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

[Lipoprotein-associated phospholipase A2 (Lp-PLA2): Relevant biomarker and therapeutic target?]

Over the last fifteen years, numerous studies have sought to decipher the role of lipoprotein-associated phospholipase A2 (Lp-PLA2) in vascular inflammation-related diseases, notably atherosclerosis. Despite the disappointing results of clinical trials using the Lp-PLA2 inhibitor darapladib, new pathophysiological, epidemiological and genetic data have enabled the development of new inhibitors. Recent studies also show that Lp-PLA2 is involved in vascular inflammation-related diseases other than atherosclerosis (ischemic stroke, Alzheimer's disease and vascular dementia, diabetes, cancers…), and inhibition of Lp-PLA2 could have beneficial therapeutic in these diseases. This review aims to present new data on Lp-PLA2 and to evaluate its current interest as a biomarker but also as a therapeutic target.

The joint association of lipoprotein(a) and Lp-PLA2 with the risk of stroke recurrence

BACKGROUND AND PURPOSE

Currently little is known about the joint association of lipoprotein (a) [Lp(a)] and Lipoprotein-associated phospholipase A2 (Lp-PLA2) with stroke recurrence.

METHODS

In this prospective multicenter cohort study, 10,675 consecutive acute ischemic stroke (IS) and transient ischemic attack patients (TIA) with Lp(a) and Lp-PLA2 were enrolled. The association of stroke recurrence within 1 year with Lp(a) and Lp-PLA2 was assessed using Cox proportional hazards models and Kaplan-Meier curves. The interaction between Lp(a) and Lp-PLA2 with stroke recurrence was evaluated by multiplicative and additive scales.

RESULTS

A significant joint association of Lp(a) and Lp-PLA2 with the risk of stroke recurrence was observed. Multivariate cox regression analysis demonstrated that the combination of elevated Lp(a) (≥ 50 mg/dL) and Lp-PLA2 (≥175.1 ng/ml) was independently associated with the risk of stroke recurrence (adjusted hazard ratio: 1.42; 95 % CI: 1.15-1.76). Both significant multiplicative [(exp(β3):1.63, 95 % CI: 1.17-2.29, P = 0.004] and additive interaction (RERI:0.55, 95 % CI: 0.20-0.90, P = 0.002; AP: 0.39, 95 %CI, 0.24-0.53) were observed between Lp(a) and Lp-PLA2.

CONCLUSIONS

Our results indicated that Lp(a) and Lp-PLA2 have a joint association with the risk of stroke recurrence in IS/TIA patients. Patients with concomitant presence of elevated Lp(a) and Lp-PLA2 have greater risk of stroke recurrence.

Associations between healthy food groups and platelet-activating factor, lipoprotein-associated phospholipase A2 and C-reactive protein: a cross-sectional study

PURPOSE

To investigate the association between pro-inflammatory markers platelet-activating factor (PAF), lipoprotein-associated phospholipase A2 (Lp-PLA2), hsCRP, and intake of core food groups including fruit, cruciferous and other vegetables, grains, meat and poultry, fish and seafood, nuts and legumes, and dairy.

METHODS

A cross-sectional study was conducted. 100 adults (49 ± 13 years, 31% male) with variable cardiovascular disease risk were recruited. Data were collected in 2021 and 2022. Fasting PAF, Lp-PLA2 activity, hsCRP and usual dietary intake (via a validated food frequency questionnaire) were measured. Intake of foods were converted into serves and classified into food groups. Correlations and multiple regressions were performed with adjustment for confounders.

RESULTS

A one-serve increase in cruciferous vegetables per day was associated with 20-24% lower PAF levels. An increase of one serve per day of nuts and legumes was associated with 40% lower hsCRP levels. There were small correlations with PAF and Lp-PLA2 and cheese, however, these were not significant at the Bonferroni-adjusted P < 0.005 level.

CONCLUSION

The lack of associations between PAF and Lp-PLA2 and other healthy foods may be due to confounding by COVID-19 infection and vaccination programs which prevents any firm conclusion on the relationship between PAF, Lp-PLA2 and food groups. Future research should aim to examine the relationship with these novel markers and healthy food groups in a non-pandemic setting.

Effect of physical exercise on immune, inflammatory, cardiometabolic biomarkers, and fatty acids of breast cancer survivors: results from the MAMA_MOVE Gaia After Treatment trial

PURPOSE

Physical exercise has positive effects on clinical outcomes of breast cancer survivors such as quality of life, fatigue, anxiety, depression, body mass index, and physical fitness. We aimed to study its impact on immune, inflammatory, cardiometabolic, and fatty acids (FA) biomarkers.

METHODS

An exploratory sub-analysis of the MAMA_MOVE Gaia After Treatment trial (NCT04024280, registered July 18, 2019) was performed. Blood sample collections occurred during the control phase and at eight weeks of the intervention phase. Samples were subjected to complete leukocyte counts, cytokine, and cardiometabolic marker evaluation using flow cytometry, enzyme-linked immunoassays, and gas chromatography.

RESULTS

Ninety-three percent of the 15 participants had body mass index ≥ 25 kg/m2. We observed a decrease of the plasmatic saturated FA C20:0 [median difference - 0.08% (p = 0.048); mean difference - 0.1 (95%CI - 0.1, - 0.0)], positively associated with younger ages. A tendency to increase the saturated FA C18:0 and the ratio of unsaturated/saturated FA and a tendency to decrease neutrophils (within the normal range) and interferon-gamma were observed.

CONCLUSIONS

Positive trends of physical exercise on circulating immune cells, inflammatory cytokines, and plasmatic FA were observed. Larger studies will further elucidate the implications of physical exercise on metabolism. These exploratory findings may contribute to future hypothesis-driven research and contribute to meta-analyses.

