Aggregated low-density lipoprotein uptake induces membrane tissue factor procoagulant activity and microparticle release in human vascular smooth muscle cells.
BACKGROUND
Tissue factor (TF) is the main initiator of the arterial blood coagulation system, and aggregated LDL (agLDL) are found in the arterial intima. Our hypothesis is that agLDL internalization by vascular smooth muscle cells (VSMCs) may trigger TF-procoagulant activity.


RESULTS
Cultured human VSMCs were obtained from human coronary arteries of explanted hearts during transplant operations. VSMCs were incubated with native LDL (nLDL) or agLDL. TF mRNA was analyzed by real-time polymerase chain reaction, and cellular and released TF protein antigen were analyzed by Western blot. TF microparticle (MP) content was analyzed by flow cytometry and TF activity by a factor Xa generation test. Both nLDL and agLDL strongly and equally increased TF mRNA and cell membrane protein expression, by approximately 5- and 9-fold, respectively. A sustained TF procoagulant activity was induced by agLDL but not by nLDL (agLDL 2.46+/-0.22 versus nLDL 0.72+/-0.12 mU/mg protein at 12 hours). AgLDL increased TF antigen release (agLDL 5.64+/-0.4 versus nLDL 3.28+/-0.22 AU) and TF MP release (agLDL 89.85+/-8.51 versus nLDL 19.69+/-4.59 TF MP/10(3) cells). TF activation and release induced by agLDL is not related to apoptosis. Blockade of LDL receptor-related protein, a receptor for agLDL, prevented the agLDL-induced release of TF protein and TF MP.


CONCLUSIONS
VSMC-TF expression is upregulated by both nLDL and agLDL. However, only agLDL engagement to LDL receptor-related protein induced cellular TF procoagulant activity and TF release by human VSMCs.
Llorente-Cortés
Vicenta
V
Cardiovascular Research Center, CSIC-ICCC, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Otero-Viñas
Marta
M
Camino-López
Sandra
S
Llampayas
Oriol
O
Badimon
Lina
L
D017304:Annexin A5 / Q000032:analysis; D002478:Cells, Cultured / Q000166:cytology / Q000378:metabolism; D003331:Coronary Vessels / Q000166:cytology; D015951:Factor Xa / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects; D019254:Genes, bcl-2; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism* / Q000494:pharmacology; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D013925:Thromboplastin / Q000378:metabolism*; D051028:bcl-2-Associated X Protein
D017304:Annexin A5; D008077:Lipoproteins, LDL; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008563:Membrane Lipids; D010743:Phospholipids; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D013925:Thromboplastin; D015951:Factor Xa