Inflammation, bioactive lipids and atherosclerosis: potential roles of a lipoprotein-associated phospholipase A2, platelet activating factor-acetylhydrolase

Lipoprotein-associated phospholipase A2 and arterial stiffness evaluation in patients with inflammatory bowel diseases

BACKGROUND AND AIMS

The association between inflammatory bowel diseases (IBD) and cardiovascular disease (CVD) remains equivocal. Arterial stiffness, as assessed by pulse wave velocity (PWV), and lipoprotein-associated phospholipase A2 (Lp-PLA2) are surrogates of CVD risk.

AIM

The aim of this study was to assess carotid-femoral PWV and Lp-PLA2 in patients with IBD without history of CVD.

METHODS

Established CVD risk factors, IBD characteristics, PWV and Lp-PLA2 activity were assessed in 44 patients with IBD, 29 with Crohn's disease (CD) and 15 with ulcerative colitis (UC), and 44 matched controls.

RESULTS

IBD patients had lower total and low density lipoprotein cholesterol (LDL-C) levels. There was no difference in PWV between patients and controls (6.8 vs. 6.4m/s), but patients with CD had higher PWV compared to those with UC (7 vs. 6.3m/s; p=0.044), and to controls. Smoking rates were significantly higher among CD patients. Factors associated with PWV were age, mean arterial pressure and smoking. Lp-PLA2 activity was significantly lower in patients with IBD (46.8 vs. 53.9 nmol/mL/min; p=0.011). There was no difference in Lp-PLA2 between CD and UC patients. LDL-C was the only significant predictor of Lp-PLA2.

CONCLUSIONS

Our study showed lower Lp-PLA2 activity in patients with IBD compared with controls, reflecting lower LDL-C in the former. There was no difference in PWV between the two groups. Arterial stiffness was higher in patients with CD, which is likely related to higher smoking rates. These findings challenge a possible association between IBD and CVD, but further studies are required.

Lipoprotein-associated phospholipase A2 and risk of dementia in the Cardiovascular Health Study

OBJECTIVE

To evaluate associations between Lipoprotein-associated phospholipase A2 (Lp-PLA2) mass and activity with risk of dementia and its subtypes.

METHODS

Analysis were completed on 3320 participants of the Cardiovascular Health Study (CHS), a population-based longitudinal study of community-dwelling adults age ≥65 years followed for an average of 5.4 years. Baseline serum Lp-PLA2 mass was measured using a sandwich enzyme immunoassay and Lp-PLA2 activity utilized a tritiated-platelet activating factor activity assay. Cox proportional hazards regression assessed the relative risk of incident dementia with higher baseline Lp-PLA2 adjusting for demographics, cardiovascular disease (CVD) and risk factors, inflammation markers and apolipoprotein E (APOE) genotype.

RESULTS

Each standard deviation higher Lp-PLA2 mass and activity were related to increased risk of dementia (fully adjusted HR: 1.11 per SD, 95% CI: 1.00-1.24 for mass; HR: 1.12 per SD, 95% CI: 1.00-1.26 for activity). Persons in the highest quartile of Lp-PLA2 mass were 50% more likely to develop dementia than those in the lowest quartile in adjusted models (HR: 1.49; 95% CI: 1.08-2.06). Among dementia subtypes, the risk of AD was increased two-fold in the highest compared to lowest quartile of Lp-PLA2 mass (adjusted HR: 1.98, 95% CI: 1.22-3.21). Results were attenuated in models of mixed dementia and VaD. Lp-PLA2 activity also doubled the risk of mixed dementia in the highest compared to lowest quartile (HR: 2.21, 95% CI: 1.12-4.373).

INTERPRETATION

These data support Lp-PLA2 as a risk factor for dementia independent of CVD and its risk factors. Further study is required to clarify the role of Lp-PLA2-related mechanisms in dementia subtypes.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) and tumor necrosis factor-alpha (TNF-α) and their relation to premature atherosclerosis in β-thalassemia children

BACKGROUND/OBJECTIVES

Beta (β)-thalassemia adults are prone to premature atherosclerosis but data about this complication among thalassemia children are few. Lipoprotein-associated phospholipase A2 (Lp-PLA2) and tumor necrosis factor-α (TNF-α) are inflammatory markers that could be implicated in atherosclerotic process. We investigated Lp-PLA2 and TNF-α levels in β-thalassemia children and their relation to subclinical atherosclerosis.

METHODS

Twenty-two β-thalassemia major (TM), 20 β-thalassemia intermedia children, and 30 age- and sex-matched healthy controls were included. Lipid profile (by colorimetric assay), serum ferritin, TNF-α, and plasma Lp-PLA2 levels (by enzyme-linked immunosorbent assay technique) were estimated. Carotid intima-media thickness (cIMT) was measured by high-resolution ultrasound.

RESULTS

Both patient groups exhibited anti-atherogenic lipid profile except increased serum triglycerides. They had significantly higher plasma Lp-PLA2 and serum TNF-α compared to the controls (P < 0.001). Elevated cIMT was documented in 57% of the thalassemia children and was higher among hepatitis C (HCV) positive patients. Serum ferritin, TNF-α, and plasma Lp-PLA2 levels were significantly higher in patients with premature atherosclerosis. cIMT correlated significantly with serum ferritin, TNF-α, and plasma Lp-PLA2 in both patient groups. Among TM children, serum ferritin had significant positive correlation with serum TNF-α and plasma Lp-PLA2. The elevation of both markers was not related to HCV infection.

CONCLUSIONS

Premature atherosclerosis is common among young thalassemia children. Lp-PLA2 and TNF-α are significantly increased in thalassemia children and show strong correlations with cIMT, suggesting that both of them may be appreciated as modulating factors in carotid atherosclerosis pathophysiological process among these children.

Unexpected inverse relationship between impaired glucose metabolism and lipoprotein-associated phospholipase A2 activity in patients with stable vascular disease

BACKGROUND

Elevated lipoprotein-associated phospholipase A2 activity (aLp-PLA2) is associated with increased risk of cardiovascular events. In patients with stable atherovascular disease, we aimed to investigate whether impaired glucose metabolism might be associated with higher risk of elevated aLp-PLA2.

METHODS

We conducted a cross-sectional study in 825 stable patients after acute coronary syndrome, coronary revascularization or after first ischemic stroke (Czech part of EUROASPIRE III surveys). We measured aLp-PLA2 using diaDexus commercial kit.

