Melatonin suppresses atherosclerosis by ferroptosis inhibition via activating NRF2 pathway.

Melatonin (MLT), a conserved small indole compound, exhibits anti-inflammatory and antioxidant properties, contributing to its cardioprotective effects. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with atherosclerosis disease risk, and is known as an atherosclerosis risk biomarker. This study aimed to investigate the impact of MLT on Lp-PLA2 expression in the atherosclerotic process and explore the underlying mechanisms involved. In vivo, ApoE-/- mice were fed a high-fat diet, with or without MLT administration, after which the plaque area and collagen content were assessed. Macrophages were pretreated with MLT combined with ox-LDL, and the levels of ferroptosis-related proteins, NRF2 activation, mitochondrial function, and oxidative stress were measured. MLT administration significantly attenuated atherosclerotic plaque progression, as evidenced by decreased plaque area and increased collagen. Compared with those in the high-fat diet (HD) group, the levels of glutathione peroxidase 4 (GPX4) and SLC7A11 (xCT, a cystine/glutamate transporter) in atherosclerotic root macrophages were significantly increased in the MLT group. In vitro, MLT activated the nuclear factor-E2-related Factor 2 (NRF2)/SLC7A11/GPX4 signaling pathway, enhancing antioxidant capacity while reducing lipid peroxidation and suppressing Lp-PLA2 expression in macrophages. Moreover, MLT reversed ox-LDL-induced ferroptosis, through the use of ferrostatin-1 (a ferroptosis inhibitor) and/or erastin (a ferroptosis activator). Furthermore, the protective effects of MLT on Lp-PLA2 expression, antioxidant capacity, lipid peroxidation, and ferroptosis were decreased in ML385 (a specific NRF2 inhibitor)-treated macrophages and in AAV-sh-NRF2 treated ApoE-/- mice. MLT suppresses Lp-PLA2 expression and atherosclerosis processes by inhibiting macrophage ferroptosis and partially activating the NRF2 pathway.

The role of lipoprotein­associated phospholipase A2 in inflammatory response and macrophage infiltration in sepsis and the regulatory mechanisms.

Lipoproteinassociated phospholipase A2 (Lp-PLA2), encoded by the phospholipase A2 group VII (Pla2g7) gene, has been pertinent to inflammatory responses. This study investigates the correlation between Lp-PLA2 and inflammatory injury in septic mice and explores its regulatory mechanism. Lp-PLA2 was found to be upregulated in the serum of septic mice induced by cecal ligation and puncture and in the culture supernatant of RAW264.7 cells following lipopolysaccharide and adenosine triphosphate treatments. The contents of Lp-PLA2 were positively correlated with increased concentrations of proinflammatory cytokines in patients with sepsis. Both animal and cellular models showed increased concentrations of proinflammatory cytokines. Spi-1 proto-oncogene (Spi1), highly expressed in these models, was found to activate Pla2g7 transcription. Knockdown of Pla2g7 or Spi1 reduced the proinflammatory cytokine production, mitigated organ damage in mice, and suppressed macrophage migration in vitro. Retinoblastoma binding protein 6 (Rbbp6), poorly expressed in both models, was found to reduce Spi1 protein stability through ubiquitination modification. Rbbp6 overexpression similarly suppressed inflammatory activation of RAW264.7 cells, which was counteracted by Pla2g7 or Spi1 upregulation. In summary, this study demonstrates that the Pla2g7 loss and Spi1 upregulation participate in inflammatory responses in sepsis by elevating the Lp-PLA2 levels.

Serum levels of lipoprotein-associated phospholipase A2 are associated with coronary atherosclerotic plaque progression in diabetic and non-diabetic patients.

