Lipoprotein-associated phospholipase A2 is an independent marker for coronary endothelial dysfunction in humans

Negative correlation between early recovery and lipoprotein-associated phospholipase A2 levels after intravenous thrombolysis

Objective

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is considered a biomarker for systemic inflammation and the risk of myocardial infarction and stroke. However, little is known about the effect of acute vascular events on marker levels. The purpose of this study was to assess the potential association of early recovery with Lp-PLA2 levels in patients with acute ischemic stroke (AIS) after intravenous thrombolysis (IVT).

Methods

Forty-three consecutive AIS patients who had their first stroke and were hospitalized within 5 hours of the onset of stroke were enrolled. All patients were treated with IVT using alteplase or urokinase. Plasma Lp-PLA2 levels were measured within 24 hours after IVT. Variables that showed a significant association with Lp-PLA2 in univariate analysis were included in the multivariate ordered logistic regression model.

Results

Early recovery was associated with Lp-PLA2 levels after IVT, and Lp-PLA2 levels tended to decrease with increased probability of early recovery. This study is the first to report a negative correlation between early recovery and Lp-PLA2 levels after IVT.

Conclusion

Early recovery after IVT was negatively correlated with Lp-PLA2 A2 levels.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

The "Hitchhiker's Guide to the Galaxy" of Endothelial Dysfunction Markers in Human Fertility

Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and represents the first step in the pathogenesis of cardiovascular diseases. The evaluation of endothelial health is fundamental in clinical practice and several direct and indirect markers have been suggested so far to identify any alterations in endothelial homeostasis. Alongside the known endothelial role on vascular health, several pieces of evidence have demonstrated that proper endothelial functioning plays a key role in human fertility and reproduction. Therefore, this state-of-the-art review updates the endothelial health markers discriminating between those available for clinical practice or for research purposes and their application in human fertility. Moreover, new molecules potentially helpful to clarify the link between endothelial and reproductive health are evaluated herein.

Lipoprotein-associated phospholipase A2 levels, endothelial dysfunction and arterial stiffness in patients with stable coronary artery disease

BACKGROUND

Lipoprotein-associated Phospholipase A2 (Lp-PLA2), can exert proinflammatory as well as proatherogenic properties on the vascular wall. The current study sought to evaluate the influence of high Lp-PLA2 levels on indices of arterial wall properties in patients with stable coronary artery disease (CAD).

METHODS

Three hundred seventy-four consecutive patients with stable CAD (mean age 61 ± 11 years, 89% males) were enrolled in this single-center cross-sectional study. Flow-mediated dilation (FMD) was used to assess endothelial function and augmentation index (AIx) of the central aortic pressure was used to assess reflected waves. ELISA was used to determine Lp-PLA2 serum levels.

RESULTS

After dividing the participants in 3 equal groups based on the tertiles of circulating Lp-PLA2 values, no significant differences were demonstrated between those in the 3rd tertile with Lp-PLA2 values > 138 μg/L, in the 2nd tertile with Lp-PLA2 values between 101 and 138 μg/L and in the 1st tertile (Lp-PLA2 values < 101 μg/L) regarding age, male gender, smoking habits, family history of CAD or history of a previous myocardial infarction, diabetes mellitus, arterial hypertension, hyperlipidemia, duration of CAD and treatment with relevant medication. Importantly, subjects with Lp-PLA2 values in the highest tertile, had significantly reduced FMD values compared to the middle and lower tertile (4.43 ± 2.37% vs. 4.61 ± 1.97% vs. 5.20 ± 2.52% respectively, P = 0.03). Patients in the highest tertile of Lp-PLA2 values had significantly higher AIx values (24.65 ± 8.69% vs. 23.33 ± 9.65%, P = 0.03), in comparison to the lowest tertile, with Lp-PLA2 values < 101 μg/L. A linear regression analysis showed that Lp-PLA2 values > 138 μg/L negatively correlated to FMD [b = - 0.45 (95% CI: - 0.79 - -0.11), P = 0.01] and AIx values [b = 1.81 (95% CI: 0.57-3.05), P < 0.001] independently of cofounders like gender, age, diabetes mellitus, arterial hypertension, dyslipidemia, smoking habits, family history of CAD, history of previous myocardial infarction, serum glucose, circulating lipid levels, duration of CAD, antihypertensive medication, antidiabetic drugs, statin therapy and treatment with β-blockers.

CONCLUSIONS

Elevated Lp-PLA2 levels relate to endothelial dysfunction and arterial stiffness in patients with stable CAD independently from classical risk factors for CAD, statin use, antihypertensive treatment, and duration of the disease.

Identification and visualization of oxidized lipids in atherosclerotic plaques by microscopic imaging mass spectrometry-based metabolomics

BACKGROUND AND AIMS

Dysregulated lipid metabolism has emerged as one of the major risk factors of atherosclerosis. Presently, there is a consensus that oxidized LDL (oxLDL) promotes development of atherosclerosis and downstream chronic inflammatory responses. Due to the dynamic metabolic disposition of lipoprotein, conventional approach to purify bioactive lipids for subsequent comprehensive analysis has proven to be inadequate for elucidation of the oxidized lipids species accountable for pathophysiology of atherosclerotic lesions. Herein, we aimed to utilize a novel mass microscopic imaging technology, coupled with mass spectrometry (MS) to characterize oxidized lipids in atherosclerotic lesions.

METHODS

We attempted to use MALDI-TOF-MS and iMScope to identify selected oxidized lipid targets and visualize their respective localizations in study models of atherosclerosis.

RESULTS

Based on the MS analysis, detection of 7-K under positive ionization through product ion peak at m/z 383 [M + H-H₂O] indicated the distinctive presence of targeted lipid within Cu²⁺-oxLDL and Cu²⁺-oxLDL loaded macrophage-like J774A.1 cells, along with other cholesterol oxidation products. Moreover, the application of two-dimensional iMScope has successfully visualized the localization of lipids in aortic atherosclerotic plaques of the Watanabe heritable hyperlipidemic (WHHL) rabbit. Distinctive lipid distribution profiles were observed in atherosclerotic lesions of different sizes, especially the localizations of lysoPCs in atherosclerotic plaques.

CONCLUSIONS

Taken together, we believe that both MALDI-TOF-MS and iMScope metabolomics technology may offer a novel proposition for future pathophysiological studies of lipid metabolism in atherosclerosis.

Assessment of peripheral endothelial function predicts future risk of solid-tumor cancer

AIMS

Cardiovascular health metrics predict the risk not only of cardiovascular diseases but also of several types of cancers. Microvascular endothelial dysfunction can predict future cardiovascular adverse events, but the predictive value of microvascular endothelial dysfunction for future risk of solid-tumor cancer has not been characterized.

METHODS

A total of 488 patients who underwent microvascular endothelial function assessment using reactive hyperemia peripheral arterial tonometry were included in this study. Microvascular endothelial dysfunction was defined as a reactive hyperemia peripheral arterial tonometry index ≤2.0.

RESULTS

Of 221 patients with a baseline reactive hyperemia peripheral arterial tonometry index ≤2.0, 21 patients (9.5%) were diagnosed with incident solid-tumor cancer during follow-up, whereas of 267 patients with a baseline reactive hyperemia peripheral arterial tonometry index >2.0, 10 patients (3.7%) were diagnosed with incident solid-tumor cancer during follow-up (p = 0.009). Patients with a reactive hyperemia peripheral arterial tonometry index ≤2.0 had lower solid-tumor cancer-free survival compared to patients with a reactive hyperemia peripheral arterial tonometry index >2.0 (log-rank p = 0.017) (median follow-up 6.0 (3.0-9.1) years). Cox proportional hazard analyses showed that a reactive hyperemia peripheral arterial tonometry index ≤2.0 predicted the incidence of solid-tumor cancer, with a hazard ratio of 2.52 (95% confidence interval 1.17-5.45; p = 0.019) after adjusting for age, sex, and coronary artery disease, 2.83 (95% confidence interval 1.30-6.17; p = 0.009) after adjusting for diabetes mellitus, hypertension, smoking status, and body mass index >30 kg/m2, 2.79 (95% confidence interval 1.21-6.41; p = 0.016) after adjusting for fasting plasma glucose, systolic blood pressure, smoking status (current or former), and body mass index, and 2.43 (95% confidence interval 1.10-5.34; p = 0.028) after adjusting for Framingham risk score.