RESULTS

In multiple step-wise regression analysis, the aLp-PLA2 was significantly positively associated with male gender, current smoking, LDL cholesterol and metabolic syndrome and negatively with statin treatment, body mass index and LDL/apoB ratio. After adjustment for these confounders, we observed an inverse relationship between aLp-PLA2 and fasting glycemia [β coefficient -2.18 (p<0.0001)] or glycated hemoglobin A1c (HbA1c) [β coefficient -5.89 (p<0.0001)]. Moreover, we found a positive association between aLp-PLA2 and pancreatic β cell function [β coefficient +0.10 (p<0.0001)], but not with an insulin sensitivity.

CONCLUSION

In present study, we cannot confirm any additive risk of impaired glucose metabolism in terms of increased activity of Lp-PLA2. On the contrary, presence of inadequately controlled diabetes mellitus was independently associated with lower risk of elevated aLp-PLA2 .

PLAC™ test for identification of individuals at increased risk for coronary heart disease

Recent advances in cardiovascular research point to a critical role of inflammatory processes in the etiology of cardiovascular disease. This has led to the discovery of novel inflammatory biomarkers, which may be useful as additional screening tools for the identification of individuals at increased risk of coronary heart disease. One such novel inflammatory biomarker is lipoprotein-associated phospholipase A(2). This review discusses the recent development of a US Food and Drug Administration-approved blood test for lipoprotein-associated phospholipase A(2) (PLAC test, diaDexus, Inc.) and its efficacy as a predictive biomarker of risk for cardiovascular disease. More specifically, the article addresses the potential target group most likely to benefit from this new screening test and provides a prospective scenario for its implementation.

Platelet-activating factor downregulates the expression of liver X receptor-α and its target genes in human neutrophils

Liver X receptors (LXRs) are ligand-activated members of the nuclear receptor superfamily that regulate the expression of genes involved in lipid metabolism and inflammation, although their role in inflammation and immunity is less well known. It has been reported that oxysterols/LXRs may act as anti-inflammatory molecules, although opposite actions have also been reported. In this study, we investigated the effect of platelet-activating factor (PAF), a proinflammatory molecule, on LXRα signalling in human neutrophils. We found that PAF exerted an inhibitory effect on mRNA expression of TO901317-induced LXRα, ATP-binding cassette transporter A1, ATP-binding cassette transporter G1, and sterol response element binding protein 1c. This negative action was mediated by the PAF receptor, and was dependent on the release of reactive oxygen species elicited by PAF, as it was enhanced by pro-oxidant treatment and reversed by antioxidants. Current data also support the idea that PAF induces phosphorylation of the LXRα molecule in an extracellular signal-regulated kinase 1/2-mediated fashion. These results suggest that a possible mechanism by which PAF exerts its proinflammatory effect is through the downregulation of LXRα and its related genes, which supports the notion that LXRα ligands exert a modulatory role in the neutrophil-mediated inflammatory response.

HDL and cholesterol: life after the divorce?

For decades, HDL and HDL-cholesterol (HDL-C) levels were viewed as synonymous, and modulation of HDL-C levels by drug therapy held great promise for the prevention and treatment of cardiovascular disease. Nevertheless, recent failures of drugs that raise HDL-C to reduce cardiovascular risk and the now greater understanding of the complexity of HDL composition and biology have prompted researchers in the field to redefine HDL. As such, the focus of HDL has now started to shift away from a cholesterol-centric view toward HDL particle number, subclasses, and other alternative metrics of HDL. Many of the recently discovered functions of HDL are, in fact, not strictly conferred by its ability to promote cholesterol flux but by the other molecules it transports, including a diverse set of proteins, small RNAs, hormones, carotenoids, vitamins, and bioactive lipids. Based on HDL's ability to interact with almost all cells and transport and deliver fat-soluble cargo, HDL has the remarkable capacity to affect a wide variety of endocrine-like systems. In this review, we characterize HDL's unique cargo and address the functional relevance and consequences of HDL transport and delivery of noncholesterol molecules to recipient cells and tissues.

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.

Combining Rosuvastatin With Angiotensin-Receptor Blockers of Different PPARγ-Activating Capacity

The effects of combining angiotensin-receptor blockers of different peroxisome proliferator-activated receptor γ-activating capacity with rosuvastatin on high-density lipoprotein (HDL) subfractions and associated enzymes in patients with mixed dyslipidemia, hypertension, and prediabetes were assessed. Patients (n = 151) were randomly allocated to rosuvastatin (10 mg/d) plus telmisartan 80 mg/d (RT group, n = 52) or irbesartan 300 mg/d (RI group, n = 48) or olmesartan 20 mg/d (RO group, n = 51). Total and intermediate HDL cholesterol (HDL-C) levels did not change in any group. Large HDL-C increased, while small HDL-C decreased significantly in all the groups ( P = not significant between the groups). The mass of HDL lipoprotein-associated phospholipase A2 (HDL-Lp-PLA2) and the activities of paraoxonase 1 remained unchanged in all the groups. However, HDL-Lp-PLA2 activity increased only in the RT group (+21.4%; P < .01 vs baseline) and did not change in the RI (−4.3%; P = .005 vs RT group) and RO (+3.2%; P = .01 vs RT) groups. In conclusion, only the combination of rosuvastatin with telmisartan increased the possibly antiatherosclerotic HDL-Lp-PLA2 activity.

Effect of tobacco smoking and smoking cessation on plasma lipoproteins and associated major cardiovascular risk factors: a narrative review

Cigarette smoking, active or passive, kills about 6 million people each year worldwide. Cardiovascular disease (CVD) is responsible for 40% of all smoking-related deaths, lung cancer accounts for 20% of all smoking-related deaths, and chronic obstructive pulmonary disease is related to another 20% of deaths. In this narrative review we consider the relationship between cigarette smoking and CVD. We discuss disease states and/or CVD risk factors related to smoking, such as dyslipidaemia, vascular inflammation, endothelial dysfunction, arterial stiffness, insulin resistance, type 2 diabetes mellitus (T2DM), chronic kidney disease (CKD), and non-alcoholic fatty liver disease (NAFLD) as well as their complex interrelations. Smoking cessation can correct abnormalities related to smoking; however, success rates are relatively low. In cases of inability to quit, measures to minimize the adverse effects of smoking specifically related to CVD should be taken. Smokers should receive best practice treatment, according to guidelines, as for non-smokers.

