Association of Lipoprotein-Associated Phospholipase A2Mass and Activity With Calcified Coronary Plaque in Young Adults

Imaging Early Life Cardiovascular Phenotype

The growing epidemics of obesity, hypertension, and diabetes, in addition to worsening environmental factors such as air pollution, water scarcity, and climate change, have fueled the continuously increasing prevalence of cardiovascular diseases (CVDs). This has caused a markedly increasing burden of CVDs that includes mortality and morbidity worldwide. Identification of subclinical CVD before overt symptoms can lead to earlier deployment of preventative pharmacological and nonpharmacologic strategies. In this regard, noninvasive imaging techniques play a significant role in identifying early CVD phenotypes. An armamentarium of imaging techniques including vascular ultrasound, echocardiography, magnetic resonance imaging, computed tomography, noninvasive computed tomography angiography, positron emission tomography, and nuclear imaging, with intrinsic strengths and limitations can be utilized to delineate incipient CVD for both clinical and research purposes. In this article, we review the various imaging modalities used for the evaluation, characterization, and quantification of early subclinical cardiovascular diseases.

Serum lipoprotein-associated phospholipase A2 as a promising prognostic biomarker in association with 90-day outcome of acute intracerebral hemorrhage

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is reflective of vascular inflammation and plays a role in the pathophysiology of cerebrovascular disease. We determine usefulness of serum Lp-PLA2 as a prognostic biomarker for intracerebral hemorrhage (ICH).

METHODS

In this prospective, observational study, serum Lp-PLA2 concentrations were detected among 164 patients with acute spontaneous basal ganglia hemorrhage and 164 healthy controls. Using multivariate analysis, we analyzed its association with poor outcome (modified Rankin Scale >2) at poststroke 90 days and hemorrhagic severity indicated by National Institutes of Health Stroke Scale (NIHSS) score and hematoma volume.

RESULTS

Serum Lp-PLA2 concentrations were remarkably higher in patients than in controls. Lp-PLA2 concentrations were independently correlated with NIHSS score (t = 5.095, P < .001) and hematoma volume (t = 2.850, P = .005). At 90-day follow-up, 85 patients (51.8%) had poor outcome. Under receiver operating characteristic curve, serum Lp-PLA2 showed a significant prognostic discriminatory capability (AUC, 0.813; 95% CI, 0.744-0.869). Serum Lp-PLA2 concentrations ≥304 ng/ml was an independent predictor associated with poor outcome (OR 7.052; 95% CI 1.971-25.228).

CONCLUSIONS

Rising serum Lp-PLA2 concentrations are closely hemorrhagic severity and clinical outcomes after ICH, substantializing serum Lp-PLA2 as a potential prognostic biomarker of ICH.

Association of lipoprotein-associated phospholipase A2 mass with asymptomatic cerebral artery stenosis

Cerebral artery stenosis (CAS) is the most important causes of ischaemic stroke. Lipoprotein-associated phospholipase A2 (Lp-PLA2) plays 2 diverse roles in atherosclerosis (pro-inflammatory and anti-inflammatory), and the association between Lp-PLA2 mass and cardiovascular or cerebrovascular events is inconsistent among previous studies. A cross-sectional study including 2012 North Chinese adults aged ≥40 years was performed in 2010-2011 to investigate whether Lp-PLA2 mass is associated with asymptomatic cerebral artery stenosis (ACAS). Serum Lp-PLA2 mass was determined by enzyme-linked immunosorbent assay (ELISA). All participants underwent transcranial Doppler (TCD) and bilateral carotid duplex ultrasound to evaluate intracranial artery stenosis (ICAS) and extracranial arterial stenosis (ECAS). The median serum Lp-PLA2 mass of the participants was 140.74 ng/mL (interquartile range: 131.79-158.07 ng/mL). The adjusted odds ratio (OR) when comparing the 4th quartile to the 1st quartile of Lp-PLA2 was 1.98 (95% confidence interval (CI): 1.42-2.78), 1.79 (95% CI: 1.08-2.94) and 1.87 (95% CI: 1.28-2.73) for the occurrence of ACAS, asymptomatic ECAS and asymptomatic ICAS, respectively, after controlling for vascular risk factors. These independently significant associations remained statistically significant in the male or elderly subgroups, but not in females or middle-aged participants. Lp-PLA2 mass is positively correlated with subclinical atherosclerosis determined by ACAS, ICAS and ECAS in North Chinese, particularly in male and older participants, suggesting that serum Lp-PLA2 mass might be potential biomarker for the detection of ACAS in the adults.

SERUM LIPOPROTEIN-ASSOCIATED PHOSPHOLIPASE A2 IN MALES WITH METABOLIC SYNDROME AND OBSTRUCTIVE SLEEP APNEA

CONTEXT

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a novel biomarker for cardiovascular diseases (CVD) risk estimation with high specificity for vascular inflammation. Few studies have investigated Lp-PLA2 levels in patients with metabolic syndrome (MetS) and obstructive sleep apnea syndrome (OSAS).

OBJECTIVE

This study aimed to evaluate the role of Lp-PLA2 levels as a marker of vascular inflammation that contributes to cardiometabolic dysfunction in patients with MetS and OSAS.

DESIGN

This is a prospective case-control study.

SUBJECTS AND METHODS

83 men were enrolled. Following anthropometric measurements, laboratory analysis and overnight sleep study, patients were divided into three groups: MetS, OSAS with/without MetS. Serum Lp-PLA2 levels were determined by ELISA method.

RESULTS

Serum Lp-PLA2 levels were statistically significant among the three groups and were higher in OSAS with MetS group than those without MetS. A significant positive relationship between increased Lp-PLA2 level and CRP (C-reactive protein) and apnea-hypopnea index (AHI) was found. Average oxygen saturation (AvO2) and the lowest oxygen saturation were negatively correlated with Lp-PLA2. The number of desaturation events, oxygen desaturation index, AvO2, AHI and CRP were significant predictors of Lp-PLA2.

CONCLUSIONS

Lp-PLA2 levels are associated with OSAS severity and might play an important role in predicting CVD in OSAS with/without MetS.

Lipoprotein-associated phospholipase A2 and oxidized low-density lipoprotein in young patients with acute coronary syndrome in China

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is considered to be a risk factor for acute coronary syndrome (ACS), but this remains controversial. This study investigated the role of Lp-PLA2 in young Chinese patients with ACS. 228 young patients (aged ≤55 years) with ACS and 237 age-matched controls were included. Lp-PLA2 and oxidized low-density lipoprotein (ox-LDL) levels were measured by sandwich enzyme-linked immunosorbent assay. Lp-PLA2 levels were significantly correlated with smoking, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and ox-LDL levels (all P < 0.05). Multivariate logistic regression analysis showed that male sex (OR = 3.25, 95%CI = 1.26–8.38), smoking (OR = 3.50, 95%CI = 1.75–7.0), triglyceride (OR = 1.76, 95%CI = 1.08–2.87), high sensitivity C-reactive protein (hs-CRP) (OR = 2.11, 95%CI = 1.14–3.90) and ox-LDL (OR = 2.98, 95%CI = 1.72–5.1) were independently associated with ACS risk in young patients. Lp-PLA2 was associated with risk of ACS in young patients when adjusted for traditional risk factors, including age, sex, diabetes, hypertension, smoking, TC, LDL-C, triglyceride and hs-CRP (OR = 1.98, 95%CI = 1.10–3.56). When further adjusted for ox-LDL levels, the association between Lp-PLA2 and ACS became insignificant (OR = 1.69, 95%CI = 0.90–3.17). Lp-PLA2 was a marker of oxidative stress and inflammation, rather than an independent risk factor for ACS in young Chinese patients.