CONCLUSION

Microvascular endothelial dysfunction, as defined by a reactive hyperemia peripheral arterial tonometry index ≤2.0, was associated with a greater than two-fold increased risk of solid-tumor cancer. Microvascular endothelial dysfunction may be a useful marker to predict the future risk of solid-tumor cancer, in addition to its known ability to predict cardiovascular disease. Further research is necessary to develop adequate cancer screening strategies for patients with microvascular endothelial dysfunction.

Inflammatory Biomarkers for Cardiovascular Risk Stratification in Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a frequent autosomal genetic disease characterized by elevated concentrations of low-density lipoprotein cholesterol (LDL) from birth with increased risk of premature atherosclerotic complications. Accumulating evidence has shown enhanced inflammation in patients with FH. In vessels, the deposition of modified cholesterol lipoproteins triggers local inflammation. Then, inflammation facilitates fatty streak formation by activating the endothelium to produce chemokines and adhesion molecules. This process eventually results in the uptake of vascular oxidized LDL (OxLDL) by scavenger receptors in monocyte-derived macrophages and formation of foam cells. Further leukocyte recruitment into the sub-endothelial space leads to plaque progression and activation of smooth muscle cells proliferation. Several inflammatory biomarkers have been reported in this setting which can be directly synthetized by activated inflammatory/vascular cells or can be indirectly produced by organs other than vessels, e.g., liver. Of note, inflammation is boosted in FH patients. Inflammatory biomarkers might improve the risk stratification for coronary heart disease and predict atherosclerotic events in FH patients. This review aims at summarizing the current knowledge about the role of inflammation in FH and the potential application of inflammatory biomarkers for cardiovascular risk estimation in these patients.

Phospholipase A2 is an Inflammatory Predictor in Cardiovascular Diseases: Is there any Spacious Room to Prove the Causation?

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an enzyme family of phospholipase A2 produced by the inflammatory cell in atherosclerotic plaque. It is transported in the circulation, attached mainly to low-density lipoprotein-cholesterol (LDL-C). It hydrolyzes glycerophospholipids particularly fatty acids at the sn-2 position and produces numerous bioactive lipids; and leads to endothelial dysfunction, atherosclerotic plaque inflammation, and development of the necrotic core in plaques. There are two kinds of phospholipase A2, namely: secretory phospholipase A2 (sPLA2) and Lp- PLA2. They are deemed as evolving predictors of cardiovascular disease (CVD) risk in hospitaland population-based studies, including healthy subjects, acute coronary syndromes (ACS) and patients with CVD. Unfortunately, Lp-PLA2 inhibitor (darapladib) and s-PLA2 inhibitor (varespladib methyl) failed to prove to lower the risk of composite CVD mortality, myocardial infarction and stroke in those with stable CVD and ACS. Herein, we describe the explanation based on the existing data why there is still a discrepancy among them. So, it highlights the opinion that phospholipase A2 is merely the inflammatory biomarkers of CVD and playing an important role in atherosclerosis. Further, there is more spacious room to prove the causation.

Increased activity of lipoprotein-associated phospholipase A2 in non-severe asthma

BACKGROUND

Given increased risk of cardiovascular events in asthma we hypothesized that lipoprotein-associated phospholipase A₂ (Lp-PLA₂), an enzyme involved in atherosclerosis, is associated with proinflammatory and prothrombotic blood alterations in this disease.

METHODS

In 164 adult asthmatics (63 with severe asthma) we measured plasma Lp-PLA₂ activity using the PLAC test. We determined its relations to inflammation and prothrombotic blood alterations.

RESULTS

In asthma, Lp-PLA₂ was inversely related to the age (β = -0.1 [-0.18 to -0.02]) and was lower in women (n = 122 [74%], 205 [182-242] vs. 243 [203-262] nmol/min/ml, p = 0.001). Interestingly, Lp-PLA₂ correlated negatively with the asthma severity score (β = -0.15 [-0.23 to -0.07]), being 10.3% higher in those with non-severe (mild or moderate) asthma (n = 101, 62%) as compared to the severe disease subtype (224 [191-261] vs. 203 [181-229], p = 0.006 after adjustment for potential confounders). Lp-PLA₂ activity was positively related to the levels of low-density lipoprotein (β = 0.1 [0.02-0.18]), triglycerides (β = 0.11 [0.03-0.19]) and glucose (β = 0.1 [0.02-0.18]) and inversely to the tumor necrosis factor α (β = -0.27 [-0.35 to -0.2]), high sensitivity C-reactive protein (β = -0.1 [-0.19 to -0.02]) and fibrinogen (β = -0.12 [-0.21 to -0.03]), as well as prothrombin (β = -0.16 [-0.24 to -0.08]), and parameters describing thrombin generation potential, such as endogenous thrombin potential (β = -0.14 [-0.21 to -0.06]) and peak thrombin generated (β = -0.2 [-0.28 to -0.12]).

CONCLUSIONS

Elevated Lp-PLA₂ activity in non-severe asthmatics suggests increased atherosclerotic risk in this group. Lower Lp-PLA₂ activity accompanied by its inverse relationship to inflammatory or prothrombotic blood biomarkers observed in turn in severe asthmatics might be related to the pathogenesis of more severe asthma phenotype.

The functional assessment of patients with non-obstructive coronary artery disease: expert review from an international microcirculation working group

Symptomatic non-obstructive coronary artery disease (NOCAD) is an increasingly recognised entity that is associated with poor cardiovascular outcomes. Nearly half of those undergoing coronary angiography for appropriate indications, such as typical angina, or a positive stress test have no obstructive lesion. There are no guideline recommendations as to how to care properly for these patients. Physiologic assessment of the coronary arteries beyond two-dimensional angiography is not standardised, yet it can provide valuable information in patients presenting with typical angina in the setting of NOCAD. In this consensus document, we detail steps for the interventional cardiologist to evaluate the patient with symptomatic NOCAD in the cardiac catheterisation laboratory, first with the assessment of coronary flow reserve (CFR), and then with delineation of deficiencies in non-endothelium-dependent CFR (CFRne) versus endothelium-dependent CFR (CFRe) using provocative agents such as adenosine and acetylcholine, respectively, followed by the evaluation of smooth muscle function with nitroglycerine (NTG). Once the mechanism behind the anginal symptoms is established, one can identify the appropriate treatment strategies to address the physiologic deficiency that is present. Despite an established safety profile, a comprehensive assessment may be considered for selected patients which requires an understanding of the appropriate invasive evaluation by the practising interventional cardiologist when evaluating not only patients with obstructive CAD but also those with NOCAD.

Sympathoexcitation and impaired arterial baroreflex sensitivity are linked to vascular inflammation in individuals with elevated resting blood pressure

Elevated Resting Blood Pressure (ERBP) in the prehypertensive range is associated with increased risk of hypertension and cardiovascular disease, the mechanisms of which remain unclear. Prior studies have suggested that ERBP may be associated with overactivation and dysregulation of the sympathetic nervous system (SNS). We hypothesized that compared to normotensives (≤120/80 mmHg), ERBP (120/80-139/89 mmHg) has higher SNS activity, impaired arterial baroreflex sensitivity (BRS), and increased vascular inflammation. Twenty-nine participants were studied: 16 otherwise healthy individuals with ERBP (blood pressure (BP) 130 ± 2/85 ± 2 mmHg) and 13 matched normotensive controls (mean BP 114 ± 2/73 ± 2 mmHg). We measured muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and continuous electrocardiogram at rest and during arterial BRS testing via the modified Oxford technique. Blood was analyzed for the following biomarkers of vascular inflammation: lipoprotein-associated phospholipase A2 (Lp-PLA2), E-selectin, and intercellular adhesion molecule 1 (ICAM-1). Resting MSNA burst frequency (22 ± 2 vs. 16 ± 2 bursts/min, P = 0.036) and burst incidence (36 ± 3 vs. 25 ± 3 bursts/100 heart beats, P = 0.025) were higher in ERBP compared to controls. Cardiovagal BRS was blunted in ERBP compared to controls (13 ± 2 vs. 20 ± 3 msec/mmHg, P = 0.032), while there was no difference in sympathetic BRS between groups. Lp-PLA2 (169 ± 8 vs. 142 ± 9 nmol/min/mL, P = 0.020) and E-selectin (6.89 ± 0.6 vs. 4.45 ± 0.51 ng/mL, P = 0.004) were higher in ERBP versus controls. E-selectin (r = 0.501, P = 0.011) and ICAM-1 (r = 0.481, P = 0.015) were positively correlated with MSNA, while E-selectin was negatively correlated with cardiovagal BRS (r = -0.427, P = 0.030). These findings demonstrate that individuals with ERBP have SNS overactivity and impaired arterial BRS that are linked to biomarkers of vascular inflammation.