BACKGROUND: Lp-PLA2 is linked to cardiovascular diseases and poor outcomes, especially in diabetes, as it functions as a pro-inflammatory and oxidative mediator. OBJECTIVES: This research aimed to explore if there is a connection between the serum levels of Lp-PLA2 and the progression of coronary plaques (PP) in individuals with type 2 diabetes mellitus (T2DM) and those without the condition. MATERIALS AND METHODS: Serum Lp-PLA2 levels were measured in 137 T2DM patients with PP and 137 T2DM patients with no PP, and in 205 non-diabetic patients with PP and 205 non-diabetic patients with no PP. These individuals met the criteria for eligibility and underwent quantitative coronary angiography at the outset and again after about one year of follow-up. The attributes and parameters of the participants at the outset were recorded. RESULTS: Increased serum levels of Lp-PLA2 were closely associated with coronary artery PP, and also significantly correlated with change of MLD, change of diameter stenosis and change of cumulative coronary obstruction in both diabetic and non-diabetic groups, with higher correlation coefficients in diabetic patients as compared with non-diabetic patients. Moreover, multivariate logistic regression analysis showed that serum Lp-PLA2 level was an independent determinant of PP in both groups, with OR values more significant in diabetic patients than in non-diabetic patients. CONCLUSIONS: Levels of serum Lp-PLA2 show a significant association with the progression of coronary atherosclerotic plaque in patients with T2DM and those without, especially among individuals with diabetes.

[Lipoprotein-associated phospholipase A2 (Lp-PLA2): Relevant biomarker and therapeutic target?] / La phospholipase A2 associée aux lipoprotéines (Lp-PLA2) : biomarqueur pertinent et cible thérapeutique ?

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.

Impaired HDL-associated enzymes and proteins in children and adolescents with weight disorders and their association with novel cardiometabolic indexes.

BACKGROUND AND AIMS: Overweight/obesity (OW/OB) is associated with modifications in lipoprotein (Lp)-associated enzymes and proteins, such as cholesteryl ester transfer protein (CETP), Lp-associated phospholipase A2 (LpPLA2) and paraoxonase (PON)1. No evidence is available regarding underweight (UW). The following indexes have been proposed to better assess atherogenic risk related to weight alterations: triglycerides-glucose index (TyG), visceral adiposity index (VAI) and height-corrected lipid accumulation product (HLAP). AIM: To analyze the presence of alterations in Lp-associated enzymes and proteins in children and adolescents with UW and OW/OB and their relation to novel cardiometabolic indexes. METHODS AND RESULTS: Thirty male children and adolescents with UW, 66 with normal weight (NW) and 30 with OW/OB were included. Anthropometric parameters, glucose, Lp profile and the activities of CETP, LpPLA2 and PON1 were evaluated. Body mass index (BMI)-z, TyG, VAI and HLAP were calculated. UW and NW showed lower CETP activity than OW/OB (Mean ± SD) (218 ± 38vs.224 ± 26vs.237 ± 26%/mL.h; p < 0.05). UW and OW/OB showed lower PON1 activity than NW (318 ± 170vs.409 ± 200vs.310 ± 184 nmol/mL.min; p < 0.05). TyG was higher in OW/OB than UW (p < 0.01), whilst both HLAP (p < 0.05) and VAI (p < 0.01) followed a linear trend across weight categories. After adjusting for age and BMI-z, TyG was an independent predictor of CETP (r2 = 0.25, ß = -0.22, p < 0.01) and LpPLA2 (r2 = 0.21,ß = -0.21,p < 0.05), while VAI (r2 = 0.21,ß = -0.32,p < 0.01) and HLAP (r2 = 0.20,ß = -0.31,p < 0.01) of CETP. CONCLUSIONS: Both UW and OW/OB showed impaired antioxidant PON1 activity. Moreover, TyG, VAI and HLAP were all capable of predicting alterations in crucial modulators of Lp metabolism and vascular inflammation in children and adolescents with varying degrees of alterations in body weight.

Changes and significance of serum monocyte chemoattractant protein-1 and Lp-PLA2 in patients with hypertension and coronary heart disease.