The association between dietary quality scores with C-reactive protein and novel biomarkers of inflammation platelet-activating factor and lipoprotein-associated phospholipase A2: a cross-sectional study

Healthy dietary patterns are associated with lower inflammation and cardiovascular disease (CVD) risk and adherence can be measured using diet quality scores. Inflammation is traditionally measured with C-reactive protein (hsCRP), however there is interest in novel pro-inflammatory markers platelet-activating factor (PAF) and lipoprotein-associated phospholipase A2 (Lp-PLA2) that are specifically involved in endothelial dysfunction and inflammation. This cross-sectional study investigated the association between PAF, Lp-PLA2, hsCRP, and six diet scores. One hundred adults (49 ± 13 years, 31% male) with variable CVD risk were recruited. Fasting PAF, Lp-PLA2 and hsCRP and usual dietary intake were measured. Adherence to Dietary Approaches to Stop Hypertension (DASH), Dairy-adjusted DASH, Vegetarian Lifestyle Index, Healthy Eating Index for Australians (HEIFA), Mediterranean Diet Adherence Screener (MEDAS) and PREDIMED-Plus (erMedDiet) scores were calculated. Correlations and multiple regressions were performed. hsCRP, but not PAF, independently correlated with several diet scores. Lp-PLA2 independently correlated with Vegetarian Lifestyle Index only in unadjusted models. A one-point increase in adherence to the DASH Index, the Dairy-adjusted DASH Index and the Vegetarian Lifestyle Index was associated with a 30%, 30%, and 33% reduction in hsCRP levels, respectively. Smaller effects were seen with the other diet scores with a one-point increase in adherence resulting in a 19%, 22% and 16% reduction in hsCRP with HEIFA, MEDAS, erMedDiet scores, respectively. The lack of stronger associations between the novel markers of inflammation and diet scores may be due to confounding by COVID-19 infection and vaccination programs, which prevents any firm conclusion on the relationship between PAF, Lp-PLA2 and healthy dietary patterns. Future research should aim to examine the relationship with these novel markers and healthy dietary patterns in a non-pandemic setting.

Interrelationships among platelet-activating factor and lipoprotein-associated phospholipase A2 activity and traditional cardiovascular risk factors

Traditionally cardiovascular disease (CVD) risk has been assessed through blood lipids and inflammatory marker C-reactive protein (hsCRP). Recent clinical interest in novel pro-inflammatory markers platelet-activating factor (PAF) and lipoprotein-associated phospholipase A₂ (Lp-PLA₂ ) recognizes that vascular damage can exist in the absence of traditional risk factors. This cross-sectional study investigated the potential relationship between circulating PAF, Lp-PLA₂ , hsCRP, and traditional risk factors for CVD. One hundred adults (49 ± 13 years, 31% male) with variable CVD risk were recruited. Fasting inflammatory markers PAF, Lp-PLA₂ and hsCRP and total, high-density lipoprotein (HDL), low-density lipoprotein (LDL) cholesterol, and triglycerides were measured. Blood pressure, body mass index, and waist circumference were measured. Medical and physical activity data were self-reported. Linear and multiple regressions were performed. PAF, Lp-PLA₂ , and hsCRP independently correlated with several CVD risk factors. PAF was correlated significantly with risk factors in an unexpected way; there was a medium positive correlation between PAF and HDL cholesterol (r = 0.394, p < 0.001) and medium negative correlations with Total:HDL cholesterol; (r = -0.436, p < 0.001) systolic blood pressure; (r = -0.307, p = 0.001); BMI (r = -0.381, p < 0.001); and waist circumference (r = -0.404, p < 0.001). There were large positive correlations between Lp-PLA₂ and LDL (r = 0.525, p < 0.001) and non-HDL cholesterol (r = 0.508, p < 0.001). There were large positive correlations between hsCRP and Total:HDL cholesterol (r = 0.524, p < 0.001); BMI (r = 0.668, p < 0.001); and waist circumference (r = 0.676, p < 0.001). PAF, Lp-PLA₂ , and hsCRP are implicated in the pathophysiology of inflammation in CVD; however, the relationships between each marker and traditional risk factors were different suggesting they may be involved in different atherogenic pathways.

Oxidized phospholipids and lipoprotein-associated phospholipase A2 (Lp-PLA2 ) in atherosclerotic cardiovascular disease: An update

Inflammation and oxidative stress conditions lead to a variety of oxidative modifications of lipoprotein phospholipids implicated in the occurrence and development of atherosclerotic lesions. Lipoprotein-associated phospholipase A2 (Lp-PLA₂ ) is established as an independent risk biomarker of atherosclerosis-related cardiovascular disease (ASCVD) and mediates vascular inflammation through the regulation of lipid metabolism in the blood and in atherosclerotic lesions. Lp-PLA₂ is associated with low- and high-density lipoproteins and Lipoprotein (a) in human plasma and specifically hydrolyzes oxidized phospholipids involved in oxidative stress modification. Several oxidized phospholipids (OxPLs) subspecies can be detoxified through enzymatic degradation by Lp-PLA₂ activation, forming lysophospholipids and oxidized non-esterified fatty acids (OxNEFAs). Lysophospholipids promote the expression of adhesion molecules, stimulate cytokines production (TNF-α, IL-6), and attract macrophages to the arterial intima. The present review article discusses new data on the functional roles of OxPLs and Lp-PLA₂ associated with lipoproteins.

Exosome-Loaded Pro-efferocytic Vascular Stent with Lp-PLA2-Triggered Release for Preventing In-Stent Restenosis

The efferocytosis defect is regarded as a pivotal event of atherosclerosis. The failure to clear apoptotic cells in atherosclerotic plaques under vascular stents causes a failure to resolve the inflammation underneath. However, efferocytosis repair is still confined to nonstenting therapeutics. Here, we identified a pro-efferocytotic agent and accordingly developed a bioresponsive pro-efferocytotic vascular stent aimed for poststenting healing. Exosomes derived from mesenchymal stem cells were found to be able to regulate efferocytosis via SLC2a1, STAT3/RAC1, and CD300a pathways and modulate foam cell formation processes through a CD36-mediated pathway. Pro-efferocytotic exosomes were encapsulated into liposome-based multivesicular chambers and grafted onto vascular stents. The multivesicular vesicles were able to release exosomes under the Lp-PLA₂ environment. Compared to bare metal stents, exosome-stents in the presence of Lp-PLA₂ enhanced the ratio of apoptotic cell clearance and reduced the neointimal thickness in the mal-efferocytotic rat model. Overall, we identified a pro-efferocytic agent─exosomes that are able to regulate target cells via multiple signaling pathways and are good candidates to serve complex pathological environments, and this bioresponsive pro-efferocytotic vascular stent is an attractive approach for prevention of poststenting complications.