Lipoprotein-associated phospholipase A2: a new marker to determine cardiovascular risk in hypercholesterolemic dyslipidaemic children

Background

Inflammation and hypercholesterolaemia contribute to atherosclerotic changes which can start in childhood. Children with hyperlipidaemias are at high risk for early coronary atherosclerosis. This study evaluates the relationship between lipoprotein-associated phospholipase A2 (Lp-PLA2), carotid intima-media thickness (CIMT) and flow-mediated dilatation in hypercholesterolaemic dyslipidaemic children.

Methods

We performed a case–control study consisting of 43 cases, aged 2 to 17 years, and 24 age-matched controls. Fasting blood samples were obtained from both groups for the measurement of a lipid profile (total cholesterol, LDL-C, HDL-C and triglycerides) and Lp-PLA2 in mass units. The latter was determined with a turbidimetric immunoassay method (PlacTest, DiaDexus Inc.) applied to an automated analyser. CIMT and flow-mediated dilatation measurements were undertaken by a paediatric cardiologist, using high-resolution B-mode ultrasonography.

Results

Total cholesterol, LDL-C and Lp-PLA2 concentrations were significantly higher in the cases than in the controls ( p < 0.001 for all three parameters). While CIMT values were also significantly higher in the patients compared to the controls ( P = 0.001), flow-mediated dilatation values were significantly lower ( P = 0.001). We found positive correlations between Lp-PLA2 and total cholesterol ( r = 0.41, P = 0.001), Lp-PLA2 and LDL-C ( r = 0.36, P = 0.004), Lp-PLA2 and CIMT ( r = 0.44, P = 0.019) and LDL-C and CIMT ( r = 0.41, P = 0.032); there were negative correlations between Lp-PLA2 and flow-mediated dilatation ( r = −0.15, P = 0.045), total cholesterol and flow-mediated dilatation ( r = −0.45, P = 0.017), LDL-C and flow-mediated dilatation ( r = −0.51, P = 0.006) and CIMT and flow-mediated dilatation ( r = −0.45, P = 0.016).

Conclusion

Lp-PLA2 concentrations are significantly elevated in hypercholesterolaemic dyslipidaemic children. Given the association of Lp-PLA2 with markers of atherosclerosis (total cholesterol, LDL-C, CIMT and flow-mediated dilatation), the finding of increased concentrations of Lp-PLA2 could be used to identify early atherosclerotic changes in hypercholesterolaemic dyslipidaemic children and may inform their clinical management.

Evaluation of lipoprotein-associated phosholipase A2 and plaque burden/composition in young adults

OBJECTIVE

The total burden of subclinical coronary atherosclerosis is significant in young adults. Serum lipoprotein-associated phospholipase A2 (Lp-PLA2) is an established predictor of morbidity and mortality because of cardiovascular disease. The aim of the present investigation was to evaluate the relationship between subclinical coronary atherosclerosis and serum Lp-PLA2 concentrations in a population of young adults.

PATIENTS AND METHODS

A total of 261 individuals younger than 45 years of age who had undergone coronary computed tomography angiography were evaluated. The study group included 101 patients in whom coronary computed tomography angiography detected subclinical coronary atherosclerosis; the control group included 160 sex-matched and age-matched healthy control patients.

RESULTS

Serum Lp-PLA2 levels were increased significantly in the study group patients compared with the control patients (15.42±11.88 vs. 8.06±4.32 ng/ml, P<0.001). Furthermore, a positive correlation was identified between the Lp-PLA2 levels and the total number of plaques and diseased arteries (r=0.495, P<0.001, and r=0.621, P<0.001, respectively). The presence of mixed plaque composition was also correlated with the Lp-PLA2 levels (r=0.657, P<0.001). Multivariate regression analysis identified four independently significant predictors of subclinical coronary atherosclerosis: high-sensitivity C-reactive protein levels, tobacco use, uric acid levels, and serum Lp-PLA2 levels.

CONCLUSION

The presence of subclinical coronary atherosclerosis is associated independently with Lp-PLA2, and it has potential utility as a novel indicator of cardiovascular disease risk in the young adult population.

Lipoprotein-Associated Phospholipase A2 and Incident Peripheral Arterial Disease in Older Adults: The Cardiovascular Health Study

OBJECTIVE

Although prior studies report a relationship between elevated lipoprotein-associated phospholipase A2 (Lp-PLA2) and incident cardiovascular disease, the prospective association of Lp-PLA2 with incident peripheral arterial disease (PAD) has not been studied. We investigated the association between Lp-PLA2 mass and activity and the risk of developing clinical PAD and low ankle-brachial index (ABI).

APPROACH AND RESULTS

Among Cardiovascular Health Study participants, a population-based cohort of 5888 adults aged ≥65 years enrolled in 1989 to 1990, Lp-PLA2 mass and activity were measured in 4537 individuals without baseline PAD. Clinical PAD, defined as leg artery revascularization or diagnosed claudication, was ascertained through 2011. Incident low ABI, defined as ABI <0.9 and decline of ≥0.15, was assessed among 3537 individuals who had an ABI >0.9 at baseline and a second ABI measurement 3 or 6 years later. Analyses were adjusted for demographics, cholesterol, smoking, comorbidities, and C-reactive protein. Each standard deviation increment in Lp-PLA2 mass (117 ng/mL) was associated with a higher risk of developing clinical PAD (hazard ratio 1.28; 95% confidence interval 1.13, 1.45) and incident low ABI (odds ratio 1.16; 95% confidence interval 1.00, 1.33). Results per standard deviation increment in Lp-PLA2 activity (13 nmol/min per mL) were similar for clinical PAD (hazard ratio 1.24; 95% confidence interval 1.07, 1.44) and low ABI (odds ratio 1.28; 95% confidence interval 1.09, 1.50).

CONCLUSIONS

Higher Lp-PLA2 mass and activity were associated with development of both incident clinical PAD and low ABI. Future studies are needed to determine whether pharmacological inhibition of Lp-PLA2 reduces the incidence of PAD.

Lipoprotein-associated phospholipase A2 distribution among lipoproteins differs in type 1 diabetes

BACKGROUND

LpPLA2 mass and activity have been variably related to cardiovascular disease risk, and the distribution of LpPLA2 in patients with type 1 diabetes (T1D), wherein cardiovascular disease risk is high despite normal or higher levels of high-density lipoprotein (HDL) cholesterol, is unknown.

OBJECTIVE

To determine whether there are differences in the distribution of LpPLA2 mass and activity across lipoproteins and their association with coronary artery calcium (CAC) in patients with T1D.

METHODS

Men with T1D (n = 19) not on statins, with and without CAC progression, and men without diabetes matched for HDL cholesterol (n = 25) had lipoproteins separated by fast protein liquid chromatography.