OBJECTIVE: To explore the combined application value of serum monocyte chemoattractant protein-1 and lipoprotein-associated phospholipase A2 in the diagnosis of hypertension and coronary heart disease. METHODS: The cross-sectional case-control study was conducted at Baoji Hospital of Traditional Chinese medicine, Shaanxi, China, from April 2018 to May 2020, and comprised patients with suspected hypertension and coronary heart disease. Patients with both hypertension and coronary heart disease formed Group A, and those with simple hypertension formed Group B. Healthy individuals formed the control Group C. Receiver operating characteristic curve was used to evaluate the value of serum monocyte chemoattractant protein-1 combined with lipoprotein-associated phospholipase A2 in the diagnosis of hypertension complicated with coronary heart disease. Data was analysed using SPSS 25. RESULTS: Of the 306 subjects, there were 122(40%) in Group A; 68(55.7%) males and 54(44.3%) females with mean age 68.77±5.76 years. There were 92(30%) cases in Group B; 51(55.4%) males and 41(44.6%) females with mean age 68.80±5.28 years. Group C had 92(30%) cases; 50(54.3%) males and 42(45.7%) females with mean age 67.85±5.29 years. Serum monocyte chemoattractant protein-1 and lipoprotein-associated phospholipase A2 levels were higher in Group A than the other two groups (p<0.001), and the levels in patients with carotid plaque total score <2 were lower than those with carotid plaque total score >2 (p<0.001). Area under receiver operating characteristic curve of the combination of the serum markers was 0.883 (95% confidence interval: 0.837-0.929, p<0.001), which was greater than that of two serum markers alone (p<0.05). CONCLUSIONS: Monocyte chemoattractant protein-1 and lipoprotein-associated phospholipase A2 may be involved in pathogenesis of elevated blood pressure and coronary artery disease. Combined detection of the two serum markers can provide a certain basis for the diagnosis and treatment of hypertension and coronary heart disease.

Time-resolved Fluorescence Immunoassay (TRFIA) for the Simultaneous Detection of MMP-9 and Lp-PLA2 in Serum.

Currently, atherosclerosis accounts for the majority of cardiovascular morbidity and mortality worldwide, and predicting the stability of atherosclerotic plaque is the main method to prevent atherosclerotic death. This study aims to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) of matrix metalloprotein-9 (MMP-9) and lipoprotein-associated phospholipaseA2 (Lp-PLA2) to predict atherosclerotic plaque stability. A dual-label TRFIA was introduced for the simultaneous quantification of MMP-9 and Lp-PLA2 using fluorescent lanthanide (Eu3+ and Sm3+) chelates. The performance (sensitivity, specificity, accuracy, precision and reference intervals in different subjects) of this TRFIA was evaluated and compared with commercial kit. The sensitivity of the TRFIA for MMP-9 was 0.85 ng/mL and for Lp-PLA2 was 0.68 ng/mL with high affinity and specificity. The average recoveries were 94.58% to 109.82%, and 104.32% to 109.26%, respectively. All intra- and inter-assay CVs ranged from 3.10% to 5.46%. For the normal subjects, the cutoff value was 160.70 ng/mL for MMP-9 and 183.73 ng/mL for LP-PLA2; for the subjects with stable plaque, the cutoff value was 181.98~309.22 ng/mL for MMP-9 and 194.73~337.89 ng/mL for LP-PLA2; for the subjects with unstable plaque, the cutoff value was 330.43 ng/mL for MMP-9 and 343.23 ng/mL for LP-PLA2. This TRFIA detection results agreed well with the results of commercial kit (R2=0.9567 and R2=0.9771, respectively) in clinical serum samples. The TRFIA developed has a wide detection range and good sensitivity for the high-throughput simultaneous detection of MMP-9 and Lp-PLA2 in serum, which provides a new method for predicting the stability of atherosclerotic plaque.

Estimating the hazard rate difference from case-cohort studies.