Increased sedentary time and decreased physical activity increases lipoprotein associated phospholipase A2 in obese individuals

BACKGROUND AND AIMS

Lipoprotein-associated Phospholipase A₂ (Lp-PLA₂) is a protein produced by inflammatory cells in circulation and is associated with cardiovascular disease (CVD) risk. Physical activity (PA) is known to reduce inflammation and risk for CVD. However, Lp-PLA₂ has yet to be examined in relation to PA and sedentary time. The purpose of this study was to determine if PA and sedentary time impacts Lp-PLA₂ mass. A total of 25 subjects with an average BMI of 30.6 ± 5.7 were included in the data analysis.

METHODS AND RESULTS

Data collected included anthropometric data, Lp-PLA₂ mass, peak oxygen uptake (VO₂peak), resting heart rate and blood pressure, obstructive sleep apnea (OSA) risk, and assessment of PA using an accelerometer. Sedentary minutes per day was positively associated with Lp-PLA₂ (r = 0.41, P < 0.05). Light intensity PA was negatively associated (r = -0.51. P = 0.01) with Lp-PLA₂. When subjects were divided into 2-quantiles by Lp-PLA₂, the group with the higher Lp-PLA₂ mass accumulated more sedentary time per day (P < 0.001) and less light intensity PA per day (P = 0.001). OSA risk and Lp-PLA₂ showed no relationship. Sedentary behavior was higher, and light intensity PA was lower in subjects with hiLp-PLA₂ mass. No difference was seen in moderate-to-vigorous intensity PA or steps per day.

CONCLUSIONS

This suggests that, total PA habits, including time spent sedentary and lower intensity PA, impacts the levels of Lp-PLA₂, an important inflammatory marker and marker of CVD risk.

Radiation-induced lipoprotein-associated phospholipase A2 increases lysophosphatidylcholine and induces endothelial cell damage

The cardiotoxicity of various anticancer therapies, including radiotherapy, can lead to cardiovascular complications. These complications can range from damaging cardiac tissues within the irradiation field to increasing the long-term risks of developing heart failure, coronary artery disease, and myocardial infarction. We analyzed radiation-induced metabolites capable of mediating critical biological processes, such as inflammation, senescence, and apoptosis. Previously, by applying QTOF-MASS analysis to irradiated human fibroblasts, we identified that metabolite sets of lysophosphatidylcholine (LPC) were increased in these cells. In this study, radiation-induced LPC accumulation in human aortic endothelial cells (HAECs) increased reactive oxygen species (ROS) production and senescence-associated-beta-galactosidase staining, in addition to decreasing their tube-forming ability. Knockdown of lipoprotein-associated phospholipase A2 (Lp-PLA2) with small interfering RNA (siRNA) inhibited the increased LPC production induced by radiation, and reduced the radiation-induced cell damage produced by ROS and oxidized low-density lipoprotein (LDL). Lp-PLA2 depletion abolished the induction of proinflammatory factors, such as interleukin 1β, tumor necrosis factor-alpha, matrix metalloproteinase 2, and matrix metalloproteinase 9, as well as adhesion molecules, such as intercellular adhesion molecule 1 (ICAM-1) and E-selection. Likewise, we showed that Lp-PLA2 expression was upregulated in the vasculature of irradiated rat, resulting in increased LPC production and LDL oxidation. Our data demonstrate that radiation-induced LPC production is a potential risk factor for cardiotoxicity that is mediated by Lp-PLA2 activity, suggesting that LPC and Lp-PLA2 offer potential diagnostic and therapeutic approaches to cardiovascular damage during radiotherapy.

EPA's pleiotropic mechanisms of action: a narrative review

Treatment with icosapent ethyl 4 g/day, a highly purified and stable ethyl ester of eicosapentaenoic acid (EPA), demonstrated a significant reduction in atherosclerotic cardiovascular disease (ASCVD) events and death in REDUCE-IT. However, analyses of REDUCE-IT and meta-analyses have suggested that this clinical benefit is greater than can be achieved by triglyceride reduction alone. EPA therefore may have additional pleiotropic effects, including anti-inflammatory and anti-aggregatory mechanisms. EPA competes with arachidonic acid for cyclooxygenase and lipoxygenase, producing anti-inflammatory and anti-aggregatory metabolites rather than the more deleterious metabolites associated with arachidonic acid. Changing the EPA:arachidonic acid ratio may shift metabolic status from pro-inflammatory/pro-aggregatory to anti-inflammatory/anti-aggregatory. EPA also has antioxidant effects and increases synthesis of nitric oxide. Incorporation of EPA into phospholipid bilayers influences membrane structure and may help to prevent cardiac arrhythmias. Clinically, this may translate into improved vascular health, including regression of atherosclerotic plaque. Overall, EPA has a range of pleiotropic effects that contribute to a reduction in ASCVD.

On the present and future role of Lp-PLA2 in atherosclerosis-related cardiovascular risk prediction and management

Circulating concentration and activity of secretory phospholipase A₂ (sPLA₂) and lipoprotein-associated phospholipase A₂ (Lp-PLA₂) have been proven as biomarkers of increased risk of atherosclerosis-related cardiovascular disease (ASCVD). Lp-PLA₂ might be part of the atherosclerotic process and may contribute to plaque destabilisation through inflammatory activity within atherosclerotic lesions. However, all attempts to translate the inhibition of phospholipase into clinically beneficial ASCVD risk reduction, including in randomised studies, by either non-specific inhibition of sPLA₂ (by varespladib) or specific Lp-PLA₂ inhibition by darapladib, unexpectedly failed. This gives us a strong imperative to continue research aimed at a better understanding of how Lp-PLA₂ and sPLA₂ regulate vascular inflammation and atherosclerotic plaque development. From the clinical viewpoint there is a need to establish and validate the existing and emerging novel anti-inflammatory therapeutic strategies to fight against ASCVD development, by using potentially better animal models and differently designed clinical trials in humans.

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

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

A new oral testosterone undecanoate therapy comes of age for the treatment of hypogonadal men

Background:

A novel formulation of oral testosterone undecanoate (TU) was studied in a long- and short-term phase III trial to evaluate safety and efficacy.

