Lipoprotein-associated phospholipase A2 and its relationship with markers of subclinical cardiovascular disease: A systematic review

Lp-PLA2 as a biomarker and its possible associations with SARS-CoV-2 infection

Lp-PLA2 is an enzyme encoded by the PLA2G7 gene located at chromosome 6p12-21, which is included in different signal transduction pathways. The potential of serum levels of Lp-PLA2 as a marker of inflammation quantifying cardio-metabolic risk, renal impairment and oxidative stress has been explored in earlier studies. It has also been used in chronic obstructive pulmonary disease, hepatic disease, metabolic conditions and exercise tolerance. Additionally, it shows promising evidence for the assessment of risk for certain cardiovascular conditions in otherwise seemingly healthy individuals. COVID-19 has affected life and the economy globally. The identification of biomarkers to assess the sickness and treatment plan is the need of the hour. This review summarizes the pathophysiological inter-relationship between serum levels of Lp-PLA2 and COVID-19. The authors hypothesize that the estimation of Lp-PLA2 levels may help in the early identification of risk and thus may play a beneficial role in the proactive management of COVID-19.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Correlation between Serum LP-PLA2 and sST2 Levels and the Condition of Patients with Acute Heart Failure and Their Prognostic Value

Acute heart failure (AHF) occurs mostly in the elderly, which is a syndrome that occurs in the later stages of the development of cardiovascular disease. Due to the sharp decline in the patient's heart function, the patient has a high mortality rate and a poor prognosis, which seriously threaten the life safety of the elderly. Therefore, early diagnosis of AHF and timely treatment are extremely important. Lipoprotein-associated phospholipase A2 (LP-PLA2) is a newly discovered cardiovascular-specific inflammatory marker, which is closely related to the formation and progression of atherosclerotic plaque and the occurrence and development of coronary heart disease. Soluble growth stimulation expression gene 2 (sST2) protein is a protein produced under the induction of mechanical stress in cardiomyocytes. It can act as a decoy receptor to mediate the interleukin-33 (IL-33)/ST2 signaling pathway to bind to IL-33, thereby reducing the myocardial protective effect and leading to myocardial remodeling. The purpose of this study was to explore the serum LP-PLA2 and sST2 levels in AHF patients and to analyze their correlation with the disease and their prognostic value. The results showed that the levels of serum LP-PLA2 and sST2 were increased in AHF patients, and the levels of serum LP-PLA2 and sST2 in patients with adverse prognostic events were higher than those in patients without adverse prognostic events. The levels of serum LP-PLA2 and sST2 are closely related to the degree of patients' illness, among which the combined prediction of AHF patients with LP-PLA2 and sST2 has the highest value, which is worthy of promotion.

Anti-Inflammatory Drugs in Patients with Ischemic Heart Disease

Inflammation has long been known to play a role in atherogenesis and plaque complication, as well as in some drugs used in therapy for atherosclerotic disease, such as statins, acetylsalicylic acid, and modulators of the renin-angiotensin system, which also have anti-inflammatory effects. Furthermore, inflammatory biomarkers have been demonstrated to predict the incidence of cardiovascular events. In spite of this, and with the exception of acetylsalicylic acid, non-steroidal anti-inflammatory drugs are unable to decrease the incidence of cardiovascular events and may even be harmful to the cardiovascular system. In recent years, other anti-inflammatory drugs, such as canakinumab and colchicine, have shown an ability to reduce the incidence of cardiovascular events in secondary prevention. Colchicine could be a potential candidate for use in clinical practice given its safety and low price, although the results of temporary studies require confirmation in large randomized clinical trials. In this paper, we discuss the evidence linking inflammation with atherosclerosis and review the results from various clinical trials performed with anti-inflammatory drugs. We also discuss the potential use of these drugs in routine clinical settings.

Inflammatory Markers in Cardiovascular Disease; Lessons Learned and Future Perspectives

BACKGROUND

Cardiovascular disease (CVD) still remains the leading cause of morbidity and mortality worldwide. It is now established that inflammation plays a crucial role in atherosclerosis and atherothrombosis, and thus, it is closely linked to cardiovascular disease.

