The recent effects of small dose of folic acid on lipoprotein-associated phospholipase A2 and systolic blood pressure variability in coronary heart disease patients with hyperhomocysteinemia: A single-center prospective cohort study.

ABSTRACT: To Investigate the recent effects of small dose of folic acid on lipoprotein-associated phospholipase A2 (LP-PLA2) and systolic blood pressure variability in coronary heart disease (CHD) patients with hyperhomocysteinemia.In this prospective cohort study, a total of 167 CHD patients with hyperhomocysteinemia were consecutively enrolled, and they were divided into Group A (without folic acid intervention, n = 99), Group B (with 0.4 mg of folic acid intervention, n = 34), Group C (0.8 mg of folic acid intervention, n = 34). General information, fasting blood glucose, and blood lipid, folic acid, homocysteine, Lp-PLA2, and blood pressure variability were compared among 3 groups. The above indicators were reviewed after 3 months of treatment.There were no statistically significant differences of age, gender, blood pressure, incidence of type 2 diabetes mellitus, fasting blood glucose, folic acid, homocysteine, Lp-PLA2, total cholesterol, 3 acyl glycerin, apolipoprotein B, lipoprotein (a), high density lipoprotein cholesterol, and low density lipoprotein cholesterol were found among 3 groups (P > .05); however, after being treated for 3 months, there was statistically significant difference in folic acid among 3 groups (P < .05), there was statistically significant difference in apolipoprotein A between Group A and Group B (t = 0.505, P = .039), and also between Group A and Group C (t = 0.052, P = .017). There were statistically significant differences in Lp-PLA2 (t = 24.320, P = .016) and systolic blood pressure variability (t = 0.154, P = .018) between Group A and Group C.For CHD patients with hyperhomocysteinemia, the higher dose (0.8 mg) of folic acid supplement was beneficial for increasing the apolipoprotein A, reducing the Lp-PLA2, and improving the systolic blood pressure variation, which might help to improve the prognosis in these patients.

[Influence of short-term intensive insulin therapy on plasma concentration of lipoprotein-associated phospholipase A(2) and secretory phospholipase A(2) in newly diagnosed type 2 diabetic patients].

The aim of the study was to explore the effect and its clinical relevance of short-term intensive insulin treatment on plasma concentrations of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and secretory phospholipase A(2) (sPLA(2)) in newly diagnosed type 2 diabetes mellitus (T2DM). Ninety newly diagnosed T2DM patients were recruited and received continuous subcutaneous insulin infusion (CSII) for about 2 weeks. After CSII, sPLA(2) levels [173.78 (80.95, 278.09) µg/L] were significantly decreased compared with the levels before [219.33 (130.03, 337.30) µg/L], P<0.01, while no statistic significant changes could be viewed in Lp-PLA(2) levels. Correlation analysis showed that the changes of Lp-PLA(2) and sPLA(2) were both positively correlated with the changes of homeostasis model assessment of insulin resistance(HOMA-IR)after CSII (r=0.537, 0.493 respectively, all P<0.05). The Lp-PLA(2) and sPLA(2) level reduction after CSII might help to protect the patients from diabetic macroangiopathy. Trial registration Chinese Clinical Trial Registry, ChiCTR-TRC-10001618.

Genetic invalidation of Lp-PLA2 as a therapeutic target: Large-scale study of five functional Lp-PLA2-lowering alleles.