Methods:

Hypogonadal men (age 18–65 years; two morning serum testosterone (T) <300 ng/dl with signs/symptoms) were recruited into a 365 day (trial I) or 105 day (trial II), randomized, multicenter trial. Patients were randomized 1:1 to oral TU (n = 161) or T-gel (n = 160) in trial I, and 3:1 to oral TU, twice daily (BID) JATENZO® (n = 166) or a topical T product [Axiron® (n = 56)] in trial II. Dose adjustments were based on average T concentrations (Cavg). Efficacy was assessed based on T levels, body composition and bone density. Safety was assessed by standard clinical measures.

Results:

Oral TU efficacy (% of patients with eugonadal T Cavg) was 84% (serum Cavg = 628 ± 343 ng/dl) and 87% (serum T equivalent Cavg ≈ 489 ± 155 ng/dl) in trials I and II, respectively. Oral TU significantly (p <0.0001) improved all Psychosexual Daily Questionnaire parameters in trials I and II. In trial I, lean mass increased 3.2 ± 2.7 kg and fat decreased by 2.4 ± 3.6 kg (both p <0.0001) and bone density improved in hip (+0.012 ± 0.0225 g/cm²) and spine (+0.018 ± 0.0422 g/cm²) after 365 days (both p <0.0001). Oral TU-associated adverse effects were consistent with other T-replacement therapies but oral TU patients experienced a greater number of mild gastrointestinal adverse effects. Oral TU subjects in both studies exhibited an increase in mean systolic blood pressure of about 3–5 mmHg. Oral TU was not associated with liver toxicity nor did it cause an elevation in high-sensitivity C-reactive protein or lipoprotein-associated phospholipase A₂ (cardiovascular safety biomarkers) after 365 days of therapy.

Conclusion:

A new oral TU formulation was safe and effective and represents a significant therapeutic advance for the treatment of appropriate hypogonadal men.

Role of vitamin D in risk factors of patients with type 2 diabetes mellitus

INTRODUCTION AND OBJECTIVES

Previous observational studies have suggested that low vitamin D status is associated with high circulating C-reactive protein levels, as well as other plasma inflammatory cytokines. However, there is no study to explore the relationship between vitamin D status and Lp-PLA2, a new biomarker of vascular-specific inflammation. The aim of this study was to examine the association between vitamin D status and circulating Lp-PLA2 levels in subjects with type 2 diabetes mellitus.

MATERIAL AND METHODS

This descriptive cross-sectional study enrolled diabetic subjects who underwent physical examination at Taizhou People's Hospital between August 2016 and January 2017. Blood pressure, anthropometry, metabolic profiles, serum 25(OH)D levels and Lp-PLA2 mass levels were measured in all participants.

RESULTS

A total of 196 participants were recruited into this study. The vitamin D insufficiency group had higher serum LP-PLA2 levels than the vitamin D sufficiency group (t=-2.765, p=.005). A significant negative correlation was noted between Lp-PLA2 and 25(OH)D in the vitamin D insufficiency group (r=-0.364, p=0.009). However, no significant relationship between serum Lp-PLA2 concentration and 25(OH)D levels was observed in subjects with vitamin D sufficiency.

CONCLUSIONS

From this cohort of patients with type 2 diabetes, regardless of traditional cardiovascular risk factors, we observed a statistically significant inverse relation between Lp-PLA2 and 25(OH)D at levels <30ng/mL.

Comparative Proteomic Analysis of Two Differently Extracted Coptis chinensis in the Treatment of Type 2 Diabetic Rats

Coptis chinensis (CC) is widely used to treat diabetes in traditional Chinese medicine due to its significant hypoglycemic and hypolipidemic effects. It was reported that CC powders are more effective than CC decoctions. In this study, a rat model of type 2 diabetes was established and treated with supercritical-extracted CC and gastric juice extracted CC, respectively. Body weight, fasting plasma insulin, insulin resistance index, and lipid profiles were measured along with oral glucose tolerance tests (OGTTs). In addition, the levels of plasma proteins were compared between type 2 diabetic rats and CC-treated rats using an iTRAQ-based quantitative proteomic analysis. The results showed that the plasma levels of triglyceride (TC), total cholesterol (TG), and low-density lipoprotein (LDL) in rats of both CC-treated groups were significantly decreased. In addition, the proteomic analysis identified 929 proteins, while 15 proteins were selected from these 929 proteins based on their expression levels and bioinformatic results. Among these 15 proteins, 9 proteins (IGF-1, Igfbp4, Igfbp-6, Igfals, C2, C4, Cfi, Prdx-2, and Prdx-3) were upregulated in the two CC-treated groups, while 6 proteins (Pla2g7, Pcyox1, ApoC-1, ApoC-3, ApoB-100, and ApoE) were downregulated. The functions of these proteins are associated with glucose metabolism, insulin action, immunity, inflammation, lipid metabolism, oxidation, and antioxidation. The two differently extracted CC did not show significant differences in terms of their treatment efficacy. This research expanded our understanding on the therapeutic effects and mechanisms of CC in the treatment of type 2 diabetes.

Exploring the plasmatic platelet-activating factor acetylhydrolase activity in patients with anti-phospholipid antibodies

Purpose

To explore the role of plasmatic platelet-activating factor acetylhydrolase (PAF-AH), a marker of cardiovascular risk, in patients with anti-phospholipid antibodies (aPL).

Methods

PAF-AH activity was assessed in a series of 167 unselected patients screened for aPL in a context of thrombotic events, risk of thrombosis or obstetric complications and in 77 blood donors.

Results

116/167 patients showed positive results for at least one aPL among IgG/IgM anti-prothrombin/phosphatidylserine (aPS/PT), anti-cardiolipin (aCL), anti-beta2-glycoprotein I (aβ2GPI) or lupus anticoagulant (LAC), while 51/167 patients resulted aPL-negative. LAC+ patients disclosed higher PAF-AH than LAC-negative (22.1 ± 6.4 nmol/min/ml vs. 19.5 ± 4.1 nmol/min/ml; p = 0.0032), and aPL-negative patients (p = 0.03). Patients presenting positive IgG aβ2GPI disclosed higher PAF-AH than patients with only IgM aβ2GPI-positive antibodies (23.1 ± 7.2 nmol/min/ml vs. 20.1 ± 5.3 nmol/min/ml; p = 0.035), as well as than patients showing only isolated LAC, aCL or aPS/PT (16.9 ± 3.8 nmol/min/ml; p = 0.003).