RESULTS

Both LpPLA2 mass and activity were found within low-density lipoprotein (LDL) and HDL pools with more LpPLA2 mass being associated with HDL (54% vs 44%; P-value <.001) and more LpPLA2 activity being associated with LDL (56% vs 40%; P value = .02). In T1D, more LpPLA2 activity was associated with large- or less-dense LDL compared to those without diabetes. However, no difference in LpPLA2 activity or mass between lipoprotein subfractions was observed between all groups, and there was no relationship between LpPLA2 activity or mass and its distribution and CAC score progression in healthy or T1D men.

CONCLUSION

LpPLA2 is found in both LDL and HDL and is distributed differently in men with T1D without any relationship to CAC score progression.

Lipoprotein-associated phospholipase A2 and risk of incident cardiovascular disease in a multi-ethnic cohort: The multi ethnic study of atherosclerosis

OBJECTIVE

Prospective studies reporting a positive association of lipoprotein-associated phospholipase A2 (Lp-PLA2) mass and activity with incident cardiovascular disease (CVD) have included primarily white individuals. We evaluated associations of Lp-PLA2 and first-time cardiovascular events in a healthy multi-ethnic cohort characterized by presence or absence of baseline subclinical atherosclerosis.

METHODS

Lp-PLA2 mass and activity were measured at baseline in 5456 participants in the Multi-Ethnic Study of Atherosclerosis. Individuals were characterized for presence of baseline subclinical disease (coronary artery calcium score > 0 or carotid intima-media thickness value > 80th percentile) and followed prospectively for development of CVD events (coronary heart disease, ischemic stroke, and cardiovascular death).

RESULTS

516 incident CVD events occurred over median follow-up of 10.2 years. In adjusted Cox proportional hazards models, each higher standard deviation of both Lp-PLA2 activity and mass was associated with an increased risk of cardiovascular events; hazard ratios (HR; 95% confidence intervals (CI)) 1.12 (1.01-1.26) for Lp-PLA2 activity and 1.10 (1.01-1.21) for mass. Associations did not differ by subclinical disease status (p-value for interaction 0.99 for Lp-PLA2 activity and 0.32 for Lp-PLA2 mass) and there was no confounding by subclinical atherosclerosis measures. Associations of Lp-PLA2 activity but not mass were weaker in Chinese participants but there were relatively few events among Chinese in race-stratified analysis.

CONCLUSION

In this multi-ethnic cohort, Lp-PLA2 was positively associated with CVD risk, regardless of the presence of coronary artery calcium or a thickened carotid-intimal media.

The association between uncarboxylated matrix Gla protein and lipoprotein-associated phospholipase A2

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is independently associated with cardiovascular risk, probably via inflammatory activity in sclerotic plaque. We speculated whether Lp-PLA2 has a role in the aetiology of vascular calcifications, estimated from circulating uncarboxylated matrix Gla protein (MGP) species and whether we could find a potential interaction of Lp-PLA2 and MGP in terms of mortality.

MATERIALS AND METHODS

We examined 798 patients (mean age 65.1 years) with stable vascular disease and followed them in a prospective study. Both, desphospho-uncarboxylated and total MGP (dp-ucMGP or t-ucMGP) were quantified by pre-commercial ELISA assays, developed by VitaK (Maastricht, The Netherland)

RESULTS

Lp-PLA2 activity was independently positively associated with desphospho-uncarboxylated MGP (dp-ucMGP) [β coeff = 0.098, p=0.006]. 1SD of Lp-PLA2 activity was associated with 37% increased risk (p=0.001) of elevated dp-ucMGP (≥977 pmol/L, top quartile). In the Cox proportional hazard model adjusted for conventional risk factors, the patients in the highest quartile of dp-ucMGP or lowest quintile of total-uncarboxylated ucMGP (<2660 nmol/L) had higher risk of all-cause mortality [HRR 2.79 (95% CI 1.97-3.94) and HRR 1.69 (95% CI 1.18-2.42), respectively]. We observed no effect of high Lp-PLA2 activity (≥195 nmol/min/mL) on total mortality.

CONCLUSIONS

We assume that Lp-PLA2 is involved in vascular calcification and that dp-ucMGP is a more appropriate biomarker of residual risk than Lp-PLA2 itself.

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

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

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Predicting the Risk of Cardiovascular Disease

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

Lipoprotein-Associated Phospholipase A2

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

Clinical utility of lipoprotein-associated phospholipase A₂ for cardiovascular disease prediction in a multiethnic cohort of women

BACKGROUND

Findings regarding the association of lipoprotein-associated phospholipase A₂ (Lp-PLA2) activity and mass with incident cardiovascular disease (CVD) have been inconsistent, and their role in risk prediction is uncertain.

METHODS

A case-cohort sample from the Women's Health Initiative Observational Study (WHI-OS) comprised 1821 CVD cases and a reference subcohort of 1992 women. We used Cox regression models with inverse sampling weights to assess the association of Lp-PLA2 mass and activity with CVD (myocardial infarction, stroke, and CVD mortality).

RESULTS

Subcohort means were 184.3 mmol/min/mL for Lp-PLA2 activity and 499.2 μg/L for Lp-PLA2 mass, with 99% having mass above 200 μg/L, the clinically recommended cut point. Both activity and mass were positively associated with incident CVD in age- and race/ethnicity-adjusted analyses. Following adjustment according to CVD risk factors, the association with activity became null (hazard ratio = 1.02 for top vs bottom quartile, 95% CI = 0.79-1.33, P for trend = 0.65), but the association with mass remained (hazard ratio = 1.84, 95% CI = 1.45-2.34, P for trend < 0.0001). In contrast to blood pressure, HDL, and hsCRP, reclassification statistics for Lp-PLA2 mass did not suggest improvement for overall CVD after full adjustment.

CONCLUSIONS

In the WHI-OS Lp-PLA2 mass, but not activity, was independently associated with CVD. However, model fit did not significantly improve with Lp-PLA2 mass, and assay calibration remains a clinical concern.

Relationship of lipoprotein-associated phospholipase A₂ mass and activity with incident vascular events among primary prevention patients allocated to placebo or to statin therapy: an analysis from the JUPITER trial

BACKGROUND

Although lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) levels are associated with cardiovascular events, Lp-PLA(2) is physically linked to LDL cholesterol (LDL-C). Whether measures of Lp-PLA(2) mass or activity continue to predict risk after LDL-C reduction by statin therapy is uncertain.

METHODS

Lp-PLA(2) mass concentration and activity were evaluated at baseline and after treatment in the Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) trial comparing rosuvastatin 20 mg to placebo among 17 802 men and women without cardiovascular disease or diabetes at study entry. The relationships of Lp-PLA(2) mass and activity with risk of future vascular events were evaluated in the placebo and rosuvastatin groups.