Aims Darapladib, a potent inhibitor of lipoprotein-associated phospholipase A2 (Lp-PLA2), has not reduced risk of cardiovascular disease outcomes in recent randomized trials. We aimed to test whether Lp-PLA2 enzyme activity is causally relevant to coronary heart disease. Methods In 72,657 patients with coronary heart disease and 110,218 controls in 23 epidemiological studies, we genotyped five functional variants: four rare loss-of-function mutations (c.109+2T > C (rs142974898), Arg82His (rs144983904), Val279Phe (rs76863441), Gln287Ter (rs140020965)) and one common modest-impact variant (Val379Ala (rs1051931)) in PLA2G7, the gene encoding Lp-PLA2. We supplemented de-novo genotyping with information on a further 45,823 coronary heart disease patients and 88,680 controls in publicly available databases and other previous studies. We conducted a systematic review of randomized trials to compare effects of darapladib treatment on soluble Lp-PLA2 activity, conventional cardiovascular risk factors, and coronary heart disease risk with corresponding effects of Lp-PLA2-lowering alleles. Results Lp-PLA2 activity was decreased by 64% ( p = 2.4 × 10-25) with carriage of any of the four loss-of-function variants, by 45% ( p < 10-300) for every allele inherited at Val279Phe, and by 2.7% ( p = 1.9 × 10-12) for every allele inherited at Val379Ala. Darapladib 160 mg once-daily reduced Lp-PLA2 activity by 65% ( p < 10-300). Causal risk ratios for coronary heart disease per 65% lower Lp-PLA2 activity were: 0.95 (0.88-1.03) with Val279Phe; 0.92 (0.74-1.16) with carriage of any loss-of-function variant; 1.01 (0.68-1.51) with Val379Ala; and 0.95 (0.89-1.02) with darapladib treatment. Conclusions In a large-scale human genetic study, none of a series of Lp-PLA2-lowering alleles was related to coronary heart disease risk, suggesting that Lp-PLA2 is unlikely to be a causal risk factor.

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.

Darapladib, a Lipoprotein-Associated Phospholipase A2 Inhibitor, Reduces Rho Kinase Activity in Atherosclerosis.

PURPOSE: Increased lipoprotein-associated phospholipase A2 (Lp-PLA2) activity and Rho kinase activity may be associated with atherosclerosis. The principal aim of this study was to examine whether darapladib (a selective Lp-PLA2 inhibitor) could reduce the elevated Lp-PLA2 and Rho kinase activity in atherosclerosis. MATERIALS AND METHODS: Studies were performed in male Sprague-Dawley rats. The atherosclerosis rats were prepared by feeding them with a high-cholesterol diet for 10 weeks. Low-dose darapladib (25 mg·kg⁻¹·d⁻¹) and high-dose darapladib (50 mg·kg⁻¹·d⁻¹) interventions were then administered over the course of 2 weeks. RESULTS: The serum levels of triglycerides, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), high-sensitivity C-reactive protein (hs-CRP), and Lp-PLA2, significantly increased in atherosclerosis model groups, as did Rho kinase activity and cardiomyocyte apoptosis (p<0.05 vs. sham group), whereas nitric oxide (NO) production was reduced. Levels of TC, LDL-C, CRP, Lp-PLA2, and Rho kinase activity were respectively reduced in darapladib groups, whereas NO production was enhanced. When compared to the low-dose darapladib group, the reduction of the levels of TC, LDL-C, CRP, and Lp-PLA2 was more prominent in the high-dose darapladib group (p<0.05), and the increase of NO production was more prominent (p<0.05). Cardiomyocyte apoptosis of the high-dose darapladib group was also significantly reduced compared to the low-dose darapladib group (p<0.05). However, there was no significant difference in Rho kinase activity between the low-dose darapladib group and the high-dose darapladib group (p>0.05). CONCLUSION: Darapladib, a Lp-PLA2 inhibitor, leads to cardiovascular protection that might be mediated by its inhibition of both Rho kinase and Lp-PLA2 in atherosclerosis.

Darapladib for the treatment of cardiovascular disease.

Elevated levels of phospholipase A2 have been linked to atherosclerotic plaque progression, instability via promoting inflammation and subsequent acute coronary events. Epidemiological studies have demonstrated the correlation between elevated levels associated phospholipase A2 and cardiovascular events. Therefore, specific inhibition of lipoprotein-associated phospholipase A2 with darapladib has been tested as a therapeutic option for atherosclerosis. The aim of this profile is to review the physiologic aspects of lipoprotein-associated phospholipase A2 and to revisit the clinical evidence of darapladib as therapeutic option for atherosclerosis.

