Hyperthermia induces platelet apoptosis and glycoprotein Ibalpha ectodomain shedding.

Hemorrhage is a significant pathological feature of some fever or hyperthermia-related diseases, such as dengue fever and heatstroke. Although the mechanisms of hemorrhage in these diseases are thought to be complex, whether there is an association between hemorrhage and hyperthermia or fever remains unclear. Platelets play a central role in maintaining integrity of endothelium and biological hemostasis. To explore the effect of hyperthermia on platelet physiology, platelet-rich plasma or washed platelets were incubated at hypothermia (22 degrees C), normothermia (37 degrees C) or hyperthermia (40 and 42 degrees C) for 1 or 2 hours. ADP and alpha-thrombin induced platelet aggregations were obviously reduced in platelets incubated at hyperthermia. Hyperthermia induced apoptotic events in platelets, including depolarization of mitochondrial inner transmembrane potential, caspase-3 dependent gelsolin cleavage and phosphatidylserine exposure. Furthermore, hyperthermia incurred platelet glycoprotein Ibalpha ectodomain shedding. Thus, these data suggest that hyperthermia induces platelet apoptosis and dysfunction. These findings have important implications for the pathogenesis of hemorrhage in fever or hyperthermia-related diseases, and also suggest that attention should be paid to platelet apoptosis under relatively high temperature conditions.