Butyphthalide in the treatment of massive Cerebral Infarction

Objective:

To evaluate the effect of butyphthalide in the treatment of massive cerebral infarction.

Methods:

One hundred and twenty patients with massive cerebral infarction who were admitted to the hospital between January 2017 and December 2017 were selected and divided into a treatment group (n = 60) and a control group (n = 60) using random number table, 80 each group. Patients in the control group were given conventional cerebral infarction therapy, while patients in the treatment group were given butyphthalide injection besides the conventional treatment. The National Institutes of Health Stroke Scale (NIHSS) score, score of activity of daily living (ADL), lipoprotein-associated phospholipase A2 (LP-PLA2) and prognosis were recorded and compared between the two groups. The response rates of the two groups were recorded.

Results:

The total response rates of the control group and treatment group were 73.85% and 93.85% respectively at the postoperative 21^st day, and the difference had statistical significance (P<0.05). The NIHSS score of the two groups obviously decreased, and the ADL score significantly increased after treatment; the differences of NIHSS score and ADL score before and after treatment in the same group had statistical significance (P<0.05). The improvement of the indexes of the treatment group was obviously superior to that of the control group, and the differences between the two groups had statistical significance (P<0.05). The level of LP-PLA2 of both groups significantly decreased at the postoperative 21^st day, and the difference before and after treatment in the same group was statistically significant (P<0.05); the treatment group had a significantly lower level of LP-PLA2 than the control group, and the difference had statistical significance (P<0.05). The treatment group had significantly higher positive outcome rate and lower mortality rate than the control group at the postoperative 90^th day, and the differences had statistical significance (P<0.05). The incidence of adverse events of the treatment group and control group was 8.3% (5/60) and 5.0% (3/60) respectively, suggesting no significant difference (P>0.05).

Conclusion:

Butyphthalide has a favourable effect in treating massive cerebral infarction. It can repair neurologic impairment, improve activity of daily living, and adjust the level of LP-PLA2, suggesting favourable application values.

Long-term darapladib use does not affect coronary plaque composition assessed using multimodality intravascular imaging modalities: a randomized-controlled study

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) may play a role in plaque progression and vulnerability. We aimed to define plaque characteristics on multimodality intravascular imaging in patients with coronary endothelial dysfunction in response to long-term inhibition of Lp-PLA2 by darapladib.

PATIENTS AND METHODS

This is a double-blinded, randomized study screening 70 patients, and enrolling 54 patients with suspected ischemia, without obstructive disease on angiography and with coronary endothelial dysfunction by invasive assessment. Patients were randomized to receive darapladib or placebo for 6 months. Forty patients underwent multimodality intravascular imaging at baseline and after 6 months of therapy. Several parameters of plaque vulnerability were measured, including maximum value of lipid core burden index for any of the 4-mm segment (maxLCBI4 mm) by near-infrared spectroscopy. Microchannels and macrophages were assessed using optical coherence tomography and necrotic core volume by virtual histology intravascular ultrasound.

RESULTS

There was no significant difference in maxLCBI4 mm [64.56 (7.74, 128.56) vs. 22.43 (0, 75.63), P=0.522] or in macrophage images angle [-9.5° (-25.53°, 12.68°) vs. -16.7° (-28.6°, -4.8°), P=0.489] between groups. There was a trend toward shorter microchannel length in the darapladib arm [0, (-4.4, 0.2) mm vs. 0.8 (-0.15, 1.9) mm, P=0.08]. Percentage of necrotic core volume was not significantly different.

CONCLUSION

Thus, long-term inhibition of endogenous Lp-PLA2 activity with darapladib was not associated with a change in plaque progression and vulnerability indices after 6 months of therapy, and the endogenous Lp-PLA2 pathway may not play a direct role in the progression of early atherosclerosis in humans.

Chronic inhibition of lipoprotein-associated phospholipase A2 does not improve coronary endothelial function: A prospective, randomized-controlled trial

AIMS

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂), a novel biomarker for vascular inflammation, is associated with coronary endothelial dysfunction (CED) and independently predicts cardiovascular events. The current study aimed to determine whether darapladib, an orally administered Lp-PLA₂ inhibitor, improved CED.

METHODS AND RESULTS

Fifty-four patients with CED were enrolled in a double-blinded randomized placebo-controlled trial, and were randomized to receive oral darapladib, 160mg daily, or placebo. Coronary angiography and invasive coronary endothelial function assessment were performed at baseline and post-6months of treatment. Primary endpoints were change in coronary artery diameter and coronary blood flow in response to acetylcholine. Additionally, Lp-PLA₂ activity was measured at baseline and on follow-up to evaluate for adherence and drug effect. Fifty-four patients were randomized to placebo (n=29) and darapladib (n=25). Mean age in darapladib group was 55.2.±11.7years vs. 54.0±10.5years (p=0.11). On follow-up, there was no significant difference in the percent response to acetylcholine of coronary artery diameter in treatment vs. placebo group (+3 (IQR -9, 15) vs. +3 (-12, 19); p=0.87) or coronary blood flow (-5 (IQR -24, 54) vs. 39 (IQR -26, 67); p=0.41). There was significant reduction in Lp-PLA₂ activity in the treatment arm vs. placebo (-76 (IQR -113, -52) vs. -7(-21, -7); p<0.001).

DISCUSSION

Lp-PLA₂ inhibition with darapladib did not improve coronary endothelial function, despite significantly reduced Lp-PLA2 activity with darapladib. This study suggests endogenous Lp-PLA₂ may not play a primary role in coronary endothelial function in humans. CLINICALTRIALS.

GOV IDENTIFIER

NCT01067339.

Lipoprotein-associated phospholipase A₂ activity is increased in patients with definite familial hypercholesterolemia compared with other forms of hypercholesterolemia

BACKGROUND AND AIM

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) plays a key role in atherosclerosis development. It is considered a marker of increased risk of cardiovascular disease (CVD) and plaque vulnerability. Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated plasma levels of low-density lipoprotein cholesterol and a higher prevalence of early CVD. Our aim was to evaluate the differences in Lp-PLA₂ activity in a population of hypercholesterolemic patients with and without definite FH.

METHODS AND RESULTS

Hypercholesterolemic patients were consecutively recruited. Definite FH was defined according to Dutch Lipid Clinic Network criteria ≥8. All patients underwent routine clinical examination and biological assessments and Lp-PLA₂ activity was measured in blood samples. Among 469 patients, 118 had a definite diagnosis of FH. Lp-PLA₂ activity was significantly higher in definite FH patients compared to non-definite FH patients (206.5 ± 54.5 vs. 180.8 ± 48.4 nmol/min/mL, p < 0.0001). Lp-PLA₂ positively correlated with total cholesterol, LDL-C and apolipoprotein B and negatively with HDL-C and apolipoprotein A-1. In multivariate analysis, definite FH diagnosis, LDL-C, HDL-C and statin treatment remained correlates of Lp-PLA₂ independently of systolic blood pressure.

