title: Silencing of Anticoagulant Protein C Evokes Low-Incident but Spontaneous Atherothrombosis in Apolipoprotein E-Deficient Mice-Brief Report.
abstract: Murine atherosclerosis models do not spontaneously develop atherothrombotic complications. We investigated whether disruption of natural anticoagulation allows preexisting atherosclerotic plaques to progress toward an atherothrombotic phenotype.
  
  
  
  On lowering of plasma protein C levels with small interfering RNA (siProc) in 8-week Western-type diet-fed atherosclerotic apolipoprotein E-deficient mice, 1 out of 4 mice displayed a large, organized, and fibrin- and leukocyte-rich thrombus on top of an advanced atherosclerotic plaque located in the aortic root. Although again at low incidence (3 in 25), comparable thrombi at the same location were observed during a second independent experiment in 9-week Western-type diet-fed apolipoprotein E-deficient mice. Mice with thrombi on their atherosclerotic plaques did not show other abnormalities and had equally lowered plasma protein C levels as siProc-treated apolipoprotein E-deficient mice without thrombi. Fibrinogen and thrombin-antithrombin concentrations and blood platelet numbers were also comparable, and plaques in siProcmice with thrombi had a similar composition and size as plaques in siProcmice without thrombi. Seven out of 25 siProcmice featured clots in the left atrium of the heart.
  
  
  
  Our findings indicate that small interfering RNA-mediated silencing of protein C in apolipoprotein E-deficient mice creates a condition that allows the occurrence of spontaneous atherothrombosis, albeit at a low incidence. Lowering natural anticoagulation in atherosclerosis models may help to discover factors that increase atherothrombotic complications.
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Amber B
authors.initials: AB
authors.lastname: Ouweneel
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Marco
authors.initials: M
authors.lastname: Heestermans
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Robin A F
authors.initials: RAF
authors.lastname: Verwilligen
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Marion J J
authors.initials: MJJ
authors.lastname: Gijbels
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Pieter H
authors.initials: PH
authors.lastname: Reitsma
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.).
authors.forename: Miranda
authors.initials: M
authors.lastname: Van Eck
authors.affiliation: From the Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands (A.B.O., R.A.F.V., M.v.E.); Einthoven Laboratory for Experimental Vascular Medicine (M.H., P.H.R., B.J.M.v.V.), and Department of Internal Medicine, Division of Thrombosis and Hemostasis (M.H., P.H.R., B.J.M.v.V.), Leiden University Medical Center, The Netherlands; Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, The Netherlands (M.J.J.G.); and Department of Medical Biochemistry, The Academic Medical Center, Amsterdam, The Netherlands (M.J.J.G.). b.j.m.van_vlijmen@lumc.nl.
authors.forename: Bart J M
authors.initials: BJM
authors.lastname: van Vlijmen
mesh_terms: D000818:Animals; D000990:Antithrombin III / Q000235:genetics / Q000378:metabolism; D001011:Aorta / Q000378:metabolism* / Q000473:pathology; D001018:Aortic Diseases / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001057:Apolipoproteins E / Q000187:drug effects* / Q000235:genetics; D050197:Atherosclerosis / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001777:Blood Coagulation; D066273:Diet, Western; D004195:Disease Models, Animal; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D008099:Liver / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010447:Peptide Hydrolases / Q000097:blood; D010641:Phenotype; D058226:Plaque, Atherosclerotic; D011486:Protein C / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D013927:Thrombosis / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: D001057:Apolipoproteins E; D011486:Protein C; C046193:antithrombin III-protease complex; D000990:Antithrombin III; D005340:Fibrinogen; D010447:Peptide Hydrolases
keywords: anticoagulation; atherosclerosis; atherothrombosis; mouse models; protein C