Conclusions

PAF-AH plasmatic activity is particularly up-regulated in LAC+ and in aβ2GPI IgG+ patients, possibly representing an alternative prognostic biomarker for the therapeutic management of APS patients.

Effect of Switching From Statin Monotherapy to Ezetimibe/Simvastatin Combination Therapy Compared With Other Intensified Lipid-Lowering Strategies on Lipoprotein Subclasses in Diabetic Patients With Symptomatic Cardiovascular Disease

Background

Patients with diabetes mellitus and cardiovascular disease may not achieve adequate low‐density lipoprotein cholesterol (LDL‐C) lowering on statin monotherapy, attributed partly to atherogenic dyslipidemia. More intensive LDL‐C–lowering therapy can be considered for these patients. A previous randomized, controlled study demonstrated greater LDL‐C lowering in diabetic patients with symptomatic cardiovascular disease who switched from simvastatin 20 mg (S20) or atorvastatin 10 mg (A10) to combination ezetimibe/simvastatin 10/20 mg (ES10/20) therapy, compared with statin dose‐doubling (to S40 or A20) or switching to rosuvastatin 10 mg (R10). The effect of these regimens on novel biomarkers of atherogenic dyslipidemia (low‐ and high‐density lipoprotein particle number and lipoprotein‐associated phospholipase A2 [Lp‐PLA₂]) was assessed.

Methods and Results

Treatment effects on low‐ and high‐density lipoprotein particle number (by NMR) and Lp‐PLA₂ (by ELISA) were evaluated using plasma samples available from 358 subjects in the study. Switching to ES10/20 reduced low‐density lipoprotein‐particle number numerically more than did statin dose‐doubling and was comparable with R10 (−133.3, −94.4, and −56.3 nmol/L, respectively; P>0.05). Increases in high‐density lipoprotein particle number were significantly greater with switches to ES10/20 versus statin dose‐doubling (1.5 and −0.5 μmol/L; P<0.05) and comparable with R10 (0.7 μmol/L; P>0.05). Percentages of patients attaining low‐density lipoprotein particle number levels <990 nmol/L were 62.4% for ES10/20, 54.1% for statin dose‐doubling, and 57.0% for R10. Switching to ES10/20 reduced Lp‐PLA₂ activity significantly more than did statin dose‐doubling (−28.0 versus −3.8 nmol/min per mL, P<0.05) and was comparable with R10 (−28.0 versus −18.6 nmol/min per mL; P>0.05); effects on Lp‐PLA₂ concentration were modest.

Conclusions

In diabetic patients with dyslipidemia, switching from statins to combination ES10/20 therapy generally improved lipoprotein subclass profile and Lp‐PLA₂ activity more than did statin dose‐doubling and was comparable with R10, consistent with its lipid effects.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00862251.

Effects of oral eicosapentaenoic acid versus docosahexaenoic acid on human peripheral blood mononuclear cell gene expression

OBJECTIVE

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have beneficial effects on inflammation and cardiovascular disease (CVD). Our aim was to assess the effect of a six-week supplementation with either olive oil, EPA, or DHA on gene expression in peripheral blood mononuclear cells (PBMC).

METHODS

Subjects were sampled at baseline and six weeks after receiving either: olive oil 6.0 g/day (n = 16), EPA 1.8 g/day (n = 16), or DHA 1.8 g/day (n = 18). PBMC were subjected to gene expression analysis by microarray with key findings confirmed by quantitative real-time polymerase chain reaction (Q-PCR).

RESULTS

Plasma phospholipid EPA increased 3 fold in the EPA group, and DHA increased 63% in the DHA group (both p < 0.01), while no effects were observed in the olive oil group. Microarray analysis indicated that EPA but not DHA or olive oil significantly affected the gene expression in the following pathways: 1) interferon signaling, 2) receptor recognition of bacteria and viruses, 3) G protein signaling, glycolysis and glycolytic shunting, 4) S-adenosyl-l-methionine biosynthesis, and 5) cAMP-mediated signaling including cAMP responsive element protein 1 (CREB1), as well as many other individual genes including hypoxia inducible factor 1, α subunit (HIF1A). The findings for CREB1 and HIF1A were confirmed by Q-PCR analysis.

CONCLUSIONS

Our data indicate that EPA supplementation was associated with significant effects on gene expression involving the interferon pathway as well as down-regulation of CREB1 and HIF1A, which may relate to its beneficial effect on CVD risk reduction.

Nonsynonymous polymorphisms in PLA2G7 gene are associated with the risk of coronary heart disease in a southern Chinese population

Lipoprotein-associated phospholipase A2 (Lp-PLA2) plays an important role in coronary heart disease (CHD). This study was aimed to investigate the associations of polymorphisms (R92H, V279F, I198T, and A379V) in PLA2G7 with CHD. A total of 322 patients with CHD and 414 CHD-free controls were included in the study. Polymorphisms in PLA2G7 were sequenced by DNA Sequencer and statistical analyses were performed to study the associations between polymorphisms and CHD. RH + HH genotype, RH genotype, and H allele of R92H were significantly associated with an increased risk of CHD (P = 0.005, P = 0.009, and P = 0.003, respectively), while no associations were observed between V279F and I198T and CHD (A379V was not analyzed because of deviation from Hardy-Weinberg equilibrium). Correlations between R92H and CHD still existed after adjustment for confounding risk factors of CHD (P = 0.001). Furthermore, stratified analyses showed subgroups of the senior, hypertension, non-smoking, non-diabetics, and male subjects brought a higher risk for CHD (P = 0.015, P = 0.001, P = 0.001, P = 0.002, and P = 0.004, respectively). We also observed a lower level of protective factor HDL-C in CHD patients carrying genotype RH + HH than patients with RR (P = 0.047). Furthermore, we conducted haplotype analysis and detected more harmful effects of haplotypes HVI and RVT as compared with other haplotypes (P = 2.538 × 10(-3) and P = 0.031). These findings indicated that R92H variant in PLA2G7 gene might contribute to CHD susceptibility in a southern Chinese population.