CONCLUSIONS

Lp-PLA₂ activity was higher in definite FH than in non-definite FH patients independently of LDL-C levels and statin treatment. These results highlight the particular phenotype of FH subjects among hypercholesterolemic patients. As increased Lp-PLA₂ activity suggests, FH patients exhibit higher arterial inflammation that may contribute to their high cardiovascular risk. Our results reinforce the potential beneficial role of statins pleiotropic effects and the need for proper identification and treatment of FH patients.

High-sensitivity C-reactive protein is an independent marker of abnormal coronary vasoreactivity in patients with non-obstructive coronary artery disease

BACKGROUND

Coronary endothelial dysfunction (CED) is an early stage of atherosclerosis and is associated with adverse cardiovascular events. Inflammation may play a role in the development of endothelial dysfunction. To date no study has evaluated the relationship between C-reactive protein and CED. We aimed to determine if C-reactive protein is associated with CED.

METHODS

In 1016 patients (mean age 50.7±12.3 years, 34% male) presenting to the catheterization laboratory with chest pain and non-obstructive coronary artery disease, coronary vasoreactivity was assessed by measuring the percent change in coronary blood flow (%ΔCBF) and coronary artery diameter (%ΔCAD) in response to intracoronary acetylcholine. Plasma high sensitivity C-reactive protein (hs-CRP) was measured and patients were divided into 2 groups: hs-CRP≤3.0 mg/L (low-intermediate cardiovascular risk n=169) and 3 mg/L<hs-CRP≤10 mg/L (high cardiovascular risk n=847).

RESULTS

Patients with a high risk hs-CRP had a significantly lower %ΔCBF and %ΔCAD in response to acetylcholine vs low risk hs-CRP (43.8±6.1 vs 65.8±4.5, P=.004 and -17.2±1.5 vs -13.1±0.8, P=.02 respectively). Low risk hs-CRP was associated with significantly higher %ΔCBF and %ΔCAD vs high risk hs-CRP (27.1±11.0, P=.01 and 4.5±1.9, P=.02 respectively). CED was associated with significantly higher hs-CRP levels and high risk hs-CRP was independently associated with abnormal coronary vasoreactivity, OR 1.82 (95% CI 1.25-2.69).

CONCLUSIONS

Hs-CRP is independently associated with and a strong predictor of abnormal coronary vasoreactivity in patients with non-obstructive coronary artery disease.

Serum lipoprotein-associated phospholipase A2 predicts the formation of carotid artery plaque and its vulnerability in anterior circulation cerebral infarction

OBJECTIVE

Circulation inflammation markers such as high-sensitive C-reactive protein (hsCRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2) are considered as predictors of cerebral and cardiac vascular diseases. However, the role of hsCRP and Lp-PLA2 in the anterior circulation cerebral infarction (ACI) is to be elaborated.

PATIENTS AND METHODS

We included 100 patients with acute anterior circulation cerebral infarction (AaCI group) and 50 non-infarction subjects (control group). Carotid artery was detected by color Doppler ultrasound. Subjects were grouped based on carotid intima-media thickness (IMT) and degree of stability of carotid atherosclerotic plaque. The levels of hsCRP and Lp-PLA2 were measured in corresponding groups and the association was analyzed.

RESULTS

hsCRP and Lp-PLA2 levels were the risk factors for AaCI. With the increment of carotid IMT and degree of plaque instability, the level of hsCRP and Lp-PLA2 showed an elevating tendency. hsCRP and Lp-PLA2 levels were significantly higher in plaque formation group than in IMT normal group (P=0.002 and P=0.001, respectively). hsCRP and Lp-PLA2 levels were significantly higher in vulnerable plaque group than in mixed plaque group and stable plaque group (P=0.003, P<0.001 for hsCRP and P<0.001, P<0.001 for Lp-PLA2). Lp-PLA2 was finally included in the atherosclerotic plaque model (OR=1.019, 95% confidence interval (CI): 1.003-1.035, P=0.020) and vulnerable plaque model (OR=1.041, 95%CI: 1.017-1.065, P=0.001) by performing multivariate logistic regression analysis. The area under the ROC curve (AUC) of Lp-PLA2 levels for atherosclerotic plaque was 0.746 (95% CI: 0.628-0.865, P<0.001). The optimal cut-off value for Lp-PLA2 level was 267.5ng/ml, and its sensitivity and specificity for diagnosis of atherosclerotic plaque were 70.8% and 67.1%, respectively.

CONCLUSIONS

The current study demonstrates that hsCRP and Lp-PLA2 are among the risk factors for AaCI. Elevated hsCRP and Lp-PLA2 are associated with carotid plaque formation. Univariate and multivariate logistic regression analysis suggests that elevated Lp-PLA2 is the independent risk factor for carotid plaque and its vulnerability.

AMP-activated protein kinase mediates the effects of lipoprotein-associated phospholipase A2 on endothelial dysfunction in atherosclerosis

The present study aimed to investigate the effects of lipoprotein-associated phospholipase A2 (Lp-PLA2) on endothelial dysfunction in an in vitro cell model of atherosclerosis, and to determine whether AMP-activated protein kinase (AMPK) mediates the effects of Lp-PLA2 on endothelial dysfunction. A total of 392 patients with coronary artery disease (CAD), including various sub-conditions, were recruited, and the plasma concentrations of Lp-PLA2 were evaluated. In addition, an in vitro model of atherosclerosis was established by exposing human umbilical vein endothelial cells (HUVECs) to oxidized low-density lipoprotein (oxLDL). SB-435495 was used to inhibit Lp-PLA2, and compound C was used to suppress AMPK expression. Lp-PLA2, AMPKα and phosphorylated-AMPKα (T172) expression in HUVECs were evaluated using western blot analysis. The concentrations of nitric oxide (NO), endothelin 1 (ET-1), intercellular adhesion molecule 1 (ICAM-1) and platelet/endothelial cell adhesion molecule 1 (PECAM-1) in cell culture supernatant were determined using commercially available ELISA kits. MTT assays were employed to indicate changes in cell viability. The current study found the plasma Lp-PLA2 levels were elevated in the CAD patients with stable angina pectoris, unstable angina pectoris, acute coronary syndromes and acute myocardial infarction, compared with a healthy control population. In addition, the in vitro results showed that Lp-PLA2 expression levels were elevated in oxLDL-exposed HUVECs. Lp-PLA2 suppression could increase cell viability, induce the production of NO and decrease the secretion of ET-1, in addition to suppressing the expression of cell adhesion molecules, including ICAM-1 and PECAM-1 in oxLDL-exposed HUVECs. The expression of AMPKα and phosphorylated-AMPKα (T172) was regulated by Lp-PLA2, and AMPK suppression was able to reverse the effects of Lp-PLA2 with regard to cell viability, endothelial vasorelaxation capacity and the secretion of adhesion molecules in oxLDL-exposed HUVECs. In conclusion, the present study provides initial evidence that Lp-PLA2 is able to cause endothelial dysfunction in an in vitro model of atherosclerosis, and the effects of Lp-PLA2 on endothelial dysfunction was at least partially a result of the downregulation of AMPKα, thus contributing to the progression of atherosclerosis.

Patients With Coronary Endothelial Dysfunction Have Impaired Cholesterol Efflux Capacity and Reduced HDL Particle Concentration

RATIONALE

Coronary endothelial dysfunction (ED)-an early marker of atherosclerosis-increases the risk of cardiovascular events.

OBJECTIVE

We tested the hypothesis that cholesterol efflux capacity and high-density lipoprotein (HDL) particle concentration predict coronary ED better than HDL-cholesterol (HDL-C).

METHODS AND RESULTS

We studied 80 subjects with nonobstructive (<30% stenosis) coronary artery disease. ED was defined as <50% change in coronary blood flow in response to intracoronary infusions of acetylcholine during diagnostic coronary angiography. Cholesterol efflux capacity and HDL particle concentration (HDL-PIMA) were assessed with validated assays. Cholesterol efflux capacity and HDL-PIMA were both strong, inverse predictors of ED (P<0.001 and 0.005, respectively). In contrast, HDL-C and other traditional lipid risk factors did not differ significantly between control and ED subjects. Large HDL particles were markedly decreased in ED subjects (33%; P=0.005). After correction for HDL-C, both efflux capacity and HDL-PIMA remained significant predictors of ED status. HDL-PIMA explained cholesterol efflux capacity more effectively than HDL-C (r=0.54 and 0.36, respectively). The efflux capacities of isolated HDL and serum HDL correlated strongly (r=0.49).