OBJECTIVE

The aim of the present review is to summarize and critically appraise the most relevant evidence regarding the potential use of inflammatory markers in the field of CVD.

METHODS

We conducted a comprehensive research of the relevant literature, searching MEDLINE from its inception until November 2018, primarily for meta-analyses, randomized controlled trials and observational studies.

RESULTS

Established markers of inflammation, mainly C-reactive protein, have yielded significant results both for primary and secondary prevention of CVD. Newer markers, such as lipoprotein-associated phospholipase A2, lectin-like oxidized low-density lipoprotein receptor-1, cytokines, myeloperoxidase, cell adhesion molecules, matrix metalloproteinases, and the CD40/CD40 ligand system, have been largely evaluated in human studies, enrolling both individuals from the general population and patients with established CVD. Some markers have yielded conflicting results; however, others are now recognized not only as promising biomarkers of CVD, but also as potential therapeutic targets, establishing the role of anti-inflammatory and pleiotropic drugs in CVD.

CONCLUSION

There is significant evidence regarding the role of consolidated and novel inflammatory markers in the field of diagnosis and prognosis of CVD. However, multimarker model assessment, validation of cut-off values and cost-effectiveness analyses are required in order for those markers to be integrated into daily clinical practice.

Integrated multiplatform-based metabonomics and network analysis to explore the mechanism of Polygonum cuspidatum on hyperlipidemia

Hyperlipidemia is a major risk factor and pathological basis for cardiovascular diseases. Polygonum cuspidatum (HZ), a famous traditional Chinese medicine, is frequently used to treat hyperlipidemia. However, little is known about its underlying mechanism. Herein, an integrated approach combining multiplatform-based metabonomics and network analysis was adopted to elucidate the ameliorative mechanism of HZ on hyperlipidemia. The global metabolomic characters of HZ on hyperlipidemia were investigated by GC-MS and LC-MS based metabonomics. Significant metabonomic alterations were observed in hyperlipidemic group, which could be restored by HZ supplementation. Furthermore, the drug-ingredients-target-metabolic pathway network was constructed, and the result indicated that HZ exhibited hypolipidemic efficacy through resveratrol, polydatin, torachrysone-8-O-β-D-(6'-oxayl)-glucoside, physciondiglucoside, (+)-catechin, β-sitosterol, quercetin, luteolin and physovenine acting on phospholipase A2, unspecific monooxygenase, arachidonate 15-lipoxygenase, aromatic-L-amino-acid decarboxylase, alcohol dehydrogenase and triacylglycerol lipase. In conclusion, this study explored potential mechanism of HZ on hyperlipidemia with the aid of the integrated approach combining multiplatform-based metabonomics and network analysis, which might provide a theoretical basis for the clinical application of HZ.

Inflammatory Markers Related to Innate and Adaptive Immunity in Atherosclerosis: Implications for Disease Prediction and Prospective Therapeutics

Several lines of evidence have linked a dysregulated inflammatory setting to the pathogenesis of atherosclerosis, which is a form of chronic vascular inflammation. Various inflammatory biomarkers have been associated with inflammation and are recognized as potential tools to monitor the progression of atherosclerosis. A well-studied inflammatory marker in the context of cardiovascular diseases is C-reactive protein (CRP) or, more accurately, highly sensitive-CRP (hs-CRP), which has been established as an inflammatory biomarker for atherosclerotic events. In addition, a growing body of investigations has attempted to disclose the potential of inflammatory cytokines, enzymes, and genetic polymorphisms related to innate and adaptive immunity as biomarkers for predicting the development of atherosclerosis. In this review article, we clarify both traditional and novel inflammatory biomarkers related to components of the innate and adaptive immune system that may mirror the progression or phases of atherosclerotic inflammation/lesions. Furthermore, the contribution of the inflammatory biomarkers in developing potential therapeutics against atherosclerotic treatment will be discussed.

