Lp-PLA₂- a novel risk factor for high-risk coronary and carotid artery disease

Sex differences in the genetic and molecular mechanisms of coronary artery disease

Sex differences in coronary artery disease (CAD) presentation, risk factors and prognosis have been widely studied. Similarly, studies on atherosclerosis have shown prominent sex differences in plaque biology. Our understanding of the underlying genetic and molecular mechanisms that drive these differences remains fragmented and largely understudied. Through reviewing genetic and epigenetic studies, we identified more than 40 sex-differential candidate genes (13 within known CAD loci) that may explain, at least in part, sex differences in vascular remodeling, lipid metabolism and endothelial dysfunction. Studies with transcriptomic and single-cell RNA sequencing data from atherosclerotic plaques highlight potential sex differences in smooth muscle cell and endothelial cell biology. Especially, phenotypic switching of smooth muscle cells seems to play a crucial role in female atherosclerosis. This matches the known sex differences in atherosclerotic phenotypes, with men being more prone to lipid-rich plaques, while women are more likely to develop fibrous plaques with endothelial dysfunction. To unravel the complex mechanisms that drive sex differences in CAD, increased statistical power and adjustments to study designs and analysis strategies are required. This entails increasing inclusion rates of women, performing well-defined sex-stratified analyses and the integration of multi-omics data.

Lipoprotein associated- phospholipase A2 in STEMI vs. NSTE-ACS patients: a marker of cardiovascular atherosclerotic risk rather than thrombosis

The precise role of Lipoprotein associated phospholipase A2 (Lp-PlA2) in the pathogenesis of acute coronary syndromes (ACS) and in the prediction of future cardiovascular events is still debated. So far, few data exist on the variations of Lp-PlA2 activity in ACS and especially in NSTE-ACS vs. STEMI patients, where thrombotic and atherosclerotic mechanisms could play a differential role. The aim of the present study was, then, to compare Lp-PlA2 activity according to the type of ACS presentation.

METHODS

A consecutive cohort of patients undergoing coronary angiography for acute coronary syndrome (ACS) were included and divided according to presentation for non ST-segment elevation-ACS or ST-segment elevation Myocardial Infarction (STEMI). Lp-PLA2 activity was assessed in blood samples drawn at admission using the Diazyme Lp-PlA2 Activity Assay.

RESULTS

We included in our study 117 patients, of whom 31 (26.5%) presented with STEMI. STEMI patients were significantly younger (p = 0.05), displayed a lower rate of hypertension (p = 0.002), previous MI (p = 0.001) and PCI (p = 0.01) and used less frequently statins (p = 0.01) and clopidogrel (p = 0.02). White blood cells and admission glycemia were increased in STEMI (p = 0.001, respectively). The prevalence and severity of CAD was not different according to ACS types, but for a higher prevalence of thrombus (p < 0.001) and lower TIMI flow (p = 0.002) in STEMI. The levels of Lp-PlA2 were significantly lower in STEMI as compared to NSTE-ACS patients, (132 ± 41.1 vs. 154.6 ± 40.9 nmol/min/mL, p = 0.01). In fact, the rate of patients with Lp-PlA2 above the median (148 nmol/min/mL) was significantly lower in STEMI patients as compared to NSTE-ACS (32.3% vs. 57%, p = 0.02, adjusted OR[95% CI] = 0.20[0.06-0.68], p = 0.010). Moreover, a direct linear relationship was observed between Lp-PlA2 and LDL-C (r = 0.47, p < 0.001), but not with inflammatory biomarkers.

CONCLUSION

The present study shows that among ACS patients, the levels of Lp-PlA2 are inversely associated with STEMI presentation and thrombotic coronary occlusion, being instead increased in NSTE-ACS patients, therefore potentially representing a marker of more aggressive chronic cardiovascular disease with an increased risk of recurrent cardiovascular events.

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.

Atherogenicity of low-density lipoproteins after switching from a protease inhibitor to dolutegravir: a substudy of the NEAT022 study

BACKGROUND

The aim of this study was to investigate whether switching from a ritonavir-boosted PI-based regimen to a dolutegravir-based regimen improved the atherogenic properties of LDL particles in patients with HIV.

METHODS

This was a substudy of the NEAT022 study (ClinicalTrials.gov NCT02098837). Adults with HIV with a Framingham score >10% or aged >50 years and being treated with a stable boosted PI-based regimen were randomized to either switch to dolutegravir or continue with boosted PI. At baseline and Week 48, we assessed atherogenic LDL properties: LDL particle size and phenotype (A, intermediate, B), oxidized LDL (ox-LDL) and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity.

RESULTS

Eighty-six participants (dolutegravir 44; PI 42) were included. Participants had a median (IQR) age of 54 (51-57) years and 79.1% were male. In the dolutegravir arm, after 48 weeks, we observed: (1) an increase in LDL size [median 1.65 Å (IQR -0.60 to 4.20); P = 0.007], correlated with the decrease in triglyceride concentration [Spearman correlation = -0.352 (P = 0.001)], with a corresponding decrease of subjects with atherogenic LDL phenotype B (36.4% to 20.5%; P = 0.039); (2) a decrease in Lp-PLA2 activity [median 1.39 μmol/min/mL (IQR -2.3 to 0.54); P = 0.002]; and (3) a decrease in ox-LDL [median 14 U/L (IQR -102 to 13); P = 0.006]. In the PI arm, none of these favourable lipid modifications was observed.

CONCLUSIONS

Forty-eight weeks after switching from a PI-based to a dolutegravir-based regimen, patients with Framingham score >10% or aged >50 years showed improvement of several atherogenic lipid features, including LDL particle phenotype, ox-LDL and Lp-PLA2.

Modified Lipoproteins Induce Arterial Wall Inflammation During Atherogenesis

Circulating apolipoprotein B-containing lipoproteins, notably the low-density lipoproteins, enter the inner layer of the arterial wall, the intima, where a fraction of them is retained and modified by proteases, lipases, and oxidizing agents and enzymes. The modified lipoproteins and various modification products, such as fatty acids, ceramides, lysophospholipids, and oxidized lipids induce inflammatory reactions in the macrophages and the covering endothelial cells, initiating an increased leukocyte diapedesis. Lipolysis of the lipoproteins also induces the formation of cholesterol crystals with strong proinflammatory properties. Modified and aggregated lipoproteins, cholesterol crystals, and lipoproteins isolated from human atherosclerotic lesions, all can activate macrophages and thereby induce the secretion of proinflammatory cytokines, chemokines, and enzymes. The extent of lipoprotein retention, modification, and aggregation have been shown to depend largely on differences in the composition of the circulating lipoprotein particles. These properties can be modified by pharmacological means, and thereby provide opportunities for clinical interventions regarding the prevention and treatment of atherosclerotic vascular diseases.