CONCLUSIONS

Cholesterol efflux capacity and HDL-PIMA are reduced in subjects with coronary ED, independently of HDL-C. Alterations in HDL-PIMA and HDL itself account for a much larger fraction of the variation in cholesterol efflux capacity than does HDL-C. A selective decrease in large HDL particles may contribute to impaired cholesterol efflux capacity in ED subjects. These observations support a role for HDL size, concentration, and function as markers-and perhaps mediators-of coronary atherosclerosis in humans.

Replacing carbohydrate with protein and fat in prediabetes or type-2 diabetes: greater effect on metabolites in PBMC than plasma

BACKGROUND

Active metabolism of peripheral blood mononuclear cells (PBMC) could suggest their suitability for metabolomics studies. This study examined whether reductions in PBMCs and plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) activities induced by dietary intervention affected the overall metabolic profiles of PBMC and plasma.

METHODS

Eighty nonobese subjects aged 40-70 years (18.5 ≤ BMI < 30 kg/m(2)) with prediabetes or newly-diagnosed type-2 diabetes were assigned to consume either the usual refined-rice diet (control group, n = 40) or to replace refined rice with whole grains and legumes as carbohydrates (whole-grain group, n = 40) for three meals per day during the 12-week intervention. Fasting PBMC and plasma metabolomes were profiled using UPLC-LTQ-Orbitrap mass spectrometry.

RESULTS

After 12 weeks, changes in fasting glucose, HbA1c, HOMA-IR, MDA, ox-LDL, LDL particle size, plasma Lp-PLA2 activity, and PBMC enzyme activity in the whole-grain group were significantly different from those in the control group before and after adjusting for baseline levels. The PBMC levels of L-leucine, oleamide, lysoPC (16:0), and lysoPC (18:0) in the whole-grain group showed greater reductions compared with those of the control group. Changes in plasma metabolites were not significantly different between the two groups. Changes in PBMC Lp-PLA2 activity positively correlated with changes in L-leucine, oleamide, lysoPC (16:0), lysoPC (18:0), glucose, and ox-LDL, and negatively correlated with changes in LDL particle size.

CONCLUSIONS

This study showed that dietary intervention in prediabetic or type-2 diabetic patients had a greater effect on PBMC Lp-PLA2 activity and metabolites compared with those of plasma metabolites.

TRIAL REGISTRATION

NCT02191644.

Hypothyroidism Is Associated With Coronary Endothelial Dysfunction in Women

BACKGROUND

Hypothyroidism is associated with an increased risk of coronary artery disease, beyond that which can be explained by its association with conventional cardiovascular risk factors. Coronary endothelial dysfunction precedes atherosclerosis, has been linked to adverse cardiovascular events, and may account for some of the increased risk in patients with hypothyroidism. The aim of this study was to determine whether there is an association between epicardial and microvascular coronary endothelial dysfunction and hypothyroidism.

METHODS AND RESULTS

In 1388 patients (mean age 50.5 [12.3] years, 34% male) presenting with stable chest pain to Mayo Clinic, Rochester, MN for diagnostic coronary angiography, and who were found to have nonobstructive coronary artery disease (<40% stenosis), we invasively assessed coronary artery endothelial-dependent microvascular and epicardial function by evaluating changes in coronary blood flow (% Δ CBF Ach) and diameter (% Δ CAD Ach), respectively, in response to intracoronary infusions of acetylcholine. Patients were divided into 2 groups: hypothyroidism, defined as a documented history of hypothyroidism or a thyroid-stimulating hormone (TSH) >10.0 mU/mL, n=188, and euthyroidism, defined as an absence of a history of hypothyroidism in the clinical record and/or 0.3<TSH≤10.0 mU/mL, n=1200. Subjects with a history of hypothyroidism had a significantly lower % Δ CBF Ach (48.26 [80.66] versus 64.58 [128.30]) compared to patients with euthyroidism, while the % Δ CAD Ach did not vary significantly between groups. After adjusting for covariates, females with hypothyroidism still had a significantly lower % Δ CBF Ach (estimated difference in % Δ CBF Ach [SE]: -16.79 [8.18]).

CONCLUSIONS

Hypothyroidism in women is associated with microvascular endothelial dysfunction, even after adjusting for confounders, and may explain some of the increased risk of cardiovascular disease in these patients.

Increased serum level of Lp-PLA2 is independently associated with the severity of coronary artery diseases: a cross-sectional study of Chinese population

Background

Lipoprotein-associated phospholipase A2 (Lp-PLA2) plays complex and adverse roles on atherosclerosis. Current study was to investigate whether increased plasma Lp-PLA2 level is independently associated with the severity of coronary artery diseases (CAD).

Methods

Totally 781 participants were enrolled and performed coronary angiography (CAG) to figure out the number of coronary artery stenosis. According to clinical presentation, electrocardiography, cardiac biomarker, and CAG result, participants were divided into control (excluded CAD), stable angina (SA), unstable angina (UA) and acute myocardial infarction (AMI) groups. Baseline characteristics were recorded. Statistical analyses were performed to evaluate the relationship between Lp-PLA2 level and CAD severity.

Results

Plasma levels of Lp-PLA2 in control, SA, UA and AMI groups were 7.38(3.33-9.26) μg/L, 5.94(2.89-8.55) μg/L, 8.56(5.34-11.95) μg/L and 8.68(5.56-13.27) μg/L respectively (P < 0.001). After adjusted for age, gender, smoking, diabetes mellitus, hypertension, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), apoprotein A (apoA) and statins, Lp-PLA2 level was still independently associated with CAD severity, with odd ratio (OR) of 1.055 (AMI group versus control group, 95% confidence interval (CI) 1.021-1.090, P < 0.05). Additionally, the relationship between Lp-PLA2 level and the number of stenosis coronary artery was also assessed. Lp-PLA2 levels in control, single-vessel, and multiple-vessels stenosis groups were 7.38(3.33-9.26) μg/L, 7.80 (4.05-10.76) μg/L and 8.29(5.18-11.76) μg/L respectively (P for trend < 0.001). After adjusted for age, gender, smoking, diabetes mellitus, hypertension, LDL-C and HDL-C, apoA and statins, Lp-PLA2 level remained independently associated with the number of coronary artery stenosis, with OR of 1.053 (multiple-vessels stenosis group versus control group, 95% CI 1.025-1.069, P < 0.05).

Conclusion

Increased Lp-PLA2 level is independently associated with CAD severity, and Lp-PLA2 level may be used to discriminate those who are at increased risk of cardiovascular events.

Circulating Lp-PLA₂ activity correlates with oxidative stress and cytokines in overweight/obese postmenopausal women not using hormone replacement therapy

Controversy remains regarding whether there is an association between circulating lipoprotein-associated phospholipase A2 (Lp-PLA2), cytokines, and oxidative stress in healthy postmenopausal women. We investigated the influence of age on Lp-PLA2 activity in postmenopausal women not using hormone therapy and the relationship of Lp-PLA2 enzyme activity to serum cytokine levels and oxidative stress indices. Normal weight (n = 1284) and overweight/obese (n = 707) postmenopausal women not using hormone therapy were categorized into five age groups: 50-54, 55-59, 60-64, 65-69, and 70-89 years. Overweight-obese women showed higher plasma Lp-PLA2 activity, urinary 8-epi-prostaglandin F2α (8-epi-PGF2α), serum interleukin (IL)-6, and smaller LDL particles than normal-weight women after adjusting for age, years postmenopause, smoking, drinking, blood pressure, glucose, insulin, lipid profiles, BMI, and waist circumference. Overweight/obese women 70-89 years old showed higher Lp-PLA2 activity than those aged 50-54 years, whereas no significant difference in Lp-PLA2 activity existed across normal-weight female age groups. Overweight/obese women aged ≥ 65 years showed higher Lp-PLA2, oxidized LDL (ox-LDL), IL-6, and 8-epi-PGF2α than age-matched normal-weight controls. Overweight/obese women aged ≥ 70 years had higher ox-LDL levels than those aged 50-59, and overweight/obese women aged 65-89 showed higher IL-6 and 8-epi-PGF2α. There were strong positive correlations between Lp-PLA2 and ox-LDL (r = 0.385, P < 0.001), Lp-PLA2 and IL-6 (r = 0.293, P < 0.001), and ox-LDL and IL-6 (r = 0.303, P < 0.001) in overweight/obese women; however, these relationships were weak in normal-weight women. These results suggest that aging and obesity-related oxidative and inflammatory mediators are associated with Lp-PLA2 activity in overweight/obese postmenopausal women not using hormone therapy.

