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Focally Acting Thrombin‐Inhibiting Nanoparticles Forestall Atherosclerosis in ApoE‐null Mice
Author(s) -
Palekar Rohun U,
Jallouk Andrew P,
Myerson Jacob W,
Pan Hua,
Wickline Samuel A
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1199.7
Subject(s) - thrombin , inflammation , aortic arch , chemistry , proinflammatory cytokine , receptor , pharmacology , medicine , endocrinology , aorta , platelet
Background Thrombin plays a central role in mediating both thrombosis and inflammation through cleavage of its receptor, protease activated receptor 1 or PAR‐1. Activation of PAR‐1 results in the expression of numerous procoagulant and proinflammatory molecules involved with the development of atherosclerotic plaques. Herein, we describe the role of thrombin inhibition with anti‐thrombin nanoparticles in limiting plaque deposition and reducing inflammation and hypercoagulability in atherosclerosis. Methods ApoE−/− mice fed a Western Diet for 4 months, receiving three intravenous treatment doses per week for the penultimate 4 weeks of Western Diet feeding. Anti‐thrombin nanoparticles were used as the treatment consisting of perfluorocarbon nanoparticles conjugated to multiple copies of the direct thrombin inhibitor D‐phenylalanyl‐L‐prolyl‐L‐arginyl‐chloromethyl ketone (PPACK‐NP). Following 1 month of treatment, aortas were removed and the aortic arch was stained en face for deposited plaques using Sudan IV. Plaque burden in the aortic arch was quantified using ImageJ. Endothelial barrier disruption was quantified by measuring the deposition of semipermeant nanoparticles after 2 hours of circulation; and vessel procoagulant activity measured by time to carotid artery occlusion after dye‐laser injury. Results Treatment of ApoE−/− mice for one month with PPACK‐NP resulted in a 22.5% overall decrease ( Fig. A) in aortic arch plaque burden compared to mice treated with saline (p = 0.03, Fig. B) in the face of no significant reduction in serum cholesterol ( Fig. C). By immunofluorescence, both tissue factor expression and phosphorylation of NF‐kB p65 were reduced (25.94%, p = 0.027 and 21.62%, p = 0.017 respectively). Endothelial barrier function improved by 33% and procoagulant activity diminished by 46%. The activated partial thromboplastin time (APTT) normalized within ~30 minutes after bolus injection of nanoparticles confirming safety of the system with respect bleeding risk. Conclusion These results demonstrate the ability of PPACK‐NP treatment to inhibit atherosclerosis in the plaque‐prone aortic arch, restore vascular barrier function, and reduce thrombotic risk without the need for cholesterol lowering or systemic anticoagulation. Support or Funding Information Research Support: NIH HL112303