RESULTS

Before randomization, levels of Lp-PLA(2) mass and activity correlated moderately with each other and with LDL-C. The magnitude of these correlations increased after statin therapy. Rosuvastatin reduced Lp-PLA(2) mass by 33.8%, Lp-PLA(2) activity by 33.2%, and LDL-C by 48.7% (all P < 0.0001). Among those study participants allocated to placebo, increasing quartiles of Lp-PLA(2) activity (P(trend) = 0.04) but not Lp-PLA(2) mass (P(trend) = 0.92) were associated with incident cardiovascular events after adjustment for LDL-C and conventional risk factors. Comparable analyses conducted among those allocated to rosuvastatin revealed no significant relationship between Lp-PLA(2) levels and subsequent vascular events. The ability of rosuvastatin to reduce vascular events was not significantly modified by baseline Lp-PLA(2) level.

CONCLUSIONS

Among JUPITER trial participants allocated to placebo, levels of Lp-PLA(2) activity, but not mass, were associated with cardiovascular risk. However, Lp-PLA(2) no longer predicted risk or modified clinical outcomes when participants were treated with rosuvastatin.

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

BACKGROUND

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

METHODOLOGY/PRINCIPAL FINDINGS

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

CONCLUSIONS/SIGNIFICANCE

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

Kidney function decline in the elderly: impact of lipoprotein-associated phospholipase A(2)

BACKGROUND

Whether lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) levels are associated with kidney function decline has not been well studied.

METHODS

We investigated associations of Lp-PLA(2) antigen and activity with kidney function decline and rapid decline over 5.7 years in the Cardiovascular Health Study (n = 4,359). We estimated kidney function by cystatin C (eGFRcys) in repeated measures, and defined rapid decline as ≥3 ml/min/1.73 m(2) per year. We stratified by baseline preserved GFR (≥60 ml/min/1.73 m(2)).

RESULTS

Mean age was 72 ± 5 years. Average eGFRcys decline was -1.79 ml/min/1.73 m(2) (SD = 2.60) per year. Among persons with preserved GFR, compared to the lowest quartile of Lp-PLA(2) antigen, eGFRcys decline was faster among persons in the second, β -0.31 (95% CI -0.52, -0.10), third -0.19 (-0.41, 0.02) and fourth quartiles -0.26 (-0.48, -0.04) after full adjustment. Persons in the highest quartile of Lp-PLA(2) antigen had increased odds of rapid decline 1.34 (1.03, 1.75), compared to the lowest. There was no significant association between levels of Lp-PLA(2) activity and eGFRcys decline or rapid decline. Associations were not statistically significant among persons with low eGFR (<60 ml/min/1.73 m(2)) at baseline.

CONCLUSION

Higher levels of Lp-PLA(2) antigen but not activity were significantly associated with faster rates of kidney function decline. These findings may suggest a novel vascular pathway for kidney disease progression.

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.

Carotid intima media thickness is associated with plasma lipoprotein-associated phospholipase A2 mass in nondiabetic subjects but not in patients with type 2 diabetes

BACKGROUND

A recent meta-analysis showed that both plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2) ) mass and activity independently predict cardiovascular events. Notably, Lp-PLA(2) activity but not mass was found to be a determinant of cardiovascular outcome in type 2 diabetes mellitus. We questioned whether relationships of carotid intima media thickness (IMT), a measure of subclinical atherosclerosis, with Lp-PLA(2) mass differ between diabetic and nondiabetic subjects.

MATERIALS AND METHODS

Relationships of IMT with plasma Lp-PLA(2) mass (turbidimetric immunoassay) were compared in 74 patients with type 2 diabetes and in 64 nondiabetic subjects.

RESULTS

IMT was increased (P=0·016), but plasma Lp-PLA(2) mass was decreased in patients with diabetes compared to nondiabetic subjects (277±66 vs. 327±62μgL(-1) , P<0·001). In nondiabetic subjects, IMT was correlated positively with Lp-PLA(2) (r=0·325, P<0·009); multiple linear regression analysis confirmed an independent association of IMT with Lp-PLA(2) (ß=0·192, P=0·048). In contrast, IMT was unrelated to Lp-PLA(2) in patients with diabetes (r=0·021, P=0·86), and the relationship of IMT with Lp-PLA(2) was different in diabetic and control subjects (P<0·001). The relationship of Lp-PLA(2) with the total cholesterol/high-density lipoprotein (HDL) cholesterol ratio also differed between diabetic and nondiabetic subjects (P<0·001).

CONCLUSIONS

Plasma Lp-PLA(2) may relate to early stages of atherosclerosis development. In diabetes mellitus, in contrast, the association of IMT with plasma Lp-PLA(2) mass is abolished, which could be partly ascribed to redistribution of Lp-PLA(2) mass from apolipoprotein B-containing lipoproteins towards HDL. These findings raise questions about the usefulness of plasma Lp-PLA(2) mass measurement as a marker of subclinical atherosclerosis in type 2 diabetes mellitus.

Ambient air pollution and lipoprotein-associated phospholipase A₂ in survivors of myocardial infarction

BACKGROUND

Increasing evidence suggests a proatherogenic role for lipoprotein-associated phospholipase A₂ (Lp-PLA2). A meta-analysis of published cohorts has shown that Lp-PLA2 is an independent predictor of coronary heart disease events and stroke.

OBJECTIVE

In this study, we investigated whether the association between air pollution and cardiovascular disease might be partly explained by increased Lp-PLA2 mass in response to exposure.

METHODS

A prospective longitudinal study of 200 patients who had had a myocardial infarction was performed in Augsburg, Germany. Up to six repeated clinical examinations were scheduled every 4-6 weeks between May 2003 and March 2004. Supplementary to the multicenter AIRGENE protocol, we assessed repeated plasma Lp-PLA2 concentrations. Air pollution data from a fixed monitoring site representing urban background concentrations were collected. We measured hourly means of particle mass [particulate matter (PM) < 10 µm (PM₁₀) and PM < 2.5 µm (PM(2.5)) in aerodynamic diameter] and particle number concentrations (PNCs), as well as the gaseous air pollutants carbon monoxide (CO), sulfur dioxide (SO₂), ozone (O₃), nitric oxide (NO), and nitrogen dioxide (NO₂). Data were analyzed using mixed models with random patient effects.

RESULTS

Lp-PLA2 showed a positive association with PM₁₀, PM(2.5), and PNCs, as well as with CO, NO₂, NO, and SO₂ 4-5 days before blood withdrawal (lag 4-5). A positive association with O₃ was much more immediate (lag 0). However, inverse associations with some pollutants were evident at shorter time lags.

CONCLUSION

These preliminary findings should be replicated in other study populations because they suggest that the accumulation of acute and subacute effects or the chronic exposure to ambient particulate and gaseous air pollution may result in the promotion of atherosclerosis, mediated, at least in part, by increased levels of Lp-PLA2.

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.

Lipoprotein-associated phospholipase A₂ activity predicts progression of subclinical coronary atherosclerosis

BACKGROUND

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is a lipoprotein-associated enzyme that cleaves oxidized phosphatidylcholines, generating pro-atherosclerotic lysophosphatidylcholine and oxidized free fatty acids. Lp-PLA₂ is independently associated with cardiovascular disease (CVD) in a variety of populations. Coronary calcium is a measure of subclinical CVD, and progression of coronary calcification predicts future CVD events. In type 1 diabetes there is an increase in coronary calcium and CVD despite a favorable lipid profile. Levels of Lp-PLA₂ in type 1 diabetes are not known, nor is the relationship between Lp-PLA₂ and progression of coronary calcification.