Targeted lipidomics - advances in profiling lysophosphocholine and platelet-activating factor second messengers

Glycerophosphocholines are the major building blocks of biological membranes. They are also precursors of low-molecular-weight second messengers with mass to charge ratios of 450-600. These messengers include lysophosphatidylcholines (LPCs) and lyso-platelet activating factors (PAFs) that may be further processed into PAFs. Often considered as a single species, LPCs, PAFs and lyso-PAFs are, in fact, families of glycerophosphocholine-derived lipids distinguished by the linkage of their sn-1 carbon chains to the phosphoglyceride backbone (ester or ether), their sn-1 carbon chain length and degree of unsaturation, and the identity of their sn-2 constituents (a hydroxyl or acetyl group). Each LPC and PAF species exhibits a different affinity for its cognate G-protein-coupled receptors, and each species elicits receptor-independent actions that play critical signalling roles. Targeted mass spectrometry-based lipidomic approaches are enabling the molecular identification and quantification of these low-abundance second messengers. Variations between datasets map the temporal landscape of second messengers available for signalling, and provide snapshots of the state of structural membrane compositional remodelling at the time of extraction. Here, we review a number of advances in lipidomic methodologies used to identify LPCs, lyso-PAFs and PAFs, and highlight how these targeted approaches are providing valuable insight into the roles played by the cellular lipidome in cell function and disease susceptibility.

Inflammatory biomarkers for predicting cardiovascular disease

The pathology of cardiovascular disease (CVD) is complex; multiple biological pathways have been implicated, including, but not limited to, inflammation and oxidative stress. Biomarkers of inflammation and oxidative stress may serve to help identify patients at risk for CVD, to monitor the efficacy of treatments, and to develop new pharmacological tools. However, due to the complexities of CVD pathogenesis there is no single biomarker available to estimate absolute risk of future cardiovascular events. Furthermore, not all biomarkers are equal; the functions of many biomarkers overlap, some offer better prognostic information than others, and some are better suited to identify/predict the pathogenesis of particular cardiovascular events. The identification of the most appropriate set of biomarkers can provide a detailed picture of the specific nature of the cardiovascular event. The following review provides an overview of existing and emerging inflammatory biomarkers, pro-inflammatory cytokines, anti-inflammatory cytokines, chemokines, oxidative stress biomarkers, and antioxidant biomarkers. The functions of each biomarker are discussed, and prognostic data are provided where available.

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.

Small high-density lipoprotein (HDL) subclasses are increased with decreased activity of HDL-associated phospholipase A₂ in subjects with prediabetes

Alterations in high-density lipoprotein (HDL) subclass distribution, as well as in the activities of HDL-associated enzymes, have been associated with increased cardiovascular disease (CVD) risk. HDL subclass distribution and the activities of HDL-associated enzymes remain unknown in prediabetic patients, a condition also associated with increased CVD risk. The aim of the present study was to assess any differences in HDL subclass distribution (using polyacrylamide gel electrophoresis) and in activities of HDL-associated enzymes between prediabetic (impaired fasting glucose, IFG, n = 80) and non-prediabetic subjects (n = 105). Subjects with prediabetes had significantly increased waist circumference, blood pressure and triacylglycerol (TAG) levels compared with subjects with fasting glucose levels <100 mg/dL (all p < 0.05). The proportion of small HDL3 over HDL cholesterol (HDL-C) was significantly increased in prediabetic subjects compared with their controls (p < 0.05). The activity of the anti-atherogenic HDL-associated lipoprotein-associated phospholipase A₂ (HDL-LpPLA₂) was significantly lower in subjects with prediabetes (p < 0.05), whereas the activity of paraoxonase 1 (using both paraoxon and phenyl acetate as substrates) did not significantly differ between subjects with or without prediabetes. In a stepwise linear regression analysis, the proportion of small HDL3 over HDL-C concentration was independently associated with the presence of prediabetes and with total cholesterol and TAG concentration (positively), as well as with HDL-C levels (negatively). We also observed a trend of increased small dense low-density lipoprotein cholesterol levels in prediabetic subjects compared with their controls. Subjects with IFG exhibit increased proportion of small HDL3 particles combined with decreased activity of the anti-atherogenic HDL-LpPLA₂.

Plasma HDL reduces nonesterified fatty acid hydroperoxides originating from oxidized LDL: a mechanism for its antioxidant ability

The antioxidant property of plasma high-density lipoprotein (HDL) is thought to be involved in potential anti-atherogenic effects but the exact mechanism is not known. We aimed to reveal the contribution of HDL on the elimination of lipid hydroperoxides (LOOH) derived from oxidized low-density lipoprotein (LDL). Oxidized LDL prepared by copper ion-induced oxidation contained nonesterified fatty acid hydroperoxides (FFA-OOH) and lysophosphatidylcholine (lysoPtdCho), in addition to cholesteryl ester hydroperoxides (CE-OOH) and phosphatidylcholine hydroperoxides (PtdCho-OOH). A platelet-activating factor-acetylhydrolase (PAF-AH) inhibitor suppressed formation of FFA-OOH and lysoPtdCho in oxidized LDL. Among LOOH species, FFA-OOH was preferentially reduced by incubating oxidized LDL with HDL. HDL exhibited selective FFA-OOH reducing ability if it was mixed with a liposomal solution containing FFA-OOH, CE-OOH and PtdCho-OOH. Two-electron reduction of the hydroperoxy group to the hydroxy group was confirmed by the formation of 13-hydroxyoctadecadienoic acid from 13-hydroperoxyoctadecadienoic acid in HPLC analyses. This reducing effect was also found in apolipoprotein A-1 (apoA-1). FFA-OOH released from PtdCho-OOH due to PAF-AH activity in oxidized LDL undergo two-electron reduction by the reducing ability of apoA1 in HDL. This preferential reduction of FFA-OOH may participate in the mechanism of the antioxidant property of HDL.