Changes in lipoprotein-Associated phospholipase A2 activity predict coronary events and partly account for the treatment effect of pravastatin: results from the Long-Term Intervention with Pravastatin in Ischemic Disease study.

BACKGROUND: Lipoprotein-associated phospholipase A2 (Lp-PLA2) levels are associated with coronary heart disease (CHD) in healthy individuals and in patients who have had ischemic events. METHODS AND RESULTS: The Long-term Intervention with Pravastatin in Ischemic Disease (LIPID) study randomized 9014 patients with cholesterol levels of 4.0 to 7.0 mmol/L to placebo or pravastatin 3 to 36 months after myocardial infarction or unstable angina and showed a reduction in CHD and total mortality. We assessed the value of baseline and change in Lp-PLA2 activity to predict outcomes over a 6-year follow-up, the effect of pravastatin on Lp-PLA2 levels, and whether pravastatin treatment effect was related to Lp-PLA2 activity change. Lp-PLA2 was measured at randomization and 1 year, and levels were grouped as quartiles. The prespecified end point was CHD death or nonfatal myocardial infarction. Baseline Lp-PLA2 activity was positively associated with CHD events (P < 0.001) but not after adjustment for 23 baseline factors (P = 0.66). In 6518 patients who were event free at 1 year, change in Lp-PLA2 was a significant independent predictor of subsequent CHD events after adjustment for these risk factors, including LDL cholesterol and LDL cholesterol changes (P < 0.001). Pravastatin reduced Lp-PLA2 by 16% compared with placebo (P < 0.001). After adjustment for Lp-PLA2 change, the pravastatin treatment effect was reduced from 23% to 10% (P = 0.26), with 59% of the treatment effect accounted for by changes in Lp-PLA2. Similar reductions in treatment effect were seen after adjustment for LDL cholesterol change. CONCLUSION: Reduction in Lp-PLA2 activity during the first year was a highly significant predictor of CHD events, independent of change in LDL cholesterol, and may account for over half of the benefits of pravastatin in the LIPID study.

Simvastatin but not bezafibrate decreases plasma lipoprotein-associated phospholipase A2 mass in type 2 diabetes mellitus: relevance of high sensitive C-reactive protein, lipoprotein profile and low-density lipoprotein (LDL) electronegativity.

OBJECTIVE: Plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) levels predict incident cardiovascular disease, impacting Lp-PLA(2) as an emerging therapeutic target. We determined Lp-PLA(2) responses to statin and fibrate administration in type 2 diabetes mellitus, and assessed relationships of changes in Lp-PLA(2) with subclinical inflammation and lipoprotein characteristics. METHODS: A placebo-controlled cross-over study (three 8-week treatment periods with simvastatin (40 mg daily), bezafibrate (400mg daily) and their combination) was carried out in 14 male type 2 diabetic patients. Plasma Lp-PLA(2) mass was measured by turbidimetric immunoassay. RESULTS: Plasma Lp-PLA(2) decreased (-21 ± 4%) in response to simvastatin (p<0.05 from baseline and placebo), but was unaffected by bezafibrate (1 ± 5%). The drop in Lp-PLA(2) during combined treatment (-17 ± 3%, p<0.05) was similar compared to that during simvastatin alone. The Lp-PLA(2) changes during the 3 active lipid lowering treatment periods were related positively to baseline levels of high sensitive C-reactive protein, non-HDL cholesterol, triglycerides, the total cholesterol/HDL cholesterol ratio and less LDL electronegativity (p<0.02 to p<0.01), and inversely to baseline Lp-PLA(2) (p<0.01). LpPLA(2) responses correlated inversely with changes in non-HDL cholesterol, triglycerides and the total cholesterol/HDL cholesterol ratio during treatment (p<0.05 to p<0.02). CONCLUSIONS: In type 2 diabetes mellitus, plasma Lp-PLA(2) is likely to be lowered by statin treatment only. Enhanced subclinical inflammation and more severe dyslipidemia may predict diminished LpPLA(2) responses during lipid lowering treatment, which in turn appear to be quantitatively dissociated from decreases in apolipoprotein B lipoproteins. Conventional lipid lowering treatment may be insufficient for optimal LpPLA(2) lowering in diabetes mellitus.

