Lipoprotein(a) in Cardiovascular Diseases

Lipoprotein(a) (Lp(a)) is an LDL-like molecule consisting of an apolipoprotein B-100 (apo(B-100)) particle attached by a disulphide bridge to apo(a). Many observations have pointed out that Lp(a) levels may be a risk factor for cardiovascular diseases. Lp(a) inhibits the activation of transforming growth factor (TGF) and contributes to the growth of arterial atherosclerotic lesions by promoting the proliferation of vascular smooth muscle cells and the migration of smooth muscle cells to endothelial cells. Moreover Lp(a) inhibits plasminogen binding to the surfaces of endothelial cells and decreases the activity of fibrin-dependent tissue-type plasminogen activator. Lp(a) may act as a proinflammatory mediator that augments the lesion formation in atherosclerotic plaques. Elevated serum Lp(a) is an independent predictor of coronary artery disease and myocardial infarction. Furthermore, Lp(a) levels should be a marker of restenosis after percutaneous transluminal coronary angioplasty, saphenous vein bypass graft atherosclerosis, and accelerated coronary atherosclerosis of cardiac transplantation. Finally, the possibility that Lp(a) may be a risk factor for ischemic stroke has been assessed in several studies. Recent findings suggest that Lp(a)-lowering therapy might be beneficial in patients with high Lp(a) levels. A future therapeutic approach could include apheresis in high-risk patients in order to reduce major coronary events.

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Defensin Stimulates the Binding of Lipoprotein (a) to Human Vascular Endothelial and Smooth Muscle Cells

Blood ◽

10.1182/blood.v89.12.4290 ◽

1997 ◽

Vol 89 (12) ◽

pp. 4290-4298 ◽

Cited By ~ 53

Author(s):

Abd Al-Roof Higazi ◽

Ehud Lavi ◽

Khalil Bdeir ◽

Anthony M. Ulrich ◽

Dara G. Jamieson ◽

...

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Cerebral Arteries ◽

Muscle Cells ◽

Tissue Type ◽

Vascular Endothelial ◽

Atherosclerotic Vascular Disease ◽

Lipoprotein A ◽

Type Plasminogen Activator

AbstractThere is evidence to suggest that elevated plasma levels of lipoprotein (a) [Lp(a)] represent a risk factor for the development of atherosclerotic vascular disease, but the mechanism by which this lipoprotein localizes to involved vessels is only partially understood. In view of studies suggesting a link between inflammation and atherosclerosis and our previous finding that leukocyte defensin modulates the interaction of plasminogen and tissue-type plasminogen activator with cultured human endothelial cells, we examined the effect of this peptide on the binding of Lp(a) to cultured vascular endothelium and vascular smooth muscle cells. Defensin increased the binding of Lp(a) to endothelial cells approximately fourfold and to smooth muscle cells approximately sixfold. Defensin caused a comparable increase in the amount of Lp(a) internalized by each cell type, but Lp(a) internalized as a consequence of defensin being present was not degraded, resulting in a marked increase in the total amount of cell-associated lipoprotein. Abundant defensin was found in endothelium and in intimal smooth muscle cells of atherosclerotic human cerebral arteries, regions also invested with Lp(a). These studies suggest that defensin released from activated or senescent neutrophils may contribute to the localization and persistence of Lp(a) in human vessels and thereby predispose to the development of atherosclerosis.

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Cell Adhesion Molecule 1 (CADM1), a Novel Venous Thrombosis Risk Factor, Is Ubiquitously Present In Vascular Endothelium and Smooth Muscle Cells

Blood ◽

10.1182/blood.v116.21.4316.4316 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4316-4316

Author(s):

Kanayo Tatsumi ◽

Douglas J Taatjes ◽

Beth A Bouchard ◽

Winifred Trotman ◽

Edwin G Bovill

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Risk Factor ◽

Smooth Muscle Cells ◽

Venous Thrombosis ◽

Peripheral Blood ◽

Muscle Cells ◽

Peripheral Blood Leukocytes ◽

Blood Leukocytes ◽

Immunogold Staining

Abstract Abstract 4316 We recently demonstrated that CADM1, interacting with protein C deficiency, is a novel risk factor for venous thrombosis (VT) Blood 114:3084-3091, 2009. CADM1 likely plays a role in maintaining endothelial barrier function. Prior to this study CADM1 had not been identified in endothelial cells. In this study we have determined the distribution of CADM1 in human vasculature. Methods: Human tissue samples representing all organs as well as large vessels were accessioned from archived paraffin blocks from the surgical pathology division of FAHC. Tissue sections were processed for immunoflourescence using as primary antibodies a chicken monoclonal anti-CADM1 IgY antibody (anti-SynCAM/TSLC1 clone 3E1, MBL Inc, Woburn, MA) and anti-smooth muscle actin (SMA) clone 1A4 (Sigma, St. Louis, MO), anti-von Willebrand factor (vWF) rabbit polyclonal antibody (DAKO Inc., Glostrup, DK). vWF staining was used to identify endothelial cells. The secondary antibodies for CADM1, SMA, and vWF were donkey anti chicken alexa 488, donkey anti mouse alexa 647, and donkey anti rabbit alexa 647, respectively. Appropriate negative and positive controls were run. Intensity of staining was rated as absent, trace or present by three observers (TK, DJT, and EGB). Immunoelectron microscopy (IEM) was performed on cultured human umbilical vein endothelial cells (Allcells LLC, Emeryville, CA) using a post embedding procedure with protein-A gold. Peripheral blood leukocytes were evaluated for the presence of CADM1 using the same antibody following cytospin preparation. Results CADM1 was found ubiquitously in the macro- and micro-vasculature of all organs as well as the aorta and saphenous vein with intensity of staining showing modest variability from organ to organ. CADM1 staining of SMA was observed in both arterial and venous vessels but was considerably stronger on the arterial side. IEM demonstrated cytoplasmic immunogold staining associated with elements of rough endoplasmic reticulum and actin filaments as well as at the membranes of filopodia. In contrast, peripheral blood monocytes, lymphocytes and granulocytes were negative for CADM1expression. Conclusions: CADM1 is expressed ubiquitously in endothelial and smooth muscle cells of the macro-and micro-vasculature with IEM evidence for its presence in filopodial cytoplasm and membranes. Peripheral blood leukocytes did not show evidence of CADM1 expression. This is the first report of CADM1 positivity in vascular smooth muscle cells. The biological role of CADM1 remains to be determined but its ubiquitous expression in the endothelium of the macro- and micro-circulation, together with an apparent role in endothelial cell motility, suggests an important role in endothelial homeostasis. Disclosures: Bovill: Haemotologic Technologies, Essex Jct., VT: Equity Ownership.

