Inhibitory effects of epi-sesamin on endothelial protein C receptor shedding in vitro and in vivo

Objective and design: Endothelial protein C receptor (EPCR) plays a pivotal role in augmenting Protein C activation by the thrombin-thrombomodulin complex. The activity of EPCR is markedly changed by ectodomain cleavage and release as the soluble protein (sEPCR). The EPCR shedding is mediated by the tumor necrosis factor-α converting enzyme (TACE). Epi-sesamin (ESM), from the roots of Asarum siebodlii, is known to exhibit anti-allergic and anti-fungal activities. However, little is known about the effects of ESM on EPCR shedding. Methods: We investigated this issue by monitoring the effects of ESM on phorbol-12-myristate 13-acetate (PMA), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and cecal ligation and puncture (CLP)-mediated EPCR shedding. Results: Data showed that ESM induced potent inhibition of PMA, TNF-α, IL-1β, and CLP-induced EPCR shedding, likely through suppression of TACE expression. In addition, treatment with ESM resulted in a reduction of PMA-stimulated phosphorylation of p38, extracellular regulated kinases (ERK) 1/2, and c-Jun N-terminal kinase (JNK). Conclusions: Given these results, ESM should be viewed as a candidate therapeutic agent for treatment of various severe vascular inflammatory diseases via inhibition of EPCR shedding.