Piperlonguminine downregulates endothelial protein C receptor shedding in vitro and in vivo.

Endothelial cell protein C receptor (EPCR) plays an important role in coagulation and inflammation. EPCR can be shed from the cell surface, and this is mediated by tumor necrosis factor-α-converting enzyme (TACE). Piperlonguminine (PL), an important component of Piper longum fruits, is known to exhibit antihyperlipidemic, antiplatelet, and antimelanogenesis activities. However, little is known about the effects of PL on EPCR shedding. Here, we investigated this issue by monitoring the effects of PL on phorbol-12-myristate 13-acetate (PMA) and on cecal ligation and puncture (CLP)-mediated EPCR shedding and underlying mechanisms. PL induced potent inhibition of PMA, and CLP induced EPCR shedding through suppression of TACE expression. And treatment with PL resulted in reduced PMA-stimulated phosphorylation of p38, extracellular regulated kinases (ERK) 1/2, and c-Jun N-terminal kinase (JNK). Given these results, PL might have potential as an anti-sEPCR shedding reagent against PMA- and CLP-mediated EPCR shedding.