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Supplemental Digital Content is available in the text., Objective: Arterial thrombosis leading to ischemic injury worsens the prognosis of many patients with cardiovascular disease. PZ-128 is a first-in-class pepducin that reversibly inhibits PAR1 (protease-activated receptor 1) on platelets and other vascular cells by targeting the intracellular surface of the receptor. The TRIP-PCI (Thrombin Receptor Inhibitory Pepducin in Percutaneous Coronary Intervention) trial was conducted to assess the safety and efficacy of PZ-128 in patients undergoing cardiac catheterization with intent to perform percutaneous coronary intervention. Approach and Results: In this randomized, double-blind, placebo-controlled, phase 2 trial, 100 patients were randomly assigned (2:1) to receive PZ-128 (0.3 or 0.5 mg/kg), or placebo in a 2-hour infusion initiated just before the start of cardiac catheterization, on top of standard oral antiplatelet therapy. Rates of the primary end point of bleeding were not different between the combined PZ-128 doses (1.6%, 1/62) and placebo group (0%, 0/35). The secondary end points of major adverse coronary events at 30 and 90 days did not significantly differ but were numerically lower in the PZ-128 groups (0% and 2% in the PZ-128 groups, 6% and 6% with placebo, p=0.13, p=0.29, respectively). In the subgroup of patients with elevated baseline cardiac troponin I, the exploratory end point of 30-day major adverse coronary events + myocardial injury showed 83% events in the placebo group versus 31% events in the combined PZ-128 drug groups, an adjusted relative risk of 0.14 (95% CI, 0.02–0.75); P=0.02. Conclusions: In this first-in-patient experience, PZ-128 added to standard antiplatelet therapy appeared to be safe, well tolerated, and potentially reduced periprocedural myonecrosis, thus providing the basis for further clinical trials. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02561000.

Objective: Destruction of arterial collagen allows monocyte and macrophage infiltration leading to atherosclerotic plaque formation, but it is not clear what role the MMP1 (matrix metalloprotease 1) collagenase plays in this process in vivo. To define the specific contribution of MMP1 to atherosclerotic plaque burden and pathogenesis, we generated ApoE −/− mice deficient in the human MMP1 ortholog, MMP1a. Approach and Results: After 12 to 16 weeks of Western diet, genetic loss of MMP1a resulted in a significant 50% reduction in total aortic plaque burden compared with control ApoE −/− mice. MMP1a deficiency led to significant reductions in plaque monocytes/macrophages, SMCs (smooth muscle cells), and necrosis, with increases in collagen content. Collagen invasion of oxidized-LDL (low-density lipoprotein) activated peripheral blood mononuclear cells from MMP1a-deficient mice was markedly attenuated and was similar to suppressive effects with pharmacological inhibitors of MMP1 and its receptor, PAR1 (protease-activated receptor 1). Patients with coronary artery disease and acute coronary syndrome undergoing cardiac catheterization in the TRIP-PCI trial (Thrombin Receptor Inhibitory Pepducin-Percutaneous Coronary Intervention) were evaluated for circulating levels of all 3 major secreted collagenases, MMP1, MMP8, and MMP13 and total number of coronary lesions with ≥50% stenosis (coronary artery disease burden). MMP1 was significantly ( P Conclusions: These data provide evidence for an important role for the MMP1a collagenase in atherosclerotic lesion development and leukocyte behavior and validate MMP1 as a compelling target in patients with coronary artery disease/acute coronary syndrome. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02561000.

Objective— Protease-activated receptor-1 (PAR1) is classically activated by thrombin and is critical in controlling the balance of hemostasis and thrombosis. More recently, it has been shown that noncanonical activation of PAR1 by matrix metalloprotease-1 (MMP1) contributes to arterial thrombosis. However, the role of PAR1 in long-term development of atherosclerosis is unknown, regardless of the protease agonist. Approach and Results— We found that plasma MMP1 was significantly correlated ( R =0.33; P =0.0015) with coronary atherosclerotic burden as determined by angiography in 91 patients with coronary artery disease and acute coronary syndrome undergoing cardiac catheterization or percutaneous coronary intervention. A cell-penetrating PAR1 pepducin, PZ-128, currently being tested as an antithrombotic agent in the acute setting in the TRIP-PCI study (Thrombin Receptor Inhibitory Pepducin-Percutaneous Coronary Intervention), caused a significant decrease in total atherosclerotic burden by 58% to 70% ( P P Conclusions— These data suggest that targeting the MMP1–PAR1 system may be effective in tamping down chronic inflammatory signaling in plaques and halting the progression of atherosclerosis.

Objective— Early recognition of an acute coronary occlusion (ACO) improves clinical outcomes. Soluble fms-like tyrosine kinase-1 (sFLT1) is an endothelium-derived protein induced by hypoxia. We tested whether sFLT1 levels are elevated in ACO. Methods and Results— Serum sFLT1 levels were measured by enzyme-linked immunosorbent assay in patients with ST-segment elevations and angiographically confirmed ACO, unstable angina/non ST-segment elevation myocardial infarction, and 2 control groups. To further explore sFLT1 release, a mouse model of ACO and in vitro human coronary artery endothelial cell injury were used. sFLT1 levels were increased in ACO compared with unstable angina/non-ST-elevation myocardial infarction, catheterized controls, or healthy volunteers (200.7±15.5 versus 70.7±44.0 versus 10.2±4.0 versus 11.7±1.7 pg/mL respectively, P 15 pg/mL, 99th percentile in controls), whereas 57% had levels of the MB isoform of creatine kinase levels >10 ng/mL ( P 0.05 ng/mL ( P P ≤0.01 for each). Within 60 minutes of ACO in mice, sFLT1 levels were elevated. Hypoxia and thrombin increased sFLT1 levels within 15 minutes in human coronary artery endothelial cells. Conclusion— sFLT1 levels may be an early indicator of endothelial hypoxia in ACO.