The elevation of apoB in hypercholesterolemic patients is primarily attributed to the relative increase of apoB/Lp-PLA₂

Research Advance of Chinese Medicine in Treating Atherosclerosis: Focus on Lipoprotein-Associated Phospholipase A2

As a serious cardiovascular disease, atherosclerosis (AS) causes chronic inflammation and oxidative stress in the body and poses a threat to human health. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a member of the phospholipase A2 (PLA2) family, and its elevated levels have been shown to contribute to AS. Lp-PLA2 is closely related to a variety of lipoproteins, and its role in promoting inflammatory responses and oxidative stress in AS is mainly achieved by hydrolyzing oxidized phosphatidylcholine (oxPC) to produce lysophosphatidylcholine (lysoPC). Moreover, macrophage apoptosis within plaque is promoted by localized Lp-PLA2 which also promotes plaque instability. This paper reviews those researches of Chinese medicine in treating AS via reducing Lp-PLA2 levels to guide future experimental studies and clinical applications related to AS.

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

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

The correlation between lipoprotein associated phospholipase A2 and central overweight status

OBJECTIVE

Being overweight is associated with an increased risk of diabetes mellitus, hypertension, and cardiovascular disease. Lipoprotein-associated phospholipase A2 (Lp-PLA2) can independently predict the risk of cardiovascular disease. This study is aimed to investigate whether Lp-PLA2 was associated with an overweight status.

METHODS

This was a cross-sectional study that enrolled 3760 Chinese adults (age, 18-50 years) who underwent medical examination department of Xiamen Chang-Gung Hospital (XCGH) from 2018 to 2020. To explore the distribution of overweight classifications in the Chinese population, we evaluated the correlation of the overweight status with Lp-PLA2, after correcting for possible influencing factors.

RESULTS

The Lp-PLA2 level was greater in male than in female subjects (p < 0.001). Subjects with a central overweight status had a greater Lp-PLA2 level than those with normal weight and a peripheral overweight status, in both male and female cohorts. The Lp-PLA2 level was significantly greater in those with additional comorbidities (namely diabetes mellitus (DM), hypertension (HTN), overweight, and metabolic syndrome (MetS)). The age-adjusted and LDL-adjusted Lp-PLA2 level also was significantly higher in the DM (+) and HTN (-) subgroups than in the DM (-), HTN (-), DM (-), and HTN (+) subgroups.

CONCLUSION

Lp-PLA2 is associated with sex, central overweight status, diabetes, hypertension, and MetS in adults aged < 50 years and the age-adjusted and LDL-adjusted Lp-PLA2 was significantly higher in the DM (+) and HTN (-) subgroups than in the DM (-) and HTN (-) and DM (-) and HTN (+) subgroups.

Association of Serum Cholesterol Ester Transfer Protein Levels with Taq IB Polymorphism in Acute Coronary Syndrome

Information on the relationship between circulating cholesteryl ester transfer protein (CETP) levels and coronary heart disease (CHD) incidence (and also, therefore, acute coronary syndrome [ACS]) is conflicting. Many studies have been published concerning this relationship, most of which have incompatible results. In our study, we aimed to determine serum CETP levels in subject individuals with ACS and healthy control individuals, and the association of those levels with Taq IB polymorphism. The current study was conducted with 62 hospitalized patients who had been diagnosed with ACS and 26 controls. All subjects were selected from a previous study of which we are among the coauthors. Serum CETP levels were determined by quantitative enzyme-linked immunosorbent assay (ELISA). The mean serum CETP levels in all patients were significantly higher than those in controls. CETP TaqIB polymorphism affected serum CETP levels, with higher serum CETP for the GA genotype in both groups than in other genotypes. Although the AA genotype showed higher CETP levels than the GG genotype in patients with ACS, the GG showed higher CETP than the AA in healthy controls. Our results support an association between high serum CETP and ACS incidence. Our study helped address some of the controversies regarding the relationship of serum CETP mass to atherosclerosis, in addition to the association of ACS occurrence with circulating CETP levels.

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.

Effect of combined vitamin D administration plus dietary intervention on oxidative stress markers in patients with metabolic syndrome: A pilot randomized study

BACKGROUND

Metabolic syndrome (MetS) patients can have low 25-hydroxyvitamin D 25(OH)VitD levels, which may be associated with increased oxidative stress. There is little data on the effect of 25(OH)VitD administration plus dietary intervention on oxidative stress markers in these patients.

AIM

To study the effect of 25(OH)VitD administration plus dietary intervention on oxidative stress markers in MetS patients.

METHODS

This is a pre-specified analysis of a previously published study (NCT01237769 ClinicalTrials.gov). MetS participants (n = 50, 52 ± 10 years) were given dietary instructions and were randomized to 25(OH)VitD 2.000 IU/day p.o. (Suppl group) or no supplementation (No-Suppl group). Serum 25(OH)VitD, oxidized LDL (ox-LDL), paraoxonase activity (PON-1), arylesterase activity (ARYL) and urine 8-isoprostane (8-iso-PGF_2a) levels were measured at baseline and after 3 months.

RESULTS

MetS patients had low baseline 25(OH)VitD levels, which increased by 90% in the Suppl group [from 16.1 (3.3-35.1) to 30.6 (8.4-67.6) ng/mL, p = 0.001] and by 33.3% in the No-Suppl group [from 9.9 (4.0-39.6) to 13.2 (3.5-36.8) ng/mL, p = NS] after intervention. Ox-LDL, PON-1 and ARYL did not change significantly at follow-up in both groups, except for urine 8-iso-PGF_2a levels that decreased by 22.7% in the Suppl group [from 48.8 (26.8-137.1) to 37.7 (12.3-99.0) ng/mmol creatinine, p = 0.015] and by 14.4% in No-Suppl group [from 45.8 (16.6-99.3) to 39.2 (13.3-120.1) ng/mmol creatinine, p = NS]. The reduction in 8-iso-PGF_2a levels did not differ significantly between the 2 groups.

CONCLUSION

The administration of 25(OH)VitD plus dietary intervention in patients with MetS was not associated with meaningful reductions in oxidative stress markers compared with dietary intervention alone.

Plasma PAF-AH (PLA2G7): Biochemical Properties, Association with LDLs and HDLs, and Regulation of Expression

This chapter is focused on the plasma form of PAF-acetylhydrolase (PAF-AH), a lipoprotein-bound, calcium-independent phospholipase A2 activity also referred to as lipoprotein-associated phospholipase A2 and PLA2G7. PAF-AH catalyzes the removal of the acyl group at the sn-2 position of PAF and truncated phospholipids generated in settings of inflammation and oxidant stress. Here, I discuss current knowledge related to the structural features of this enzyme, including the molecular basis for association with lipoproteins and susceptibility to oxidative inactivation. The circulating form of PAF-AH is constitutively active and its expression is upregulated by mediators of inflammation at the transcriptional level. Several new mechanisms of regulation have been identified in recent years, including effects mediated by PPARs, VEGFR, and the state of cellular differentiation. Moreover, I discuss recent studies describing significant variations in the structure and regulation of PAF-AH from diverse species, which is likely to have important implications for the function of this enzyme in vivo.