Impaired coronary artery distensibility is an endothelium-dependent process and is associated with vulnerable plaque composition

Coronary endothelial-dependent microvascular dysfunction, an early reversible stage of coronary artery disease (CAD), is associated with poor clinical outcome. The current study investigated whether coronary artery distensibility index (CDI) is associated with: (i) coronary endothelial-dependent microvascular dysfunction and (ii) vulnerable plaque composition among subjects with non-obstructive CAD. Seventy-four subjects with non-obstructive CAD (luminal stenosis <30%) were studied. In 20 subjects with and without coronary endothelial-dependent microvascular dysfunction, coronary flow reserve (CFR) of target segment during intracoronary (IC) infusion of acetylcholine (Ach) and bolus injection of adenosine as well as CDI at rest of corresponding target segment were measured. In 54 subjects, plaque compositions and CDI at rest of 154 non-obstructive coronary segments as well as proximal segment without disease were measured by intravascular ultrasound (IVUS). CDI was defined as: [(Early-diastolic cross-sectional-area (CSA) - End-diastolic CSA of target segment)/(end-diastolic CSA of target segment × coronary-pulse-pressure) × 10(3) ]. There is a direct association between endothelial dysfunction and impaired CDI of a coronary segment both in the given coronary segment and corresponding microvessels in which a strong agreement between CDI and CFR Ach (r(2)  = 0·85, P = 0·0001) was observed. Multivariable regression-analysis showed that CDI was an independent predictor of the vulnerable plaque characteristics. The risk of impaired CDI was 125% higher in segments with necrotic core and 60% higher in segments with fibrofatty components as compared to normal segments (P = 0·001). In conclusions, the current study reveals that impaired CDI is an endothelial-dependent process of both given coronary segment and corresponding microvessels and is associated with vulnerable plaque composition.

Coronary endothelial dysfunction is associated with inflammation and vasa vasorum proliferation in patients with early atherosclerosis

OBJECTIVE

Endothelial dysfunction is an early manifestation of atherosclerosis. Inflammation and vasa vasorum play a pivotal role in the pathophysiology of plaque initiation, development, and complications. Optical coherence tomography allows high-resolution imaging of tissue microstructure. Therefore, the aim of this study was to test the hypothesis that segments with endothelial dysfunction show macrophages and vasa vasorum in patients with early coronary artery disease.

APPROACH AND RESULTS

Optical coherence tomography images were obtained from 40 patients with mild coronary atherosclerosis who underwent coronary endothelial function assessment. Optical coherence tomography findings, including macrophages and microchannels, were evaluated in 76 coronary segments corresponding to those in endothelial response to acetylcholine. Coronary artery diameter change in response to acetylcholine was more severe in segments showing macrophages (-17.7±14.7% versus -6.3±13.9%; P<0.01) and microchannels (-15.9±15.9% versus -6.4±13.5%; P<0.01) than those without. There were increasing trends of the prevalence of macrophages and microchannels with endothelial dysfunction as stratified by quartiles of coronary artery diameter change (P<0.01 and P=0.02 for trend, respectively). In particular, segments with both macrophages and microchannels (n=12) tended to have worse endothelial function than those with macrophages alone (n=15) and microchannels alone (n=15; -22.1±14.6% versus -10.9±15.6% and -10.9±15.6%; P=0.07 and P=0.06, respectively).

CONCLUSIONS

Epicardial endothelial dysfunction was associated with optical coherence tomography -identified macrophages and microchannels in mild coronary atherosclerosis. The current study further supports the role of inflammation and vasa vasorum proliferation in the early stage of coronary atherosclerosis.

Lipoprotein-associated phospholipase A2 levels are associated with erectile dysfunction in patients without known coronary artery disease

Endothelial dysfunction and microvascular damage play a crucial role in the pathogenesis of erectile dysfunction (ED). Lp-PLA2 is a calcium-independent member of the phospholipase A2 family and hydrolyses oxidised phospholipids on low-density lipoprotein (LDL) particles that plays a pivotal role in ox-LDL-induced endothelial dysfunction. The purpose of the current study was to determine the association between Lp-PLA2 levels and ED in patients without known coronary artery disease (CAD). All patients were evaluated for ED and divided into two groups: 88 patients suffering from ED for >1 year were enrolled as an experimental group and 88 patients without ED were enrolled as a control group in this study. Diagnosis of ED was based on the International Index of Erectile Function Score-5. Levels of Lp-PLA2 were measured in serum by colorimetric assay. The relationship between Lp-PLA2 levels and ED in patients was evaluated statistically. The mean age of patients with ED group was 59.4 ± 11.32 and 55.8 ± 9.67 in the control group. Plasma Lp-PLA2 levels were significantly higher in ED than in the control group (220.3 ± 66.90 and 174.8 ± 58.83 pg ml(-1) , respectively, P < 0.001). The Lp-PLA2 levels were negatively correlated with score of ED (r = -0.482, P < 0.05). In logistic regression analysis, enhanced plasma Lp-PLA2 levels result in approximately 1.2-fold increase in ED [1.22 (1.25-2.76)]. In this study, serum Lp-PLA2 levels were found to be associated with endothelial dysfunction predictive of ED. Serum Lp-PLA2 level appears to be a specific predictor of ED, and it may be used in early prediction of ED in the male population.

Lipoprotein-associated phospholipase A2 and cardiovascular disease risk in HIV infection

OBJECTIVES

HIV-infected patients on antiretroviral therapy (ART) have an increased cardiovascular disease (CVD) risk as a result of heightened inflammation and immune activation, despite at times having normal lipids and few traditional risk factors. Biomarkers are needed to identify such patients before a clinical event. Lipoprotein-associated phospholipase A2 (Lp-PLA2 ) predicts CVD events in the general population. This study investigated the relationship between Lp-PLA2 and markers of CVD risk, systemic inflammation, immune activation, and coagulation in HIV infection.

METHODS

One hundred subjects on stable ART with normal fasting low-density lipoprotein (LDL) cholesterol were enrolled in the study. Plasma Lp-PLA2 concentrations were measured by enzyme-linked immunosorbent assay (ELISA; > 200 ng/mL was considered high CVD risk). Subclinical atherosclerosis, endothelial function, inflammation, immune activation and fasting lipids were also evaluated.

RESULTS

The median age of the patients was 47 years and 77% were male. Median (range) Lp-PLA2 was 209 (71-402) ng/mL. Fifty-seven per cent of patients had Lp-PLA2 concentrations > 200 ng/mL. Lp-PLA2 was positively correlated with soluble markers of inflammation or immune activation (tumour necrosis factor receptor-II, intercellular and vascular cellular adhesion molecules, and CD14; all R = 0.3; P < 0.01), and negatively correlated with coagulation markers (D-dimer and fibrinogen; both R = -0.2; P < 0.04). Lp-PLA2 was not correlated with lipids, coronary artery calcium score, or flow-mediated vasodilation, but trended towards a significant correlation with carotid intima-media thickness (R = 0.2; P = 0.05).

CONCLUSIONS

In this population with stable ART and normal LDL cholesterol, Lp-PLA2 was in the high CVD risk category in the majority of subjects. Lp-PLA2 appears to be associated with inflammation/immune activation, but also with anti-thrombotic effects. Lp-PLA2 may represent a valuable early biomarker of CVD risk in HIV infection before subclinical atherosclerosis can be detected.