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.

Therapeutic modulation of lipoprotein-associated phospholipase A2 (Lp-PLA2).

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a calcium-independent phospholipase A2 that circulates in plasma in association with lipoprotein particles, whereas in atherosclerotic plaques it is co-localized with macrophages. Lp-PLA2 generates two proinflammatory mediators, lysophosphatidylcholine and oxidized nonesterified fatty acids, which play a role in the development of atherosclerotic lesions and formation of a necrotic core, leading to more vulnerable plaques. Epidemiologic studies demonstrate that increased circulating levels of Lp-PLA2 predict an increased risk of myocardial infarction, stroke and cardiovascular mortality. Furthermore, histologic examination of diseased human coronary arteries reveals intense presence of the enzyme in atherosclerotic plaques that are prone to rupture. These considerations suggest Lp-PLA2 as a promising therapeutic target in cardiovascular disease. Plasma levels of Lp-PLA2 are increased in various types of hyperlipidemias, while hypolipidemic drugs reduce plasma Lp-PLA2 activity and mass along with the improvement of plasma lipid profile. A selective inhibitor of Lp-PLA2 activity, darapladib, has been developed and studies in animal models and humans have shown that it effectively and safely reduces Lp-PLA2 activity in plasma and in atherosclerotic plaques. Furthermore, in animal models darapladib decreases plaque area and necrotic core area whereas in humans it prevents the expansion of necrotic core volume. Whether the results obtained from the use of darapladib in studies in vitro, as well as in preclinical and clinical studies would translate into benefits on cardiovascular event outcomes, awaits to be proved in 2 ongoing phase 3 trials.

Combining rosuvastatin with sartans of different peroxisome proliferator-activated receptor-γ activating capacity is not associated with different changes in low-density lipoprotein subfractions and plasma lipoprotein-associated phospholipase A2.

BACKGROUND: Rosuvastatin reduces low-density lipoprotein cholesterol (LDL-C) and plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) Some sartans partially activate peroxisome proliferator-activated receptor-γ (PPARγ), possibly having a favorable effect on metabolic parameters. Telmisartan is the most potent partial PPARγ activator, followed by irbesartan, whereas olmesartan does not hold such capacity. In an open-label randomized study, we assessed the effects of combining sartans of different PPARγ- activating capacity with rosuvastatin on LDL subfractions and plasma Lp-PLA2 in patients with mixed dyslipidemia, hypertension, and prediabetes. METHODS: Following dietary intervention, patients were allocated randomly to rosuvastatin (10 mg/day) plus telmisartan 80 mg/day (RT group, n = 52) or irbesartan 300 mg/day (RI group, n = 48) or olmesartan 20 mg/day (RO group, n = 51). After 6 months of treatment, changes in LDL subfraction cholesterol and plasma Lp-PLA(2) activity and mass were evaluated blindly. RESULTS: A total of 151 patients (73 male; mean age 60 years) were included. Large LDL-C decreased in the RT (-36%), RI (-39%), and RO (-41%) groups (P < 0.001 for all vs. baseline). Small dense LDL-C decreased in the RT (-67%), RI (-58%), and RO (-61%) groups (P < 0.001 for all vs. baseline). All regimens increased LDL particle size versus baseline (RT + 1.4%, P = 0.002; RI + 1.0%, P = 0.04; and RO + 1.4%, P = 0.001). No difference for the change of LDL subfractions and LDL size was noticed among groups. Plasma Lp-PLA2 activity decreased equally in all groups (RT -38%, RI -38%, RO -43%) (P < 0.001 for all vs. baseline). Plasma Lp-PLA2 mass decreased similarly in all groups versus baseline (RT -28%, P = 0.001; RI -32%, P = 0.01; and RO -27%, P = 0.001). No difference for the change of Lp-PLA2 mass or activity was noticed among groups. CONCLUSIONS: The combination of rosuvastatin with sartans of different PPARγ-activating capacity did not differentiate alterations of LDL subfraction cholesterol and plasma Lp-PLA(2) activity and mass.