Correlation between plasma lipoprotein-associated phospholipase A2 and peripheral arterial disease

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is a recently identified and potentially useful plasma biomarker for cardiovascular diseases. However, its role in peripheral arterial disease (PAD) remains unclear. The objective of this study was to assess the independent association of Lp-PLA₂ and other inflammatory markers with the reduced ankle-brachial blood pressure index (ABI), a marker of PAD. We performed a cross-sectional study in 982 individuals aged ≥40 years who were recruited from the First Affiliated Hospital of Zhengzhou University. PAD was defined as an ABI <0.9 in at least one leg. The individuals were further divided into two groups, 145 with PAD and 837 without PAD. Following adjustment for traditional cardiovascular risk factors, the odds ratios of PAD when comparing the highest to the lowest quartiles were 3.24 (95% CI, 1.68–3.94) for Lp-PLA₂, 2.14 (95% CI, 1.07–3.11) for homocysteine, 1.93 (95% CI, 1.02–4.01) for fibrinogen, 2.26 (95% CI, 1.32–5.74) for apolipoprotein B and 1.3 (95% CI, 0.75–2.49) for high-sensitivity C-reactive protein (hsCRP). When Lp-PLA₂ and inflammatory markers were simultaneously included in the full model, the corresponding odds ratios were 1.81 (95% CI, 1.14–3.68) for Lp-PLA₂, 1.15 (95% CI, 0.49–2.69) for homocysteine, 1.21 (95% CI, 0.88–5.57) for fibrinogen, 0.98 (95% CI, 0.51–3.85) for apolipoprotein B and 1.23 (95% CI, 1.12–3.51) for hsCRP. Lp-PLA₂ levels were significantly and independently associated with PAD following adjustment for other inflammatory markers. These findings reflect the potential role of circulating Lp-PLA₂ as a marker of atherosclerosis.

Influence of obesity and cardiometabolic makers on lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in adolescents: the healthy young cross-sectional study

BACKGROUND

Lipoprotein-associated phospholipase A2 activity (Lp-PLA2) is a good marker of cardiovascular risk in adults. It is strongly associated with stroke and many others cardiovascular events. Despite this, the impact of obesity on this enzyme activity and its relation to biomarkers of cardiovascular disease in adolescents is not very well investigated. The purpose of this article is to evaluate the influence of obesity and cardiometabolic markers on Lp-PLA2 activity in adolescents.

RESULTS

This cross-sectional study included 242 adolescents (10-19 years) of both gender. These subjects were classified in Healthy Weight (n = 77), Overweight (n = 82) and Obese (n = 83) groups. Lipid profile, glucose, insulin, HDL size, LDL(-) and anti-LDL(-) antibodies were analyzed. The Lp-PLA2 activity was determined by a colorimetric commercial kit. Body mass index (BMI), waist circumference and body composition were monitored. Food intake was evaluated using three 24-hour diet recalls. The Lp-PLA2 activity changed in function to high BMI, waist circumference and fat mass percentage. It was also positively associated with HOMA-IR, glucose, insulin and almost all variables of lipid profile. Furthermore, it was negatively related to Apo AI (β = -0.137; P = 0.038) and strongly positively associated with Apo B (β = 0.293; P < 0.001) and with Apo B/Apo AI ratio (β = 0.343; P < 0.001). The better predictor model for enzyme activity, on multivariate analysis, included Apo B/Apo AI (β = 0.327; P < 0.001), HDL size (β = -0.326; P < 0.001), WC (β = 0.171; P = 0.006) and glucose (β = 0.119; P = 0.038). Logistic regression analysis demonstrated that changes in Apo B/Apo AI ratio were associated with a 73.5 times higher risk to elevated Lp-PLA2 activity.

CONCLUSIONS

Lp-PLA2 changes in function of obesity, and that it shows important associations with markers of cardiovascular risk, in particular with waist circumference, glucose, HDL size and Apo B/Apo AI ratio. These results suggest that Lp-PLA2 activity can be a cardiovascular biomarker in adolescence.

The impact of rapid weight loss on oxidative stress markers and the expression of the metabolic syndrome in obese individuals

OBJECTIVE

Obesity is linked with a state of increased oxidative stress, which plays an important role in the etiology of atherosclerosis and type 2 diabetes mellitus. The aim of our study was to evaluate the effect of rapid weight loss on oxidative stress markers in obese individuals with metabolic syndrome (MetS).

DESIGN AND METHODS

We measured oxidative stress markers in 40 obese subjects with metabolic syndrome (MetS+), 40 obese subjects without metabolic syndrome (MetS-), and 20 lean controls (LC) at baseline and after three months of very low caloric diet.

RESULTS

Oxidized low density lipoprotein (ox-LDL) levels decreased by 12% in MetS+ subjects, associated with a reduction in total cholesterol (TC), even after adjustment for age and sex. Lipoprotein associated phospholipase A₂ (Lp-PLA₂) activity decreased by 4.7% in MetS+ subjects, associated with a drop in LDL-cholesterol (LDL-C), TC, and insulin levels. Multivariate logistic regression analysis showed that a model including ox-LDL, LpPLA₂ activity, and myeloperoxidase (MPO) improved prediction of MetS status among obese individuals compared to each oxidative stress marker alone.

CONCLUSIONS

Oxidative stress markers were predictive of MetS in obese subjects, suggesting a higher oxidative stress. Rapid weight loss resulted in a decline in oxidative stress markers, especially in MetS+ patients.

Phospholipid profiling of 57 soybean (Glycine max) varieties by high-performance liquid chromatography-tandem mass spectrometry and principal component analysis to classify Korean soybean germplasm

Phospholipids (PLs) in 57 varieties of soybeans were profiled by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry and principal component analysis (PCA) to discriminate PL-rich soybeans. The PL calibration curves showed linearity with correlation coefficients >0.9964. The recoveries at 5 mg/L spiked level ranged from 72.8 to 86.7% and those at 12.5 mg/L from 78.2 to 85.1%. The repeatability at a 5 mg/L spiked level ranged from 2.5 to 7.0% and those at 12.5 mg/L from 1.2 to 3.9%. The average total PL content in the 57 soybean varieties was about 35.3 mg/kg. The total PL content was the highest in Aodaiz (35, 48.7 ± 1.4 mg/kg) and the lowest in Poongsannamul (56, 16.0 ± 0.7 mg/kg). The PCA showed that RS-78sun (42), Gyeongsang #1 (3) and Aodaiz (35) are the most improved varieties of the investigated 57 varieties from the viewpoint of PL content.

Genome-Wide Association Study Evaluating Lipoprotein-Associated Phospholipase A 2 Mass and Activity at Baseline and After Rosuvastatin Therapy

Background—

Lipoprotein-associated phospholipase A 2 (Lp-PLA 2 ) is a proinflammatory enzyme bound to low-density lipoprotein cholesterol and other circulating lipoproteins. Two measures of Lp-PLA 2 , mass and activity, are associated with increased cardiovascular risk. Data are sparse regarding genetic determinants of Lp-PLA 2 mass and activity, and no prior data are available addressing genetic determinants of statin-induced changes for this proinflammatory biomarker.