Inflammation and atherosclerosis--revisited

Atherogenesis has been traditionally viewed as a metabolic disease representing arterial obstruction by fatty deposits in its wall. Today, it is believed that atherogenesis involves highly specific biochemical and molecular responses with constant interactions between various cellular players. Despite the presence of inflammatory reaction in each and every step of atherosclerosis from its inception to terminal manifestation, the cause--effect relationship of these 2 processes remains unclear. In this article, we have attempted to review the role of inflammation in the development of atherosclerosis and in its major complication--coronary heart disease.

Changes in lipoprotein-Associated phospholipase A2 activity predict coronary events and partly account for the treatment effect of pravastatin: results from the Long-Term Intervention with Pravastatin in Ischemic Disease study

Background

Lipoprotein‐associated phospholipase A2 (Lp‐PLA₂) levels are associated with coronary heart disease (CHD) in healthy individuals and in patients who have had ischemic events.

Methods and Results

The Long‐term Intervention with Pravastatin in Ischemic Disease (LIPID) study randomized 9014 patients with cholesterol levels of 4.0 to 7.0 mmol/L to placebo or pravastatin 3 to 36 months after myocardial infarction or unstable angina and showed a reduction in CHD and total mortality. We assessed the value of baseline and change in Lp‐PLA₂ activity to predict outcomes over a 6‐year follow‐up, the effect of pravastatin on Lp‐PLA₂ levels, and whether pravastatin treatment effect was related to Lp‐PLA₂ activity change. Lp‐PLA₂ was measured at randomization and 1 year, and levels were grouped as quartiles. The prespecified end point was CHD death or nonfatal myocardial infarction. Baseline Lp‐PLA₂ activity was positively associated with CHD events (P<0.001) but not after adjustment for 23 baseline factors (P=0.66). In 6518 patients who were event free at 1 year, change in Lp‐PLA₂ was a significant independent predictor of subsequent CHD events after adjustment for these risk factors, including LDL cholesterol and LDL cholesterol changes (P<0.001). Pravastatin reduced Lp‐PLA₂ by 16% compared with placebo (P<0.001). After adjustment for Lp‐PLA₂ change, the pravastatin treatment effect was reduced from 23% to 10% (P=0.26), with 59% of the treatment effect accounted for by changes in Lp‐PLA₂. Similar reductions in treatment effect were seen after adjustment for LDL cholesterol change.

Conclusion

Reduction in Lp‐PLA₂ activity during the first year was a highly significant predictor of CHD events, independent of change in LDL cholesterol, and may account for over half of the benefits of pravastatin in the LIPID study.

Comparison of change in coronary atherosclerosis in patients with stable versus unstable angina pectoris receiving statin therapy (from the Treatment With Statin on Atheroma Regression Evaluated by Intravascular Ultrasound With Virtual Histology [TRUTH] study)

Although statin-induced regression in coronary atherosclerosis seems to be greater in patients with acute coronary syndrome than in those with stable coronary artery disease, no reports have examined this. The purpose of the present study was to compare the changes in coronary atherosclerosis in patients with stable versus unstable angina pectoris (AP). The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intravascular ultrasound, and analyzable intravascular ultrasound data were obtained from 119 patients (83 patients with stable AP and 36 with unstable AP). A significant decrease in plaque volume was observed in patients with unstable AP (-2.2%, p = 0.02) but not in patients with stable AP. A significant increase in the necrotic-core component (0.30 mm(3)/mm, p = 0.009) was observed only in patients with unstable AP. Significant positive correlations were observed between the percentage of change in platelet-activating factor acetylhydrolase and the percentage of change in plaque volume (r = 0.346, p = 0.05) in patients with unstable AP. No significant correlations were observed in patients with stable AP. Multivariate regression analyses showed that a reduction in platelet-activating factor acetylhydrolase was associated with regression in coronary atherosclerosis, particularly of the fibrous component (β = 0.443, p = 0.003), in patients with unstable AP. In conclusion, regression of the coronary artery plaque volume was greater, although statin therapy did not halt the increases in plaque vulnerability, in patients with unstable AP compared to those with stable AP. A reduction in the serum platelet-activating factor acetylhydrolase level was associated with regression in coronary atherosclerosis, particularly the fibrous plaque volume, in patients with unstable AP.

Lipoprotein phospholipase A2 and cerebral microbleeds in the Framingham Heart Study

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMB) attributable to cerebral amyloid angiopathy generally occur in lobar regions, whereas those attributable to hypertensive vasculopathy are deep. Inflammation may be an underlying mechanism for CMB, with varying associations according to CMB location. Lipoprotein phospholipase-A2 (Lp-PLA2) is a circulating enzyme marker of vascular inflammation associated with risk of ischemic stroke and dementia. We hypothesized that higher Lp-PLA2 levels would be related to higher prevalence of CMB, with possible regional specificity.

METHODS

Framingham Offspring participants aged 65 years or older with available Lp-PLA2 measures and brain magnetic resonance imaging were included. Logistic regression models were used to relate Lp-PLA2 activity and mass to presence of CMB, adjusted for age, sex, medication use (aspirin, anticoagulants, and statins), systolic blood pressure, APOE, current smoking, and diabetes.

RESULTS

Eight-hundred nineteen participants (mean age, 73 years; 53% women) were included; 106 (13%) had CMB, 82 (10%) were lobar, and 27 (3%) were deep. We did not observe significant associations of CMB and LpPLA2 measures in multivariable adjusted analyses. However, there was a significant interaction between APOE genotype and Lp-PLA2 activity in their relation to presence of deep CMB (P interaction=0.01). Among persons with APOE ε3/ε3, the odds ratio for deep CMB was 0.95 (confidence interval, 0.59-1.53; P=0.83), whereas among those with at least 1 ε2 or ε4 allele, odds ratio was 3.46 (confidence interval, 1.43-8.36; P=0.006).

CONCLUSIONS

In our community-based sample of older adults, there was no significant association of Lp-PLA2 with total or lobar CMB. The association of higher levels of Lp-PLA2 activity with deep CMB among those with at least 1 APOE ε2 or ε4 allele merits replication.

Higher lipoprotein-associated phospholipase A2 levels are associated with coronary atherosclerosis documented by coronary angiography

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) has been proposed as an inflammatory marker of cardiovascular disease. The present study investigates associations between Lp-PLA2 and other important biomarkers in Japanese patients with coronary artery disease.

METHODS

We measured Lp-PLA2 levels in 141 consecutive patients (age 62.6 ± 3.8 years; men 69.2%) with angiographic evidence of coronary artery disease (acute coronary syndrome [ACS]; n = 38), stable angina pectoris (SAP; n = 72) or with angiographically normal coronary arteries (NCA; n = 31).

RESULTS

Levels of Lp-PLA2 significantly correlated with low-density lipoprotein-cholesterol (r = 0.302), homocysteine (r = 0.528) and paraoxonase (r = 0.401) in all patients (all P < 0.01). Levels of Lp-PLA2 were significantly higher in patients with coronary atherosclerosis (ACS and SAP) than with NCA (P < 0.05). Levels of highly sensitive C-reactive protein were significantly higher in patients with ACS than with SAP and NCA (both P < 0.05). Multivariate logistic regression analyses revealed that higher Lp-PLA2 levels were independently associated with coronary atherosclerosis (odds ratio: 1.058; 95% confidence interval: 1.012-1.121; P = 0.001).

CONCLUSIONS

Higher Lp-PLA2 levels are associated with coronary atherosclerosis independently of traditional coronary risk factors. Thus, Lp-PLA2 is a novel biomarker of coronary atherosclerosis in Japanese patients.

