Oxidized low-density lipoprotein cholesterol and plaque vulnerability

Aim In-stent neoatherosclerosis (NA) has emerged as an important contributing factor to late stent failure and cardiovascular events. The aim of this study was to investigate whether lipid markers are associated with NA using optical coherence tomography (OCT) after percutaneous coronary intervention (PCI) in patients with coronary artery disease under well-controlled low density lipoprotein cholesterol (LDL-c) on statin treatment. Methods We enrolled consecutive 115 patients under statin treatment who underwent PCI with current-generation drug-eluting stent for acute and chronic coronary syndrome. OCT image and various lipid markers were obtained at 1-year for scheduled research assessment. NA was defined as a lipid laden neointima or calcified neointima. Both small dense LDL-c (sd-LDL-c) and remnant lipoprotein cholesterol (RL-c) were measured using direct homogenous assay. Results During an average follow-up of 13 months, NA was observed in 14 (13.6%) patients. Not LDL-c but sd-LDL-c, Malondialdehyde-modified LDL (MDA-LDL) as oxidized LDL and (RL-c) were significantly higher in patients with NA. The optimal threshold values of sd-LDL-c, MDA-LDL and RL-c for predicting NA according to receiver operating characteristics analysis were 32.3 mg/dl, 91.0 U/L, and 3.3 mg/dL, respectively. On multivariate logistic regression analysis, sd-LDL-c (≥32.3 mg/dL) and MDA (≥91.0 U/L) were significantly associated with NA (odds ratio [OR]:13.62, p=0.016, OR: 12.68, p=0.01, respectively). Conclusions In statin-treated patients, sd-LDL-c and MDA-LDL but not LDL-c might be useful biomarkers to identify the formation of NA at 1 years after PCI. Aggressive reduction of these atherogenic LDL may have a potential to prevent the formation of NA. Funding Acknowledgement Type of funding sources: None.

Increased Levels of Low-Density Lipoprotein Oxidation in Patients with Familial Hypercholesterolemia and in End-Stage Renal Disease Patients on Hemodialysis

Quantitative assessment of macrophage accumulation is appealing in evaluating plaque inflammation. In optical coherence tomography (OCT) imaging, local macrophage clusters may be a feasible marker for macrophage quantification. 404 patients presenting with acute coronary syndrome who underwent OCT evaluation were included. This study aims to assess the relationships between systemic inflammatory biomarkers [including monocytes, high-density lipoprotein cholesterol (HDL-C), and monocyte-to-HDL ratio (MHR)], plaque characteristics, and local macrophage clusters in coronary plaque. Macrophage clusters were present in 218 patients, with a median arc value of 72° (50°-163°). Patients with macrophage clusters showed markedly higher levels of inflammatory biomarkers and plaque vulnerability. Multivariate logistic regression analysis demonstrated that MHR, lipid index, and microchannel were independently associated with the presence of macrophage clusters. The DeLong test showed the area under the curve of the above three combined indicators was significantly larger than that of single indicators (0.774 vs. 0.692, 0.665, 0.624, respectively, p < 0.001). The macrophage cluster arc correlated positively with MHR and lipid index (r = 0.219, p = 0.001; and r = 0.229, p = 0.001, respectively). More superficial macrophage infiltration, thin cap fibroatheromas, plaque rupture, and thinner fibrous cap thickness were observed in the large macrophage cluster group (>72°) compared to the small macrophage cluster group (50°-72°). The macrophage cluster arc in the low MHR + lipid index group was significantly lower than that in the high MHR + lipid index group (68° ± 17° vs. 84° ± 26°, p = 0.001). Multiple linear regression analysis demonstrated that MHR, age, and lipid index were independently associated with macrophage cluster arc. In subgroup analysis stratified by clinical presentation and high-sensitivity C-reactive protein level, higher MHR and lipid index levels were observed in large macrophage clusters than in the non-macrophage cluster group, irrespective of the inflammation background. The macrophage cluster was a valuable index for quantifying local plaque inflammation. MHR, lipid index, and microchannel were independently associated with macrophage clusters. Large macrophage clusters were independently associated with high MHR and high lipid plaque burden.