The Relationship Between Lipoprotein-Associated Phospholipase-A2 and Coronary Artery Aneurysm in Children With Kawasaki Disease

BACKGROUND

Coronary artery lesions including aneurysm, as the most severe complications of Kawasaki disease (KD), remain of great concern. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is implicated in the regulation of inflammatory response and lipid metabolism. Since excessive inflammatory response and aberrant lipid metabolism have involved in the development of KD, we in this study sought to investigate the relationship between coronary artery aneurysm (CAA) and Lp-PLA2 and other blood parameters in children with KD.

METHODS

The participants included 71 KD patients, 63 healthy controls (HCs) and 51 febrile controls (FCs). KD patients were divided into KD-CAA (KD with CAA) group and KD-NCAA (KD without CAA) group. Serum Lp-PLA2 levels were measured using enzyme-linked immunosorbent assays. Other routine clinical parameters were also detected.

RESULTS

Serum Lp-PLA2 levels in KD group [4.83 μg/mL (3.95-6.77)] were significantly higher than those in HC [1.29 μg/mL (0.95-2.05)] and FC [1.74 μg/mL (1.18-2.74)] groups. KD-CAA group [5.56 μg/mL (4.55-22.01)] presented substantially higher serum Lp-PLA2 levels as compared with KD-NCAA group [4.64 μg/mL (2.60-5.55)]. In KD group, serum Lp-PLA2 level was positively related with erythrocyte sedimentation rate, the levels of leukocytes, platelets, albumin, creatine kinase-MB, and D-dimer, and the Z-scores of left main CA, right CA, left anterior descending CA, and left circumflex CA; and negatively related with mean corpuscular hemoglobin concentration and mean platelet volume. Moreover, receiver operating characteristic curves showed that Lp-PLA2 exhibited superior and moderate diagnostic performance for distinguishing KD patients from HC and FC ones, respectively, and possessed the potential ability to predict the occurrence of CAAs in KD.

CONCLUSION

Lp-PLA2 may be related to KD and the formation of CAAs, and thus may serve as a potential diagnostic biomarker for KD.

Carotid Plaque Inflammation Assessed by 18F-FDG PET/CT and Lp-PLA2 Is Higher in Symptomatic Patients

Carotid plaque inflammation assessed by 2-deoxy-2-[¹⁸F]fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and lipoprotein-associated phospholipase A2 (Lp-PLA₂) levels are higher in symptomatic patients. The aim of this study was to assess correlations between ¹⁸F-FDG uptake on PET scan of carotid artery plaques, plasma levels of Lp-PLA₂, and cerebrovascular symptoms. The study included 45 consecutive patients (22 symptomatic, 23 asymptomatic) with >70% carotid stenosis. Patients were examined by hybrid PET/CT, and maximum standardized uptake values (SUV_max) were recorded. Blood samples were obtained, and plasma was stored at -80 °C for subsequent Lp-PLA₂ analysis. Symptomatic and asymptomatic patients showed no significant difference in classical cardiovascular risk factors. Asymptomatic carotid stenosis patients more frequently had a history of coronary artery disease (P = .025) and peripheral artery disease (P = .012). The symptomatic group had higher ¹⁸F-FDG uptake in carotid plaques (P < .001), higher plasma Lp-PLA₂ (P < .01), and higher high-sensitive C-reactive protein (P = .022). 2-Deoxy-2-[¹⁸F]fluoro-D-glucose uptake on PET/CT and plasma Lp-PLA₂ show a statistically significant association with the symptomatic status of carotid plaques.

The significance of Agaricus blazei as an immunomodulator of the level of IL-17 in Balb/C mice with atherosclerosis

Atherosclerosis is a disease caused by an inflammatory response which involved the interaction between endothelial cells, macrophages and lymphocytes, and is closely related to IL-17 regulation. This study is important to investigate the activity of Agaricusblazei in modulating the immunological activity based on the profile of CD4⁺IL-17⁺, CD8⁺IL-17⁺, and CD11b⁺ IL-17⁺ in high-fat diet (HFD)-induced Balb/c mice. Mice in dietary groups were fed with HFD and then fed with A. blazei extract with three different doses including D1 (100 mg/kg BW), D2 (200 mg/kg BW), and D3 (400 mg/kg BW) once a day for 12 weeks. The cells were analyzed using flow cytometry and tested statistically with one-way ANOVA with α = 0.05 by using SPSS 16.00 software. The results showed that mice with HFD treatment had a higher level of Lp-PLA2 (atherosclerosis marker) compared with the control group (data not shown). The level of IL-17 in the atherosclerotic mice in the D1 group was significantly depleted compared to the control group. Of the three doses above, D1 may be an optimal dose to minimize or prevent the damage from atherosclerosis than the other doses.

UPLC-QTOF/MS-based metabolomics analysis of plasma reveals an effect of Xue-Fu-Zhu-Yu capsules on blood-stasis syndrome in CHD rats

ETHNOPHARMACOLOGICAL RELEVANCE

Blood-stasis syndrome (BSS) is a specific ZHENG type of coronary heart disease (CHD) in traditional Chinese medicine (TCM). The Xue-Fu-Zhu-Yu (XFZY) decoction is a common herbal formula that has been used for several centuries to treat BSS, but its mechanism has not been thoroughly elucidated to date.

AIM OF THE STUDY

In this study, serum lipid, blood haemorheology and metabolomics analyses were performed to depict a complete profile of XFZY capsules for the treatment of CHD with BSS and to reveal the potential mechanism of the XFZY capsules.

MATERIALS AND METHODS

A rat model of CHD with BSS was generated by combining a high-fat diet (HFD) with a left anterior descending coronary artery (LAD) ligation. After four weeks of treatment with XFZY capsules or simvastatin pills, an echocardiography was performed for a therapeutic evaluation. Blood samples and heart tissues were then collected for further analyses. A UPLC-QTOF/MS-based metabolomics analysis of the plasma was performed, and all metabolic features were fit by PCA and OPLS-DA pattern for the biomarker screen. The identified biomarkers were later implemented into a metabolic pathway analysis. Furthermore, we used qRT-PCR and Western blot analyses to verify the treatment effects of the XFZY capsules.

RESULTS

A total of 49 metabolites (VIP>1.0, p < 0.05, RSD%<20%) were identified in the Model rats, and 27 metabolites (VIP>1.0, p < 0.05, RSD%<20%) were identified in the XFZY-H rats. The results of the pathway analysis indicated that the XFZY capsules treated CHD primarily by regulating cardiac energy, phospholipid, polyunsaturated fatty acid (PUFA) and amino acid metabolism. In addition, blood viscosity and serum lipid assays suggested that XFZY capsules could decrease serum triglycerides, total cholesterol, low-density lipoprotein cholesterol and whole blood viscosity at a low shear rate.

CONCLUSION

This study demonstrated that the XFZY capsule effectively decreases serum lipids and whole blood viscosity in CHD with BSS. The underlying metabolic mechanism mainly included improving cardiac energy supply, reducing phospholipid peroxide, maintaining the PUFA metabolic balance and regulating amino acid metabolism.