The effects of statin monotherapy and low-dose statin/ezetimibe on lipoprotein-associated phospholipase A2.

BACKGROUND: Many of the pleiotropic effects of statins remain to be elucidated. HYPOTHESIS: Different statin regimens with similar lipid-lowering efficacy may have different effects on biomarkers of atherothrombosis including lipoprotein-associated phospholipase A2 (Lp-PLA2 ). METHODS: After a 4-week dietary lead-in, 82 hypercholesterolemic patients were randomized to 1 of 2 treatment groups: atorvastatin 20 mg or atorvastatin/ezetimibe 5 mg/5 mg. After 8 weeks of drug treatment, the groups were compared for percent change in lipid parameters, Lp-PLA2 , interleukin-6 (IL-6), monocyte chemoattractant protein-1, and fibrinogen. RESULTS: Low-density lipoprotein cholesterol (LDL-C) lowering was comparable between the 2 groups (-47% ± 11% and -49% ± 7% in the atorvastatin and combination groups, respectively). Although Lp-PLA2 was reduced in both groups, the reduction was greater in the atorvastatin group (-42% and -9% [median], respectively, P = 0.03). Although IL-6 was decreased only in the atorvastatin group, IL-6 changes were not significantly different between the 2 groups. The changes in monocyte chemoattractant protein-1 and fibrinogen were similar in each group. CONCLUSIONS: Atorvastatin monotherapy was stronger at reducing plasma Lp-PLA2 than the low-dose atorvastatin/ezetimibe combination after equivalent LDL-C lowering. This result may provide evidence of potential statin effects beyond the lowering of LDL-C.

The role of lipoprotein-associated phospholipase a2 as a marker and potential therapeutic target in atherosclerosis.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an enzyme that generates inflammatory mediators within atherosclerotic plaques. In epidemiologic studies there is an association between higher plasma Lp-PLA2 activity and myocardial infarction, stroke and cardiovascular mortality. In animal models, darapladib, a specific inhibitor of Lp-PLA2, decreases the size of the atheroma necrotic core and plaques with thin fibrous caps. Early clinical trials suggest darapladib effectively and safely inhibits Lp-PLA2 activity both in plasma and in carotid atheroma. Two large phase III clinical trials that are currently in progress will determine whether darapladib will reduce the risk of myocardial infarction, stroke, and cardiovascular death by stabilizing atherosclerotic plaques.

Lipoprotein-associated phospholipase A2 mass is significantly reduced in dyslipidemic patients treated with lifestyle modification and combination lipid-modifying drug therapy.

Lipoprotein-associated phospholipase A2 (Lp-PLA(2)) mass is a novel inflammatory biomarker. In human blood, Lp-PLA(2) is predominately associated with low-density lipoprotein (LDL). This study examines the ability of lifestyle modification (diet and exercise) and combination lipid therapy to reduce Lp-PLA(2) levels while also determining the relationship between changes in LDL cholesterol and Lp-PLA(2). Thirty dyslipidemic patients who received lifestyle intervention and combination lipid therapy for an average of 6 months were included in these analyses (mean age, 60.9 years); 40% had stable angiographically established coronary artery disease, 40% had the metabolic syndrome, and 70% were men. Drug therapy included omega-3 fish oil, extended-release niacin, colesevelam hydrochloride, and a fixed combination of 10-mg ezetimibe and 40-mg simvastatin. The study revealed a 33% reduction in mean Lp-PLA(2) values (baseline 224.9+/-47.5 vs posttreatment 149.5+/-35.5 ng/mL; P<.001). Significant changes in mean LDL cholesterol from baseline (127.9+/-49.3 vs posttreatment 65.2+/-32.1 mg/dL; P<.001) were also observed. However, regression analysis revealed only a weak positive relationship between changes in LDL cholesterol and Lp-PLA(2) mass (R(2)=0.29; P<.01). Thus, Lp-PLA(2) mass is significantly reduced with lifestyle and combination lipid therapy. Changes in Lp-PLA(2) were only partially explained by the changes observed for LDL cholesterol.