Objective. It is well-established that rupture of lipid-rich atherosclerotic lesions in the coronary arteries (referred to as vulnerable, high-risk, or unstable plaques) with subsequent coronary artery thrombosis is the most common cause of acute coronary syndrome and sudden cardiac death. Vulnerable plaques are most accurately detected using optical coherence tomography (OCT). Given the high cost of OCT, an urgent task is to search for markers of the development of vulnerable atherosclerotic plaques in the coronary arteries based on routine examination data, which will allow developing effective strategies for the prevention of associated coronary events. In hypertensive patients potential markers may include indicators of systemic inflammation, but little information is available on this topic.Aim: To identify potential markers of vulnerable atherosclerotic plaques in coronary arteries in patients with stable coronary artery disease and hypertension based on routine laboratory testing.Material and Methods. The study included patients &gt;18 years old, with a diagnosis of stable coronary artery disease and indications for OCT-guided PCI (extended/calcified/bifurcation lesions and/or diabetes), who gave informed consent to participate in the study. All patients underwent laboratory and instrumental examination in accordance with approved standards of medical care. A total of 30 patients were included in the study: aged 66.5±9.2 years (including 17 men); office BP 134.4±12.4/78.3±6.05 mmHg (systolic, SBP/ diastolic, DBP, respectively); type 2 diabetes mellitus (DM2) was detected in 30%; body mass index was 30.7±5.3 kg/m2.Results. According to OCT data, patients were divided into two groups: group 1 (n = 19) with the presence of vulnerable atherosclerotic plaque morphology (rich lipid core, lipid plaque with lipid arc expansion&gt;180°, presence of macrophage clusters) and group 2 (n = 11) with atherosclerotic plaques without signs of vulnerability. The groups were comparable in terms of gender, age, blood pressure, antihypertensive, hypoglycemic and lipid-lowering therapy. However, patients in group 1 had statistically significantly higher levels of fibrinogen (3.39±0.86 vs. 2.75±0.45, p = 0.038), platelet-lymphocyte ratio (119.2±31.9 vs. 84.0±30, p = 0.006) and blood creatinine (88.3±13.2 vs. 76.7±7.8, p = 0.014). According to multivariate logistic regression analysis, blood fibrinogen and plateletlymphocyte ratio were independent markers of the presence of vulnerable atherosclerotic plaques.Conclusion. Platelet-lymphocyte ratio and blood fibrinogen levels, determined as part of a routine examination and reflecting increased activity of systemic inflammation, are markers of the development of vulnerable atherosclerotic plaques in the coronary arteries in patients with stable coronary artery disease and hypertension.

To compare optical coherence tomography (OCT)-derived plaque characteristics of coronary target lesions between diabetic patients with acute coronary syndrome (ACS) versus stable angina pectoris (SAP). In vivo assessment of plaque composition of coronary culprit lesions in a cardiovascular high-risk population with diabetes mellitus is incompletely elucidated. 102 diabetic patients with coronary de novo lesions were enrolled and categorized into an ACS-group (40 patients) and a SAP-group (62 patients) according to their clinical presentation. Assessment of clinical data, angiographic, and OCT imaging including the analysis of plaque composition and lipid content of the target lesions were performed prior to percutaneous coronary intervention and compared between the two groups. Plaque characteristics of patients in the ACS-group compared with the SAP-group showed a higher incidence of lipid-rich plaque [33 (82.5%) vs. 25 (40.3%)], thin-capped fibroatheroma [29 (72.5%) vs. 10 (16.1%)], macrophage infiltration [32 (80.0%) vs. 21 (33.9%)], thrombus [23 (57.5%) vs. 2 (3.2%)], and plaque rupture [27 (67.5%) vs. 2 (3.2%)] (all P < 0.001). Moreover, there was a wider lipid arc (174.5 ± 33.8° vs. 122.9 ± 43.9°), a longer lipid plaque length (6.52 ± 2.04 mm vs. 3.73 ± 2.16 mm), a greater lipid volume index (1117.2 ± 349.9 vs. 504.8 ± 379.3), and a smaller minimal fibrous cap thickness (51.52 ± 9.14 µm vs. 80.33 ± 26.71 µm) within lipid-rich lesions of ACS patients (all P < 0.001). Diabetic patients with ACS exhibit more vulnerable plaque features in coronary culprit lesions compared with diabetic patients with SAP. This may provide rationale for a specific therapeutic strategy either by pharmacological plaque stabilization or coronary intervention in any lesion with vulnerable plaque morphology in patients with diabetes.

