammatory bleeding. For the latter task, platelets integrate activation signals via glycoprotein VI and integrin αIIbβ3 to undergo procoagulant transformation, triggering local and restricted coagulation. We provided an overview of how these mechanisms are also associated with hyperinflammation and immunopathology, and how procoagulant activity is a driver of arterial and venous thrombosis. Moreover, we discussed that platelets increase their propensity for immune engagement over their lifespan while losing hemostatic prowess. Finally, we summarized additional relevant new data on this topic presented during the 2025 International Society on Thrombosis and Haemostasis Congress.