METHODS

The Coronary Artery Calcification in Type 1 Diabetes study measured coronary calcium by electron-beam computed tomography twice over a 2.6 ± 0.3-year interval. Lp-PLA₂ mass and activity were measured at baseline (n = 1,097 subjects, 506 with and 591 without type 1 diabetes).

RESULTS

In type 1 diabetes Lp-PLA₂ mass was marginally higher (285 ± 79 vs. 278 ± 78 ng/mL, P = 0.1), and Lp-PLA₂ activity was significantly lower (137 ± 30 vs. 146 ± 36 nmol/min/mL, P < 0.0001) than in those without diabetes. There was a greater proportion of those with progression of coronary calcification in type 1 diabetes compared with those without diabetes (24% vs. 10%, P < 0.0001). Lp-PLA₂ activity was independently associated with progression of coronary calcification in multivariate analysis (4th quartile verses bottom three quartiles, odds ratio = 1.77 [1.08-2.91], P = 0.02). LpPLA₂ mass was not significantly associated with progression of coronary calcification in this cohort (P = 0.09).

CONCLUSIONS

Lp-PLA₂ activity predicts progression of subclinical atherosclerosis in individuals with and without type 1 diabetes.

Rates and determinants of coronary and abdominal aortic artery calcium progression in the Veterans Affairs Diabetes Trial (VADT)

OBJECTIVE

To determine the predictors of progression of calcified atherosclerosis and the effect of intensive glycemic control on this process in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

As part of the Risk Factors, Atherosclerosis, and Clinical Events in Diabetes (RACED) substudy of the Veterans Affairs Diabetes Trial (VADT), 197 and 189 individuals with type 2 diabetes received baseline and follow-up computed tomographic scans for measurement of coronary and abdominal artery calcium, respectively. Standard and novel risk factors were assessed at baseline, and progression of calcified atherosclerosis was determined by several methods. Progression was defined both as a categorical (square root increase of volumetric scores ≥ 2.5 mm(3)) and continuous variable. In addition, annualized percent change of volume scores was determined.

RESULTS

After an average follow-up of 4.6 years, >75% of individuals demonstrated coronary (CAC) and abdominal artery calcification (AAC) progression. Progression increased with higher baseline calcium categories but was not influenced by standard risk factors. However, the albumin-to-creatinine ratio (ACR) (P = 0.02) and lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) (P = 0.01) predicted progression of CAC, and these results were not altered by adjustment for age and other traditional risk factors. Treatment assignment (intensive versus standard) within the VADT did not influence CAC or AAC progression, irrespective of baseline calcium category.

CONCLUSIONS

In patients with long-standing type 2 diabetes, baseline CAC, Lp-PLA(2), and ACR predicted progression of CAC. Intensive glycemic control during the VADT did not reduce progression of calcified atherosclerosis.

Omega-3 fatty acids and lipoprotein associated phospholipase A(2) in healthy older adult males and females

PURPOSE

Lipoprotein associated phospholipase A(2) (Lp-PLA(2)) is a novel inflammatory factor that has been independently associated with stroke and cardiovascular disease (CVD). Omega-3 fats have been implicated in reducing inflammation associated with CVD. The aim of this study was to determine if an 8-week isocaloric diet supplemented with eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) in the form of fish oil or α-linolenic acid (ALA) in the form of flaxseed oil would alter Lp-PLA(2) among healthy adults ages 50 years and older.

METHODS

Fifty-nine healthy adults (~75% female, average age 61 years) were randomized to one of three groups with equal amounts of total fat intake. All capsules contained ~1 g of fat. The control group (n = 19) consumed olive oil capsules (~11 g/day); the ALA group (n = 20) consumed flaxseed oil capsules (~11 g/day) and the EPA/DHA group (n = 20) consumed fish oil capsules (~2 g/day + 9 g/day of olive oil). Fasting blood samples were obtained before and after the 8-week intervention for determination of Lp-PLA(2) mass and activity as well as lipid values.

RESULTS

We did not find any significant changes in Lp-PLA(2) mass or activity after the intervention in any of the groups; however, change in oxidized LDL was associated with change in Lp-PLA(2) mass (r = 0.37, p < 0.01).

CONCLUSION

Supplementing the diet with omega-3 fatty acids for 8-weeks did not influence Lp-PLA(2) activity or mass among older adults; altering oxidized LDL may be necessary to see changes in Lp-PLA(2) levels.

Lipoprotein-associated phospholipase A2 activity and incident coronary heart disease among men and women with type 2 diabetes

OBJECTIVE

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) has been shown to be associated with increased risk of coronary heart disease (CHD) in general adult populations. Because men and women with type 2 diabetes are at particularly high risk for CHD, the aim of this study was to assess the association of Lp-PLA(2) with future coronary events among diabetic men and women.

RESEARCH DESIGN AND METHODS

We measured Lp-PLA(2) activity among 740 men and 777 women with confirmed diabetes enrolled in the Health Professionals Follow-Up Study (HPFS) and Nurses' Health Study (NHS). Participants were free of all cardiovascular disease and cancer at baseline.

RESULTS

During 10 years of follow-up among men and 14 years among women, we documented 178 and 146 cases of CHD, respectively. We defined CHD as coronary artery bypass graft, angioplasty, nonfatal myocardial infarction, and fatal CHD. After adjustment for age, smoking, medical history, and biomarkers including C-reactive protein, HDL, and LDL, the relative risk of total CHD comparing extreme tertiles of Lp-PLA(2) was 1.39 (95% CI 1.01-1.90; P trend = 0.03). When we restricted analyses to only nonfatal myocardial infarction and fatal CHD, the relative risk was 1.75 (95% CI 1.05-2.92; P for trend = 0.001). LDL, HDL, C-reactive protein, hormone replacement therapy use, and diabetes duration did not modify these relationships.

CONCLUSIONS

Levels of Lp-PLA(2) activity were significantly associated with incident CHD among men and women with type 2 diabetes, independent of traditional and inflammatory risk factors. This positive association was strongest for more severe clinical end points.

Association of lipoprotein-associated phospholipase A2 with coronary artery disease in African-Americans and Caucasians

CONTEXT

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is bound predominately to low-density lipoprotein and has been implicated as a risk factor for coronary artery disease (CAD).

OBJECTIVE

We investigated the association between Lp-PLA(2) and CAD in a biethnic African-American and Caucasian population.

DESIGN

Lp-PLA(2) mass, activity, and index, an integrated measure of mass and activity, and other cardiovascular risk factors were determined in 224 African-Americans and 336 Caucasians undergoing coronary angiography.

MAIN OUTCOME MEASURES

We assessed the distribution of Lp-PLA(2) levels and determined the predictive role of Lp-PLA(2) as a risk factor for CAD.