Lipoprotein oxidation, dyslipidemia, and hypertension are important underlying causes of accelerated atherosclerosis in patients with diabetes mellitus. The potential of antihypertensive medications to reduce lipid oxidation is, therefore, an important determinant in the choice of agents for patients with diabetes mellitus. The aim of this study was to compare the lowering effect of a new dihydropyridine calcium antagonist, lercanidipine, with that of the first angiotensin-receptor blocker, losartan, on low-density lipoprotein (LDL) oxidation. Forty patients in metabolically stable condition who had type 2 diabetes mellitus with hypertension were studied in this single-blind, randomized, prospective crossover study, comprising 2 treatment periods of 16 weeks each, separated by a 4-week washout period. LDL oxidation was evaluated by dialdehyde analysis by means of the thiobarbituric acid-reactive substances assay with and without cupric sulfate, as well as determination of conjugated dienes in the LDL lipid extract. Lercanidipine and losartan both significantly reduced the propensity of the serum to oxidize LDL (P =.001). With one method of estimation (conjugated dienes), the effect of lercanidipine was superior to that of losartan (P =.04). Losartan lowered urinary albumin excretion but lercanidipine did not. Both lercanidipine and losartan attenuate LDL oxidation in patients with type 2 diabetes mellitus and hypertension. This observation may offer insight into the mechanisms of the therapeutic effects of these agents in patients with diabetes mellitus.

Objective. Studies that have evaluated correlation between body mass index (BMI) and novel lipid indices such as triglycerides (TG)/high-density lipoprotein-cholesterol (HDL-C), total cholesterol (TC)/HDL-C, and low-density lipoprotein cholesterol (LDL-C)/HDL-C in type 2 diabetes mellitus (T2DM) are scarce. Hence, the aim of the present study was to explore the correlation between BMI and novel lipid indices in Bosnian patients with T2DM. Methods. Present study included 117 patients with T2DM (mean age: 66.51 years) and 68 controls (mean age: 68.37 years). BMI was calculated as weight/height². Lipids were measured by standard methods. TG/HDL-C, TC/HDL-C, and LDL-C/HDL-C ratios were separately calculated. The differences between the groups were assessed by Student's t-test or Man Whitney U test. Correlations were determined by Spearman's test. Results. In a total sample of T2DM patients, 41.0% were overweight and 44.4% were obese. In the control group, 51.5% of subjects were overweight and 25.0% were obese. In T2DM group, a significant correlation was observed between BMI and HDL-C, LDL-C, TG/HDL, TC/HDL-C, and LDL-C/HDL-C ratios. In the control group, there was a significant correlation found between BMI and HDL-C, TG, TG/HDL, TC/HDL-C, and LDL-C/HDL-C-ratios. Correlation between BMI and other lipid parameters in T2DM and the control group was not determined. Conclusion. The present study showed significant correlation between BMI and novel lipid indices in both T2DM patients and the control group of subjects. Possible explanation for the observed results might be prevalence of overweight and obese participants in this study sample. Since novel lipid indices are used in the prediction of cardiometabolic risk, results obtained in the present study have valuable clinical implications.