The case-cohort design, among many two-phase sampling designs, substantially reduces the cost of an epidemiological study by selecting more informative participants within the full cohort for expensive variable measurements. Despite their benefits, additive hazards models, which estimate hazard differences, have rarely been used for the analysis of case-cohort studies due to the lack of software and application examples. In this paper, we describe a newly developed estimation method that fits the additive hazards models to general two-phase sampling studies along with the R package addhazard that implements it. It allows for missing covariates among cases, cohort stratification, robust variances, and the incorporation of auxiliary information from the full cohort to enhance inference precision. We demonstrate the use of this tool to estimate the association of the risk of coronary heart disease (CHD) with biomarkers high-sensitivity C-reactive protein (hs-CRP) and Lipoprotein-associated phospholipase A2 (Lp-PLA2) by analyzing the Atherosclerosis Risk in Communities Study, which adopted a two-phase sampling design for studying these two biomarkers. We show that the use of auxiliary variables from the full cohort based on calibration techniques improves the precision of the hazard difference being estimated. We observe a synergistic effect of the two biomarkers among participants with lower LDL cholesterol (LDL-C): the CHD hazard rate attributable to the combined action of high hs-CRP and high Lp-PLA2 exceeded the sum of the CHD hazard rate attributable to each one independently by 11.58 (95% CI 2.16-21.01) cases per 1000 person-years. With higher LDL-C, we observe the CHD hazard rate attributable to the combined action of high hs-CRP and medium Lp-PLA2 was less than the sum of their individual effects by 13.42 (95% CI 2.44-24.40) cases per 1000 person-years. This demonstration serves the dual purposes of illustrating analysis techniques and providing insights about the utility of hs-CRP and Lp-PLA2 for identifying the high-risk population of CHD that the traditional risk factors such as the LDL-C may miss. Epidemiologists are encouraged to use this new tool to analyze other case-cohort studies and incorporate auxiliary variables embedded in the full cohort in their analysis.

Oxidized LDL induces procoagulant profiles by increasing lysophosphatidylcholine levels, lysophosphatidylethanolamine levels, and Lp-PLA2 activity in borderline hypercholesterolemia.

BACKGROUND AND AIMS: The increased risk of cardiovascular disease under hypercholesterolemia is due to associations between oxidized low-density lipoprotein (ox-LDL) and lipoprotein-associated phospholipase A2 (Lp-PLA2) and between ox-LDL and coagulant profiles. We investigated the impact of different ox-LDL levels on coagulation time and plasma metabolomes in subjects with borderline hypercholesterolemia. METHODS AND RESULTS: One hundred thirty-one subjects with borderline hypercholesterolemia (serum cholesterol ≥200 mg/dL) were divided into low ox-LDL (n = 66) and high ox-LDL (n = 65) groups. After adjusting for confounding factors, the high ox-LDL group exhibited a significantly decreased activated partial thromboplastin time (aPTT) and prothrombin time (PT) and increased Lp-PLA2 activity. Compared to the low ox-LDL group, the high ox-LDL group exhibited significantly increased intensities of 17 lysophosphatidylcholines (lysoPCs) and 7 lysophosphatidylethanolamines (lysoPEs). Ox-LDL was inversely correlated with aPTT and PT and positively correlated with Lp-PLA2 activity. Positive correlations were also found among ox-LDL, Lp-PLA2 activity, lysoPCs, and lysoPEs. LysoPCs and lysoPEs were inversely correlated with PT and aPTT. The identified plasma metabolites, including amino acids, fatty acid amides, acylcarnitines, and lysophospholipids, were significantly upregulated in the high ox-LDL group. CONCLUSION: High ox-LDL levels may be involved in the development of a procoagulant state in subjects with borderline hypercholesterolemia by increasing Lp-PLA2 activity and lysoPC and lysoPE levels.

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.

Regioselectivity of thiouracil alkylation: Application to optimization of Darapladib synthesis.

Darapladib is one of the most potent Lp-PLA2 (Lipoprotein-associated phospholipase A2) inhibitor with an IC50 of 0.25 nM. We demonstrate that a crucial step of Darapladib synthesis was not correctly described in the literature, leading to the production of wrong regioisomers. Moreover we show that the inhibitory activity is directly linked to the position on N1 since compounds bearing alkylation on different sites have potentially less interaction within the active site of Lp-PLA2.

Association of Lp-PLA2 G994T gene polymorphism with risk of ischemic stroke in Chinese population.

The association between lipoprotein-associated phospholipase A2 (Lp-PLA2) G994T gene polymorphism and the risk of ischemic stroke is unclear. The aim of this study is to investigate the influence of Lp-PLA2 G994T genetic variant on the pathogenesis of ischemic stroke in Chinese population. A total of 348 patients with a clinical diagnosis of ischemic stroke and 260 gender-matched control subjects under physical examination were recruited from hospitals and genotyped for G994T gene polymorphism. The results showed that there was a significant difference in the genotype distribution between the two groups and people with GT or TT genotype were associated with the higher risk of ischemic stroke even after adjusting the effects of potential confounding factors. In addition, both ischemic stroke patients and control subjects carrying T allele showed relatively lower Lp-PLA2 activity and higher oxLDL level. Therefore, Lp-PLA2 G994T gene polymorphism may be an independent risk factor of ischemic stroke in Chinese population.