RESULTS

Levels of Lp-PLA(2) mass and activity were higher among Caucasians compared with African-Americans (293 +/- 75 vs. 232 +/- 76 ng/ml, P < 0.001 for mass and 173 +/- 41 vs. 141 +/- 39 nmol/min/ml, P < 0.001 for activity, respectively). However, Lp-PLA(2) index was similar in the two groups (0.61 +/- 0.17 vs. 0.64 +/- 0.19, P = NS). In both ethnic groups, Lp-PLA(2) activity and index was significantly higher among subjects with CAD. African-American subjects with CAD had significantly higher Lp-PLA(2) index than corresponding Caucasian subjects (0.69 +/- 0.20 vs. 0.63 +/- 0.18, P = 0.028). In multivariate regression analyses, after adjusting for other risk factors, Lp-PLA(2) index was independently (odds ratio 6.7, P = 0.047) associated with CAD in African-Americans but not Caucasians.

CONCLUSIONS

Lp-PLA(2) activity and index was associated with presence of CAD among African-Americans and Caucasians undergoing coronary angiography. The findings suggest an independent impact of vascular inflammation among African-Americans as contributory to CAD risk and underscore the importance of Lp-PLA(2) as a cardiovascular risk factor.

Dietary, lifestyle, and clinical predictors of lipoprotein-associated phospholipase A2 activity in individuals without coronary artery disease

BACKGROUND

Elevated lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) may be positively associated with risk of coronary artery disease, yet little is known about potentially modifiable factors related to Lp-PLA(2).

OBJECTIVE

The aim of this study was to determine dietary, lifestyle, and clinical measures associated with Lp-PLA(2) activity.

DESIGN

We measured Lp-PLA(2) activity in 853 female participants of the Nurses' Health Study and 878 male participants of the Health Professionals Follow-Up Study who were free of cancer and cardiovascular disease. Multivariable linear regression models were used to assess the relation between potentially modifiable factors and Lp-PLA(2).

RESULTS

The replacement of 5% of energy from carbohydrates with energy from protein was associated with 2.2 nmol . min(-1) . mL(-1) lower levels of Lp-PLA(2) (95% CI: -3.1, -0.4) activity, and every 15-g/d increase in alcohol consumption was associated with 4.4 nmol . min(-1) . mL(-1) lower levels of Lp-PLA(2) activity (95% CI: -6.4, -2.4). Smoking (beta = 10.2; 95% CI: 4.8, 15.5), being overweight (beta = 7.5; 95% CI: 3.6, 11.3), aspirin use (beta = 6.0; 95% CI: 2.1, 10.0), hypercholesterolemia (beta = 15.0; 95% CI: 11.3, 18.8), and age (beta = 2.5; 95% CI: 1.34, 3.74) were associated with elevated Lp-PLA(2) activity, whereas postmenopausal hormone use (beta = -15.8; 95% CI: -19.4, -12.1) and cholesterol medication use (beta = -9.6; 95% CI: -18.2, -1.1) were inversely associated.

CONCLUSION

We found that not smoking, use of postmenopausal hormones, having a body mass index (in kg/m(2)) < or =25, increased alcohol consumption, and increased protein consumption all represent potential modifiable factors that may favorably influence Lp-PLA(2) activity.

Lipoprotein-associated phospholipase A(2), inflammatory biomarkers, and risk of cardiovascular disease in the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER)

OBJECTIVE

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an inflammatory biomarker that circulates mainly bound to LDL. We evaluated the association of Lp-PLA(2) with vascular events in the elderly where the importance of LDL is diminished as a risk factor for coronary disease.

METHODS

Mass and activity of Lp-PLA(2) were related to risk over 3.2 years for vascular events (definite or suspected death from CHD, non-fatal MI, fatal or non-fatal stroke) in the 2804 men and 3000 women age 70-82 years in the Prospective Study of Pravastatin in the Elderly (PROSPER).

RESULTS

Lp-PLA(2) showed a moderate, positive association with risk of a vascular event with hazard ratios of 1.25 (confidence interval (CI) 1.02-1.54) for mass and 1.39 (CI 1.14-1.70) for activity for top versus bottom quartile. Risk associations were attenuated when classical risk factors, lipids and inflammatory markers - C-reactive protein and white cell count - were included in the models. Lp-PLA(2) was unrelated to stroke risk. Inclusion of all three inflammatory markers in multivariate models negated the association of HDL cholesterol with risk (hazard ratio 0.98; CI 0.88-1.10) and increased prediction of coronary events; the C statistic rose from 63.2% to 64.4% (P<0.001).

CONCLUSION

In elderly people Lp-PLA(2), alongside other inflammatory indices, is a potential biomarker for vascular events, particularly CHD.

High-sensitivity C-reactive protein and lipoprotein-associated phospholipase A2 stability before and after stroke and myocardial infarction

BACKGROUND AND PURPOSE

High-sensitivity C-reactive protein (hsCRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2) are hypothesized to be biomarkers of systemic inflammation and risk of myocardial infarction (MI) and stroke. Little is known, however, about the stability of these markers over time, and in particular, about the effects of acute vascular events on these marker levels.

METHODS

Serum samples were collected at 4 annual intervals in 52 stroke-free participants from the Northern Manhattan Study (NOMAS) and assayed for hsCRP and Lp-PLA2 mass and activity levels using standard techniques. Log transformation of levels was performed as needed to stabilize the variance. Stability of marker levels over time was assessed using random effects models unadjusted and adjusted for demographics and other risk factors. In addition, samples from 37 initially stroke-free participants with stroke (n=17) or MI (n=20) were available for measurement before and after the vascular event (median 5 days, range 2 to 40 days). Levels before and after events were compared using nonparametric tests.

RESULTS

HsCRP and Lp-PLA2 activity levels were stable over time, whereas Lp-PLA2 mass levels decreased on average 5% per year (P=0.0015). Using accepted thresholds to define risk categories of Lp-PLA2 mass, there was no significant change over time. HsCRP increased after stroke (from median 2.2 mg/L prestroke to 6.5 mg/L poststroke; P=0.0067) and MI (from median 2.5 mg/L pre-MI to 13.5 mg/L post-MI; P<0.0001). Lp-PLA2 mass and activity levels both decreased significantly after stroke and MI (for Lp-PLA2 mass, from median 210.0 ng/mL to 169.4 ng/mL poststroke, P=0.0348, and from median 233.0 ng/mL to 153.9 post-MI, P<0.0001).

CONCLUSION

Lp-PLA2 mass levels decrease modestly, whereas hsCRP and Lp-PLA2 activity appear stable over time. Acutely after stroke and MI, hsCRP increases whereas Lp-PLA2 mass and activity levels decrease. These changes imply that measurements made soon after stroke and MI are not reflective of prestroke levels and may be less reliable for long-term risk stratification.

Lipoprotein-associated phospholipase A(2) and risk of congestive heart failure in older adults: the Cardiovascular Health Study

BACKGROUND

Inflammation may be a causative factor in congestive heart failure (CHF). Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an inflammation marker associated with vascular risk. One previous study showed an association of Lp-PLA(2) activity with CHF risk, but there were only 94 CHF cases and Lp-PLA(2) antigen, which is available clinically in the United States, was not measured.