Heart disease is common in humans and chimpanzees, but is caused by different pathological processes

Heart disease is common in both humans and chimpanzees, manifesting typically as sudden cardiac arrest or progressive heart failure. Surprisingly, although chimpanzees are our closest evolutionary relatives, the major cause of heart disease is different in the two species. Histopathology data of affected chimpanzee hearts from two primate centers, and analysis of literature indicate that sudden death in chimpanzees (and in gorillas and orangutans) is commonly associated with diffuse interstitial myocardial fibrosis of unknown cause. In contrast, most human heart disease results from coronary artery atherosclerosis, which occludes myocardial blood supply, causing ischemic damage. The typical myocardial infarction of humans due to coronary artery thrombosis is rare in these apes, despite their human-like coronary-risk-prone blood lipid profiles. Instead, chimpanzee ‘heart attacks’ are likely due to arrythmias triggered by myocardial fibrosis. Why do humans not often suffer from the fibrotic heart disease so common in our closest evolutionary cousins? Conversely, why do chimpanzees not have the kind of heart disease so common in humans? The answers could be of value to medical care, as well as to understanding human evolution. A preliminary attempt is made to explore possibilities at the histological level, with a focus on glycosylation changes.

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 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.

Baseline elevated Lp-PLA2 is associated with increased risk for re-stenosis after stent placement

Background

Lipoprotein associated phospholipase A2 (Lp-PLA2) is a novel biomarker for cardiovascular risk prediction. Whether increased Lp-PLA2 level is associated with re-stenosis after stent-placement is unclear.

Methods

Totally 326 participants eligible for stent-placement were enrolled and divided into two groups according to baseline Lp-PLA2 levels (named normal and elevated groups). Baseline characteristics and clinical outcomes were compared between normal and elevated groups. The relationships between Lp-PLA2 and other risk factors with re-stenosis were evaluated.

Results

Only the between-group difference of Lp-PLA2 was significant (123.2 ± 33.6 ng/mL vs 336.8 ± 85.4 ng/mL, P < 0.001) while other demographic and clinical characteristics between these two groups were comparable. Approximately 55.1% and 58.5% of participants in normal and elevated groups presented with acute coronary syndrome, and the percentage of tri-vessels stenoses was significantly higher in elevated group (40.8% vs 32.1%, P = 0.016). Nearly 96.0% and 94.0% of participants in normal and elevated Lp-PLA2 groups were placed with drug-eluting stents, and the others were with bare-metal stents. After 1 year’s follow-up, the incidence of clinical end-points was comparable (13.3% vs 15.4%, P = 0.172). Nevertheless, the incidence of re-stenosis was marginally higher in elevated Lp-PLA2 group (8.5% versus 4.6%, P = 0.047). With multivariate analysis, after adjustment for other risk factors, Lp-PLA2 remained an independent predictor for re-stenosis with a hazard ratio of 1.140. No synergistic effect between Lp-PLA2 and other risk factors for re-stenosis was found.

Conclusion

Increased Lp-PLA2 level is associated with an increased risk of re-stenosis. Lp-PLA2 assessment may be useful in predicting subjects who are at increased risk for re-stenosis.

Lipoprotein-associated phospholipase A2, a novel cardiovascular inflammatory marker, in HIV-infected patients

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an emerging biomarker of cardiovascular disease. This study was conducted to describe the distribution of Lp-PLA2 in a cohort of human immunodeficiency virus (HIV)-infected adults and to determine associations between Lp-PLA2, cardiometabolic risk factors, and subclinical atherosclerosis in this population.

METHODS

Lp-PLA2 was assessed in 341 (25% women, 52% white, 74% on highly active antiretroviral therapy [HAART]) participants of a cohort with detailed characterization of atherogenic risk factors, including surrogate markers of carotid and coronary atherosclerosis.

RESULTS

Mean Lp-PLA2 mass was 313 ± 105 ng/mL and activity 173 ± 49 nmol/minute/mL. Seventy-five percent of participants had abnormal Lp-PLA2. Those in the highest Framingham Risk Score tertile had significantly higher Lp-PLA2 activity. Participants with abnormal carotid intima-media thickness (cIMT) had higher Lp-PLA2 mass and activity. Those with coronary artery calcium (CAC) scores >100 had significantly higher Lp-PLA2 mass than those with lower or nondetectable calcium. Those on HAART and protease inhibitor (PI)-based treatment had significantly higher Lp-PLA2 mass and activity than those who were treatment-naive or not on PIs. In multivariate regression, HAART and PI use were positively associated with Lp-PLA2 activity and mass after adjusting for age, race, sex, low-density and high-density lipoprotein cholesterol levels, triglyceride level, and smoking. Adding Lp-PLA2 activity tertiles to the model improved the predictive value for abnormal common cIMT, but not internal cIMT or CAC score.

CONCLUSIONS

Lp-PLA2 is highly abnormal in HIV-infected patients and is associated with several cardiovascular and HIV treatment-specific risk factors. Lp-PLA2 may be used as an additional and more vascular specific biomarker for cardiovascular risk stratification in HIV-positive patients.

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.

Icosapent ethyl, a pure ethyl ester of eicosapentaenoic acid: effects on circulating markers of inflammation from the MARINE and ANCHOR studies

BACKGROUND

Icosapent ethyl (IPE) is a high-purity prescription form of eicosapentaenoic acid ethyl ester approved by the US Food and Drug Administration as an adjunct to diet to reduce triglyceride (TG) levels in adult patients with severe (≥500 mg/dL) hypertriglyceridemia. In addition to TG-lowering effects, IPE also reduces non-high-density lipoprotein cholesterol and apolipoprotein B levels without significantly increasing low-density lipoprotein cholesterol (LDL-C) in patients with very high TG levels ≥500 mg/dL (MARINE study) and in patients with well-controlled LDL-C and residually high TG levels 200-500 mg/dL (ANCHOR study). This analysis examined the effect of IPE on inflammatory markers in patients from MARINE and ANCHOR.

METHODS

MARINE (N = 229) and ANCHOR (N = 702) were Phase III, double-blind studies that randomized hypertriglyceridemic patients to IPE 4 g/day, 2 g/day, or placebo. This analysis assessed the median placebo-adjusted percentage change from baseline in markers representing various stages of atherosclerotic inflammation such as intercellular adhesion molecule-1 (ICAM-1), oxidized low-density lipoprotein (Ox-LDL), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP).