Relationship of lipoprotein-associated phospholipase A2(Lp-PLA2) and periprocedural myocardial injury in patients undergoing elective percutaneous coronary intervention

BACKGROUND

Percutaneous coronary intervention (PCI) is one of the dominant methods for revascularization in patients with coronary heart disease (CHD). However, periprocedural myocardial injury (PMI) is a frequent complication following PCI and is known to be a predictor of postprocedural cardiovascular morbidity and mortality. Although several studies try to identify serum markers to predict the PMI, there is a little information about the role of lipoprotein-associated phospholipase A2 (Lp-PLA2) as a predictor of PMI. Therefore, we aimed to investigate the relationship of Lp-PLA2 levels and PMI in patients undergoing elective PCI.

METHODS

This study included 265 consecutive patients with normal preprocedural cardiac troponin T(cTNT) who received elective PCI. The samples for cTNT were collected at 8, 16, and 24 h after PCI to assess perioperative myocardial injury. The Lp-PLA2 and other serum lipid parameters were measured after 12 fasting hours before PCI.

RESULTS

The data suggested that the patients with preprocedural high Lp-PLA2 were strongly and independently correlated with the risk of PMI. Pearson correlation analysis showed that preprocedural Lp-PLA2 was significantly positively correlated with postprocedural cTnT elevation (r = 0.694, p < 0.05). Binary logistic regression analysis was used to analyze the risk factors of PMI, we found that Lp-PLA2 was independent risk factor for postprocedural cTnT elevation. The area under Receiver Operating Characteristic curve of Lp-PLA2 was 0.757 (95%CI 0.692 ~ 0.821, p < 0.001), the best cut-off point was 185 ng/ml, sensitivity and specificity were 65.33% and 76.32%.

CONCLUSION

Our study demonstrated that preprocedural Lp-PLA2 was associated with postprocedural cTnT elevation and was the independent risk factor of PMI.

Elevated Lipoprotein-Associated Phospholipase A2 is Valuable in Prediction of Coronary Slow Flow in Non-ST-Segment Elevation Myocardial Infarction Patients

Background Coronary flow is a determinative factor of non-ST-segment elevation myocardial infarction (NSTEMI) patients. Lipoprotein-Associated Phospholipase A2(Lp-PLA2) as a vascular specific inflammatory cytokine might relate to coronary slow flow in these patients. Methods 105 NSTEMI patients and 83 UAP patients were enrolled. Another group division was made by Lp-PLA2 tertile data. Corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) was adopted to represent coronary flow condition. Correlation analysis was made between CTFC and other clinical indicators. Multivariable regression analysis was used to identify the influential factors of coronary flow in NSTEMI patients. ROC curve was used to determine the diagnostic value of Lp-PLA2 with coronary slow flow (CSF). Results High sensitive C reactive protein (hsCRP, P < 0.01), Lp-PLA2(P < 0.01), N-terminal pro-brain natriuretic peptide (NT-proBNP, P < 0.05), mean platelet volume (MPV, P<0.05), CTFC(P < 0.05) was higher in NSTEMI than UAP patients. hsCRP(P < 0.01), MPV(P < 0.01), NT-proBNP(P < 0.01) CTFC(P < 0.01) was higher in high-Lp-PLA2 group. Lp-PLA2 and hsCRP (r = 0.22, P < 0.01), MPV (r = 0.21, P < 0.05), CTFC (r = 0.69, P < 0.01) had a positive correlation in NSTEMI group. Multivariable regression analysis showed that Lp-PLA2 could explain most part changes of CTFC in NSTEMI patients, CTFC = 0.55*Lp-PLA2+0.03*hsCRP+0.005*NT-proBNP+15.843. Lp-PLA2 was specific and sensitive in diagnosis of CSF in NSTEMI group, AUC = 0.851(95% confidence interval (CI): 0.771-0.924, P < 0.01), Cutoff=196.96ng/ml, sensitivity = 84%, specificity = 81%. Conclusions Lp-PLA2 is closely correlated with coronary flow in NSTEMI patients. Lp-PLA2 over 196.96ng/ml could be used to predict CSF in NSTEMI patients.

Lipoprotein-associated phospholipase A2 predicted cardiovascular disease in obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is an independent risk factor for cardiovascular disease (CVD). As a new inflammatory biomarker of CVD, rare attention has been paid to the roles of lipoprotein-associated phospholipase (Lp-PLA2) in OSAS studies. In this study, we aimed to investigate the correlation between Lp-PLA2 and concomitant CVD in OSAS patients.

