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

Ischemic cardiomyopathy is associated with coronary plaque progression and higher event rate in patients after cardiac transplantation

Background

Cardiac allograft vasculopathy is the leading cause of graft failure and death in heart transplant (HTx) recipients; however, the association between the etiology of heart failure (ischemic cardiomyopathy [ICM] or non‐ICM) that led to HTx and progression of cardiac allograft vasculopathy, and adverse events after HTx has not been explored.

Methods and Results

We retrospectively included 165 HTx patients, who were followed‐up with at least 2 virtual histology–intravascular ultrasound examinations after HTx, and grouped them as ICM (n=46) or non‐ICM (n=119). Coronary artery plaque volume was analyzed using virtual histology–intravascular ultrasound, and cardiovascular event data—a composite of myocardial infarction, hospitalization for heart failure and arrhythmia, revascularization, retransplantation, and death including cardiovascular death—were collected from the medical records of all study subjects. ICM patients had significantly higher plaque volume at both first (P=0.040) and follow‐up (P=0.015) intravascular ultrasound examinations. After multivariate adjustment for traditional coronary risk factors, ICM was significantly associated with plaque progression (odds ratio 3.10; CI 1.17 to 9.36; P=0.023). Ten‐year cardiovascular event‐free survival was 50% in ICM patients compared with 84% in non‐ICM patients (log‐rank test P=0.003). In multivariate Cox proportional hazard analysis, ICM was significantly associated with a higher event rate after HTx (hazard ratio 2.02; 95% CI 1.01 to 4.00; P=0.048).

Conclusion

Our study demonstrates that ischemic etiology of cardiomyopathy prior to HTx may be independently associated with plaque progression and higher event rate after HTx.

Everolimus therapy is associated with reduced lipoprotein-associated phospholipase A2 (Lp-Pla2) activity and oxidative stress in heart transplant recipients

BACKGROUND

Several studies demonstrated decreased severity and incidence of cardiac allograft vasculopathy (CAV) in heart transplant recipients receiving immunosuppressive therapy with everolimus. However, data regarding the influence of everolimus on risk factors predisposing to CAV are hitherto limited. We here systematically evaluated cardiovascular risk factors in heart transplanted patients, who underwent conversion to everolimus or were maintained on conventional therapy with calcineurin inhibitors (CNI).

METHODS

50 Patients receiving everolimus and 91 patients receiving CNI in addition to mycophenolate mofetil and low-dosed steroids were included in the study. CAV risk factors were determined in plasma or urine using standard enzymatic or immunochemical methods.

RESULTS

No significant differences were observed between both groups with regard to lipid (total, LDL- and HDL-cholesterol), metabolic (glucose, insulin), inflammatory (C-reactive protein, IL-6, myeloperoxidase) and cardiac (troponin I, NT-proBNP) risk factors. However, significantly lower activity of lipoprotein-associated phospholipase A2 (Lp-PLA2) and a negative correlation between the Lp-PLA2 activity and the everolimus concentration were observed in plasmas from everolimus-treated patients. Conversion to everolimus significantly lowered Lp-PLA2 activity in heart transplant recipients. Studies in vitro revealed reduced Lp-PLA2 expression in hepatocytes and macrophages pre-exposed to everolimus. In addition, reduced plasma markers of oxidative stress including oxidized LDL, 8-iso-prostaglandin F2α and protein carbonyls were noted in heart transplant recipients receiving everolimus therapy.

CONCLUSION

Our results suggest that everolimus specifically lowers plasma activity and cellular production of Lp-PLA2 and thereby dampens oxidative stress. These effects may additionally contribute to the reduced CAV incidence observed in heart transplant recipients receiving everolimus therapy.

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.

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.

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.

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

Lipoprotein-associated phospholipase A2 (Lp-PLA₂) is at the crossroads of lipid metabolism and the inflammatory response. It is produced by inflammatory cells, bound to LDL and other lipoproteins, and once in the arterial wall facilitates hydrolysis of phospholipids. Elevated serum levels of Lp-PLA₂ have been associated with increased cardiovascular risk in healthy populations and in patients with known vascular disease. Here, we review the role of Lp-PLA₂ in the development of atherosclerosis and progression to unstable disease, the utility of Lp-PLA₂ as a risk predictor for coronary and carotid events and the potential clinical benefit of pharmacologic inhibition of Lp-PLA₂.

Lipoprotein-associated phospholipase A2 as a biomarker of coronary heart disease and a therapeutic target

PURPOSE OF REVIEW

Lipoprotein-associated phospholipase A2 (Lp PLA2) is postulated to occupy a key position in the pathogenic sequence leading to formation of complex atherosclerotic lesions. This study reviews evidence supporting its role as a biomarker of vascular disease and as a possible therapeutic target.

RECENT FINDINGS

Evidence continues to build supporting the usefulness of Lp PLA2 as a predictor of coronary events in the general population and in those with established coronary heart disease. Elevated Lp PLA2 is also associated with stroke and heart failure. The crystal structure of Lp PLA2 is now available and offers insight into the links between structure, function and atherogenic properties. Recently completed studies on the efficacy of darapladib, a specific Lp PLA2 inhibitor, show beneficial changes in plaque morphology in animal models and in humans.

SUMMARY

Lp PLA2 is gaining acceptance as a useful biomarker of chronic inflammation and as a predictor of vascular disease. Early results with darapladib offer promise, but not definitive proof, of a potential role for Lp PLA2 inhibition in coronary heart disease prevention.

Lipoprotein-associated phospholipase A2 as a novel risk marker for cardiovascular disease: a systematic review of the literature

We sought to critically assess the role of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) in the prediction of cardiovascular events in primary and secondary prevention settings. The inclusion criteria for our study included population-based epidemiologic studies and the presence of clinical outcomes of interest, including atherosclerotic disease, coronary events, stroke, and cardiovascular death. Studies that lacked clinical outcomes or that involved animals were excluded. We included primary and secondary prevention studies of subjects in all ethnic groups and of either sex, with no age limitation. We searched MEDLINE, Google Scholar, and the Cochrane Library for studies with publication dates from January 1970 through July 2009, and we searched major cardiology meeting abstracts from 2000 through 2009. From each study, we used predictive ability-including relative risk, hazard ratio, odds ratio, and prevalence of high Lp-PLA(2) levels, with adjustment-along with baseline population characteristics.Of 33 studies that met our inclusion criteria, 30 showed a significant association between Lp-PLA(2) and cardiovascular events. Most of the studies had been adjusted for major Framingham risk factors and other variables that might influence the effect under question. After multivariate adjustments in cohort and nested case-control studies, increased levels of Lp-PLA(2) remained a significant predictor of cardiovascular events. The available body of evidence suggests that Lp-PLA(2) is a reliable marker of risk for cardiovascular events.

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.