Methods and Results —

We performed a genome-wide association study of Lp-PLA 2 mass and activity at baseline and after 12 months of rosuvastatin therapy (20 mg/d) among 6851 participants of European ancestry from the Justification for Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) and performed replication in a meta-analysis of 13 664 participants from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. Novel associations were identified and replicated at MS4A4E and TMEM49 for baseline Lp-PLA 2 activity with genome-wide significant joint P values ( P =2.0×10 −11 and P =2.9×10 −9 , respectively). In addition, genome-wide associations ( P <5×10 −8 ) were identified and replicated for baseline Lp-PLA 2 mass at CETP and for Lp-PLA 2 activity at the APOC1-APOE and PLA2G7 loci. Among 2673 statin-allocated participants, both Lp-PLA 2 mass and activity were reduced by >30% and low-density lipoprotein cholesterol by 50% after 12 months of statin therapy ( P <0.001 for both). Variants in ABCG2 and LPA were associated with change in statin-induced Lp-PLA 2 activity at genome-wide significance but were substantially attenuated after adjustment for statin-induced changes in lipid levels.

Conclusions—

Genome-wide significant associations at MS4A4E and TMEM49 may reflect novel influences on circulating levels of Lp-PLA 2 activity. In addition, genome-wide significant associations with rosuvastatin-induced change in Lp-PLA 2 activity were observed in ABCG2 and LPA , likely because of their impact on statin-induced low-density lipoprotein cholesterol lowering.

Lipoprotein-associated phospholipase A(2) bound on high-density lipoprotein is associated with lower risk for cardiac death in stable coronary artery disease patients: a 3-year follow-up

OBJECTIVES

The aim of this study was to examine the prognostic value of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) associated with high-density lipoprotein (HDL) (HDL-Lp-PLA(2)) in patients with stable coronary artery disease (CAD).

BACKGROUND

Lp-PLA(2) is a novel risk factor for cardiovascular disease. It has been postulated that the role of Lp-PLA(2) in atherosclerosis may depend on the type of lipoprotein with which it is associated.

METHODS

Total plasma Lp-PLA(2) and HDL-Lp-PLA(2) mass and activity, lipids, and C-reactive protein were measured in 524 consecutive patients with stable CAD who were followed for a median of 34 months. The primary endpoint was cardiac death, and the secondary endpoint was hospitalization for acute coronary syndromes, myocardial revascularization, arrhythmic event, or stroke.

RESULTS

Follow-up data were obtained from 477 patients. One hundred twenty-three patients (25.8%) presented with cardiovascular events (24 cardiac deaths, 47 acute coronary syndromes, 28 revascularizations, 22 arrhythmic events, and 2 strokes). Total plasma Lp-PLA(2) mass and activity were predictors of cardiac death (hazard ratio [HR]: 1.013; 95% confidence interval [CI]: 1.005 to 1.021; p = 0.002; and HR: 1.040; 95% CI: 1.005 to 1.076; p = 0.025, respectively) after adjustment for traditional risk factors for CAD. In contrast, HDL-Lp-PLA(2) mass and activity were associated with lower risk for cardiac death (HR: 0.972; 95% CI: 0.952 to 0.993; p = 0.010; and HR: 0.689; 95% CI: 0.496 to 0.957; p = 0.026, respectively) after adjustment for traditional risk factors for CAD.

CONCLUSIONS

Total plasma Lp-PLA(2) is a predictor of cardiac death, while HDL-Lp-PLA(2) is associated with lower risk for cardiac death in patients with stable CAD, independently of other traditional cardiovascular risk factors.

Lipid oxidation in carriers of lecithin:cholesterol acyltransferase gene mutations

OBJECTIVE

Lecithin:cholesterol acyltransferase (LCAT) has been shown to play a role in the depletion of lipid oxidation products, but this has so far not been studied in humans. In this study, we investigated processes and parameters relevant to lipid oxidation in carriers of functional LCAT mutations.

METHODS AND RESULTS

In 4 carriers of 2 mutant LCAT alleles, 63 heterozygotes, and 63 family controls, we measured activities of LCAT, paraoxonase 1, and platelet-activating factor-acetylhydrolase; levels of lysophosphatidylcholine molecular species, arachidonic and linoleic acids, and their oxidized derivatives; immunodetectable oxidized phospholipids on apolipoprotein (apo) B-containing and apo(a)-containing lipoproteins; IgM and IgG autoantibodies to malondialdehyde-low-density lipoprotein and IgG and IgM apoB-immune complexes; and the antioxidant capacity of high-density lipoprotein (HDL). In individuals with LCAT mutations, plasma LCAT activity, HDL cholesterol, apoA-I, arachidonic acid, and its oxidized derivatives, oxidized phospholipids on apo(a)-containing lipoproteins, HDL-associated platelet-activating factor-acetylhydrolase activity, and the antioxidative capacity of HDL were gene-dose-dependently decreased. Oxidized phospholipids on apoB-containing lipoproteins was increased in heterozygotes (17%; P<0.001) but not in carriers of 2 defective LCAT alleles.

CONCLUSIONS

Carriers of LCAT mutations present with significant reductions in LCAT activity, HDL cholesterol, apoA-I, platelet-activating factor-acetylhydrolase activity, and antioxidative potential of HDL, but this is not associated with parameters of increased lipid peroxidation; we did not observe significant changes in the oxidation products of arachidonic acid and linoleic acid, immunoreactive oxidized phospholipids on apo(a)-containing lipoproteins, and IgM and IgG autoantibodies against malondialdehyde-low-density lipoprotein. These data indicate that plasma LCAT activity, HDL-associated platelet-activating factor-acetylhydrolase activity, and HDL cholesterol may not influence the levels of plasma lipid oxidation products.

Inflammatory markers in coronary artery disease

Coronary artery disease (CAD) is one of the most common manifestations of atherosclerosis. Inflammation is considered one of the major processes that contribute to atherogenesis. Inflammation plays an important role not only on the initiation and progression of atherosclerosis but also on plaque rupture, an event that leads to acute vascular events. Various biomarkers express different pathways and pathophysiologic mechanisms of cardiovascular disease, and inflammatory biomarkers express different parts of the atherogenic process, regarding the initiation and progression of atherosclerosis or the destabilization of the atherosclerotic plaque. Therefore, inflammatory biomarkers may prove to be useful in the detection, staging, and prognosis of patients with CAD. Furthermore, the fact that inflammatory processes are essential steps in the course of the disease offers future therapeutic targets for the interruption of the atherogenic process or for the management of acute events.

