Introduction:
Interleukin 33 (IL-33) was previously shown to induce angiogenesis and inflammatory activation of endothelial microparticles (EMPs). Tissue factor (TF) plays a central role in hemostasis and thrombosis.

Material and methods:
The study analyzed the coronary blood of level of CD31+EMPs, TF protein and IL-33 protein in acute myocardial infarction (AMI) and stable coronary artery disease (SCAD) patients. Human coronary artery endothelial cells (HCAECs) were treated with IL-33 to obtain EMPs. The TF activity of EMPs was tested by Thermo Fisher by adding the TF antibody. Furthermore, TF and tissue factor pathway inhibitor (TFPI) protein were tested by ELISA. Finally, NF-κB inhibitor dimethyl fumarate (DMF) and soluble extracellular domain of ST2 coupled to the Fc fragment of human IgG1 (sST2) were added to HCAECs which were treated with IL-33, and the TF protein level was also tested by ELISA.

Results:
The AMI patients had higher levels of CD31+EMPs, TF protein and IL-33 protein than the SCAD patients in the coronary artery. In AMI patients (n = 27), the IL-33 protein positively correlated with CD31+EMPs (r = 0.794, p < 0.01). According to the ROC curve analysis, the AUC of CD31+EMPs, TF protein and IL-33 protein were 0.888, 0.962 and 0.778 respectively. In the cell culture, the TF activity and TF protein in EMPs increased gradually with time of intervention by the treatment of IL-33. IL-33 binding to the ST2 receptor promoted TF expression by regulating NF-κB activation in EMPs of HCAECs.

Conclusions:
Activated endothelial cells and EMPs they release simultaneously express TF, which is a risk factor for cardiovascular disease.