Lp-PLA2 silencing protects against ox-LDL-induced oxidative stress and cell apoptosis via Akt/mTOR signaling pathway in human THP1 macrophages.

Atherosclerosis is a disease of the large- and medium-size arteries that is characterized by the formation of atherosclerotic plaques, in which foam cells are the characteristic pathological cells. However, the key underlying pathomechanisms are still not fully elucidated. In this study, we investigated the role of lipoprotein-associated phospholipase A2 (Lp-PLA2) in ox-LDL-induced oxidative stress and cell apoptosis, and further, elucidated the potential machanisms in human THP1 macrophages. Flow cytometry and western blot analyses showed that both cell apoptosis and Lp-PLA2 expression were dose-dependently elevated after ox-LDL treatment for 24 h and also time-dependently increased after 50 mg/L ox-LDL incubation in THP1 macrophages. In addition, Lp-PLA2 silencing decreased ox-LDL-induced Lp-PLA2 and CD36 expression in THP1 macrophages. We also found that the levels of oil red O-staining, triglyceride (TG) and total cholesterol (TC) were significantly upregulated in ox-LDL-treated THP1 cells, but inhibited by Lp-PLA2 silencing. Furthermore, ox-LDL treatment resulted in significant increases of ROS and MDA but a marked decrease of SOD, effects that were reversed by Lp-PLA2 silencing in THP1 cells. Lp-PLA2 silencing reduced ox-LDL-induced cell apoptosis and caspase-3 expression in THP1 cells. Moreover, Lp-PLA2 siRNA transfection dramatically lowered the elevated levels of p-Akt and p-mTOR proteins in ox-LDL-treated THP1 cells. Both PI3K inhibitor LY294002 and mTOR inhibitor rapamycin decreased the augmented caspase-3 expression and TC content induced by ox-LDL, respectively. Taken together, these results revealed that Lp-PLA2 silencing protected against ox-LDL-induced oxidative stress and cell apoptosis via Akt/mTOR signaling pathway in human THP1 macrophages.

Effect of intensive insulin treatment on plasma levels of lipoprotein-associated phospholipase A2 and secretory phospholipase A2 in patients with newly diagnosed type 2 diabetes.

BACKGROUND: China has the highest absolute disease burden of diabetes worldwide. For diabetic patients, diabetes-related vascular complications are major causes of morbidity and mortality. The roles of lipoprotein-associated phospholipase A2 (Lp-PLA2) and secretory phospholipase A2 (sPLA2) as inflammatory markers have been recently evaluated in the pathogenesis of both diabetes and atherosclerosis. We aimed to determine the mechanism through which patients with newly diagnosed type 2 diabetes gain long-term vascular benefit from intensive insulin therapy by evaluating the change in Lp-PLA2 and sPLA2 levels after early intensive insulin treatment and its relevance with insulin resistance and pancreatic ß-cell function. METHODS: In total, 90 patients with newly diagnosed type 2 diabetes mellitus were enrolled. All patients received continuous subcutaneous insulin infusion (CSII) for approximately 2 weeks. Intravenous glucose-tolerance test (IVGTT) and oral glucose-tolerance test (OGTT) were performed, and plasma concentrations of Lp-PLA2 and sPLA2 were measured before and after CSII. RESULTS: Levels of Lp-PLA2 and sPLA2 were significantly higher in diabetic patients with macroangiopathy than in those without (P < 0.05). After CSII, the sPLA2 level decreased significantly in all diabetic patients (P < 0.05), while the Lp-PLA2 level changed only in those with macroangiopathy (P < 0.05). The area under the curve of insulin in IVGTT and OGTT, the acute insulin response (AIR3-5), early phase of insulin secretion (ΔIns30/ΔG30), modified ß-cell function index, and homeostatic model assessment for ß-cell function (HOMA-ß) increased after treatment even when adjusted for the influence of insulin resistance (IR; P < 0.001). The HOMA-IR was lower after treatment, and the three other indicators adopted to estimate insulin sensitivity (ISIced, IAI, and QUICKI) were higher after treatment (P < 0.05). Correlation analysis showed that the decrease in the Lp-PLA2 and sPLA2 levels was positively correlated with a reduction in HOMA-IR after CSII (P < 0.05). Additionally, multiple linear regression analysis showed that Lp-PLA2 and sPLA2 independently correlated with HOMA-IR (P < 0.05). CONCLUSIONS: Lp-PLA2 and sPLA2 are closely related to insulin resistance and macroangiopathy in diabetic patients. Intensive insulin therapy might help improve IR and protect against diabetic macroangiopathy by influencing the Lp-PLA2 and sPLA2 levels. TRIAL REGISTRATION: ChiCTR-TRC-10001618 2010 September 16.