Lipidomic profiling of model organisms and the world's major pathogens

Lipidomics is a subspecialty of metabolomics that focuses on water insoluble metabolites that form membrane barriers. Most lipidomic databases catalog lipids from common model organisms, like humans or Escherichia coli. However, model organisms' lipid profiles show surprisingly little overlap with those of specialized pathogens, creating the need for organism-specific lipidomic databases. Here we review rapid progress in lipidomic platform development with regard to chromatography, detection and bioinformatics. We emphasize new methods of comparative lipidomics, which use aligned datasets to identify lipids changed after introducing a biological variable. These new methods provide an unprecedented ability to broadly and quantitatively describe lipidic change during biological processes and identify changed lipids with low error rates.

From circulating biomarkers to genomics and imaging in the prediction of cardiovascular events in the general population

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. In the last decades numerous markers have been considered and investigated for the prediction of CV events, but only a few of them resulted in improved global risk assessment beyond traditional risk factors when incorporated into coronary evaluation scores. Recent genetic studies have pointed out a few but consistent loci or genes which are independently associated with CV risk. The idea is fascinating that these genetic markers could lead to improved individual CV risk assessment and tailored pharmacological interventions. In this brief review we will not make a systematic review of all non-genetic and genetic markers of CV risk but we will try to make a brief overview of the most interesting ones with the aim to underline potential 'pros' and 'cons' of their implementation in clinical practice.

High-density lipoprotein and atherosclerosis: the role of antioxidant activity

Levels of high-density lipoprotein (HDL) cholesterol are generally inversely associated with the risk for the development of atherosclerosis. The mechanism by which HDL imparts protection from the initiation and progression of occlusive vascular disease is complex and multifactorial. The major anti-atherosclerotic effect of HDL is felt to be reverse cholesterol transport. HDL has been demonstrated to scavenge cholesterol from the peripheral vasculature with transport to the liver, where is it excreted in the biliary system. However, HDL exhibits multiple other physiologic effects that may play a role in the reduced risk for atherosclerosis. HDL has been demonstrated to exhibit beneficial effects on platelet function, endothelial function, coagulation parameters, inflammation, and interactions with triglyceride-rich lipoproteins. Increasing amounts of clinical and experimental data have shown that HDL cholesterol has significant antioxidant effect that may significantly contribute to protection from atherosclerosis.

The relationship of vitamin D with non-traditional risk factors for cardiovascular disease in subjects with metabolic syndrome

INTRODUCTION

Several studies implicate an inverse relationship between 25-hydroxy vitamin D (25(OH)Vit D) serum levels and metabolic syndrome (MetS). We sought to investigate a possible relationship between 25(OH)Vit D and emerging risk factors associated with MetS, such as small dense low-density lipoprotein cholesterol (sdLDL-C) concentration, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) activity and high-sensitivity C-reactive protein (hsCRP) levels.

MATERIAL AND METHODS

We studied 110 consecutive otherwise healthy individuals. Of these, 52 were diagnosed with MetS and 58 who did not meet the MetS criteria served as controls. Low-density lipoprotein (LDL) subclass analysis was performed by polyacrylamide gel electrophoresis. Lp-PLA(2) activity was determined in total plasma by the trichloroacetic acid precipitation procedure. Serum 25(OH)Vit D was determined quantitatively by an enzyme immunoassay method.

RESULTS

Metabolic syndrome subjects had significantly lower 25(OH)Vit D levels (11.8 [0.6-48.3] ng/ml; 29.5 [1.5-120.75] nmol/l) compared with controls (17.2 [4.8-62.4] ng/ml; 43 [12-156] nmol/l, p = 0.027). Univariate regression analysis showed that 25(OH)Vit D concentration was inversely related to triglycerides (r= - 0.416, p = 0.003) and sdLDL-C (r= - 0.305, p = 0.004). There was no association of 25(OH)Vit D with waist circumference, blood pressure, high-density lipoprotein cholesterol (HDL-C), fasting glucose, Lp-PLA(2) and hsCRP. In multivariate regression analysis the relationship between 25(OH)Vit D and sdLDL-C became insignificant when triglycerides were included in the model.

CONCLUSIONS

Subjects with MetS exhibit lower 25(OH)Vit D serum levels compared with non-MetS individuals. Low 25(OH)Vit D is associated with higher sdLDL-C levels possibly through elevated triglycerides. No association between 25(OH)Vit D and Lp-PLA(2) or hsCRP was found.

Modulation of oxidative stress, inflammation, and atherosclerosis by lipoprotein-associated phospholipase A2

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), also known as platelet-activating factor acetylhydrolase (PAF-AH), is a unique member of the phospholipase A(2) superfamily. This enzyme is characterized by its ability to specifically hydrolyze PAF as well as glycerophospholipids containing short, truncated, and/or oxidized fatty acyl groups at the sn-2 position of the glycerol backbone. In humans, Lp-PLA(2) circulates in active form as a complex with low- and high-density lipoproteins. Clinical studies have reported that plasma Lp-PLA(2) activity and mass are strongly associated with atherogenic lipids and vascular risk. These observations led to the hypothesis that Lp-PLA(2) activity and/or mass levels could be used as biomarkers of cardiovascular disease and that inhibition of the activity could offer an attractive therapeutic strategy. Darapladib, a compound that inhibits Lp-PLA(2) activity, is anti-atherogenic in mice and other animals, and it decreases atherosclerotic plaque expansion in humans. However, disagreement continues to exist regarding the validity of Lp-PLA(2) as an independent marker of atherosclerosis and a scientifically justified target for intervention. Circulating Lp-PLA(2) mass and activity are associated with vascular risk, but the strength of the association is reduced after adjustment for basal concentrations of the lipoprotein carriers with which the enzyme associates. Genetic studies in humans harboring an inactivating mutation at this locus indicate that loss of Lp-PLA(2) function is a risk factor for inflammatory and vascular conditions in Japanese cohorts. Consistently, overexpression of Lp-PLA(2) has anti-inflammatory and anti-atherogenic properties in animal models. This thematic review critically discusses results from laboratory and animal studies, analyzes genetic evidence, reviews clinical work demonstrating associations between Lp-PLA(2) and vascular disease, and summarizes results from animal and human clinical trials in which administration of darapladib was tested as a strategy for the management of atherosclerosis.

Lower CSF amyloid beta peptides and higher F2-isoprostanes in cognitively intact elderly individuals with major depressive disorder

OBJECTIVE

Major depressive disorder is common in the elderly, and symptoms are often not responsive to conventional antidepressant treatment, especially in the long term. Soluble oligomeric and aggregated forms of amyloid beta peptides, especially amyloid beta 42, impair neuronal and synaptic function. Amyloid beta 42 is the main component of plaques and is implicated in Alzheimer's disease. Amyloid beta peptides also induce a depressive state in rodents and disrupt major neurotransmitter systems linked to depression. The authors assessed whether major depression was associated with CSF levels of amyloid beta, tau protein, and F2-isoprostanes in elderly individuals with major depressive disorder and age-matched nondepressed comparison subjects.