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Plasminogen Activator Inhibitor-1 Expression in Human Liver and Healthy or Atherosclerotic Vessel Walls

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648809 ◽

1994 ◽

Vol 72 (01) ◽

pp. 044-053 ◽

Cited By ~ 76

Author(s):

N Chomiki ◽

M Henry ◽

M C Alessi ◽

F Anfosso ◽

I Juhan-Vague

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Plasminogen Activator ◽

Human Liver ◽

Plasminogen Activator Inhibitor ◽

Muscle Cells ◽

Vessel Walls ◽

Activator Inhibitor ◽

Pai 1

SummaryIndividuals with elevated levels of plasminogen activator inhibitor type 1 are at risk of developing atherosclerosis. The mechanisms leading to increased plasma PAI-1 concentrations are not well understood. The link observed between increased PAI-1 levels and insulin resistance has lead workers to investigate the effects of insulin or triglyceride rich lipoproteins on PAI-1 production by cultured hepatocytes or endothelial cells. However, little is known about the contribution of these cells to PAI-1 production in vivo. We have studied the expression of PAI-1 in human liver sections as well as in vessel walls from different territories, by immunocytochemistry and in situ hybridization.We have observed that normal liver endothelial cells expressed PAI-1 while parenchymal cells did not. However, this fact does not refute the role of parenchymal liver cells in pathological states.In healthy vessels, PAI-1 mRNA and protein were detected primarily at the endothelium from the lumen as well as from the vasa vasorum. In normal arteries, smooth muscle cells were able to produce PAI-1 depending on the territory tested. In deeply altered vessels, PAI-1 expression was observed in neovessels scattering the lesions, in some intimal cells and in smooth muscle cells. Local increase PAI-1 mRNA described in atherosclerotic lesions could be due to the abundant neovascularization present in the lesion as well as a raised expression in smooth muscle cells. The increased PAI-1 in atherosclerosis could lead to fibrin deposit during plaque rupture contributing further to the development and progression of the lesion.

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Thrombin Inhibition and Thrombin Generation by Cultured Aortic Endothelial and Smooth Muscle Cells from Minipig

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657227 ◽

1982 ◽

Vol 48 (01) ◽

pp. 101-103 ◽

Cited By ~ 1

Author(s):

B Kirchhof ◽

J Grünwald

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Vessel Wall ◽

Thrombin Generation ◽

Muscle Cells ◽

Thrombin Inhibition ◽

Generating Capacity ◽

Wall Interaction ◽

Cells Cultured

SummaryEndothelial and smooth muscle cells cultured from minipig aorta were examined for their inhibitory activity on thrombin and for their thrombin generating capacity.Endothelial cells showed both a thrombin inhibition and an activation of prothrombin in the presence of Ca++, which was enhanced in the presence of phospholipids. Smooth muscle cells showed an activation of prothrombin but at a lower rate. Both coagulation and amidolytic micro-assays were suitable for studying the thrombin-vessel wall interaction.

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Vascular Smooth Muscle Cells Inhibit the Plasminogen Activators Secreted by Endothelial Cells

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661265 ◽

1985 ◽

Vol 53 (02) ◽

pp. 165-169 ◽

Cited By ~ 24

Author(s):

Walter E Laug

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Conditioned Medium ◽

Vascular Smooth Muscle Cells ◽

Inhibitory Activity ◽

Muscle Cells ◽

Plasminogen Activators ◽

Bovine Endothelial Cells

SummaryTPure cultures of bovine endothelial cells (EC) produce and secrete large amounts of plasminogen activators (PA). Cocultivation of EC with vascular smooth muscle cells (SMC) resulted in a significant decrease of PA activities secreted by the EC, whereas the cellular PA activities remained unaffected. Secreted PA activities were absent in the growth medium as long as the SMC to EC ratio was 2:1 or higher. The PA inhibitory activity of the SMC was rapid and cell-to-cell contact was not necessary.The PA inhibitory activity was present in homogenates of SMC as well as in the medium conditioned by them but not in the extracellular matrix elaborated by these cells. Serum free medium conditioned by SMC neutralized both tissue type (t-PA) and urokinase like (u-PA) plasminogen activators. Gel electrophoretic analysis of SMC conditioned medium followed by reverse fibrin autography demonstrated PA inhibitory activities in the molecular weight (Mr) range of 50,000 to 52,000 similar to those present in media conditioned by bovine endothelial cells or fibroblasts. Regular fibrin zymography of SMC conditioned medium incubated with u-PA or t-PA revealed the presence of a component with a calculated approximate Mr of 45,000 to 50,000 which formed SDS resistant complexes with both types of PA.These data demonstrate that vascular SMC produce and secrete (a) inhibitor(s) of PAs which may influence the fibrinolytic potential of EC.

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