Plasma Lipoprotein-Associated Phospholipase A2 Levels Correlated with the Cardio-Ankle Vascular Index in Long-Term Type 2 Diabetes Mellitus Patients.

The circulating levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) can be a simple, but practical and useful marker of cardiovascular disease (CVD). As limited studies are available in patients with diabetes mellitus (DM), further studies are needed to establish the clinical application of Lp-PLA2 in DM practice. The present study investigated the correlation between Lp-PLA2 and the cardio-ankle vascular index (CAVI), a recent marker of arterial stiffness, in DM patients according to their diabetes duration. Clinical data, including the plasma Lp-PLA2 mass and CAVI values, were collected from CVD-free type 2 DM female patients (n = 65, mean age 62 years, mean hemoglobin A1c 7.0%). The Lp-PLA2 level of patients with a diabetes duration of <10 years (n = 40:20.2 IU/mL) was not significantly different from that of patients with a diabetes duration of ≥10 years (n = 25:20.5 IU/mL), while the CAVI level was significantly higher in patients with ≥10 years (9.0) than in those with <10 years (8.1; p < 0.05). A stepwise multiple regression analysis found a positive correlation between the Lp-PLA2 and CAVI levels (ß = 0.43, p < 0.01) in patients with a diabetes duration of ≥10 years. This correlation between Lp-PLA2 and CVAI suggests the possible use of Lp-PLA2 in DM patients with long-term disease. Further studies on Lp-PLA2 are warranted in DM practice in relation to the disease duration.

[Lp-PLA2, a biomarker of vascular inflammation and vulnerability of atherosclerosis plaques]. / La Lp-PLA2, marqueur d'inflammation vasculaire et de vulnérabilité de la plaque d'athérosclérose.

A chronic inflammation is involved in various stages of development of the atherosclerotic plaques. Among the emerging biomarkers of atherogenesis, the lipoprotein-associated phospholipase A2 (Lp-PLA2), formerly known as PAF-acetylhydrolase (McIntyre et al., 2009), hydrolyses the oxidized short chain phospholipids of low-density lipoproteins (LDL), thereby releasing pro-inflammatory mediators (lysophospholipids and oxidized fatty acids). Lp-PLA2, produced by monocytes/macrophages and T-lymphocytes, and mainly associated with LDL (Gazi et al., 2005), is predominantly expressed in the necrotic center of the atherosclerotic plaques and in the macrophage-rich areas (Kolodgie et al., 2006). It would have a predictive role of cardiovascular (CV) events in relation to the vulnerability of atherosclerotic plaques. Determination of Lp-PLA2 has been proposed in the assessment of the CV risk, to ensure a better stratification of populations at intermediate risk for targeted therapy (Davidson et al., 2008). Its proatherogenic role suggested that inhibition of its activity could ensure a better vascular protection in combination with cholesterol-lowering agents. Nevertheless, Lp-PLA2 is not yet a fully validated marker for use in daily clinical practice, especially since the studies using an inhibitor of Lp-PLA2 (darapladib) (STABILITY Investigators et al., 2014; O'Donoghue et al., 2014) did not show any reduction in coronary events. Lp-PLA2 could have a site-specific role in plaque inflammation and development (Fenning et al., 2015). High Lp-PLA2 activity could reflect a response to pro-inflammatory stress characteristic of atherosclerosis (Marathe et al., 2014). This presentation aims at clarifying the involvement of Lp-PLA2 in the pathophysiology of atherosclerosis, and at assessing its interest both as a biomarker for the onset of CV events and as a therapeutic target.

