Original Investigation
Carbamylated Low-Density Lipoproteins Induce a Prothrombotic State Via LOX-1: Impact on Arterial Thrombus Formation In Vivo

https://doi.org/10.1016/j.jacc.2016.07.755Get rights and content
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Abstract

Background

Carbamylation alters low-density lipoprotein (LDL) structure and is thought to promote vascular inflammation and dysfunction in patients with chronic kidney disease (CKD).

Objectives

This study sought to determine whether carbamylated LDL (cLDL) exerts prothrombotic effects in vascular cells and platelets and whether cLDL enhances arterial thrombus formation in vivo.

Methods

LDL was isolated from healthy subjects or patients with CKD by sequential ultracentrifugation. Ex vivo carbamylation of LDL from healthy subjects was induced with potassium cyanate. Arterial thrombus formation was analyzed in a murine carotid artery photochemical injury model. Protein expression and mRNA levels were analyzed by Western blotting, flow cytometry, and real-time PCR. Platelet aggregation was measured by impedance aggregometry.

Results

Intravenous administration of cLDL in mice accelerated arterial thrombus formation compared to treatment with native LDL (nLDL) or vehicle. Tissue lysates of mouse carotid arteries revealed that cLDL induced the expression of TF, PAI-1, and LOX-1 mRNA in vascular cells. In human aortic smooth muscle and endothelial cells, cLDL induced TF and PAI-1 expression. In contrast, nLDL had no effect on either cell type. While nLDL and cLDL had no aggregatory effect on resting platelets, cLDL enhanced platelet aggregation in response to different agonists. This effect was mediated by mitogen-activated protein kinase p38 phosphorylation and LOX-1 translocation to the surface. LDL isolated from patients with CKD mimicked the prothrombotic effects of cLDL on vascular cells, platelets, and thrombus formation in vivo.

Conclusions

We found that cLDL induces prothrombotic effects in vascular cells and platelets by activation of the LOX-1 receptor and enhances thrombus formation in vivo. This observation reveals a new mechanism underlying the increased incidence of acute thrombotic events observed in patients with CKD and may lead to the development of new lipid-targeting therapies in this population.

Key Words

aggregation
arterial thrombosis
chronic kidney disease
platelets
vascular smooth muscle cells

Abbreviations and Acronyms

AoSMC
aortic smooth muscle cell
CKD
chronic kidney disease
cLDL
carbamylated low-density lipoprotein
HAEC
human aortic endothelial cell
LDL
low-density lipoprotein
LOX-1
lectin-like oxidized LDL receptor 1
MAP kinase
mitogen-activated protein kinase
NFκB
nuclear factor kappa B
nLDL
native low-density lipoprotein
PAI-1
plasminogen activator inhibitor type 1
TF
tissue factor

Cited by (0)

The study was supported by grants from the Swiss National Science Foundation and the Swiss Heart Foundation.

Dr. Beer has received grant support and compensation as advisor, speaker, and CME from Bayer, Boehringer-Ingelheim, Sanofi, Pfizer, and Bristol-Myers Squibb. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Drs. Holy and Akhmedov contributed equally to this work.

Listen to this manuscript's audio summary by JACC Editor-in-Chief Dr. Valentin Fuster.