Parmodulins inhibit thrombus formation without inducing endothelial injury caused by vorapaxar

Abstract

Key Points Parmodulins are a new class of PAR1 inhibitors that target the cytosolic face of PAR1 to block signaling through Gαq, but not Gα12/13. Unlike vorapaxar, which causes endothelial injury, parmodulins selectively block proinflammatory, but not cytoprotective, signaling.

Factor VII activating protease (FSAP) regulates the expression of inflammatory genes in vascular smooth muscle and endothelial cells

“…Parmodulins which selectively block down-stream effects of PAR through blocking of G-protein coupling 161 are not yet commercially available.…”

Cytoprotective activated protein C averts Nlrp3 inflammasome–induced ischemia-reperfusion injury via mTORC1 inhibition

“…Considering that parmodulin-2 targets Gaq signaling, we suspect that aPC-PAR-1-Gaq signaling conveys aPC-mediated inflammasome suppression. 32 Furthermore, various receptors complement aPC signaling via PAR-1 in cell-and context-specific fashions. 26,65,66 The coreceptors required for aPC PAR-1-mediated inflammasome suppression remain unknown.…”

“…For the myocardial IRI model (left anterior descending artery ligation for 90 minutes followed by 24 hours of reperfusion), mice were injected with phosphate-buffered saline (PBS; control; equal volume intraperitoneally [IP]), aPC (1 mg/kg IP), 24 aPC-HAPC1573 complex (aPC was preincubated before injection with HAPC1573 antibody at a 1:1 molar ratio for 10 minutes under gentle agitation to block its anticoagulant activity), [24][25][26][27] an aPC variant lacking specifically anticoagulant function (3K3A-aPC; 1 mg/kg IP), 28,29 the inhibitory PAR-1 pepducin (P1pal-12S; 2.5 mg/kg subcutaneously) followed by aPC (1 mg/kg IP), 26,30,31 or parmodulin-2 (5 mg/kg IV) 32 reperfusion), 25 mice were injected with PBS (control; 1 mg/kg IP) or aPC (1 mg/kg IP) 30 minutes before IRI. P1pal-12S and parmodulin-2 have been previously described.…”

“…15,42 Recently, structural biochemistry-created compounds, parmodulins, were shown to block only specific aspects of biased PAR signaling. 32 We used parmodulin-2, which blocks cytodisruptive, but not cytoprotective, PAR-1 signaling 32 and evaluated its anti-inflammatory and cytoprotective effects in myocardial IRI. Treatment of mice with parmodulin-2 (5 mg/kg; Figure 6A) before myocardial IRI was as sufficient as that with aPC, reducing the infarct size ( Figure 6B-C), cardiac expression of inflammasome regulators (Nlrp3, cl-Casp1, cl-IL1b; Figure 6D-E), and plasma IL-1b levels ( Figure 6F).…”

“…P1pal-12S and parmodulin-2 have been previously described. [30][31][32][33] Infarct size was determined as described in the supplemental Methods.…”