METHODS

In this prospective study, 152 OSAS patients were further divided into mild, moderate, and severe OSAS subgroups. They presented heart failure, coronary artery disease, or arrhythmia were confirmed with CVD. Thirty-one subjects without OSAS were recruited for the control group. The relationship between Lp-PLA2 and concomitant CVD in OSAS patients was analyzed.

RESULTS

Serum Lp-PLA2 values were significantly higher in the severe and moderate OSAS group compared with mild OSAS and OSAS negative groups (P = 0.025). Significant increase was noticed in serum Lp-PLA2 levels in CVD patients compared with those without in severe-moderate-mild OSAS (P < 0.05). In logistic regression analysis, the level of Lp-PLA2 was proved as a significant independent predictor for CVD (OR = 1.117, P = 0.008). The ROC analysis indicated that the best cut-off value of Lp-PLA2 for predicting CVD in OSAS patients was 238.09 ng/ml. The positive and negative predictive values were 72.5% and 70.5%, respectively. The sensitivity was 46.8% and the specificity was 87.8%.

CONCLUSIONS

Lp-PLA2 might be associated with the severity of OSAS and the occurrence of CVD in OSAS patients. Lp-PLA2 is expected to be a promising biomarker candidate in predicting CVD in patients with OSAS due to test convenience.

Selected cardiovascular risk factors in early stages of chronic kidney disease

Cardiovascular diseases, including hypertension, congestive heart failure, myocardial infarction, stroke and atherosclerosis, are common in patients with chronic kidney disease. Aside from the standard biomarkers, measured to determine cardiovascular risk, new ones have emerged: markers of oxidative stress, apoptosis, inflammation, vascular endothelium dysfunction, atherosclerosis, organ calcification and fibrosis. Unfortunately, their utility for routine clinical application remains to be elucidated. A causal relationship between new markers and cardiovascular diseases in patients with chronic kidney disease remains to be established. First of all, there is a lack of large, randomized trials. Moreover, most studies focus on patients with end-stage renal disease as well as on dialysed patients. In such patients, cardiovascular diseases are already present and advanced while early detection of cardiovascular disease risk factor in patients with early-stages of chronic kidney disease would allow more precise prognosis and, as a result, changes in treatment algorithm. In this article, we conduct a comprehensive review of literature for publications relating to cardiovascular risk factors in patients with early-stages of chronic kidney disease. Overall, there are many encouraging advances in detection of cardiovascular risk factors that are making the future more promising for patients suffering from chronic kidney disease.

Energy Intake and Plasma Adiponectin as Potential Determinants of Lipoprotein-Associated Phospholipase A2 Activity: A Cross-Sectional Study

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂ ) is associated with increased risk of cardiovascular diseases (CVD) and type 2 diabetes mellitus. Lp-PLA₂ activity is positively associated with male sex, Caucasian race, the presence of metabolic syndrome (MetS) and low-density lipoprotein (LDL)-cholesterol, but it is negatively associated with high-density lipoprotein (HDL)-cholesterol. Associations with other cardiometabolic risk factors, inflammation markers, and lifestyle factors are few or inconsistent. We investigated potential determinants of Lp-PLA₂ activity among both nonmodifiable and modifiable CVD risk factors in a middle-aged Greek cohort without overt CVD. Two hundred eighty four subjects (159 men, 53 ± 9 years and 125 women 52 ± 9 years) participated in a cross-sectional study carried out during 2011-2012 in Athens, Attica. Cardiometabolic risk factors, inflammation markers, lifestyle factors, and Lp-PLA₂ activity were evaluated with established methods. The American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) criteria were used to define MetS. Lp-PLA₂ activity was not associated with MetS, but was associated with MetS components, markers of liver function, and macronutrient intake. Increased total energy intake was associated with increased Lp-PLA₂ activity (odds ratio, 95% confidence interval: 1.07, 1.01-1.14 and 1.10, 1.03-1.16 for the 4th and 3rd quartiles, respectively, compared to the 1st quartile) after adjustments for sex, pack-years of smoking, LDL-cholesterol, and statin treatment. Adiponectin tended to be inversely associated with Lp-PLA₂ activity (0.91, 0.82-1.00, and 4th versus 1st quartile). Our results suggested that total energy intake and adiponectin levels are potential determinants of Lp-PLA₂ activity.

