Conclusions
Treatment with tafamidis lowers the thrombotic potential in human primary endothelial cells by reducing TF expression and activity. This previously unknown off-target effect may provide a novel mechanistic explanation for the lower number of thromboembolic complications in ATTR cardiomyopathy patients treated with tafamidis.
Methods
Primary human aortic endothelial cells (HAECs) were treated with tafamidis at clinically relevant concentrations and with plasma of patients, before and after the initiation of treatment with tafamidis. The expression of TF was induced by incubation with Tumor Necrosis Factor α (TNFα). Intracellular expression of tissue factor (TF) was measured by western blot. TF activity was measured by a colorimetric assay. Gene expressions of TF were measured by quantitative polymerase chain reaction.
Results
Treatment with tafamidis dose-dependently reduced the expression and activity of TNFα-induced TF. This effect was confirmed in cells treated with patients' plasma. Signal Transducer and Activator of Transcription 3 (STAT3) phosphorylation was significantly inhibited by tafamidis. Incubation of HAECs with tafamidis and the STAT3 activator colivelin partially rescued the expression of TF. Conclusions: Treatment with tafamidis lowers the thrombotic potential in human primary endothelial cells by reducing TF expression and activity. This previously unknown off-target effect may provide a novel mechanistic explanation for the lower number of thromboembolic complications in ATTR cardiomyopathy patients treated with tafamidis.