Performance Characteristics and Clinical Value of the Lipoprotein-Associated Phospholipase A2 by an Enzymatic Kinetic Method

OBJECTIVE

To analyze the performance characteristics, stability, and clinical value of lipoprotein-associated phospholipase A2 (Lp-PLA2) using an enzymatic kinetic method.

METHODS

The performance characteristics included reference intervals, precision, and accuracy. We assessed Lp-PLA2 stability by comparing Lp-PLA2 changes under different conditions. Lp-PLA2 was determined in the following groups: control individuals, patients with coronary heart disease (CHD), patients of different lipid subgroups within CHD, and patients with high total cholesterol (TC). Also, correlations between Lp-PLA2 and traditional cardiovascular risk factors were assessed.

RESULTS

The mean (SD) reference interval of serum Lp-PLA2 activity was 451 (113) U per L with sex differences. Inter- and intra-assay precision revealed coefficients of variance (CVs) of 1.81% to 2.63% and 1.43% to 1.77%. The average bias was 0.33%. Lp-PLA2 activity was stable. In the CHD group, high-lipid subgroups, and high-TC group, Lp-PLA2 was elevated, and correlation was observed between Lp-PLA2 and traditional risk factors.

CONCLUSION

Lp-PLA2 activity has important clinical value in CHD.

Is Admission Lipoprotein-Associated Phospholipase A2 a Novel Predictor of Vasospasm and Outcome in Patients With Aneurysmal Subarachnoid Hemorrhage?

BACKGROUND

The relationships between lipoprotein-associated phospholipase A2 (Lp-PLA2) level, vasospasm, and clinical outcome of patients with aneurysmal subarachnoid hemorrhage (aSAH) are still unclear.

OBJECTIVE

To identify the associations between admission Lp-PLA2 and vasospasm following subarachnoid hemorrhage and the clinical outcome of aSAH.

METHODS

A total of 103 aSAH patients who had Lp-PLA2 level obtained within 24 h postbleeding were included. The relationships between Lp-PLA2 level, vasospasm, and clinical outcome were analyzed.

RESULTS

Vasospasm was observed in 52 patients (50.49%). Patients with vasospasm had significantly higher Lp-PLA2 level than those without (P &lt; .001). Both modified Fisher grade (P = .014) and Lp-PLA2 level (P &lt; .001) were significant predictors associated with vasospasm. The Z test revealed that power of Lp-PLA2 was significantly higher than that of modified Fisher grade in predicting vasospasm (Z = 2.499, P = .012). At 6-mo follow-up, 44 patients (42.72%) had unfavorable outcome and 36 patients (34.95%) died. The World Federation of Neurosurgical Societies (WFNS) grade and Lp-PLA2 level were both significant predictors associated with 6-mo unfavorable outcome and mortality (all P &lt; .001). The predictive values of Lp-PLA2 for unfavorable outcome and mortality at 6-mo tended to be lower than those of the WFNS grade, but the differences were not statistically significant (P = .366 and 0.115, respectively). Poor-grade patients having Lp-PLA2 &gt; 200 μg/L had significantly worse 6-mo survival rate than poor-grade patients having Lp-PLA2 ≤ 200 μg/L (P = .001).

CONCLUSION

The Lp-PLA2 might be useful as a novel predictor in aSAH patients. A total of 30 poor-grade patients; those with elevated Lp-PLA2 level have higher risk of 6-mo mortality compared to those without.

Effect of lipoprotein-associated phospholipase A2 inhibitor on insulin resistance in streptozotocin-induced diabetic pregnant rats

This paper aims to investigate the influence of lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor, darapladib, on insulin resistance (IR) in streptozotocin (STZ)-induced diabetic pregnant rats. The rat models were divided into Control (normal pregnancy), STZ + saline (STZ-induced diabetic pregnant rats), STZ + Low-dose and STZ + High-dose darapladib (STZ-induced diabetic pregnant rats treated with low-/high-dose darapladib) groups. Pathological changes were observed by Hematoxylin-eosin (HE) and Immunohistochemistry staining. Lp-PLA2 levels were determined by enzyme-linked immunosorbent assay (ELISA). An automatic biochemical analyzer was used to measure the serum levels of biochemical indicators, and homeostatic model assessment for insulin resistance (HOMA-IR) and insulin sensitivity index (ISI) were calculated. Western blot was applied to determine levels of inflammatory cytokines. Compared with Control group, rats in the STZ + saline group were significantly decreased in body weight, the number of embryo implantation, the number of insulin positive cells and pancreatic islet size as well as the islet endocrine cells, and high-density lipoprotein (HDL-C) level, but substantially increased in Lp-PLA2, low-density lipoprotein (LDL-C), fatty acids (FFA), serum total cholesterol (TC), triglyceride (TG) levels. Moreover, the increased fasting plasma glucose (FPG) and HOMA-IR and inflammatory cytokines but decreased fasting insulin (FINS) and ISI were also found in diabetic pregnant rats. On the contrary, rats in the darapladib-treated groups were just opposite to the STZ + saline group, and STZ + High-dose group improved better than STZ + Low-dose group. Thus, darapladib can improve lipid metabolism, and enhance insulin sensitivity of diabetic pregnant rats by regulating inflammatory cytokines.

The Prognostic Value of Lipoprotein-Associated Phospholipase A2 in the Long-Term Care of Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is an independent risk factor for cardiovascular disease. Accordingly, studies from many countries around the world have shown an association between Lp-PLA₂ and cardiovascular events in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI), but this association has not been documented among the Chinese. The aim of this study was to assess the use of Lp-PLA₂ as a useful marker for predicting the long-term prognosis of Chinese patients with ACS undergoing PCI. A total of 651 consecutive patients undergoing PCI between September 2013 and January 2015 were divided into 2 groups: the high Lp-PLA₂ group (n = 262, Lp-PLA₂ > 138 nmol/L) and the low Lp-PLA₂ group (n = 389, Lp-PLA₂ ≤ 138 nmol/L). The end point was all-cause mortality and rehospitalization. The median follow-up was 24 months. Multivariate analysis showed that high Lp-PLA₂ was an independent predictor of all-cause mortality and rehospitalization (hazard ratio: 1.429, 95% confidence interval [CI]: 1.411-1.448; P < .05). The Lp-PLA₂ had good accuracy for predicting all-cause mortality and rehospitalization among patients with ACS undergoing PCI (area under the receiver-operating characteristic curve: 0.858, 95% CI: 0.819-0.898; P < .05), and a good correlation with the Global Registry of Acute Coronary Event score ( r = 0.525, P < .05). This study provided evidence that Lp-PLA₂ could predict all-cause mortality and rehospitalization risk among patients with ACS undergoing PCI.