METHODS AND RESULTS

We measured baseline Lp-PLA(2) antigen and activity in 3991 men and women without baseline CHF or cardiovascular disease who were participating in the Cardiovascular Health Study, a prospective observational study of adults 65 years or older. Cox proportional hazards models adjusted for age, sex, clinic site, race, low-density and high-density lipoprotein cholesterol, body mass index, systolic and diastolic blood pressure, hypertension, smoking status, pack-years, and diabetes were used to calculate hazard ratios and 95% CIs for incident CHF. Further models adjusted for coronary disease events during follow-up and C-reactive protein. Eight hundred twenty-nine participants developed CHF during 12.1 years. Adjusted hazard ratios for CHF with Lp-PLA(2) in the fourth compared with the first quartile were 1.44 (95% CI, 1.16 to 1.79) for Lp-PLA(2) antigen and 1.06 (95% CI, 0.84 to 1.32) for activity. Adjustment for incident coronary disease attenuated the hazard ratio for Lp-PLA(2) antigen to 1.26 (95% CI, 1.02 to 1.57), adjustment for C-reactive protein had minimal impact.

CONCLUSIONS

Lp-PLA(2) antigen was associated with risk of future CHF in older people, independent of CHF and coronary risk factors, and partly mediated by coronary disease events. Further clinical and basic research is needed to better understand the role of Lp-PLA(2) in CHF.

Lipoprotein-associated phospholipase A2: a cardiovascular risk predictor and a potential therapeutic target

Lipoprotein-associated phospholipase A2 (Lp-PLA2), present in the circulation and in atherosclerotic plaque, is an inflammatory marker with potential use as a predictor of cardiovascular risk and as a therapeutic target. Although Lp-PLA2 is associated with both LDL and HDL, it is important to determine whether Lp-PLA2 has a predominantly pro- or anti-atherogenic effect. Increasing evidence suggests a proatherogenic role for Lp-PLA2. ©iEpidemiologic and clinical evidence suggests Lp-PLA2 is an independent predictor of risk and may be superior to other inflammatory markers owing to its specificity and minimal biovariation. Lp-PLA2 inhibitors currently being investigated in clinical trials are promising novel anti-inflammatory agents with a specificity for the vascular bed and a potential for decreasing plaque vulnerability.

Association of Lipoprotein-Associated Phospholipase A2 Mass and Activity with Coronary and Aortic Atherosclerosis: Findings from the Dallas Heart Study

Background: Our aim was to characterize the association of lipoprotein-associated phospholipase A2 (Lp-PLA2) with coronary and aortic atherosclerosis in a large population-based study.

Methods: Lp-PLA2 mass and activity were measured in 2171 subjects 30–65 years old participating in the Dallas Heart Study. We examined the association of Lp-PLA2 levels with 3 atherosclerosis phenotypes: coronary artery calcium (CAC) measured by electron-beam computed tomography and abdominal aortic plaque (AAP) and aortic wall thickness (AWT) measured by magnetic resonance imaging.

Results: CAC and AAP were detected in 21% and 40% of subjects, respectively, and mean AWT (SD) was 1.70 (0.32) mm. In univariable analyses, Lp-PLA2 mass (but not activity) was higher in both men (P = 0.04) and women (P = 0.02) with detectable CAC. Lp-PLA2 mass and activity were higher (P = 0.004 and P = 0.01, respectively) and AWT was greater (P &lt; 0.001 and P = 0.02, respectively) in women with aortic atheroma, but not in men. After adjustment for traditional atherosclerosis risk factors and C-reactive protein concentrations, Lp-PLA2 mass and activity were not associated with AAP or AWT in either sex, but Lp-PLA2 mass remained modestly associated with detectable CAC only in men (odds ratio 1.20 per 1 standard deviation increase, 95% CI 1.01–1.42, P = 0.04).

Conclusions: Although Lp-PLA2 mass was independently associated with CAC in men, it was not associated with AAP or AWT in men or with any of the atherosclerosis phenotypes in women. These findings suggest that if Lp-PLA2 independently influences clinical events, it does so by promoting atherosclerotic plaque instability rather than by stimulating atherogenesis.

Lipoprotein-associated phospholipase A2 activity and risk of recurrent stroke

BACKGROUND

Mass levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), a leukocyte-derived enzyme involved in the metabolism of low-density lipoprotein to pro-inflammatory mediators, are associated with prognosis after stroke. Lp-PLA(2) mass correlates only moderately with levels of Lp-PLA(2) activity. The relationship of Lp-PLA(2) activity to risk of stroke recurrence is unknown. We hypothesized that Lp-PLA(2) activity levels would predict risk of recurrence.

METHODS

In the population-based Northern Manhattan Stroke Study, first ischemic stroke patients >or=40 years were followed for recurrent stroke. Levels of Lp-PLA(2) activity were assessed in 467 patients, and categorized by quartile. Cox proportional hazard models were used to calculate hazard ratios (HR) and 95% confidence intervals (95% CI) for risk of recurrent stroke associated with marker quartiles after adjusting for demographics, vascular risk factors, and high-sensitivity C-reactive protein (hsCRP).

RESULTS

Mean age was 68.9 +/- 12.7 years; 54.6% were women; 53.3% Hispanic, 27.2% black, and 17.8% white. Median follow-up was 4.0 years, and there were 80 recurrent strokes. Compared to the lowest quartile of Lp-PLA(2) activity, those in the highest had an increased risk of recurrent stroke (adjusted HR 2.54, 95% CI 1.01-6.39).

CONCLUSION

Stroke patients with Lp-PLA(2) activity levels in the highest quartile, compared to those in the lowest quartile, had an increased risk of recurrence after first ischemic stroke. Further studies are warranted to determine whether this biomarker has clinical utility in determining high-risk populations of stroke survivors, and whether anti-inflammatory strategies that reduce levels of activity of Lp-PLA(2) reduce the risk of stroke recurrence.

Effects of a low-calorie diet associated with weight loss on lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in healthy obese women

INTRODUCTION

Platelet-activating factor acetylhydrolase (PAF-AH or Lp-PLA(2)) is a Ca(2+)-independent phospholipase A(2) primarily associated in plasma with low density lipoproteins (LDL), especially with small dense LDL (sdLDL) particles. Increased plasma Lp-PLA(2) levels have been associated with increased cardiovascular risk in large clinical trials.

AIM

To assess the effects of weight loss on Lp-PLA(2) activity and to examine the association of Lp-PLA(2) activity changes with the alterations of sdLDL, the primary carrier of Lp-PLA(2) in plasma.

METHODS

Twenty-eight obese, non-diabetic women participated in a weight reduction program. Anthropometric parameters were assessed and parameters of glucose metabolism, lipid profile, Lp-PLA(2) activity, and LDL phenotype (using a 3% polyacrylamide gel-tube electrophoresis method), were determined at baseline and after 4months of weight loss.

RESULTS

A 10% diet-induced weight loss resulted in significant improvement in most parameters of lipid and glucose metabolism. Moreover, Lp-PLA(2) activity was significantly reduced (-10.2%, p<0.01). Mean LDL particle diameter did not change after the weight loss program. The cholesterol levels of very low-density lipoprotein (VLDL) and large-buoyant LDL particles were significantly reduced, but neither the cholesterol levels of sdLDL particles nor the % proportion of the sdLDL-cholesterol over the total LDL-cholesterol were changed after the intervention program. Interestingly, the changes in Lp-PLA(2) activity were correlated with the changes of VLDL-cholesterol (r=0.39, p<0.05), but not with the changes of anthropometric or other lipid variables.

