Oxidized low-density lipoprotein and high-density lipoprotein cholesterol modulate coronary arterial remodeling: an intravascular ultrasound study

Pathophysiology of coronary vascular remodeling: relationship with traditional risk factors for coronary artery disease

The relationship between cardiovascular risk factors and vascular remodeling is a relatively new area of investigation. We discuss the various mechanisms by which cardiovascular risk factors cause vascular remodeling. Endothelial dysfunction, lipoprotein alterations, inflammation, and platelet activation are the mechanisms by which remodeling occurs. Plaque composition also plays an important role in directing remodeling. Plaque with extensive calcification is more likely to undergo constrictive remodeling. Positive and negative remodeling is based on how these factors coordinate and determine the direction of remodeling. Matrix metalloproteinases perform a crucial role in vascular remodeling. Advanced glycation end-products are key substances involved in the negative remodeling associated with diabetes. Remodeling in hypertension can be either eutrophic or hypertrophic. Endothelial dysfunction and low-grade inflammation lead to negative remodeling in hypertension. Dyslipidemia can be associated with either positive or negative remodeling. High high-density lipoprotein is associated with positive remodeling and high low-density lipoprotein with negative remodeling. Smoking causes endothelial dysfunction, increased oxidative stress, and decreased nitric oxide synthesis leading to inward remodeling. Aging also causes endothelial dysfunction and predisposes to negative remodeling. Knowledge of these associations can elucidate various clinical presentations and guide therapeutic choices in the future.

Vessel shrinkage as a sign of atherosclerosis progression in type 2 diabetes: a serial intravascular ultrasound analysis

OBJECTIVE

The aim of this study was to determine the natural history of vascular remodeling of atherosclerotic plaques in patients with type 2 diabetes and the predictors of vessel shrinkage.

RESEARCH DESIGN AND METHODS

In this serial intracoronary ultrasound (IVUS) study, 237 coronary segments from 45 patients enrolled in the DIABETES I, II, and III trials were included. Quantitative volumetric IVUS analyses (motorized pullbacks at 0.5 mm/s) were performed in the same coronary segment after the index procedure and at the 9-month follow-up. Nontreated mild lesions (angiographic stenosis <25%) with > or =0.5 mm plaque thickening and length of > or =5 mm assessed by IVUS were included. Vessel shrinkage was defined as a Deltaexternal elastic membrane area/Deltaplaque area < 0. Statistical adjustment by multiple segments and multiple lesions per patient was performed.

RESULTS

Vessel shrinkage was identified in 37.1% of segments and was associated with a significant decrease in lumen area at 9 months (vessel shrinkage, 10 +/- 4 mm(2) vs. non-vessel shrinkage, 11 +/- 4 mm(2); P = 0.04). Independent predictors of vessel shrinkage were insulin requirements (odds ratio 4.6 [95% CI 1.40-15.10]; P = 0.01), glycated hemoglobin (1.5 [1.05-2.10]; P = 0.02), apolipoprotein B (0.96 [0.94-0.98]; P < 0.001), hypertension (3.7 [1.40-10.30]; P = 0.009), number of diseased vessels (5.6 [2.50-12.50]; P < 0.001), and prior revascularization (17.5 [6.50-46.90]; P < 0.001).

CONCLUSIONS

This serial IVUS study suggests that progression of coronary artery disease in patients with type 2 diabetes may be mainly attributed to vessel shrinkage. Besides, vessel shrinkage is influenced by insulin requirements and metabolic control and is associated with more advanced coronary atherosclerosis.

Human ApoA-I Transfer Attenuates Transplant Arteriosclerosis via Enhanced Incorporation of Bone marrow–derived Endothelial Progenitor Cells

Objective— Transplant arteriosclerosis is the leading cause of graft failure and death in patients with heart transplantation. Endothelial progenitor cells (EPCs) contribute to endothelial regeneration in allografts. We investigated whether increased HDL cholesterol induced by adenoviral human apoA-I (AdA-I) transfer increases number and function of EPCs, promotes incorporation of EPCs in Balb/c allografts transplanted paratopically in C57BL/6 ApoE −/− mice, and attenuates transplant arteriosclerosis.

Methods and Results— EPC number in ApoE −/− mice was increased after AdA-I transfer as evidenced by 1.5-fold ( P <0.01) higher Flk-1 Sca-1–positive cells and 1.4-fold ( P <0.01) higher DiI-acLDL isolectin-positive spleen cells. In addition, HDL enhanced EPC function in vitro. Incorporation of bone marrow–derived EPCs was 5.8-fold ( P <0.01) higher at day 21 after transplantation in AdA-I-treated apoE −/− mice compared with control mice. Enhanced endothelial regeneration in AdA-I-treated apoE −/− mice as evidenced by a 2.6-fold ( P <0.01) increase of CD31-positive endothelial cells resulted in a 1.4-fold ( P =0.059) reduction of neointima and a 3.9-fold ( P <0.01) increase of luminal area.

Conclusion— Human apoA-I transfer increases the number of circulating EPCs, enhances their incorporation into allografts, promotes endothelial regeneration, and attenuates neointima formation in a murine model of transplant arteriosclerosis.

