thromboplastin and convallatoxin

Convallatoxin (CNT) is a natural cardiac glycoside extracted from lily of the valley ( Convallaria majalis ). Although it is empirically known to cause blood coagulation disorders, the underlying mechanism remains unclear. CNT exerts cytotoxicity and increases tissue factor (TF) expression in endothelial cells. However, the direct action of CNT on blood coagulation remains unclear. Therefore, herein, we investigated the effects of CNT on whole blood coagulation system and TF expression in monocytes.. Blood samples were collected from healthy volunteers to measure plasma thrombin-antithrombin complex (TAT) concentration using ELISA and to perform rotational thromboelastometry (ROTEM) and whole-blood extracellular vesicle (EV)-associated TF (EV-TF) analysis. The effects of CNT were also investigated using the monocytic human cell line THP-1. Quantitative real-time PCR and western blotting were performed, and PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, was used to elucidate the action mechanism of CNT-mediated TF production.. CNT treatment increased EV-TF activity, shortened the whole blood clotting time in rotational thromboelastometry analysis, and increased TAT levels, which is an index of thrombin generation. Furthermore, CNT increased TF mRNA expression in THP-1 cells and EV-TF activity in the cell culture supernatant. Therefore, CNT may induce a hypercoagulable state with thrombin generation, in which elevated EV-TF activity derived from monocytes might be involved. These procoagulant effects of CNT were reversed by PD98059, suggesting that CNT-induced TF production in monocytes might be mediated by the MAPK pathway.. The findings of the present study have further clarified the procoagulant properties of CNT.

Topics: Endothelial Cells; Extracellular Vesicles; Humans; Monocytes; Protein Kinase Inhibitors; Thrombin; Thrombophilia; Thromboplastin

Convallotoxin (CNT), present in lily of the valley (Convallaria majalis), is a toxin that causes food poisoning among humans and companion animals. Although various symptoms of CNT poisoning have been well described, hypercoagulability owing to CNT is only empirically known among some veterinarians, and the underlying mechanism remains to be elucidated. CNT exerts cytotoxic effects on endothelial cells.. This study aimed to determine whether CNT induces the expression of tissue factor (TF), a potent initiator of the extrinsic coagulation cascade, in endothelial cells and leads to a hypercoagulable state.. Human umbilical vein endothelial cells (HUVECs) were used for in vitro experiments. HUVECs were treated with or without CNT (50 and 100 nM) for 4 h. Phosphate-buffered saline was used as a control. Cell viability was determined using the WST-8 assay. Quantitative real-time polymerase chain reaction was performed to determine TF mRNA expression. TF protein expression was observed using a laser scanning confocal microscope.. The viability of HUVECs significantly reduced after CNT treatment compared with that of non-treated cells (p < 0.05). Moreover, a significant increase in TF mRNA and protein expression was observed after 4 h of CNT treatment. CNT elicited these effects in a dose-dependent manner.. TF expression induced by CNT in endothelial cells can contribute to the development of a hypercoagulable state. The present study partially revealed the mechanisms underlying the CNT-induced hypercoagulable state. The findings can contribute to the development of a novel therapy for lily of the valley poisoning.

Topics: Animals; Cardiac Glycosides; Convallaria; Endothelial Cells; Strophanthins; Thromboplastin