Predicting the Risk of Cardiovascular Disease

Although an atherogenic lipoprotein phenotype has been well recognized as an important predictor of cardiovascular disease, recent studies have demonstrated a number of additional lipid-related markers as emerging biomarkers to identify patients at risk for future coronary heart disease. Among them, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), seems to be a promising candidate that might be added to the clinical armamentarium for improved prediction of cardiovascular disease in the future. Of particular note, Lp-PLA(2) is the only enzyme that cleaves oxidized low-density lipoprotein (oxLDL) in the subendothelial space, with further generation of proinflammatory mediators such as lysophosphatidylcholine (LysoPC) and oxidized fatty acid (oxFA), thereby probably linking two important features of atherogenesis, namely oxidation of LDL and local inflammatory processes within the atherosclerotic plaque. This overview aims to summarize our current knowledge based on observations from recent experimental and clinical studies. Emphasis has been put on potential pathophysiological mechanisms of action and on the clinical relevance of Lp-PLA(2) in a wide variety of clinical settings, including apparently healthy individuals, patients with stable angina or acute coronary syndromes, after myocardial infarction, and with subclinical disease. Although a growing body of evidence from epidemiological and clinical studies suggests that Lp-PLA(2) may represent an independent and clinically relevant long-term risk marker for coronary heart disease and, probably, also for stroke, the role of this enzyme in the setting of the acute coronary syndrome remains to be established.

Lipoprotein-Associated Phospholipase A2

The role of inflammation in atherosclerosis continues to emerge. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), a novel plasma biomarker, circulates in the blood bound mainly to low-density lipoprotein (LDL) and promotes vascular inflammation. Several epidemiological studies have shown that circulating levels of Lp-PLA(2) are an independent risk factor for cardiovascular events. Recent studies demonstrate that Lp-PLA(2) is also associated with endothelial dysfunction and early atherosclerosis. This review provides an overview of these studies, suggests plausible mechanisms for the association between endothelial dysfunction and Lp-PLA(2), and highlights future potential therapies.

Circulating and PBMC Lp-PLA2 associate differently with oxidative stress and subclinical inflammation in nonobese women (menopausal status)

BACKGROUND

This study aimed to determine the association of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) activity in circulation and peripheral blood mononuclear cells (PBMCs) with inflammatory and oxidative stress markers in nonobese women and according to menopausal status. Lp-PLA(2) activity, a marker for cardiovascular risk is associated with inflammation and oxidative stress.

METHODOLOGY/PRINCIPAL FINDINGS

Eighty postmenopausal women (53.0±4.05 yr) and 96 premenopausal women (39.7±9.25 yr) participated in this study. Lp-PLA(2) activities, interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β in plasma as well as in PBMCs were measured. Plasma ox-LDL was also measured. Postmenopausal women demonstrated higher circulating levels of ox-LDL and IL-6, as well as IL-6, TNF-α, and IL-1β in PBMCs, than premenopausal women. In both groups, plasma Lp-PLA(2) activity positively correlated with Lp-PLA(2) activity in PBMCs and plasma ox-LDL. In premenopausal women, Lp-PLA(2) activities in plasma and PBMCs positively correlated with IL-6, TNF-α, and IL-1β in PBMCs. In postmenopausal women, plasma ox-LDL positively correlated with PBMC cytokine production. In subgroup analysis of postmenopausal women according to plasma ox-LDL level (median level: 48.715 U/L), a significant increase in Lp-PLA(2) activity in the plasma but not the PBMCs was found in the high ox-LDL subgroup. Plasma Lp-PLA(2) activity positively correlated with unstimulated PBMC Lp-PLA(2) activity in the low ox-LDL subgroup (r = 0.627, P<0.001), whereas in the high ox-LDL circulating Lp-PLA(2) activity positively correlated with plasma ox-LDL (r = 0.390, P = 0.014) but not with Lp-PLA(2) activity in PBMCs.

CONCLUSIONS/SIGNIFICANCE

The lack of relation between circulating Lp-PLA(2) activity and Lp-PLA(2) activity in PBMCs was found in postmenopausal women with high ox-LDL. This may indicate other sources of circulating Lp-PLA(2) activity except PBMC in postmenopausal women with high ox-LDL. We also demonstrated that circulating Lp-PLA(2) and PBMC secreted Lp-PLA(2) associate differently with markers of oxidative stress and sub clinical inflammation in nonobese women, particularly according to the menopausal states.

Increased circulating plasma lysophosphatidic acid in patients with acute coronary syndrome

BACKGROUND

The platelet activator lysophosphatidic acid (LPA) has recently been identified as an ingredient in oxidized LDL and it has been isolated from atherosclerotic plaques. The lysophospholipase D activity of autotaxin produces LPA extracellularly from lysophosphatidylcholine (LPC). The present study determines whether circulating LPA is associated with acute coronary syndrome (ACS).

METHODS

We enrolled 141 consecutive patients (age, 62.6±3.8 y; male, 69.2%) with ACS (n=38), stable angina pectoris (SAP; n=72) or angiographically normal coronary arteries (NCA; n=31). The relationships between LPA and other established biomarkers were examined. Concentrations of plasma LPA were determined using an enzymatic assay.

RESULTS

Concentrations of LPA significantly correlated with LPC (r=0.549), autotaxin (r=0.370) and LDL-C (r=0.307) (all p<0.01). Lysophosphatidic acid concentrations were significantly higher in patients with ACS than with SAP and NCA (p<0.01), but did not significantly differ between patients with SAP and NCA. Multivariate logistic regression analyses revealed that the highest LPA tertile was independently associated with ACS (odds ratio 1.99, 95% CI: 1.18-3.39, p=0.02).

CONCLUSIONS

The present study demonstrated that increased circulating plasma LPA concentrations are significantly associated with ACS.

C-reactive protein is released in the coronary circulation and causes endothelial dysfunction in patients with acute coronary syndromes

BACKGROUND

C-reactive protein (CRP) plasma levels correlate with cardiovascular events. Although a direct role for CRP in atherothrombosis has been suggested, at the moment little is known about its involvement in the pathophysiology of acute coronary syndromes (ACS). Thus, the aim of this study was to determine whether CRP is produced in the culprit lesion and released within the coronary circulation of patients with ACS and whether it may affect coronary endothelial function.

METHODS

Blood samples were simultaneously obtained from the aorta (Ao) and the coronary sinus (CS) of patients with normal coronary artery (n=16), stable angina (n=30), and ACS (n=29) for later measurement of plasma CRP levels. Endothelium-dependent and -independent coronary vasodilation were evaluated by means of a Doppler Flow Wire in response to the increasing intracoronary doses of acetylcholine and adenosine, respectively.

RESULTS

CRP plasma levels were significantly higher across the coronary circulation only in ACS patients with the culprit lesion located in the left coronary artery, while no differences between CS and Ao CRP plasma levels were observed in all other groups. Transcardiac CRP levels were correlated with impairment in coronary endothelium-dependent vasodilation. In six additional patients (SA=3 and ACS=3), subjected to coronary atherectomy, real-time quantitative PCR revealed presence of CRP mRNA only in unstable plaques.

CONCLUSIONS

Thus, CRP is produced and released within the coronary circulation of patients with ACS; this is associated with impairment of endothelial function, suggesting a new pathophysiological link between CRP and ACS.

Association of lipoprotein-associated phospholipase A2 and endothelial function in the Multi-Ethnic Study of Atherosclerosis (MESA)

Mechanisms underlying the role of lipoprotein-associated phospholipase A2 (Lp-PLA2) in atherosclerotic development are not completely understood. We evaluated the relationship of Lp-PLA2 with endothelial dysfunction, an early manifestation of atherosclerosis, in a cohort without known clinical cardiovascular disease. A total of 2809 participants in the Multi-Ethnic Study of Atherosclerosis underwent plasma Lp-PLA2 mass and activity measurement and brachial artery flow-mediated vasodilation testing. In adjusted linear regression models, higher Lp-PLA2 mass and activity levels were not associated with lower endothelial function (−0.04%, p = 0.51 and −0.09%, p = 0.10, respectively). Among individuals with subclinical atherosclerosis based on ankle–brachial index (ABI) or carotid intima–media thickness (IMT), Lp-PLA2 mass and activity were not associated with lower endothelial function (−0.03%, p = 0.88 and −0.31%, p = 0.16 for ABI < 1.00; 0.01%, p = 0.94 and −0.15%, p = 0.20 for abnormal carotid IMT). In summary, Lp-PLA2 is not associated with endothelial dysfunction, suggesting its role in atherosclerosis development is primarily related to other factors.