All-Trans Retinoic Acid Modulates the Balance of ADAMTS13 and VWF In Human Microvascular Endothelial Cells

All-trans retinoic acid (ATRA) can modulate the hypercoagulable state of human microvascular endothelial cell, which has been confirmed by the reports that ATRA can chang the expression of some procoagulant or anticoagulant factor, such as upregulation tissue factor and downregulation thrombomodulin. While, the balance between ADAMTS13 and von Willebrand factor (VWF) of microvascular endothelial cell, very related with the formation of microvascular platelet thrombsis, play an important role on the controlling the hypercoagulable state of microvascular endothelial cell. And it has been reported that the balance interrupted by some inflammatory cytokines may contribute to microvascular platelet thrombsis. In this study, to better understand the antithrombotic property of ATRA, we investigated whether ATRA may affect the balance.

We observed the effects of ATRA (compared to TNF-α) on the expression of ADAMTS13mRNA in human microvascular endothelial cell (HMEC-1 cell line) by real-time polymerase chain reaction amplification (RT-PCR). The levels of ADAMTS13 and VWF antigen in the conditioned medium of HMEC-1 cells were also detected by western blot or enzyme-linked immunosorbent assay (ELISA), and the proteolytic activity of ADAMTS13 was also determined by using GST-VWF73-His peptide as a specific substrate.

In a dose-dependent manner, ATRA significantly upregulated the expression of ADAMTS13mRNA which could be almost up to 4.63 times with 10uM ATRA, while TNF-α inhibited ADAMTS13mRNA expression which could drop to 41% of the control group with 10ng/ml TNF-α. ATRA also reverse the inhibition of TNF-α to ADAMTS13mRNA expression. The results were confirmed from the levels of ADAMTS13 protein and its activity, while ATRA had no significant affection on triggering release of VWF known as a specific substrate of ADAMTS13.

This study provides the evidence that ATRA modulates the balance of ADAMTS13 and VWF in human microvascular endothelial cell, which may be a very relevant compartment for the antithrombotic property of ATRA.

No relevant conflicts of interest to declare.