The differentiating effect of glimepiride and glibenclamide on paraoxonase 1 and platelet-activating factor acetylohydrolase activity.

AIMS: The present study was designed to examine the effect of sulphonylureas, glimepiride (GM) and glibenclamide (GB), on paraoxonase 1 (PON1) and platelet activating factor acetylohydrolase (PAF-AH) activity in normal and streptozotocin (STZ)-induced (50 mg/kg) diabetic rats. MAIN METHODS: In treated groups, glimepiride (0.1 mg/kg) or glibenclamide (2 mg/kg) was given orally for 4 weeks. A PON1 and PAF-AH activity were estimated by spectrophotometric method. KEY FINDINGS: Hyperglycemia was accompanied by a significant decrease in plasma PON1 activity toward paraoxon (P < 0.001) and phenyl acetate (P < 0.01) and increase in plasma PAF-AH activity (P < 0.01). In STZ-induced diabetic rats the administration of both GM and GB had no effect on plasma PON1 activity but reversed elevated plasma PAF-AH activity (GM: P < 0.05, GB: P < 0.01). In non-diabetic rats after either GM or GB administration the decreased PON1 activity in the plasma was observed (GM: P < 0.001, GB: P < 0.05), but plasma PAF-AH activity remained unchanged. Both GM and GB had no effect on total plasma antioxidant capacity in diabetic and control treated groups. Additionally, both drugs increased PON1 activity toward phenyl acetate in the liver, in diabetic rats (GM: P < 0.05, GB:ns) as well as in non-diabetic rats (GM: P < 0.001, GB: P < 0.001), and reduced lipid peroxidation in the liver. SIGNIFICANCE: These results demonstrate that in streptozotocin-induced diabetic rats as well as in normal rats glimepiride and glibenclamide have no beneficial effects on circulating PON1 and PAF-AH activities, but both drugs increase PON1 activity in the liver.

Editorial: why inhibition of lipoprotein-associated phospholipase A2 has the potential to improve patient outcomes.

PURPOSE OF REVIEW: Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a risk factor as strong as low-density lipoprotein (LDL) cholesterol. Therapies targeting Lp-PLA2 in plasma and plaque are now being developed. This article will review these data. RECENT FINDINGS: Lp-PLA2 is intimately involved in the development of atherosclerosis and is found in vulnerable human plaques. Multiple epidemiological studies have shown that Lp-PLA2 is related to the occurrence of myocardial infarction (MI), stroke and vascular death.Darapladib is a novel oral compound that selectively inhibits Lp-PLA2 in plasma and in human plaques. Darapladib has also been shown to halt necrotic core progression in coronary arteries over a 12-month period and to have few adverse effects. SUMMARY: Two large phase III trials are randomizing 26,000 patients to darapladib or placebo with chronic coronary heart disease or following an acute coronary syndrome. The primary composite outcomes are cardiovascular death, MI or stroke and results should be available in 2012. Darapladib has the potential to improve patient outcomes in addition to evidence-based treatments by modulating mechanisms of disease that have not been addressed by current therapies.

Lipoprotein-associated phospholipase A2: a new therapeutic target.

Lipoprotein-associated phospholipase A2 is an enzyme produced by inflammatory cells, which binds to apolipoprotein B-containing lipoproteins and degrades oxidatively modified phospholipids in low-density lipoprotein cholesterol particles, leading to formation of proinflammatory and cytotoxic products. Experimental studies suggest a role for lipoprotein-associated phospholipase A2 in the formation of advanced rupture-prone atherosclerotic lesions, and epidemiological investigations have linked it to increased cardiovascular risk. Ongoing trials are evaluating the role of novel pharmacological inhibitors of this enzyme, such as darapladib, in the management of high-risk coronary artery disease patients.

Lp-PLA2: A new target for statin therapy.