Postprandial effects of wine consumption on Platelet Activating Factor metabolic enzymes

Platelet Activating factor (PAF) is a potent inflammatory mediator that is involved in the initiation and the prolongation of atherosclerosis. The purpose of the study was to investigate the effect of wine consumption on the activity of PAF metabolic enzymes and on IL-6 levels as a cytokine inflammatory marker. Healthy men participated in 4 daily trials and consumed a standardized meal along with Robola wine (trial R), or Cabernet Sauvignon (trial CS), or ethanol solution (trial E), or water (trial W). A significant trial effect was found in the activity of lyso-PAF acetyltransferase (Lyso-PAF AT) (p_trial=0.01). In specific, R trial decreased enzyme activity compared to E trial (p=0.03) while a trend for differentiation was observed between CS trial and E one (p=0.06) as well as between R trial and W one (p=0.07). Concerning PAF-cholinephosphotransferase (PAF-CPT) activity, a significant trial effect was found (p_trial<0.00). Specifically, both R (p=0.002) and CS (p=0.001) trials decreased enzyme activity compared to E trial. Concerning lipoprotein-associated phospholipase A2 (LpPLA2) no time either trial effect was observed. Concerning IL-6 levels a significant time effect was found (p_time<0.00) while no trial effect was revealed. In conclusion, the protective effect of wine consumption could partly be explained through the modulation of PAF metabolism by wine micro-constituents that lead to lower PAF levels.

Association between Lp-PLA2 and coronary heart disease in Chinese patients

Objective

To evaluate the association between plasma lipoprotein-associated phospholipase A2 (Lp-PLA2; known to release inflammatory mediators that promote atherosclerosis) and coronary heart disease (CHD) in Chinese patients.

Methods

This observational, cross-sectional study included a patient cohort who were assessed by coronary angiography and divided into patients with coronary heart disease and patients with normal coronary angiography (controls). Data for several biochemical indicators were collected. Plasma Lp-PLA2 concentrations were measured by enzyme-linked immunosorbent assay. Univariate and multivariate logistic regression were used to analyse the association between Lp-PLA2 concentration and CHD.

Results

A total of 531 patients were included, comprising 391 with CHD and 140 with normal coronary angiography (controls). Plasma Lp-PLA2 concentration was significantly higher in patients with CHD versus controls (median, 251 µg/l versus 219 µg/l, respectively), and particularly among patients with acute myocardial infarction and stable angina pectoris (249 µg/l and 266 µg/l, respectively). Multivariate analysis showed that Lp-PLA2 ≥ 292 µg/l (upper quartile of the whole cohort) was independently associated with CHD (odds ratio 2.814, 95% confidence interval 1.519, 5.214).

Conclusion

Plasma Lp-PLA2 concentration was independently associated with CHD in Chinese patients.

Advantages of the lipoprotein-associated phospholipase A2 activity assay

OBJECTIVES

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is increased in circulation in patients at higher risk of coronary heart disease (CHD) events and stroke. Therefore, measurement of Lp-PLA2 can be used as an adjunct to traditional cardiovascular risk factors for identifying individuals at higher risk of cardiovascular events. Recently, a reagent for measuring Lp-PLA2 activity (diaDexus, San Francisco, CA) received FDA approval. Here we evaluate the assay performance of the Lp-PLA2 activity assay.

METHODS

Lp-PLA2 activity assay reagent performance was evaluated on an open user-defined channel on a Cobas 6000/c501 (Roche Diagnostics, Indianapolis, IN) using a 5-point calibration curve (0-400nmol/min/mL). Analytical performance was established for the following parameters: precision, linearity, accuracy, analytical sensitivity, analytical specificity, reference interval, reagent lot-to-lot comparison, specimen type, on-board reagent stability, and sample stability.

RESULTS

Assay limit of detection was determined to be 7.8nmol/min/mL with an average %CV of 2.8%. Precision studies revealed a coefficient of variation ≤1.6% between 79 and 307nmol/min/mL and accuracy was demonstrated between 4.8-368.7nmol/min/mL. Comparable results were generated in paired SST serum and EDTA plasma. No age association was found with Lp-PLA2 activity at the 95th percentile however a gender association was identified resulting in gender-specific 95th percentile limits in a healthy reference population. No bias was found when comparing results from several different lots of assay reagent. Lp-PLA2 activity results are extremely stable in both serum and EDTA plasma under refrigerate and frozen storage conditions up to 31days.

CONCLUSIONS

Lp-PLA2 activity assay displays accurate and precise performance characteristics on the Cobas c501 platform. The assay performance is significantly improved over the predecessor immunoassay allowing for adoption of Lp-PLA2 activity in clinical practice.

Atherosclerotic plaque inflammation varies between vascular sites and correlates with response to inhibition of lipoprotein-associated phospholipase A2

Background

Despite systemic exposure to risk factors, the circulatory system develops varying patterns of atherosclerosis for unclear reasons. In a porcine model, we investigated the relationship between site‐specific lesion development and inflammatory pathways involved in the coronary arteries (CORs) and distal abdominal aortas (AAs).

Methods and Results

Diabetes mellitus (DM) and hypercholesterolemia (HC) were induced in 37 pigs with 3 healthy controls. Site‐specific plaque development was studied by comparing plaque severity, macrophage infiltration, and inflammatory gene expression between CORs and AAs of 17 DM/HC pigs. To assess the role of lipoprotein‐associated phospholipase A₂ (Lp‐PLA₂) in plaque development, 20 DM/HC pigs were treated with the Lp‐PLA₂ inhibitor darapladib and compared with the 17 DM/HC untreated pigs. DM/HC caused site‐specific differences in plaque severity. In the AAs, normalized plaque area was 4.4‐fold higher (P<0.001) and there were more fibroatheromas (9 of the 17 animals had a fibroatheroma in the AA and not the COR, P=0.004), while normalized macrophage staining area was 1.5‐fold higher (P=0.011) compared with CORs. DM/HC caused differential expression of 8 of 87 atherosclerotic genes studied, including 3 important in inflammation with higher expression in the CORs. Darapladib‐induced attenuation of normalized plaque area was site‐specific, as CORs responded 2.9‐fold more than AAs (P=0.045).

Conclusions

While plaque severity was worse in the AAs, inflammatory genes and inflammatory pathways that use Lp‐PLA₂ were more important in the CORs. Our results suggest fundamental differences in inflammation between vascular sites, an important finding for the development of novel anti‐inflammatory therapeutics.