Association between serum lipoprotein-associated phospholipase A2, ischemic modified albumin and acute coronary syndrome: a cross-sectional study

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a newly emerging biomarker with strong pro-inflammatory effects, and is an independent risk predictor of atherosclerotic plaque rupture and thrombosis. In addition, ischemic modified albumin (IMA) is another important marker for the evaluation of myocardial ischemia, and has been approved by the U.S. Food and Drug Administration. The objective of this study was to investigate serum Lp-PLA2 and IMA in the early diagnosis, progression and prognosis of acute coronary syndrome (ACS). Serum Lp-PLA2 and IMA were detected using an AU5800 automatic biochemical analyzer in samples from 180 patients with ACS [n = 60 with unstable angina pectoris (UA), n = 56 with non-ST segment elevation myocardial infarction (NSTEMI), and n = 64 with ST segment elevation myocardial infarction (STEMI)] and 60 healthy control subjects. The relationship between Lp-PLA2 and IMA with Gensini score and the number of coronary artery lesions was explored, and logistic regression was conducted to identify risk factors for major adverse cardiovascular events (MACE). Serum Lp-PLA2 and IMA were significantly higher in all ACS subgroups compared to the control group (P < 0.05), were positively associated with the severity of ACS based on the Gensini score (P < 0.05), and were significantly higher in patients with double- and triple-vessel lesions compared to those with single-vessel lesions and healthy controls (P < 0.05). Logistic regression identified Lp-PLA2, IMA, and troponin I levels as independent risk factors for MACE. Lp-PLA2 and IMA were predictive of the degree of myocardial ischemia in patients with ACS, and may provide important clinical significance for the early diagnosis of ACS and the choice of treatment strategy.

13-HODE, 9-HODE and ALOX15 as potential players in Rett syndrome OxInflammation

Mutations in the MECP2 gene are the main cause of Rett syndrome (RTT), a pervasive neurodevelopmental disorder, that shows also multisystem disturbances associated with a metabolic component. The aim of this study was to investigate whether an increased production of oxidized linoleic acid metabolites, specifically 9- and 13-hydroxyoctadecadienoic acids (HODEs), can contribute to the altered the redox and immune homeostasis, suggested to be involved in RTT. Serum levels of 9- and 13-HODEs were elevated in RTT and associated with the expression of arachidonate 15-Lipoxygenase (ALOX15) in peripheral blood mononuclear cells (PBMCs). Omega-3 polyunsaturated fatty acids supplementation has shown to lower HODEs levels in RTT. Statistically significant correlation was demonstrated between the increased plasma HODEs levels and the lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Collectively, these findings reinforce the concept of the key role played by lipid peroxidation in RTT, and the possible ability of omega-3 polyunsaturated fatty acids supplementation in improving the oxinflammation status in RTT.

Chemiluminescence immunoassay for sensing lipoprotein-associated phospholipase A2 in cardiovascular risk evaluation

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA₂) is a novel inflammatory biomarker, which is useful as an adjunct identification tool for cardiovascular disease. However, the important limitation of the conventional enzyme-linked immunosorbent assay (PLAC ELISA) for Lp-PLA₂ assay is its relatively low sensitivity and time consuming. A method to measure the Lp-PLA₂ simply, rapidly and sensitively is essential for predicting cardiovascular events in clinic.

METHODS

We took advantage of magnetic separation integrated with chemiluminescence to detect Lp-PLA₂. The concentration of Lp-PLA₂ was measured through a one-step process by mixing antibody labelled magnetic beads, antigen and antibody at one time.

RESULTS

Our method realized the sample to answer within 17 min. The detection limit and measurement range were 0.18 ng/ml and 0.18-1350 ng/ml, respectively. The specificity assay showed that no appreciable interference was observed for the substances of bilirubin, triglyceride, hemoglobin, rheumatoid factor and human anti-mouse antibody up to the concentrations of 40 mg/dl, 1000 mg/dl, 2000 mg/dl, 1500 IU/ml and 30 ng/ml, separately. We also tested 122 clinical samples using our method, presenting good overall correlations (R² = 0.979) to the PLAC ELISA. It is worth mentioning that, our method was faster, had a wider range of measurement and higher sensitivity compared with the PLAC ELISA.