METHOD

CSF was obtained from 47 cognitively intact volunteers (major depression group, N=28; comparison group, N=19) and analyzed for levels of soluble amyloid beta, total and phosphorylated tau proteins, and isoprostanes.

RESULTS

Amyloid beta 42 levels were significantly lower in the major depression group relative to the comparison group, and amyloid beta 40 levels were lower but only approaching statistical significance. In contrast, isoprostane levels were higher in the major depression group. No differences were observed in total and phosphorylated tau proteins across conditions. Antidepressant use was not associated with differences in amyloid beta 42 levels.

CONCLUSIONS

Reduction in CSF levels of amyloid beta 42 may be related to increased brain amyloid beta plaques or decreased soluble amyloid beta production in elderly individuals with major depression relative to nondepressed comparison subjects. These results may have implications for our understanding of the pathophysiology of major depression and for the development of treatment strategies.

Apolipoprotein E-containing HDL-associated platelet-activating factor acetylhydrolase activities and malondialdehyde concentrations in patients with PCOS

PAF and PAF-like oxidized phospholipids hydrolysed by platelet-activating factor (PAF) acetylhydrolase (AH) are potent lipid mediators involved in inflammation and atherosclerosis. Apolipoprotein (apo) E-containing high-density lipoprotein (HDL) has antioxidant, anti-inflammatory and anti-atherogenic properties. The study investigated apoE-containing HDL-associated PAF-AH (HDL-PAF-AH) and total (apoE-containing+apoE-poor) HDL-PAF-AH activities as well as malondialdehyde (MDA) concentration in 291 patients with polycystic ovary syndrome (PCOS) using the Rotterdam consensus criteria and 281 control women. Compared with the control women, patients with hyperandrogenism+oligo/anovulation+polycystic ovaries (PCO) or hyperandrogenism+PCO had lower total, apoE-containing and apoE-poor HDL-PAF-AH activities, while those with oligo/anovulation+PCO showed decreased total and apoE-poor HDL-PAF-AH activities. Other factors including insulin resistance and obesity in PCOS had the adverse effects associated with the HDL-PAF-AH activities. Serum MDA concentration was associated with PCOS, hyperandrogenism, insulin resistance and hypertriglyceridaemia in patients with PCOS. Decreased total and apoE-containing HDL-PAF-AH activities and increased serum MDA concentration may contribute to the pathogenesis of PCOS and potentially link to related complications responsible for oxidative stress and inflammation such as an increased risk for type 2 diabetes mellitus and/or future cardiovascular diseases in PCOS patients.

The inhibition of lipoprotein-associated phospholipase A2 exerts beneficial effects against atherosclerosis in LDLR-deficient mice

AIM

To investigate the effects of darapladib, a specific inhibitor of lipoprotein-associated phospholipase A2 (lp-PLA2), on inflammation and atherosclerotic formation in the low density lipoprotein receptor (LDLR)-deficient mice.

METHODS

Six-week-old LDLR-deficient mice were fed an atherogenic high-fat diet for 17 weeks and then randomly divided into two groups. One group was administered darapladib (50 mg·kg(-1)·d(-1); po) for 6 weeks. The other group was administered saline as a control. Serum lipid levels were measured using the corresponding kits, and three inflammatory markers--interleukin-6 (IL-6), C reactive protein (hs-CRP), and platelet activating factor (PAF)--were determined using ELISA. Atherosclerotic plaque areas were stained with Sudan IV, and inflammatory gene expression at the lesions was evaluated using quantitative real-time PCR.

RESULTS

The body weight and serum lipid level between the two groups were similar at the end of the dietary period. The serum lp-PLA2 activity, hs-CRP and IL-6 levels, however, were significantly reduced in the darpladib group. The inhibition of lp-PLA2 did not alter the serum PAF level. Furthermore, the plaque area, from the aortic arch to the abdominal aorta, was significantly reduced in the darpladib group. Additionally, the expression of inflammatory genes monocyte chemotactic protein-1 (MCP-1) and vascular cell adhesion molecule-1 (VCAM-1) was significantly reduced at the lesions in the darapladib group.

CONCLUSION

Inhibition of lp-PLA2 by darapladib decreases the inflammatory burden and atherosclerotic plaque formation in LDLR-deficient mice, which may be a new strategy for the treatment of atherosclerosis.

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.

The effects of rosuvastatin alone or in combination with fenofibrate or omega 3 fatty acids on inflammation and oxidative stress in patients with mixed dyslipidemia

OBJECTIVE

Mixed dyslipidemia, oxidative stress and inflammation are related to a high risk for cardiovascular events. The aim of this open-label randomized study was to compare the effects of high-dose rosuvastatin, low-dose rosuvastatin plus fenofibrate and low-dose rosuvastatin plus omega 3 fatty acids on inflammation and oxidative stress indices in patients with mixed dyslipidemia.

METHODS

Ninety patients with mixed dyslipidemia participated in the study. Patients were randomly allocated to receive rosuvastatin 40 mg (n = 30, group R), rosuvastatin 10 mg plus fenofibrate 200 mg (n = 30, group RF) or rosuvastatin 10 mg plus omega 3 fatty acids 2 g daily (n = 30, group RΩ). Plasma and high-density lipoprotein (HDL)-associated lipoprotein-associated phospholipase A2 (LpPLA2) activities, high-sensitivity C reactive protein (hsCRP), plasma isoprostane and paraoxonase (PON1) activities were measured at baseline and after 3 months of treatment.

RESULTS

Serum concentrations of non-HDL cholesterol and low-density lipoprotein cholesterol (LDL-C) were significantly reduced in all study groups. However, these changes were more pronounced in the rosuvastatin monotherapy group. In all treatment groups a significant reduction in total plasma LpPLA2 activity was observed (by 41, 38 and 30% for groups R, RF and RΩ, respectively). This decrease was greater in the R and RF groups compared with the RΩ combination (p < 0.05). HDL-LpPLA2 activity was increased more in the RF group (+43%) compared with the R and RΩ groups (+ 18% and + 35%, respectively; p < 0.05 for both comparisons). In all treatment groups there was a nonsignificant reduction in plasma 8-iso-PGF2α levels. A 53% reduction of hsCRP levels was observed in the R group, while in the RF and RΩ groups the reduction was 28 and 23%, respectively (p < 0.05 and p < 0.01 for the comparisons of group R with groups RF and RΩ, respectively). No significant changes were observed in PON activities in all treatment groups.