High-dose simvastatin exhibits enhanced lipid-lowering effects relative to simvastatin/ezetimibe combination therapy

Statins are the frontline in cholesterol reduction therapies; however, their use in combination with agents that possess complimentary mechanisms of action may achieve further reductions in low-density lipoprotein cholesterol. Thirty-nine patients were treated with either 80 mg simvastatin (n=20) or 10 mg simvastatin plus 10 mg ezetimibe (n=19) for 6 weeks. Dosing was designed to produce comparable low-density lipoprotein cholesterol reductions, while enabling assessment of potential simvastatin-associated pleiotropic effects. Baseline and post-treatment plasma were analyzed for lipid mediators (eg, eicosanoids and endocannabinoids) and structural lipids by liquid chromatography tandem mass spectrometry. After statistical analysis and orthogonal projections to latent structures multivariate modeling, no changes were observed in lipid mediator levels, whereas global structural lipids were reduced in response to both monotherapy (R(2)Y=0.74; Q(2)=0.66; cross-validated ANOVA P=7.0×10(-8)) and combination therapy (R(2)Y=0.67; Q(2)=0.54; cross-validated ANOVA P=2.6×10(-5)). Orthogonal projections to latent structures modeling identified a subset of 12 lipids that classified the 2 treatment groups after 6 weeks (R(2)Y=0.65; Q(2)=0.61; cross-validated ANOVA P=5.4×10(-8)). Decreases in the lipid species phosphatidylcholine (15:0/18:2) and hexosyl-ceramide (d18:1/24:0) were the strongest discriminators of low-density lipoprotein cholesterol reductions for both treatment groups (q<0.00005), whereas phosphatidylethanolamine (36:3e) contributed most to distinguishing treatment groups (q=0.017). Shifts in lipid composition were similar for high-dose simvastatin and simvastatin/ezetimibe combination therapy, but the magnitude of the reduction was linked to simvastatin dosage. Simvastatin therapy did not affect circulating levels of lipid mediators, suggesting that pleiotropic effects are not associated with eicosanoid production. Only high-dose simvastatin reduced the relative proportion of sphingomyelin and ceramide to phosphatidylcholine (q=0.008), suggesting a pleiotropic effect previously associated with a reduced risk of cardiovascular disease.

Lipoprotein-associated phospholipase A₂ is related to plaque stability and is a potential biomarker for acute coronary syndrome

PURPOSE

Plasma lipoprotein-associated phospholipase A₂ (Lp-PLA₂) binds to low-density lipoprotein. The levels of Lp-PLA₂ reflect the plaque burden, and are upregulated in acute coronary syndrome (ACS). We investigated the diagnostic value of Lp-PLA2 levels and found that it might be a potential biomarker for ACS.

MATERIALS AND METHODS

We classified 226 study participants into three groups: patients without significant stenosis (control group), patients with significant stenosis with stable angina (SA group), and patients with ACS (ACS group).

RESULTS

Lp-PLA₂ and high-sensitivity C-reactive protein (hs-CRP) levels were significantly greater in the ACS group than in the SA group (p=0.044 and p=0.029, respectively). Multivariate logistic regression analysis revealed that Lp-PLA₂ levels are significantly associated with ACS (odds ratio=1.047, p=0.013). The addition of Lp-PLA₂ to the ACS model significantly increased the global χ² value over traditional risk factors (28.14 to 35.602, p=0.006). The area under the receiver operating characteristic curve for Lp-PLA₂ was 0.624 (p=0.004). The addition of Lp-PLA₂ level to serum hs-CRP concentration yielded an integrated discrimination improvement of 0.0368 (p=0.0093, standard error: 0.0142) and improved the ability to diagnose ACS.

CONCLUSION

Lp-PLA₂ levels are related to plaque stability and might be a diagnostic biomarker for ACS.

Synergistic effects of colchicine combined with atorvastatin in rats with hyperlipidemia

Background

Inflammation and endothelial dysfunction is implicated in the atherosclerosis initiation and progression in the setting of hyperlipidemia. Colchicine is a potent anti-inflammatory agent and whether colchicine combined with atorvastatin has synergistic effects on inflammation amelioration and endothelial function improvement is unknown.

Methods

Hyperlipidemic rat model was produced by high-fat and high-cholesterol diet for 6 weeks. Rats with normal diet were served as shame group. In hyperlipidemic group, normal saline, atorvastatin (10 mg/kg body weight/day), colchicines (0.5 mg/kg body weight/day), or atorvastatin combined with colchicines (same dosages) were prescribed for 2 weeks. Serum levels of lipid profile, C-reactive protein (CRP), liver enzyme, lipoprotein associated phospholipase A2 (Lp-PLA2) and nitric oxide (NO) production were serially assessed.

Results

Before the beginning of the study, all laboratory variables were comparable among each group. After 6 weeks of hyperlipidemic model production, serum levels of cholesterols, CRP and Lp-PLA2 were significantly increased when compared to sham group, whereas NO production was reduced. With 2 weeks of colchicine therapy, serum levels of CRP and Lp-PLA2 were decreased and NO production was enhanced in the colchicine group in a lipid-lowering independent manner. Added colchicine into atorvastatin therapy further improved NO production and decreased CRP and Lp-PLA2 levels, indicating a potential synergism of colchicine and atorvastatin.

Conclusion

Colchicine combined with atorvastatin may have stronger protective effects on improving endothelial function and ameliorating inflammation in rats with hyperlipidemia.

Can lipoprotein-associated phospholipase A2 be used as a predictor of long-term outcome in patients with acute coronary syndrome?

Studies indicate that elevated plasma concentrations of lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with increased risk of cardiovascular disease. Lp-PLA2 seems to play a crucial role in the formation of plaques and acute inflammation, and plasma Lp-PLA2 could therefore potentially be used as a predictor of long-term outcome in ACS patients. To evaluate this, data concerning Lp-PLA2 as a predictor in ACS patients was gathered through a systematic literature review, and studies on this issue were extracted from relevant databases, incl. PubMed and Cochrane. A total of 14 articles were retrieved, but after thorough evaluation and elimination of irrelevant articles only seven studies were eligible for the literature review. All studies except two showed significant correlation between Lp-PLA2 and CV events in ACS patients. Only one study found an independent value to predict CV events 30 days after ACS. Altogether, there was inconsistency in the findings regarding the potential use of Lp-PLA2 and a lack of knowledge on several issues. Lp-PLA2 seems to give valuable information on which ACS patients are prone to new events and also provides important information on plaque size. However, more focused studies concerning genetic variations, time-window impact, patients with and without CV risk factors (e.g. diabetes), and treatment effects are needed. In conclusion, Lp-PLA2 offers new insight in the pathophysiological development of ACS, but until the aforementioned issues are addressed the biomarker will mainly be of interest in a research setting, not as a predictive parameter in a clinical setting.