Critical appraisal of inflammatory markers in cardiovascular risk stratification.

Despite great progress in prevention strategies, pharmacotherapy and interventional treatment of coronary artery disease (CAD), cardiovascular events still constitute the leading cause of mortality and morbidity in the modern world. Traditional risk factors, including hypertension, diabetes mellitus, smoking, obesity, dyslipidemia, and positive family history account for the occurrence of the majority of these events, but not all of them. Adequate risk assessment remains the most challenging in individuals classified into low or intermediate risk categories. Inflammation plays a key role in the initiation and promotion of atherosclerosis and may lead to acute coronary syndrome (ACS) by the induction of plaque instability. For this reason, numerous inflammatory markers have been extensively investigated as potential candidates for the enhancement of cardiovascular risk assessment. This review aims to critically assess the clinical utility of well-established (C-reactive protein [CRP] and fibrinogen), newer (lipoprotein-associated phospholipase A2 [Lp-PLA2] and myeloperoxidase [MPO]) and novel (growth differentiation factor-15 [GDF-15]) inflammatory markers which, reflect different pathophysiological pathways underlying CAD. Although according to the traditional approach all discussed inflammatory markers were shown to be associated with the risk of future cardiovascular events in individuals with and without CAD, their clear clinical utility remains not fully elucidated. Current recommendations of numerous scientific societies predominantly advocate routine assessment of CRP in healthy people with intermediate cardiovascular risk. However, these recommendations substantially vary in their strength among particular societies. These discrepancies have a multifactorial background, including: (i) the strong prognostic value of CRP supported by solid scientific evidence and proven to be comparable in magnitude with that of total and high-density lipoprotein cholesterol, or hypertension, (ii) favourable analytical characteristics of commercially available CRP assays, (iii) lack of CRP specificity and causal relationship between CRP concentration and cardiovascular risk, and (iv) CRP dependence on other classical risk factors. Of major importance, CRP measurement in healthy men ≥50 years of age or healthy women ≥60 years of age with low-density lipoprotein cholesterol <130 mg/dL may be helpful in the selection of patients for statin therapy. Additionally, evaluation of CRP and fibrinogen or Lp-PLA2 may be considered to facilitate risk stratification in ACS patients and in healthy individuals with intermediate cardiovascular risk, respectively. Nevertheless, the clinical utility of CRP requires further investigation in a broad spectrum of CAD patients, while other promising inflammatory markers, particularly GDF-15 and Lp-PLA2, should be tested in individuals both with and without established CAD. Further studies should also focus on novel performance metrics such as measures of discrimination, calibration and reclassification, in order to better address the clinical utility of investigated biomarkers and to avoid misleadingly optimistic results. It also has to be emphasized that, due to the multifactorial pathogenesis of CAD, detailed risk stratification remains a complex process also involving, beyond assessment of inflammatory biomarkers, the patient's clinical characteristics, results of imaging examinations, electrocardiographic findings and other laboratory parameters (e.g. lipid profile, indices of renal function, markers of left ventricular overload and fibrosis, and biomarkers of myocardial necrosis, preferably cardiac troponins).

Lp-PLA2 is associated with structural valve degeneration of bioprostheses.