CONCLUSION

The greater non-HDL-C- and LDL-C-lowering efficiency of rosuvastatin monotherapy along with its more potent effect on LpPLA2 activity and hsCRP levels indicate that this regimen is a better treatment option for patients with mixed dyslipidemia.

Plasma lipoprotein-associated phospholipase A2 in patients with metabolic syndrome and carotid atherosclerosis

Background

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is a recently identified and potentially useful plasma biomarker for cardiovascular and atherosclerotic diseases. However, the correlation between the Lp-PLA₂ activity and carotid atherosclerosis remains poorly investigated in patients with metabolic syndrome (MetS). The present study aimed to evaluate the potential role of Lp-PLA₂ as a comprehensive marker of metabolic syndrome in individuals with and without carotid atherosclerosis.

Methods

We documented 118 consecutive patients with MetS and 70 age- and sex-matched healthy subjects served as controls. The patients were further divided into two groups: 39 with carotid plaques and 79 without carotid plaques to elucidate the influence of Lp-PLA₂ on carotid atherosclerosis. The plasma Lp-PLA₂ activity was measured by using ELISA method and carotid intimal-media thickness (IMT) was performed by ultrasound in all participants.

Results

Lp-PLA₂ activity was significantly increased in MetS subgroups when compared with controls, and was higher in patients with carotid plaques than those without plaques (P < 0.05). Furthermore, we found that significant difference in Lp-PLA₂ was obtained between patients with three and four disorders of metabolic syndrome (P < 0.01). Age (β = 0.183, P = 0.029), LDL-cholesterol (β = 0.401, P = 0.000) and waist-hip ratio (β = 0.410, P = 0.000) emerged as significant and independent determinants of Lp-PLA₂ activity. Multiple stepwise regression analysis revealed that LDL-cholesterol (β = 0.309, P = 0.000), systolic blood pressure (β = 0.322, P = 0.002) and age (β = 0.235, P = 0.007) significantly correlated with max IMT, and Lp-PLA₂ was not an independent predictor for carotid IMT.

Conclusions

Lp-PLA₂ may be a modulating factor for carotid IMT via age and LDL-cholesterol, not independent predictor in the pathophysiological process of carotid atherosclerosis in patients with MetS.

Circulating platelet-activating factor is primarily cleared by transport, not intravascular hydrolysis by lipoprotein-associated phospholipase A2/ PAF acetylhydrolase

RATIONALE

The phospholipid platelet-activating factor (PAF) stimulates all cells of the innate immune system and numerous cardiovascular cells. A single enzyme (plasma PAF acetylhydrolase [PAF-AH] or lipoprotein-associated phospholipase [Lp-PL]A(2)) in plasma hydrolyzes PAF, but significant controversy exists whether its action is pro- or antiinflammatory and accordingly whether its inhibition will slow cardiovascular disease.

OBJECTIVE

We sought to define how PAF and related short-chain oxidized phospholipids turnover in vivo and the role of PAF acetylhydrolase/Lp-PLA(2) in this process.

METHODS AND RESULTS

[(3)H-acetyl]PAF was hydrolyzed by murine or human plasma (t(1/2), 3 and 7 minutes, respectively), but injected [(3)H-acetyl]PAF disappeared from murine circulation more quickly (t(1/2), <30 seconds). [(3)H]PAF clearance was unchanged in PAF receptor(-/-) animals, or over the first 2 half-lives in PAF-AH(-/-) animals. [(3)H]PAF turnover was reduced by coinjecting excess unlabeled PAF or an oxidatively truncated phospholipid, and [(3)H]PAF clearance was slowed in hyperlipidemic apolipoprotein (apo)E(-/-) mice with excess circulating oxidatively truncated phospholipids. [(3)H]PAF, fluorescent NBD-PAF, or fluorescent oxidatively truncated phospholipid were primarily accumulated by liver and lung, and were transported into endothelium as intact phospholipids through a common mechanism involving TMEM30a.

CONCLUSIONS

Circulating PAF and oxidized phospholipids are continually and rapidly cleared, and hence continually and rapidly produced. Saturable PAF receptor-independent transport, rather than just intravascular hydrolysis, controls circulating inflammatory and proapoptotic oxidized phospholipid mediators. Intravascular PAF has access to intracellular compartments. Inflammatory and proapoptotic phospholipids may accumulate in the circulation as transport is overwhelmed by substrates in hyperlipidemia.

The differentiating effect of glimepiride and glibenclamide on paraoxonase 1 and platelet-activating factor acetylohydrolase activity

AIMS

The present study was designed to examine the effect of sulphonylureas, glimepiride (GM) and glibenclamide (GB), on paraoxonase 1 (PON1) and platelet activating factor acetylohydrolase (PAF-AH) activity in normal and streptozotocin (STZ)-induced (50 mg/kg) diabetic rats.

MAIN METHODS

In treated groups, glimepiride (0.1 mg/kg) or glibenclamide (2 mg/kg) was given orally for 4 weeks. A PON1 and PAF-AH activity were estimated by spectrophotometric method.

KEY FINDINGS

Hyperglycemia was accompanied by a significant decrease in plasma PON1 activity toward paraoxon (P < 0.001) and phenyl acetate (P < 0.01) and increase in plasma PAF-AH activity (P < 0.01). In STZ-induced diabetic rats the administration of both GM and GB had no effect on plasma PON1 activity but reversed elevated plasma PAF-AH activity (GM: P < 0.05, GB: P < 0.01). In non-diabetic rats after either GM or GB administration the decreased PON1 activity in the plasma was observed (GM: P < 0.001, GB: P < 0.05), but plasma PAF-AH activity remained unchanged. Both GM and GB had no effect on total plasma antioxidant capacity in diabetic and control treated groups. Additionally, both drugs increased PON1 activity toward phenyl acetate in the liver, in diabetic rats (GM: P < 0.05, GB:ns) as well as in non-diabetic rats (GM: P < 0.001, GB: P < 0.001), and reduced lipid peroxidation in the liver.

SIGNIFICANCE

These results demonstrate that in streptozotocin-induced diabetic rats as well as in normal rats glimepiride and glibenclamide have no beneficial effects on circulating PON1 and PAF-AH activities, but both drugs increase PON1 activity in the liver.