Lipoprotein-associated phospholipase A₂ mass level is increased in elderly subjects with type 2 diabetes mellitus

OBJECTIVE. Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is extensively expressed by advanced atherosclerotic lesions and may play a role in plaque instability. We selected a group of elderly subjects that underwent transcatheter aortic valve implantation (TAVI) or balloon angioplasty (BA) and separated them into two groups, diabetic and nondiabetic, to compare the level of Lp-PLA₂ mass between them. METHODS. 44 patients aged 79.6 ± 5.6 years with symptomatic severe aortic valve stenosis underwent TAVI (n = 35) or BA (n = 9). 21 subjects had confirmed type 2 diabetes mellitus. Lp-PLA₂ mass was measured using an enzyme-linked immunosorbent assay kit (USCN Life Science, China) before and 3 days after the procedure. RESULTS. Lp-PLA₂ mass was significantly elevated in this population (1296 ± 358 ng/mL before TAVI; 1413 ± 268 ng/mL before BA) and further increased after TAVI (1604 ± 437 ng/mL, P < 0.01) or BA (1808 ± 303 ng/mL, P < 0.01). Lp-PLA₂ mass was significantly increased on the diabetic group before these interventions. CONCLUSION. Lp-PLA₂ may be a novel biomarker for the presence of rupture-prone atherosclerotic lesions in elderly patients. Levels of Lp-PLA₂ in diabetic patients may accompany the higher amount of small dense LDL particles seen in these subjects.

Lysophosphatidylcholine and carotid intima-media thickness in young smokers: a role for oxidized LDL-induced expression of PBMC lipoprotein-associated phospholipase A2?

Background

Although cigarette smoking has been associated with carotid intima-media thickness (CIMT) the mechanisms are yet not completely known. Lysophosphatidylcholine (lysoPC), a main product of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity, appears to be a major determinant of the pro-atherogenic properties of oxidized LDL (oxLDL) and to induce proteoglycan synthesis, a main player in intimal thickening. In this study we assessed whether cigarette smoking-induced oxidative stress may influence plasma Lp-PLA2 and lysoPC and Lp-PLA2 expression in peripheral blood mononuclear cells (PBMC), as well as the relationship between lysoPC and CIMT.

Methods/Results

45 healthy smokers and 45 age and sex-matched subjects participated in this study. Smokers, compared to non-smokers, showed increased plasma concentrations of oxLDL, Lp-PLA2 and lysoPC together with up-regulation of Lp-PLA2 (mRNA and protein) expression in PBMC (P<0.001). Plasma Lp-PLA2 positively correlated with both lysoPC (r=0.639, P<0.001) and PBMC mRNA Lp-PLA2 (r=0.484, P<0.001) in all subjects. Moreover CIMT that was higher in smokers (P<0.001), positively correlated with lysoPC (r=0.55, P<0.001). Then in invitro study we demonstrated that both oxLDL (at concentrations similar to those found in smoker’s serum) and oxidized phospholipids contained in oxLDL, were able to up-regulate mRNA Lp-PLA2 in PBMC. This effect was likely due, at least in part, to the enrichment in oxidized phospholipids found in PBMC after exposure to oxLDL. Our results also showed that in human aortic smooth muscle cells lysoPC, at concentrations similar to those found in smokers, increased the expression of biglycan and versican, two main proteoglycans.

Conclusions

In smokers a further effect of raised oxidative stress is the up-regulation of Lp-PLA2 expression in PBMC with subsequent increase of plasma Lp-PLA2 and lysoPC. Moreover the correlation between lysoPC and CIMT together with the finding that lysoPC up-regulates proteoglycan synthesis suggests that lysoPC may be a link between smoking and intimal thickening.

Physical activity and cardiometabolic risk in male children and adolescents: the Balcarce study

AIMS

This study aims to evaluate the relationship between the amount of physical activity and different traditional and novel cardiometabolic risk factors, as well as atheroprotective agents, in male children and adolescents.

MAIN METHODS

Cross-sectional study. A total of 337 male children and adolescents aged 7-14 years old from the rural city of Balcarce, Buenos Aires, Argentina were studied.

KEY FINDINGS

The main finding of the present study was that, in male children and adolescents, physical activity was inversely associated with lipoprotein-associated phospholipase A2 (Lp-PLA2) activity (r=-0.39, p<0.001) and with cholesteryl ester transfer protein activity (r=-0.23, p<0.05) apart from other proatherogenic agents after adjusting for age and BMI. Strikingly, among the parameters evaluated, overweight, hyperglycemia and Lp-PLA2 activity resulted to be independently related to physical activity as shown by stepwise regression analysis.

SIGNIFICANCE

The strong negative association between exercise and Lp-PLA2 activity and the fact that the latter resulted to be the unique continuous variable that persisted associated with physical activity would add an additional benefit of exercise in early prevention of vascular inflammation and atherogenesis.

Elevated PLA2G7 gene promoter methylation as a gender-specific marker of aging increases the risk of coronary heart disease in females

PLA2G7 gene product is a secreted enzyme whose activity is associated with coronary heart disease (CHD). The goal of our study is to investigate the contribution of PLA2G7 promoter DNA methylation to the risk of CHD. Using the bisulphite pyrosequencing technology, PLA2G7 methylation was measured among 36 CHD cases and 36 well-matched controls. Our results indicated that there was a significant association between PLA2G7 methylation and CHD (adjusted P = 0.025). Significant gender-specific correlation was observed between age and PLA2G7 methylation (males: adjusted r = −0.365, adjusted P = 0.037; females: adjusted r = 0.373, adjusted P = 0.035). A breakdown analysis by gender showed that PLA2G7 methylation was significantly associated with CHD in females (adjusted P = 0.003) but not in males. A further two-way ANOVA analysis showed there was a significant interaction between gender and status of CHD for PLA2G7 methylation (gender*CHD: P = 6.04E−7). Moreover, PLA2G7 methylation is associated with the levels of total cholesterols (TC, r = 0.462, P = 0.009), triglyceride (TG, r = 0.414, P = 0.02) and Apolipoprotein B (ApoB, r = 0.396, P = 0.028) in females but not in males (adjusted P>0.4). Receiver operating characteristic (ROC) curves showed that PLA2G7 methylation could predict the risk of CHD in females (area under curve (AUC) = 0.912, P = 2.40E−5). Our results suggest that PLA2G7 methylation changes with aging in a gender-specific pattern. The correlation between PLA2G7 methylation and CHD risk in females is independent of other parameters including age, smoking, diabetes and hypertension. PLA2G7 methylation might exert its effects on the risk of CHD by regulating the levels of TC, TG, and ApoB in females. The gender disparities in the PLA2G7 methylation may play a role in the molecular mechanisms underlying the pathophysiology of CHD.

