Induction of monocytic tissue factor expression after rewarming from hypothermia in vivo is counteracted by heat shock in c-Jun-dependent manner.

OBJECTIVE Triggering of tissue factor (TF)-mediated blood coagulation leads to the development of disseminated intravascular coagulation during rewarming from hypothermia. We studied post-rewarming TF levels, activity, and surface redistribution, along with the regulation of TF gene transcription in mononuclear cells (MNCs) obtained from an in vivo rat model. METHODS AND RESULTS Rewarming after a 5-hour episode of 15 degrees C hypothermia caused an increase in TF activity, protein levels, and externalization of TF antigen in rat MNCs. This was accompanied by a dramatic elevation of c-Jun and JNK phosphorylation, and the absence of EGR-1 and NF-kappaB activation. To search for a stimulus to counteract c-Jun-mediated induction of TF activity in MNCs from rewarmed rats, we applied heat shock pretreatment one day before the hypothermia/rewarming experiment. This restored post-rewarming TF activity, protein levels, and surface-to-total TF ratio in rat MNCs to normothermic levels. Furthermore, in heat shock-pretreated animals, rewarming failed to increase phosphorylated c-Jun and JNK levels. We attribute this to the profound overexpression of heat shock protein 70 and inhibition of JNK. CONCLUSIONS MNCs respond to rewarming from hypothermia by an induction of active TF antigen. This effect is dependent on c-Jun activation and is abolished by heat shock pretreatment.