CONCLUSIONS

The Lp-PLA₂ assay is straightforward, sensitive and precise, which is highly suitable to further explore the clinical performance of Lp-PLA₂ in studies of cardiovascular risk management.

Measuring lipoprotein-associated phospholipase A2 activity in China: Protocol comparison and recalibration

BACKGROUND

Lp-PLA2 is a novel inflammation marker in cardiovascular disease. While several manufactures have registered Lp-PLA2 activity reagents, few studies have investigated the consistency among these assays. In this study, we compared and recalibrated Lp-PLA2 activity assays.

METHODS

Serum samples from 110 patients and 140 healthy individuals were collected for method comparison and reference interval validation, respectively. Fresh human serum pools (847 and 442 U/L) were used for recalibration. Lp-PLA2 activity was analyzed using all five assays with a Beckman AU 5800 analyzer. Passing-Bablok regression equations and Bland-Altman plots were used to estimate the relationship and bias among the results. A 2.5% confidence interval (CI) and 97.5% CI were used to establish a laboratory reference interval.

RESULTS

Assay imprecision varied from 0.8%-2.9%, while the overall coincidence rates ranged from 75.5%-98.2%. Passing-Bablok regression shows excellent linear correlation between Evermed and Diasys (R²  = 0.999), while that between Diazyme and Evermed was poor (R²  = 0.846). The R² and correlation coefficient r among assays were 0.846-0.999 and 0.8947-0.9993, respectively. The mean bias percentages ranged from -71.5%-1.6% and -2.0%-11.6% before and after recalibration. As Diazyme and Diasys were not comparable, the Diazyme assay was not recalibrated. The reference intervals determined for Diasys, Evermed, Hengxiao, and Zybio were 184-605, 208-704, 81-328, and 273-696 U/L, respectively.

CONCLUSIONS

Our results indicate that recalibration increased assay agreement and also highlight the need for each laboratory to establish its own reference interval for Lp-PLA2 activity.

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.

Performance characteristics of lipoprotein-associated phospholipase A2 activity assay on the Dimension Vista analyser and preliminary study of a healthy Italian population

Introduction

Lipoprotein-associated phospholipase A2 (Lp-PLA₂) is a marker of vascular inflammation associated with coronary heart disease and stroke. We evaluated analytical performance of the PLAC® Activity Test on Siemens Dimension Vista® 1500 analyzer and measured Lp-PLA₂ activity in Italian adults to establish reference intervals (RIs) and evaluate correlation with circulating lipids and age.

Materials and methods

The evaluation protocol consisted of precision, linearity, sensitivity, method comparison, substrate depletion (“hook”) effect and interference assessment. Inhibitor (Darapladib) effect was also evaluated. Lp-PLA₂ activity was measured in 250 healthy donors (123 males, 127 females, aged 18-70 years). Central 95% RIs were established using nonparametric statistics.

Results

Intra-assay and inter-assay precision showed CVs of 0.6% - 1.4% and 0.9% - 2.0%, respectively. Linearity replicates showed R² > 0.98. Limit of quantitation was 5.8 U/L (CV = 9.4%). Bland Altman plot showed bias - 0.9, 95% limits of agreement -6.5 - 4.72. Passing-Bablok regression showed excellent correlation (Slope = 1.02, 95% CI: 1.01 to 1.03; Intercept = - 1.86, 95% CI: - 3.08 to - 1.26; R² = 0.999). No “hook effect” was observed at Lp-PLA₂ activities ≤ 1000 U/L. Average Lp-PLA₂ activity in 250 healthy donors was 182 ± 44 U/L (mean ± SD). Males showed statistically significant higher activities than females (P < 0.001). RIs were 107 - 265 U/L for males and 84 - 225 U/L for females. Moderate significant correlation (r = 0.29, P < 0.001) was found between Lp-PLA₂ activity and total cholesterol.

Conclusions

The PLAC® Activity Test shows very good performance characteristics on Dimension Vista® 1500.