CONCLUSIONS

A low-calorie diet associated with weight loss in obese women resulted in the significant reduction of the plasma levels of Lp-PLA(2), the potentially new predictor for incident atherosclerotic disease.

Role of lipoprotein-associated phospholipase A2 in atherosclerosis

Lipoprotein-associated phospholipase A(2)(Lp-PLA(2)) is a biomarker that can be used to assess the risk for cardiovascular disease and events. In addition to being a useful marker of a risk factor, several studies suggest that Lp-PLA(2) has a pathophysiologic role in the atherosclerotic disease process. In this article, we review this aspect and its therapeutic implications.

Lipoprotein-associated phospholipase A2 predicts progression of cardiac allograft vasculopathy and increased risk of cardiovascular events in heart transplant patients

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a risk factor for coronary artery disease (CAD) in nontransplant patients. We evaluated the association between Lp-PLA2, cardiac allograft vasculopathy (CAV) assessed by 3D intravascular ultrasound, and incidence of cardiac adverse events in heart transplant recipients.

MATERIALS AND METHODS

Fasting blood samples were obtained and stored from a cross-section of 112 cardiac transplant recipients attending the Mayo cardiac transplant clinic in 2000 to 2001, mean of 4.7 years after transplant. Lp-PLA2 was measured in plasma aliquots using an enzyme-linked immunoassay. Fifty-six of these patients subsequently underwent two 3D intravascular ultrasound studies in 2004 to 2006 12 months apart. Cardiovascular (CV) events included percutaneous coronary intervention, coronary artery bypass grafting (CABG), reduction in left ventricular ejection fraction (LVEF) < or =45% secondary to CAV and CV death.

RESULTS

High Lp-PLA2 level was associated with increase in plaque volume (r=0.43, P=0.0026) and percent plaque volume (r=0.45, P=0.0004). The association remained significant after adjusting for clinical and lipid variables. During follow-up of 5.1+/-1.6 years, 24 CV adverse events occurred in 15 of 112 (13%) heart transplant patients. Lp-PLA2 level>236 ng/mL (higher tertile) identified a subgroup of patients having a 2.4-fold increase of relative risk for combined endpoint of CV events (percutaneous coronary intervention, CABG, LVEF<45%, and CV death; 95% CI 1.16-5.19, P=0.012) compared with patients with Lp-PLA2< or =236 ng/mL.

CONCLUSIONS

Lp-PLA2 is independently associated with progression of CAV and predicts a higher incidence of CV events and CV death in transplant patients. This finding supports the concept that systemic inflammation is an important mediator of CAV. Lp-PLA2 may be a useful marker for risk of CAV and a therapeutic target in posttransplant patients.

Lipoprotein-associated phospholipase A2: a risk marker or a risk factor?

Multiple cardiovascular biomarkers are associated with increased cardiovascular disease (CVD) risk. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) appears to be relatively unique in its high specificity for and the causal pathway of plaque inflammation. In both primary and secondary prevention study populations, Lp-PLA(2) was consistently associated with higher cardiovascular risk, and the risk estimate appears to be relatively unaffected by adjustment for conventional CVD risk factors. Risk ratios were similar, whether the mass concentration or activity of the enzyme was measured. The purpose of this article is to review the evidence for the clinical utility of Lp-PLA(2), both as a risk marker and as a risk factor involved in the causal pathway of plaque inflammation and the formation of rupture-prone plaque.

Review of the evidence for the clinical utility of lipoprotein-associated phospholipase A2 as a cardiovascular risk marker

A substantial body of peer-reviewed studies has been published validating the role of inflammation in atherogenesis and supporting lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) as a cardiovascular risk marker independent of and additive to traditional risk factors. As with elevated high-sensitivity C-reactive protein, an elevated Lp-PLA(2) level approximately doubles the risk for primary and secondary cardiovascular events. Interestingly, when both inflammatory markers are increased together, they provide an even greater predictive capability to help identify very-high-risk individuals who would benefit most from aggressive lipid-lowering therapy. High levels of Lp-PLA(2) are present in inflamed, rupture-prone plaques, and it appears that Lp-PLA(2) is released from these plaques into the circulation. Over 25 prospective epidemiologic studies have demonstrated the association of elevated Lp-PLA(2) levels with future coronary events and stroke-11 of 12 prospective studies have shown a statistically significant association between elevated Lp-PLA(2) and primary coronary or cardiovascular events, 12 of 13 have shown a statistically significant association with recurrent coronary or cardiovascular events, and 6 studies have shown a positive association with stroke. Lp-PLA(2) should be viewed today as an important cardiovascular risk marker whose utility is as an adjunct to the major risk factors to adjust absolute risk status and thereby modify low-density lipoprotein cholesterol goals. The low biologic fluctuation and high vascular specificity of Lp-PLA(2) makes it possible to use a single measurement in clinical decision making, and it also permits clinicians to follow the Lp-PLA(2) marker serially. Ultimately, Lp-PLA(2) may also be classified as a risk factor, but this should not detract from its utility today as a risk marker.

Markers of inflammation and coronary artery calcification: a systematic review

OBJECTIVES

The goal of this systematic review is to assess the cross-sectional relationship of inflammatory markers with the presence and extent of coronary artery calcium (CAC) to identify asymptomatic individuals with a higher risk of coronary heart disease (CHD).

BACKGROUND

Markers of subclinical inflammation and subclinical atherosclerosis have both been used to improve detection of individuals at high risk of developing cardiovascular disease. CAC has emerged as a surrogate maker for underlying coronary atherosclerosis, and has been shown to predict future CHD events. Although inflammation is intimately associated with atherosclerosis, and levels of inflammatory markers predict cardiovascular risk, the relationship of subclinical inflammatory markers with the burden of coronary atherosclerosis is not clear.

METHODS

Medline and Pub Med databases were searched for all studies assessing the relationship of inflammatory markers with CAC published till July 2007.

RESULTS

We found 12 studies that met our criteria. CRP, fibrinogen, metallic metalloproteinase-9 (MMP-9), monocyte chemotactic protein 1 (MCP-1), resistin, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), IL-6, tumor necrosis factor alpha (TNF-alpha) and beta-fibroblast growth factor (bFGF) were used as inflammatory markers. There was a wide variation among studies with regards to population size, inclusion criterias, age range and techniques. It was observed that in almost all studies the relationship between inflammatory markers and CAC was weak, and was mostly found upon univariate analysis in women. However, this association was lost after correction for obesity and BMI. The data on the relationship of inflammation and CAC with progression of atherosclerosis is scarce and did not show any predictive benefits for future CHD.

CONCLUSION

Variable associations between CAC and inflammatory markers were identified. In most studies where a positive relationship was found, this relationship disappeared after appropriate correction for the presence of traditional risk factors. Our data suggests that an approach in which inflammatory markers are used to further characterize risk in individuals with an established coronary artery disease burden is more warranted than using biomarkers as sole risk predictors of future CHD events. Large, well-planned comprehensive studies are required to identify the combined role of measuring inflammatory markers in assessment of atherosclerotic disease.