Monocyte tissue factor–dependent activation of coagulation in hypercholesterolemic mice and monkeys is inhibited by simvastatin
A. Phillip Owens III, … , Ryan E. Temel, Nigel Mackman
A. Phillip Owens III, … , Ryan E. Temel, Nigel Mackman
Published January 3, 2012
Citation Information: J Clin Invest. 2012;122(2):558-568. https://doi.org/10.1172/JCI58969.
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Research Article

Monocyte tissue factor–dependent activation of coagulation in hypercholesterolemic mice and monkeys is inhibited by simvastatin

Abstract

Hypercholesterolemia is a major risk factor for atherosclerosis. It also is associated with platelet hyperactivity, which increases morbidity and mortality from cardiovascular disease. However, the mechanisms by which hypercholesterolemia produces a procoagulant state remain undefined. Atherosclerosis is associated with accumulation of oxidized lipoproteins within atherosclerotic lesions. Small quantities of oxidized lipoproteins are also present in the circulation of patients with coronary artery disease. We therefore hypothesized that hypercholesterolemia leads to elevated levels of oxidized LDL (oxLDL) in plasma and that this induces expression of the procoagulant protein tissue factor (TF) in monocytes. In support of this hypothesis, we report here that oxLDL induced TF expression in human monocytic cells and monocytes. In addition, patients with familial hypercholesterolemia had elevated levels of plasma microparticle (MP) TF activity. Furthermore, a high-fat diet induced a time-dependent increase in plasma MP TF activity and activation of coagulation in both LDL receptor–deficient mice and African green monkeys. Genetic deficiency of TF in bone marrow cells reduced coagulation in hypercholesterolemic mice, consistent with a major role for monocyte-derived TF in the activation of coagulation. Similarly, a deficiency of either TLR4 or TLR6 reduced levels of MP TF activity. Simvastatin treatment of hypercholesterolemic mice and monkeys reduced oxLDL, monocyte TF expression, MP TF activity, activation of coagulation, and inflammation, without affecting total cholesterol levels. Our results suggest that the prothrombotic state associated with hypercholesterolemia is caused by oxLDL-mediated induction of TF expression in monocytes via engagement of a TLR4/TLR6 complex.

Authors

A. Phillip Owens III, Freda H. Passam, Silvio Antoniak, Stephanie M. Marshall, Allison L. McDaniel, Lawrence Rudel, Julie C. Williams, Brian K. Hubbard, Julie-Ann Dutton, Jianguo Wang, Peter S. Tobias, Linda K. Curtiss, Alan Daugherty, Daniel Kirchhofer, James P. Luyendyk, Patrick M. Moriarty, Shanmugam Nagarajan, Barbara C. Furie, Bruce Furie, Douglas G. Johns, Ryan E. Temel, Nigel Mackman

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Figure 2

oxLDL induction of monocytic TF expression and the release of TF+ MPs.

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oxLDL induction of monocytic TF expression and the release of TF+ MPs. ...
THP-1 cells were treated with LDL (50 μg/ml) or oxLDL (50 μg/ml) for different times, and (A) cellular TF activity and (B) MP TF activity in the culture supernatant were analyzed. THP-1 cells were treated for either 8 hours and analyzed for (C) cellular TF activity or 24 hours and analyzed for (D) MP TF activity in the culture supernatant after pretreatment with simvastatin (20 μM, sim) for 12 hours, the TLR4 inhibitor TAK-242 (1 μg/ml) for 2 hours, or the LPS-neutralizing antibiotic peptide polymyxin B (10 μg/ml) for 30 minutes. Human monocytes were also pretreated with the same agents; (E) cellular TF activity was analyzed after 8 hours, and (F) MP TF activity in the culture supernatant was analyzed after 24 hours. Data are represented as mean ± SEM. All experiments were performed 5 times in triplicate. *P < 0.01, oxLDL-treated versus untreated and LDL-treated cells; #P < 0.01, simvastatin-treated versus untreated cells; †P < 0.001, simvastatin-treated or TAK-242–treated versus cells without inhibitor. Data in A and B were analyzed with 1-way ANOVA with Holm-Sidak post hoc, while data in C–F were analyzed via 2-way ANOVA with Holm-Sidak post hoc.