An association study between genetic polymorphisms related to lipoprotein-associated phospholipase A(2) and coronary heart disease

Previous genome-wide association studies (GWAS) have revealed seven single nucleotide polymorphisms (SNPs) that affect lipoprotein-associated phospholipase A₂ (Lp-PLA₂) activity or levels in American and European individuals. A total of 290 coronary heart disease (CHD) patients, 198 non-CHD patients and 331 unrelated healthy volunteers were recruited for the present case-control study of Han Chinese. Four SNPs (rs964184 of ZNF259, rs7528419 of CELSR2 and rs7756935 and rs1805017 of PLA2G7) were shown to be significantly associated with CHD. The rs964184-G allele of the ZNF259 gene was identified as a risk factor of CHD in females (odds ratio (OR) =1.49, 95% confidence interval (CI) =1.00–2.22, P=0.05). The rs7528419-G allele of the CELSR2 gene was protective against CHD in males (OR=0.48, 95% CI=0.25–0.93, P=0.04). The other two alleles (rs7756935-C and rs1805017-A) of the PLA2G7 gene acted as protective factors against CHD in females (rs7756935-C: OR=0.59, 95% CI=0.35–1.00, P=0.05; rs1805017-A: OR=0.51, 95% CI=0.28–0.93, P=0.03). Moreover, rs1805017 of the PLA2G7 gene was associated with the severity of CHD only in females (r²=0.02, P=0.04). We identified four Lp-PLA₂-associated SNPs significantly associated with CHD in a Han Chinese population. Specifically, rs7528419 was protective factor against CHD in males, while the other two SNPs (rs7756935 and rs1805017 of the PLA2G7 gene) were protective factors against CHD in females and rs964184 of the ZNF259 gene was regarded as a risk factor for CHD in females.

Alteration in lipoprotein-associated phospholipase A2 levels during acute coronary syndrome and its relationship to standard biomarkers

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) probably plays an important role in the development of acute coronary syndrome (ACS); elevated levels of Lp-PLA2 are associated with a poorer prognosis in patients with ischemic heart disease. Alterations of Lp-PLA2 levels during ACS and its relationship to standard biomarkers are, however, unclear.

FINDINGS

Fifty-one consecutive ACS patients were enrolled in the study. All were managed with early invasive strategy and according to the current guidelines for pharmacotherapy; intensive statin therapy was started in all patients at admission. Serum levels of Lp-PLA2, LDL-cholesterol (LDL), troponin l (Tnl), and C-reactive protein (CRP) were assessed at admission (D0), on the first morning (D1), and on the second morning of hospitalization (D2). Mean serum levels of Lp-PLA2 (ng/mL) decreased from 264.6±19.1 at D0, to 193.2±14.4 at D1 (P < 0.001 vs. D0) and 189.8±22.6 at D2 (P = 0.002 vs. D0; P = not significant vs. D1). Alterations in Lp-PLA2 levels significantly correlated with changes in LDL (r = 0.43; P = 0.008). On the other hand, no relationship between Lp-PLA2 and Tnl or CRP was found.

CONCLUSIONS

Initially, serum levels of Lp-PLA2 were significantly elevated in ACS patients, but decreased within the first 24 hours after admission and subsequently remained stable. Lp-PLA2 levels correlated with LDL levels but not with Tnl or CRP levels. Our results demonstrated dynamic alterations in Lp-PLA2 levels during the early stages of ACS and, therefore, indirectly support the hypothesis of an active role for Lp-PLA2 in the pathogenesis of ACS.

Lipoprotein-associated phospholipase A2 activity predicts cardiovascular events in high risk coronary artery disease patients

Objective

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is deemed to play a role in atherosclerosis and plaque destabilization as demonstrated in animal models and in prospective clinical studies. However, most of the literature is either focused on high-risk, apparently healthy patients, or is based on cross sectional studies. Therefore, we tested the hypothesis that serum Lp-PLA2 mass and activity are useful for predicting cardiovascular (CV) events over the coronary atherosclerotic burden and conventional risk factors in high-risk coronary artery disease patients.

Methods and Results

In a prospective cohort study of 712 Caucasian patients, who underwent coronary angiography and measurement of both Lp-PLA2 mass and activity at baseline, we determined incident CV events at follow-up after splitting the patients into a high and a low Lp-PLA2 mass and activity groups based on ROC analysis and Youden index. Kaplan-Meier and propensity score matching analysis were used to compare CV event-free survival between groups. Follow-up data were obtained in 75% of the cohort after a median of 7.2 years (range 1–12.7 years) during which 129 (25.5%) CV events were observed. The high Lp-PLA2 activity patients showed worse CV event-free survival (66.7% vs. 79.5%, p = 0.023) and acute coronary syndrome-free survival (75.4% vs. 85.6%, p = 0.04) than those in low Lp-PLA2 group.

Conclusions

A high Lp-PLA2 activity implies a worse CV prognosis at long term follow up in high-risk Caucasian patients referred for coronary angiography.

LDL subclasses and lipoprotein-phospholipase A2 activity in suppressed HIV-infected patients switching to raltegravir: Spiral substudy

OBJECTIVE

To analyze the effect of switching the ritonavir-boosted protease inhibitor (PI/r) in a stable combined antiretroviral therapy (cART) regimen to raltegravir on low-density lipoprotein (LDL) particles, and lipoprotein-associated phospholipase A2 (Lp-PLA2).

DESIGN

Substudy of a multicenter randomized trial that compared the efficacy of switching a PI/r to raltegravir-based cART in stable HIV-infected patients.

METHODS

LDL size and phenotype (by gel-gradient electrophoresis), Lp-PLA2 (by 2-thio-PAF [Cayman]), proprotein convertase subtilisin/kexin type 9 (PCSK9) (by ELISA), and standard lipid parameters were measured at baseline and week 48.

RESULTS

Eighty-one (PI/r n = 41 and raltegravir n = 40) patients were evaluated. No differences in baseline demographic and metabolic variables between arms were found except in apolipoprotein (Apo) B (p = 0.042). At week 48, total cholesterol (TC) (p < 0.001), LDL-c (p = 0.023), non-high density lipoprotein cholesterol non-high-density lipoprotein cholesterol (non-HDL-c) (p < 0.001), TC/HDL (p = 0.026), triglyceride (p < 0.001), Apo B (p < 0.001), Apo A-I (p = 0.004) and Lp (a) (p = 0.005) decreased in raltegravir arm compared to PI/r arm. At week 48, a shift from LDL phenotype B to the less atherogenic phenotype A was observed only in raltegravir arm (p < 0.001). LDL size increased (PI/r 2.1 nm, p = 0.019; raltegravir 3.8 nm, p = 0.001) and cholesterol content in small and dense LDL subfractions (LDL 4,5,6) decreased (PI/r p = 0.007, raltegravir p = 0.006) at week 48 in both arms. Total Lp-PLA2 activity (PI/r p = 0.037 and raltegravir p = 0.051) and PCSK9 plasma concentration decreased in both arms (PI/r p = 0.034 and raltegravir p < 0.001).

CONCLUSIONS

Switching a PI/r to a raltegravir-based cART in virologically suppressed HIV-infected patients was associated with an overall improvement in lipid profile, including a shift to a less atherogenic LDL phenotype.

Apo E4 and lipoprotein-associated phospholipase A2 synergistically increase cardiovascular risk

OBJECTIVE

Apolipoprotein E (apoE) has been implicated as conveying increased risk for coronary artery disease (CAD). Previous studies suggest a role of apoE as a modulator of immune response and inflammatory properties. We hypothesized that the presence of apo E4 is associated with an increased inflammatory burden in subjects with CAD as compared to subjects without CAD.