Inhibition of injury-induced arterial remodelling and carotid atherosclerosis by recombinant human antibodies against aldehyde-modified apoB-100

OBJECTIVE

The immune system plays an important regulatory role in the development of atherosclerotic plaques and neointima formation following various types of angioplasty. In the present study we investigated the effect of antibodies against aldehyde-modified apolipoprotein B-100 (apoB-100), a component of oxidized LDL, on atherosclerosis and response to arterial injury in mice.

METHODS

The ability of a high affinity human recombinant antibody (2D03), specific for malondialdehyde-modified apoB-100, to influence formation of atherosclerosis as well as remodelling and neointima formation after a collar-induced injury of the carotid artery was studied in LDL receptor(-/-) mice over-expressing human apoB-100.

RESULTS

The antibody recognized epitopes present in mouse plasma and reduced the plasma level of oxidized LDL by 34%. Antibody treatment inhibited injury-induced restrictive vascular remodelling but did not influence the size of the neointima. Atherosclerosis in the uninjured contra lateral carotid artery was determined by computerized image analysis and the mean plaque area in animals given control IgG1 was 7608+/-10,336 micro m(2). In contrast, essentially no plaques were present in animals treated with the 2D03 antibody (397+/-235 micro m(2), P<0.01 versus control IgG1).

CONCLUSIONS

Treatment with antibodies against aldehyde-modified apoB-100 dramatically reduces atherosclerosis and inhibits restrictive vascular remodelling in mice expressing human apoB-100.

Development, advances and applications of diagnostic ultrasound in animals

Ultrasound has many industrial applications but it was first introduced as a medical diagnostic aid in the 1940s with its first veterinary application, the detection of ovine pregnancy, being reported in 1966. Since then, improvements in equipment quality combined with an increased awareness of the benefits of ultrasound as an imaging technique have led to its widespread use in the veterinary field. Recent advances in computer technology have significantly influenced equipment design and the miniaturization of transducers allows intra-operative and intra-vascular applications. Software advances have improved the ability to manipulate and process data, leading to an increased amount of information being obtained from each examination and the advent of 'remote diagnosis'. Ultrasound guided interventional techniques can now be used for diagnostic or therapeutic purposes. Many of these developments have been introduced by equipment manufacturers but have found specific applications in the veterinary field. Ultrasound is currently employed in a very diverse range of situations, not just as a diagnostic tool in the routine clinical workup of a range of species, but also for disease screening, conservation projects, commercial services, herd management and clinical research.

Relationship of a comprehensive panel of plasma oxidized low-density lipoprotein markers to angiographic restenosis in patients undergoing percutaneous coronary intervention for stable angina

BACKGROUND

This study was performed to assess the relationship between oxidized low-density lipoprotein (OxLDL) and restenosis. OxLDL induces up-regulation of inflammatory genes and cytokines and recruits monocytes to the vessel wall. Elevated levels of monocytes post-percutaneous coronary intervention (PCI) are associated with in-stent restenosis.

METHODS AND RESULTS

One hundred forty-one patients with stable angina pectoris had serial blood samples drawn before PCI (68% balloon only, 32% stent), immediately post-PCI and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apoB-100 detected by antibody E06 (OxPL/apoB), autoantibodies to malondialdehyde-LDL and copper-oxidized LDL, and apoB-immune complexes were measured in all samples. Quantitative and qualitative coronary angiography was performed with 94% angiographic follow-up. Restenosis was defined as >50% diameter stenosis (%DS). The overall angiographic restenosis rate was 32% (39% in balloon group, 16% in stent group). OxPL/apoB levels rose significantly and OxLDL autoantibody titers decreased immediately post-PCI in patients both with and without restenosis, but there were no significant differences among groups. There was also no relationship of any OxLDL marker to lesion length, %DS, or minimal lumen diameter. No differences were noted in stent versus balloon-treated patients.

CONCLUSIONS

Serial measurement of a comprehensive panel of circulating OxLDL markers after uncomplicated PCI for stable angina does not predict restenosis.

LDL-cholesterol predicts negative coronary artery remodelling in diabetic patients: an intravascular ultrasound study

AIMS

To investigate the relationship between coronary artery remodelling and glycaemic and lipid profiles in diabetic patients.

METHODS AND RESULTS

Intravascular ultrasound analyses of 131 angiographically non-significant coronary stenoses in 80 diabetic patients were performed. The remodelling index (RI) was calculated as the ratio between total vessel area at target site and total vessel area at proximal reference, and was assessed in two ways: as a continuous variable, and as a binary categorical variable: RI<1 namely, negative remodelling (group I), or RI> or =1 (group II). Percentage cross-sectional narrowing was 57+/-13%. On average, RI was 0.93+/-0.13. Coronary shrinkage was found in 94 (71.7%) lesions. Significant inverse correlations were demonstrated between RI and total cholesterol (r=-0.26, P=0.003), apolipoprotein-B (r=-0.23, P=0.01) and LDL-cholesterol (r=-0.3, P=0.001) levels. Multivariable lineal regression analysis identified LDL-cholesterol as the only independent predictor of RI (P=0.001).

CONCLUSION

Negative remodelling is a frequent finding in diabetics and it is associated with LDL-cholesterol levels. This may contribute to the diffuse coronary artery disease observed in diabetic patients.