Background The relation between culprit plaque morphology and the clinical presentation of an acute myocardial infarction (AMI) has not been examined in detail. Purpose To study the culprit plaque morphology in patients with AMI with or without preinfarction angina using optical coherence tomography (OCT) imaging. Methods A total of 102 patients with AMI (32 STEMI, 70 NSTEMI) who underwent OCT imaging before percutaneous coronary intervention were enrolled. Patients were classified as: i) having either intermittent chest pain in the six hours preceding the final episode of pain, or unstable angina (or both) in the week preceding AMI (preinfarction angina group); or ii) having a single episode of chest pain without unstable symptoms in the preceding week (no preinfarction angina group). Culprit plaque was classified as plaque rupture (PR) or intact fibrous cap (IFC), as previously described. Prati thrombus score was calculated, and the prevalence of calcification, neovascularization, and OCT-defined macrophage accumulation was assessed. Results Patients with preinfarction angina showed a significantly higher prevalence of IFC than PR, while those without preinfarction angina showed a significantly higher prevalence of PR than IFC (Figure). PR in patients with preinfarction angina were more frequently associated with macrophage accumulation, while those in patients without preinfarction angina were not (Figure). White thrombus tended to be more frequent in patients with preinfarction angina than in those without (85.7% vs. 63.6%, p=0.097), and Prati thrombus score tended to be lower [22.0 (15.8–30.3) vs. 38.5 (12.8–67.5), p=0.145]. Calcifications were significantly less frequent in patients with preinfarction angina than in those without (22.0% vs. 40.4%, p=0.045), while neovascularization tended to be more frequent (58.0% vs. 42.3%, p=0.113). Conclusions Patients with preinfarction angina have a distinct culprit plaque phenotype, frequently characterized by IFC and a relatively lower thrombotic burden, probably reflecting a prevalence of reparative mechanisms and spontaneous thrombolytic activity in these patients.

The impact of serum trans fatty acids concentration on plaque vulnerability in patients with coronary artery disease: Assessment via optical coherence tomography

In atherosclerosis, plaque vulnerability is strongly related to rupture, and vulnerable plaques contain numerous inflammatory cells, particularly macrophages, suggesting that inflammation is closely associated with plaque instability. Recently, it has been suggested that F-18 fluorodeoxyglucose (FDG) on positron emission tomography (PET) is a useful technique for detection of local inflamed atherosclerotic lesions. We therefore examined the effects of atorvastatin on F-18-FDG accumulations in atherosclerotic plaques at common carotid and ascending aorta. A total of 20 patients with dyslipidemia but not treated with medication were enrolled and imaged using F-18-FDG -PET and CT for baseline measurement. They were randomized to receive 20-mg or 5-mg atorvastatin after imaging and F-18-FDG -PET and CT were checked again 6 months later. Changes in the standard uptake value (SUV) of F-18-FDG-accumulation rate (plaque/integral plasma) between baseline and follow-up were evaluated. After atorvastatin treatment, serum C-reactive protein (CRP) levels, low-density lipoprotein (LDL) cholesterol levels and malondialdehyde-modified LDL (MDA-LDL) cholesterol levels were significantly reduced (CRP levels: from 1277±704 mg/dl to 609±314 mg/dl, p &lt; 0.0001, LDL cholesterol levels: from 154±29 mg/dl to 98±29 mg/dl, p &lt; 0.0001, MDA-LDL cholesterol levels: 178.4±70.8 IU/l to 125.4±49.7 IU/l, p &lt; 0.0001, respectively). The maximum SUV significantly decreased at follow-up (common carotid arteries: from 1.36 ±0.13 g/dl to 1.28 ±0.22 g/dl, p = 0.047, ascending aorta: from 1.63 ±0.20 g/dl to 1.53 ±0.16 g/dl, p = 0.032, respectively). Notably, the decrease in the SUV was well correlated with reduction of serum CRP levels (common carotid arteries: r = 0.52, ascending aorta: r = 0.47, respectively), LDL cholesterol levels (common carotid arteries: r = 0.46, ascending aorta: r = 0.43, respectively) and MDA-LDL cholesterol levels (common carotid arteries: r = 0.47, ascending aorta: r = 0.43, respectively). Six-month atorvastatin treatment had anti-inflammatory effects and decreased SUV detected by F-18-FDG -PET, which might represent regression of aortic vulnerability.