RESULTS

Compared to placebo, IPE 4 g/day significantly decreased Ox-LDL (13 %, p < 0.0001, ANCHOR), Lp-PLA(2) (14 %, p < 0.001, MARINE; 19 %, p < 0.0001, ANCHOR), and hsCRP levels (36 %, p < 0.01, MARINE; 22 %, p < 0.001, ANCHOR), but did not significantly change ICAM-1 and IL-6 levels. In the MARINE study, IPE 2 g/day did not significantly change ICAM-1, Ox-LDL, Lp-PLA(2), IL-6, or hsCRP levels. Also, compared to placebo in the ANCHOR study, IPE 2 g/day significantly decreased Lp-PLA(2) levels (8 %, p < 0.0001), but did not significantly change levels of other assessed inflammatory markers.

CONCLUSION

Compared to placebo, in hypertriglyceridemic patients, IPE 4 g/day significantly decreased Ox-LDL, Lp-PLA(2), and hsCRP levels.

Emerging biomarkers and intervention targets for immune-modulation of atherosclerosis - a review of the experimental evidence

The role of inflammation in atherosclerosis and plaque vulnerability is well recognized. However, it is only during recent years it has become evident that this inflammation is modulated by immune responses against plaque antigens such as oxidized LDL. Interestingly, both protective and pathogenic immune responses exist and experimental data from animal studies suggest that modulation of these immune responses represents a promising new target for treatment of cardiovascular disease. It has been proposed that during early stages of the disease, autoimmune responses against plaque antigens are controlled by regulatory T cells that inhibit the activity of auto-reactive Th1 effector T cells by release of anti-inflammatory cytokines such as IL-10 and TGF-β. As the disease progresses this control is gradually lost and immune responses towards plaque antigens switch towards activation of Th1 effector T cells and release of pro-inflammatory cytokines such as interferon-γ, TNF-α and IL-1β. Several novel immune-modulatory therapies that promote or mimic tolerogenic immune responses against plaque antigens have demonstrated athero-protective effects in experimental models and a first generation of such immune-modulatory therapies are now in early or about to enter into clinical testing. A challenge in the clinical development of these therapies is that our knowledge of the role of the immune system in atherosclerosis largely rests on data from animal models of the disease. It is therefore critical that more attention is given to the characterization and evaluation of immune biomarkers for cardiovascular risk.

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.

Utility of Lp-PLA2 in lipid-lowering therapy

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a vascular-specific inflammatory marker. It is so named because of its association with low-density lipoprotein in plasma. Atherosclerosis is an inflammatory disease. Lp-PLA2 is recognized as a risk marker in primary or secondary prevention of atherosclerosis. Elevated Lp-PLA2 levels are associated with the increased risk for cardiovascular events, even after multivariable adjustment for traditional risk factors. Patients with dyslipidemia are shown to benefit largely from the modification of Lp-PLA2. The degree of coronary artery disease (0-, 1-, 2-, or 3-vessel disease) and plasma low-density lipoprotein cholesterol significantly correlated to Lp-PLA2 levels. The low biologic fluctuation and high vascular specificity of Lp-PLA2 make it possible to use a single measurement in clinical decision making, and it also permits clinicians to follow the Lp-PLA2 marker serially. Simvastatin significantly reduces macrophage content, lipid retention, and the intima to media ratio but increased the content of smooth muscle cells in atherosclerotic lesions. Statin treatment markedly reduced Lp-PLA2 in both plasma and atherosclerotic plaques with attenuation of the local inflammatory response and improved plaque stability due to reduced inflammation and decreased apoptosis of macrophages. Darapladib, an inhibitor of Lp-PLA2 when added to lipid-lowering therapy such as statins, offers great benefit in the reduction of plaque formation. This article explores the atherosclerotic process at molecular level, role of Lp-PLA2 in atherosclerosis, the effect of lipid-lowering drugs on Lp-PLA2, effect of direct Lp-PLA2 inhibitor darapladib in the atherosclerosis process, the therapeutic implications of Lp-PLA2 as risk marker, and finally the net effect on plaque stabilization.

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

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

Translational studies of lipoprotein-associated phospholipase A₂ in inflammation and atherosclerosis

OBJECTIVES

This study sought to examine the role of lipoprotein-associated phospholipase A₂ (Lp-PLA₂/PLA2G7) in human inflammation and coronary atherosclerosis.

BACKGROUND

Lp-PLA₂ has emerged as a potential therapeutic target in coronary heart disease. Data supporting Lp-PLA₂ are indirect and confounded by species differences; whether Lp-PLA₂ is causal in coronary heart disease remains in question.

METHODS

We examined inflammatory regulation of Lp-PLA₂ during experimental endotoxemia in humans, probed the source of Lp-PLA₂ in human leukocytes under inflammatory conditions, and assessed the relationship of variation in PLA2G7, the gene encoding Lp-PLA₂, with coronary artery calcification.

RESULTS

In contrast to circulating tumor necrosis factor-alpha and C-reactive protein, blood and monocyte Lp-PLA₂ messenger ribonucleic acid decreased transiently, and plasma Lp-PLA₂ mass declined modestly during endotoxemia. In vitro, Lp-PLA₂ expression increased dramatically during human monocyte to macrophage differentiation and further in inflammatory macrophages and foamlike cells. Despite only a marginal association of single nucleotide polymorphisms in PLA2G7 with Lp-PLA₂ activity or mass, numerous PLA2G7 single nucleotide polymorphisms were associated with coronary artery calcification. In contrast, several single nucleotide polymorphisms in CRP were significantly associated with plasma C-reactive protein levels but had no relation with coronary artery calcification.

CONCLUSIONS

Circulating Lp-PLA₂ did not increase during acute phase response in humans, whereas inflammatory macrophages and foam cells, but not circulating monocytes, are major leukocyte sources of Lp-PLA₂. Common genetic variation in PLA2G7 is associated with subclinical coronary atherosclerosis. These data link Lp-PLA₂ to atherosclerosis in humans while highlighting the challenge in using circulating Lp-PLA₂ as a biomarker of Lp-PLA₂ actions in the vasculature.

Evidence supporting a key role of Lp-PLA2-generated lysophosphatidylcholine in human atherosclerotic plaque inflammation

OBJECTIVE

To determine whether the level of lysophosphatidylcholine (lysoPC) generated by lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with severity of inflammation in human atherosclerotic plaques. Elevated plasma Lp-PLA2 is associated with increased cardiovascular risk. Lp-PLA2 inhibition reduces atherosclerosis. Lp-PLA2 hydrolyzes low-density lipoprotein-oxidized phospholipids generating lysoPCs. According to in vitro studies, lysoPCs are proinflammatory but the association between their generation and plaque inflammation remains unknown.