OBJECTIVES: In this study, we sought to determine the metabolic markers associated with structural valve degeneration (SVD). BACKGROUND: Structural valve degeneration (SVD) is the major cause of bioprosthetic valve failure leading to bioprostheses (BPs) stenosis or regurgitation. We hypothesized that lipoprotein-associated phospholipase A2 (Lp-PLA2) is involved in the SVD of BPs. METHODS: We included 197 patients who underwent aortic valve replacement with a bioprosthetic valve and had echocardiographic follow-up to evaluate valve function. Moreover, explanted BPs (n = 39) were analysed by immunohistochemistry for the expression of Lp-PLA2. RESULTS: After a mean follow-up of 7·9 ±0·2 years, forty-one patients (21%) were identified as developing SVD. Patients with SVD had significantly higher plasma level of Lp-PLA2 mass (151·8 ± 9·2 ng/mL vs. 133·2 ± 3·4 ng/mL, P = 0·03) and activity (27·6 ± 0·9 nmol/min/mL vs. 25·0 ± 0·4 nmol/min/mL, P = 0·005). Multivariate analysis revealed that Lp-PLA2 activity (OR: 1·09, 95% CI: 1·01-1·18; P = 0·03) was the strongest independent predictor of SVD. Immunohistochemistry studies of explanted BP showed that 77% of explanted BPs had the expression of Lp-PLA2, which correlated with the density of macrophages (CD68), and ox-LDL levels in bioprosthetic tissues. CONCLUSIONS: Increased blood plasma activity of Lp-PLA2 is associated with higher prevalence of SVD. These findings open new avenues for the identification of patients at risk for SVD and for the development of pharmacotherapy aiming at the prevention of SVD.

Metformin suppresses metabolic dysfunction-associated fatty liver disease by ferroptosis and apoptosis via activation of oxidative stress.

Metformin is known for its antioxidant properties and ability to ameliorate metabolic dysfunction-associated fatty liver disease (MAFLD) and is the focus of this study. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is linked to MAFLD risk. This study investigated the effects of metformin on ferroptosis in free fatty acid (FFA)-treated Huh7 hepatoma cells and its association with MAFLD risk. Using Western blot, immunofluorescence, and ELISA, this study revealed that FFA treatment led to increased intracellular fat and iron accumulation, heightened Lp-PLA2 expression, reduced levels of the cysteine transporter SLC7A11 and glutathione peroxidase 4 (GPX4), altered glutathione (GSH)/oxidized glutathione (GSSG) ratios, generation of reactive oxygen species (ROS), and initiation of lipid peroxidation, which ultimately resulted in cell ferroptosis. Importantly, metformin reversed FFA-induced iron accumulation, and this effect was attenuated by ferrostatin-1 but enhanced by erastin, RSL3, and si-GPX4. Additionally, metformin activated antioxidant and antiapoptotic mechanisms, which reduced lipid peroxidation and suppressed Lp-PLA2 expression in FFA-treated Huh7 cells. In conclusion, our findings indicate that metformin may protect against MAFLD by inhibiting iron accumulation and Lp-PLA2 expression through the ROS, ferroptosis, and apoptosis signaling pathways. This study highlights potential therapeutic strategies for managing MAFLD-related risks and emphasizes the diverse roles of metformin in maintaining hepatocyte balance.

Metformin lowered Lp-PLA2 levels in human Huh7 hepatoma cells.Both fatty acid and iron metabolism improved after metformin treatment.Metformin alleviated oxidative stress, apoptosis, lipid peroxidation and ferroptosis.

Association of High-Sensitivity C-Reactive Protein and Lipoprotein-Associated Phospholipase A2 with Metabolically Unhealthy Phenotype: A Cross Sectional Study.

Objective: Whether the combination of high-sensitivity C-reactive protein (hs-CRP) and Lipoprotein-associated Phospholipase A2 (Lp-PLA2) was an independent risk factor for metabolic unhealthy is unknown. This study aimed to evaluate the association between combining hs-CRP and Lp-PLA2 and metabolic unhealthy. Methods: A total of 3198 participants who underwent routine health check-up examinations. The participants completed inflammation indicators (hs-CRP and Lp-PLA2) examination and physical assessments. Four phenotypes were determined according to obesity and metabolic health status. Meanwhile, the participants were divided into four groups according to the level of hs-CRP and Lp-PLA2. The cross-sectional association between hs-CRP, Lp-PLA2 and metabolic unhealthy was tested by logistic regression analysis. Results: About 30.48%, 17.35%, 17.32% and 34.83% had MHNO, MUNO, MHO, and MUO, respectively. The combination of the hs-CRP and Lp-PLA2 levels was significantly correlated with metabolic unhealthy in non-obese subjects. However, in obese subjects, only hs-CRP level was significantly correlated with metabolic unhealthy. Conclusion: The hs-CRP and Lp-PLA2 together were significantly associated with metabolic unhealthy in non-obese subjects. hs-CRP level was significantly correlated with metabolic unhealthy in obese subjects.