METHODS

ApoE genotypes, systemic (C-reactive protein [CRP], fibrinogen, serum amyloid-A [SAA]) and vascular inflammatory markers (Lipoprotein-associated phospholipase A(2) [Lp-PLA(2)] and pentraxin-3 [PTX-3]) were assessed in 324 Caucasians and 208 African Americans, undergoing coronary angiography.

RESULTS

For both ethnic groups, Lp-PLA(2) index, an integrated measure of Lp-PLA(2) mass and activity, increased significantly and stepwise across apoE isoforms (P = 0.009 and P = 0.026 for African Americans and Caucasians respectively). No differences were found for other inflammatory markers tested (CRP, fibrinogen, SAA and PTX-3). For the top cardiovascular score tertile, apo E4 carriers had a significantly higher level of Lp-PLA(2) index in both ethnic groups (P = 0.027 and P = 0.010, respectively).

CONCLUSION

The presence of the apo E4 isoform was associated with a higher level of Lp-PLA(2) index, a marker of vascular inflammation. Our results suggest that genetic variation at the apoE locus may impact cardiovascular disease risk through enhanced vascular inflammation.

Effects of lipoprotein-associated phospholipase A2 on arginase/nitric oxide pathway in hemodialysis patients

Lipoprotein-associated phospholipase A2 (Lp-PLA2) and arginase are recently described inflammatory biomarkers associated with cardiovascular disease. In this study, we aimed to investigate the possible effects of serum Lp-PLA2 mass levels on arginase/nitric oxide (NO) pathway as a cardiovascular risk marker in hemodialysis (HD) patients. Forty-three HD patients and 15 healthy subjects were included in this study. Lipid profile, high sensitivity C-reactive protein (hs-CRP), albumin, creatinine, body mass index (BMI), Lp-PLA2 and total nitrite levels, and arginase activity were determined in serum samples from patients and control subjects. Lp-PLA2 levels were found to be positively correlated with arginase, triglycerides, total cholesterol, low-density lipoprotein-cholesterol, and age and negatively correlated with high-density lipoprotein-cholesterol and total nitrite levels, while there was no correlation with BMI and hs-CRP, albumin, and creatinine levels in HD patients. We conclude that elevated Lp-PLA2 mass levels may contribute to impaired arginase/NO pathway in HD patients and that increased the arginase activity and Lp-PLA2 mass levels with decreased total nitrite levels seem to be useful biochemical markers in terms of reflecting endothelial dysfunction and associated cardiovascular risks in HD patients.

Atherosclerosis: current pathogenesis and therapeutic options

Coronary artery disease (CAD) arising from atherosclerosis is a leading cause of death and morbidity worldwide. The underlying pathogenesis involves an imbalanced lipid metabolism and a maladaptive immune response entailing a chronic inflammation of the arterial wall. The disturbed equilibrium of lipid accumulation, immune responses and their clearance is shaped by leukocyte trafficking and homeostasis governed by chemokines and their receptors. New pro- and anti-inflammatory pathways linking lipid and inflammation biology have been discovered, and genetic profiling studies have unveiled variations involved in human CAD. The growing understanding of the inflammatory processes and mediators has uncovered an intriguing diversity of targetable mechanisms that can be exploited to complement lipid-lowering therapies. Here we aim to systematically survey recently identified molecular mechanisms, translational developments and clinical strategies for targeting lipid-related inflammation in atherosclerosis and CAD.

Systematic Review of the Association between Lipoprotein-Associated Phospholipase A2 and Atherosclerosis

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a novel inflammatory biomarker. Basic research has shown that Lp-PLA2 is involved in the pathogenesis of atherosclerosis. In the past decade, an increasing number of epidemiological studies have investigated the association of Lp-PLA2 with atherosclerosis, but its roles in the different stages of atherosclerosis are not established. By undertaking a systematic review of the epidemiological studies on the relationship between Lp-PLA2 and atherosclerotic cardiovascular disease (CVD)/subclinical atherosclerosis, we tried to evaluate the relationship between Lp-PLA2 and the different stages of atherosclerosis. MEDLINE, Cochrane Library, and National Knowledge Infrastructure (CNKI) were searched up to September 1st, 2011. The references in all the located articles were manually searched. Epidemiological studies on the association of Lp-PLA2 with CVD and subclinical atherosclerosis, with total CVD, coronary heart disease (CHD), stroke, and subclinical atherosclerosis as their observation endpoints or outcome variables, were included in this study. Studies which did not assess the hazard ratio (HR), relative risk (RR), or odds ratio (OR) of Lp-PLA2 or which did not adjust for other known risk factors were excluded. The general information, study design, sample size, outcome variables and their definitions, follow-up duration, Lp-PLA2 measurements, variables adjusted in the multivariate analysis and main results in the literatures were retrieved. Thirty-nine studies were enrolled in this systematic review. Thirty-three studies (49, 260 subjects) investigated the relationship between Lp-PLA2 and CVD, among which 31 showed that increased Lp-PLA2 is associated to high risk for incidence or mortality of CVD: HR/RR per 1 standard deviation (SD) increase = 1.17-1.40; RR for the highest as compared with the lowest quartile was 1.41-3.75 (1.8-2.5 in most studies). Six studies (four cross-sectional studies and two case-control studies, with an overall sample size of 5,537) explored the relationship between Lp-PLA2 and subclinical atherosclerosis; among them, two studies demonstrated that Lp-PLA2 was associated with coronary artery calcification in young adults and men. In conclusion, many epidemiological studies have demonstrated that Lp-PLA2 increases the risk of clinical CVD events. However, whether there is a similar association between Lp-PLA2 and subclinical atherosclerosis remains unclear. Whether Lp-PLA2 exerts its effect during the occurrence of clinical events promoted by unstable plaques or at the early stage of atherosclerosis needs to be clarified in further prospective studies.

Antioxidant and inflammatory aspects of lipoprotein-associated phospholipase A₂ (Lp-PLA₂): a review

The association of cardiovascular events with Lp-PLA₂ has been studied continuously today. The enzyme has been strongly associated with several cardiovascular risk markers and events. Its discovery was directly related to the hydrolysis of the platelet-activating factor and oxidized phospholipids, which are considered protective functions. However, the hydrolysis of bioactive lipids generates lysophospholipids, compounds that have a pro-inflammatory function. Therefore, the evaluation of the distribution of Lp-PLA₂ in the lipid fractions emphasized the dual role of the enzyme in the inflammatory process, since the HDL-Lp-PLA₂ enzyme contributes to the reduction of atherosclerosis, while LDL-Lp-PLA₂ stimulates this process. Recently, it has been verified that diet components and drugs can influence the enzyme activity and concentration. Thus, the effects of these treatments on Lp-PLA₂ may represent a new kind of prevention of cardiovascular disease. Therefore, the association of the enzyme with the traditional assessment of cardiovascular risk may help to predict more accurately these diseases.