METHODS AND RESULTS

Inflammatory activity in carotid plaques (162 patients) was determined immunohistochemically and by analyzing cytokines in homogenates (multiplex immunoassay). LysoPCs were quantified using mass spectrometry and Lp-PLA2 and the lysoPC metabolite lysophosphatidic acid (LPA) by ELISA. There was a strong correlation among lysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 in plaques. LysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 correlated with interleukin-1β, interleukin-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, regulated on activation normal T-cell expressed and secreted, and tumor necrosis factor-α in plaques. High lysoPC and Lp-PLA2 correlated with increased plaque macrophages and lipids and with low content of smooth muscle cells, whereas LPA only correlated with plaque macrophages. Lp-PLA2, lysoPC 16:0, 18:0, and 18:1, but not LPA were higher in symptomatic than in asymptomatic plaques.

CONCLUSIONS

The associations among Lp-PLA2, lysoPCs, LPA, and proinflammatory cytokines in human plaques suggest that lysoPCs play a key role in plaque inflammation and vulnerability. Our findings support Lp-PLA2 inhibition as a possible strategy for the prevention of cardiovascular disease.

Developing and assessing cardiovascular biomarkers

Atherosclerosis is a slow process that over time can lead to fatal events. Early identification and prediction of future risk can allow for preventive strategies to be instituted. There is an increasing interest in utilizing novel biomarkers in cardiovascular disease screening and management. These novel biomarkers may help in cardiovascular disease risk assessment and treatment monitoring, and some may be treatment targets. To be useful for risk prediction, novel biomarkers need to show a significant association with cardiovascular disease events and bring additional value in risk stratification when added to known risk prediction models. Biomarkers used for treatment monitoring need to show that they can serve as good surrogates of cardiovascular disease status. In this article, we present 3 biomarkers that are currently approved by the U.S. Food and Drug Administration for use in cardiovascular disease management and risk assessment: C-reactive protein, lipoprotein-associated phospholipase A2, and myeloperoxidase. Other new biomarkers have also been shown recently to help in cardiovascular disease risk prediction and management. In this article, we will review 2 of these new biomarkers: cardiac troponin T measured by a highly sensitive assay and brain natriuretic peptide.

Lipoprotein-associated phospholipase A2 (Lp-PLA2): a review of its role and significance as a cardiovascular biomarker

OBJECTIVE

To conduct a comprehensive, systematic review of studies assessing the significance of lipoprotein-associated phospholipase A2 in cardiovascular diseases (CVDs).

MATERIAL AND METHODS

A review of the literature was performed using the search term "Lipoprotein-associated phospholipase A2 (Lp-PLA2)" and each of the following terms: "cardiovascular risk," "cardiovascular death," "atherosclerotic disease," "coronary events," "transient ischemic attack (TIA)," "stroke," and "heart failure." The searches were performed on Medline, Google Scholar and ClinicalTrials.gov.

RESULTS

The majority of published studies showed a significant association between Lp-PLA2 levels and cardiovascular events after multivariate adjustment. The association was consistent across a wide variety of subjects of both sexes and different ethnic backgrounds.

CONCLUSIONS

The role of Lp-PLA2 as a significant biomarker of vascular inflammation was confirmed, and Lp-PLA2 seems to be closely correlated to cardiovascular events. It may be an important therapeutic target and may have an important role in prevention, risk stratification and personalised medicine.

Clinical utility of inflammatory markers and advanced lipoprotein testing: advice from an expert panel of lipid specialists

The National Cholesterol Education Program Adult Treatment Panel guidelines have established low-density lipoprotein cholesterol (LDL-C) treatment goals, and secondary non-high-density lipoprotein (HDL)-C treatment goals for persons with hypertriglyceridemia. The use of lipid-lowering therapies, particularly statins, to achieve these goals has reduced cardiovascular disease (CVD) morbidity and mortality; however, significant residual risk for events remains. This, combined with the rising prevalence of obesity, which has shifted the risk profile of the population toward patients in whom LDL-C is less predictive of CVD events (metabolic syndrome, low HDL-C, elevated triglycerides), has increased interest in the clinical use of inflammatory and lipid biomarker assessments. Furthermore, the cost effectiveness of pharmacological intervention for both the initiation of therapy and the intensification of therapy has been enhanced by the availability of a variety of generic statins. This report describes the consensus view of an expert panel convened by the National Lipid Association to evaluate the use of selected biomarkers [C-reactive protein, lipoprotein-associated phospholipase A(2), apolipoprotein B, LDL particle concentration, lipoprotein(a), and LDL and HDL subfractions] to improve risk assessment, or to adjust therapy. These panel recommendations are intended to provide practical advice to clinicians who wrestle with the challenges of identifying the patients who are most likely to benefit from therapy, or intensification of therapy, to provide the optimum protection from CV risk.

Association of serum lipoprotein-associated phospholipase A2 level with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most common causes of chronic liver disease, worldwide. Lipoprotein-associated phospholipase A2 (Lp-PLA2) was recently characterized as a novel inflammatory biomarker that is correlated with several components constituting the metabolic syndrome.

METHODS

In this study, we determined the serum levels of Lp-PLA2 in patients with definite nonalcoholic steatohepatitis (NASH, n=25), borderline NASH (n=22), simple fatty liver (n=10), and healthy controls without evidence of liver disease (n=38). The levels of Lp-PLA2 were measured by enzyme-linked immunosorbent assay and compared in the four study groups. Moreover, concentrations of Lp-PLA2 were assessed in relation to the general characteristics of the study participants and the results of liver biopsy.

RESULTS

Concentrations of Lp-PLA2 were significantly higher in patients with definite NASH (161.8±0.9 μg/L, P<0.001), borderline NASH (135.4±47.7 μg/L, P=0.001), and simple fatty liver (132.4±46.2 μg/L, P=0.042) compared with healthy controls (86.2±40.7 μg/L). Furthermore, the serum Lp-PLA2 level was strongly associated to histological steatosis scores in patients with NAFLD (β=0.32, t=2.50, P=0.016).

CONCLUSION

Although subject to future confirmation, our data suggest that Lp-PLA2 levels are elevated in NAFLD.

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

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

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

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