Inflammation plays an important role in atherogenesis and plaque vulnerability. Inflammatory-type markers have been evaluated for their association with atherosclerotic vascular disease and their ability to improve cardiovascular disease (CVD) risk stratification. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is a vascular-specific inflammatory enzyme that increases the risk of CVD events and stroke approximately twofold. A consensus panel recently recommended the measurement of Lp-PLA(2) in moderate-risk and high-risk patients for improved risk stratification and modification of low-density lipoprotein target levels. Lipid-lowering agents, particularly statins, lower Lp-PLA(2) mass and activity; therefore, Lp-PLA(2) may represent an important target of lipid-lowering therapy for reducing the inflammatory nature of atherosclerosis and plaque vulnerability. It is unknown whether lowering inflammatory markers such as Lp-PLA(2) will have a direct benefit on CVD events and mortality. A large morbidity and mortality trial was recently initiated to evaluate the long-term safety and efficacy of darapladib, an Lp-PLA(2) antagonist, in patients with high-risk coronary heart disease.

Darapladib and atherosclerotic plaque: should lipoprotein-associated phospholipase A2 be a therapeutic target?

There is great interest in developing a reliable measure of atherosclerotic disease activity that can serve as an index of response to antiatherosclerotic therapies. The epidemiologic relationship between lipid measures, most notably low-density lipoprotein cholesterol (LDL-C), and binary cardiovascular events has been confirmed in treatment trials reliably demonstrating a reduction in LDL-C translating into improved cardiovascular outcomes. Lipoprotein-associated phospholipase A2 (LpPLA2) is part of a family of lipases involved in the modification of lipids within the atheroma and may be a complimentary therapeutic target to the reduction of LDL-C in patients with advanced atherosclerosis. Darapladib is an orally available, specific inhibitor of LpPLA2 activity and has been shown to reduce lysophosphatidylcholine content and expression of multiple genes associated with macrophage and T-lymphocyte functioning, with considerable decrease in plaque and necrotic core area. Thus, this agent holds the hope of being a bona fide antiatherosclerotic therapy that can be gauged through blood measurement of LpPLA2 activity.

Anti-platelet-activating factor effects of highly active antiretroviral therapy (HAART): a new insight in the drug therapy of HIV infection?

Platelet-activating factor (PAF) is a potent inflammatory mediator, which seems to play a role in the pathogenesis of several AIDS manifestations such as AIDS dementia complex, Kaposi's sarcoma, and HIV-related nephropathy. PAF antagonists have been studied in these conditions with promising results. In order to examine the possible interactions between PAF and antiretroviral therapy, we studied the effect of nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and protease inhibitors against PAF biological activities and its basic biosynthetic enzymes dithiothreitol-insensitive PAF-cholinephosphotransferase (PAF-CPT) and lyso-PAF-acetyltransferase (Lyso-PAF-AT), as well as its main degradative enzyme PAF-acetylhydrolase, of human mesangial cell line (HMC). We also studied the effect of several backbones and highly active antiretroviral therapy (HAART) regimens against PAF activity. Among the drugs tested, several inhibited PAF-induced platelet aggregation in a concentration-depended manner, with tenofovir, efavirenz, and ritonavir exhibiting the higher inhibitory effect. In addition, when these drugs were combined in backbones and HAART regimens based on American antiretroviral therapy proposals, they also synergistically exhibited an inhibitory effect against PAF-induced platelet aggregation. Several of these drugs have also inhibited in vitro microsomal PAF-CPT activity, and concentrations of lopinavir-r or tenofovir-DF (similar to their IC(50) against PAF-induced platelet aggregation) exhibited the same effect against PAF-CPT and Lyso-PAF-AT when added in the cell medium of cultured HMC. In addition, in naïve patients treated with one of the most potent anti-PAF HAART regimens (efavirenz/emtricitabine/tenofovir-DF) for a period of 1 month, a significant reduction of the specific activity of PAF-CPT of washed human leukocytes of these patients was also observed, compared with its levels before the HAART treatment. These promising results need to be further studied and confirmed by additional in vivo tests in order to optimize HAART efficacy.