The association of hyperbilirubinemia in Gilbert's syndrome (GS) with a decrease in prevalence of coronary artery disease is a well-known phenomenon. In this study, the state of low-density lipoprotein (LDL) oxidation which has been postulated to be a significant determinant at the etiopathogenesis of atherosclerotic disorders was investigated among individuals with GS. For this purpose, serum cholesterol, LDL cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, apolipoprotein A and B, bilirubins, thiobarbituric acid-reactive substances, and the sensitivity of LDL oxidation levels, as well as serum alanine aminotransferase, aspartate aminotranserfase, gamma glutamyl transferase, and alkaline phosphatase activities, were determined in 17 patients with Gilbert's syndrome and 15 healthy adults. There was no significant difference between the groups except the indirect bilirubin parameter (P < 0.001). In comparison with the healthy individuals, LDL oxidation levels between 75 and 120 min were significantly lower (P < 0.005) along with prolonged lag-phase in GS patients, indicating a delay in oxidation susceptibility. It is suggested that the chronic hyperbilirubinemia leading to a lag-phase prolongation in LDL oxidation and a decrease in LDL oxidation may be reason for the low percentage of coronary artery disease.

Acute thrombosis secondary to atherosclerotic plaque rupture is the main cause of acute cardiac and cerebral ischemia. An animal model of unstable atherosclerotic plaques is highly important for investigating the mechanism of plaque rupture and thrombosis. However, current animal models involve complex operations, are costly, and have plaque morphologies that are different from those of humans. We aimed to establish a simple animal model of vulnerable plaques similar to those of humans. Rabbits were randomly divided into three groups. Group A was given a normal formula diet for 13 weeks. Group C underwent surgery on the intima of the right carotid artery with – 80 °C cryofluid-induced injury after 1 week of a high-fat diet and further feeding a 12-week high-fat diet. Group B underwent the same procedure as Group C but without the – 80 °C cryofluid. Serum lipid levels were detected via ELISA. The plaque morphology, stability and degree of stenosis were evaluated through hematoxylin–eosin (HE) staining, Masson trichrome staining, Elastica van Gieson staining (EVG), and oil red O staining. Macrophages and inflammatory factors in the plaques were assessed via immunohistochemical analysis. The serum low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and total cholesterol (TC) levels in groups B and C were significantly greater than those in group A. No plaque formation was observed in group A. The plaques in group B were very small. In group C, obvious plaques were observed in the blood vessels, and the plaques exhibited a thin fibrous cap, a large lipid core, and partially visible neovascularization, which is consistent with the characteristics of vulnerable plaques. In the plaques of group C, a large number of macrophages were present, and matrix metalloproteinase 9 (MMP-9) and lectin-like oxidized LDL receptor 1 (LOX-1) were abundantly expressed. We successfully established a rabbit model of vulnerable carotid plaque similar to that of humans through the combination of cryofluid-induced endothelial injury and a high-fat diet, which is feasible and cost effective.

Cystatin C, which is an endogenous marker for renal function, has been reported to be associated with outcomes and risk stratification of coronary vascular disease patients. In this study, the relationship between the serum cystatin C level and characteristics of coronary plaques is evaluated in patients with coronary artery disease. The study involved 137 lesions in 82 patients. Plaque vulnerability, rupture, fibrotic cap thickness, microchannel, and calcified nodules were evaluated by optical coherence tomography. Cystatin C levels in acute coronary syndrome (ACS) patients and in non-ACS patients were 1.160 ± 0.595 and 0.973 ± 0.158 mg/L, respectively (&lt;it&gt;P&lt;/it&gt; = 0.046). The cystatin C levels were not different between patients with and without ruptured plaques (&lt;it&gt;P&lt;/it&gt; = 0.396), or between stable and unstable lesions (&lt;it&gt;P&lt;/it&gt; = 0.223). There was correlation between cystatin C and calcified nodule in plaque (&lt;it&gt;r&lt;/it&gt; = 0.188, &lt;it&gt;P&lt;/it&gt; = 0.032). A significant negative correlation exists between the cystatin C levels and fibrous cap tissue thickness (&lt;it&gt;r&lt;/it&gt; = −0.242, &lt;it&gt;P&lt;/it&gt; = 0.018). Prior statin usage, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and cystatin C were independent contributors to fibrous cap thickness (&lt;it&gt;P&lt;/it&gt;-value was 0.001, 0.001, 0.026, and 0.037, respectively). Cystatin C is not related with plaque rupture or stability, but it related with some plaque morphology, such as thin fibrous cap thickness and calcified nodule.

We evaluated whether supplementation of patients with type 2 diabetes with an olive oil-enriched diet and young barley leaf essence affected the susceptibility of different low-density lipoprotein (LDL) subfractions to oxidation and free radical activity. Thirty type 2 diabetic patients were randomly assigned to three groups. The first control group of subjects received placebo only. The second group of subjects received 15 g of barley leaf essence. The third group received 15 g of barley leaf essence plus an olive oil-enriched diet. The study lasted for 4 weeks. There were no changes in fatty acid composition of the LDL particles in either the barley leaf essence group or the control group. The olive oil-enriched diet induced fatty acid composition changes, increasing C18:1 (oleic acid) and decreasing C18:2 (linoleic acid) significantly. The vitamin E content and lag times of LDL subfractions of both test groups increased significantly compared to the con troll group. The addition of olive oil to the diet increased further the vitamin E content and lag time, and decreased the ΔA234 levels of B-LDL and Sd-LDL. The blood lucigenin-chemiluminescence and luminol-chemiluminescence levels were significantly reduced in both test groups compared with the control group. Thus, dietary supplementation with barley leaf essence may help to scavenge oxygen free radicals and inhibit LDL oxidation. Furthermore, adding olive oil to the diet with the barley leaf essence was more effective than barley leaf essence alone at inhibiting Sd-LDL oxidation and this may be protective against vascular disease in type 2 diabetic patients.

Autoantibodies to oxidation-specific epitopes of low density lipoprotein (LDL), such as malondialdehyde-modified LDL (MDA-LDL), occur in plasma and atherosclerotic lesions of humans and animals. Plasma titers of such antibodies are correlated with atherosclerosis in murine models, and several such autoantibodies have been cloned. However, human-derived monoclonal antibodies to epitopes of oxidized LDL (OxLDL) have not yet been reported. We constructed a phage display antibody library from a patient with high plasma anti-MDA-LDL titers and isolated 3 monoclonal IgG Fab antibodies, which specifically bound to MDA-LDL. One of these, IK17, also bound to intact OxLDL as well as to its lipid and protein moieties but not to those of native LDL. IK17 inhibited the uptake of OxLDL by macrophages and also bound to apoptotic cells and inhibited their phagocytosis by macrophages. IK17 strongly immunostained necrotic cores of human and rabbit atherosclerotic lesions. When (125)I-IK17 was injected intravenously into LDL receptor-deficient mice, its specific uptake was greatly enriched in atherosclerotic plaques versus normal aortic tissue. Human autoantibodies to OxLDL have important biological properties that could influence the natural course of atherogenesis.