Paraoxonase 1 and platelet-activating factor acetylhydrolase activities in patients with low hdl-cholesterol levels with or without primary hypertriglyceridemia

doi:10.1016/j.arcmed.2004.02.002

Archives of Medical Research

Volume 35, Issue 3, May–June 2004, Pages 235-240

https://doi.org/10.1016/j.arcmed.2004.02.002 Get rights and content

Abstract

Background

Previous studies have shown that high density lipoprotein (HDL)-deficient states are associated with reduced paraoxonase 1 (PON1) activity. However, HDL reduction caused by primary hypertriglyceridemia has not been fully explored. The aim of the present study was to evaluate whether PON1 and platelet-activating factor acetylhydrolase (PAF-AH), two antioxidant enzymes, were altered in patients with low HDL-cholesterol levels with or without primary hypertriglyceridemia in comparison with control normolipemic subjects.

Methods

We studied 24 patients with low HDL-cholesterol levels with (n = 12) or without (n = 12) primary hypertriglyceridemia in comparison with 12 control subjects who presented normal HDL-cholesterol and triglyceride levels. Paraoxon and phenylacetate were used as substrate for measuring PON1 activities and 1-hexadecyl-2-[³H]acetyl-glycero-3-phosphocholine for platelet-activating factor acetylhydrolase (PAF-AH) activity. Double substrate method was used to assign phenotypes. Lipid, lipoprotein, apolipoprotein, and lipoprotein particles were determined by standardized methods.

Results

Both PON1 activities were significantly reduced in patients with low HDL-cholesterol levels. This reduction could be selectively attributed to the hypertriglyceridemic subgroup. PAF-AH activity was not different between hypoalphalipoproteinemic patients and controls. PON1 activities correlated positively and significantly with HDL-cholesterol, HDL₂-cholesterol, HDL₃-cholesterol, HDL-phospholipids, apo A-I, apo A-II, and LpA-I:A-II. PAF-AH correlated positively and significantly with total and low density lipoprotein-cholesterol.

Conclusions

Data from this study would suggest that in hypoalphalipoproteinemic syndrome, particularly when associated with hypertriglyceridemia, there is impairment in enzymatic antioxidant activity exclusively related with HDL.

Introduction

High density lipoprotein (HDL) is known to play a relevant antiatherogenic role that is not solely limited to its participation in reverse cholesterol transport. It is also able to protect low density lipoprotein (LDL) against in vitro oxidation (1) and consequent monocyte-endothelial cell interaction (2). HDL antioxidant potential can be assigned to different factors such as its chemical composition, content of liposoluble antioxidants, and presence of associated enzymes such as paraoxonase 1 (PON1) (EC 3.1.1.2) and platelet-activating factor acetylhydrolase (PAF-AH; EC 3.1.1.47) (3).

It was postulated that PON1 could be responsible for inactivating multi-oxygenated phospholipids present in mildly oxidized LDL, thus constituting a first line of defense against oxidative damage (2). In cases where PON1 activity is low, oxidized phospholipids may have undergone oxidative fragmentation; these fragmented phospholipids could then be scavenged by PAF-AH, the second line of defense (2).

PON1 circulates in plasma exclusively bound to HDL particles (3) and exhibites substrate-dependent activity polymorphism in humans (4). The R alloenzyme is more active than the Q alloenzyme toward some substrates, such as paraoxon; for other substrates such as phenylacetate, there is no difference between the two alloenzymes (4). Thus, data obtained by measuring enzymatic activity with phenylacetate would be independent of genetic polymorphism. Additionally, Mackness et al. (5) showed that determination of PON1 genetic polymorphism would be less important in establishing presence of coronary heart disease than evaluation of PON1 activity or concentration. Moreover, it was recently described that other nongenetic factors such as cigarette smoking were significant predictors of PON1 activity (6).

PAF-AH is associated with very low density lipoprotein (VLDL), LDL, and HDL with approximate distributions of 6, 83, and 11%, respectively (7). This enzyme was associated with different inflammatory diseases such as asthma, sepsis, and vascular diseases (8).

In a previous study (9), our group proved that the main steps of reverse cholesterol transport were altered in patients with low HDL-cholesterol (HDL-C) levels and primary hypertriglyceridemia. This syndrome was found to induce quantitative and qualitative abnormalities in HDL and its subclasses, and consequently in cholesterol efflux promotion, lecithin:cholesterol acyltransferase, and cholesteryl ester transfer protein.

Given that PON1 and PAF-AH exist in plasma exclusively anchored to lipoprotein particles, alterations in lipoprotein chemical composition could compromise this binding, thus resulting in modifications of enzymatic activity measured in whole plasma. One dyslipidemia most frequently related with qualitative abnormalities of whole lipoprotein spectrum and mainly of HDL fraction is increase in plasma triglyceride levels, considered a conditional factor for atherosclerosis 10., 11.. Moreover, on the basis of recent meta-analysis of prospective studies, the Third Report of the National Cholesterol Education Program identified hypertriglyceridemia as an independent risk factor for atherosclerosis (12). The aim of the present study was to evaluate PON1 and PAF-AH activities in patients with low HDL-C levels with or without primary hypertriglyceridemia in comparison with control subjects who presented normal HDL concentration and normal triglyceride levels.

Section snippets

Subjects

We studied samples from 36 males aged between 21 and 65 years. Subjects were included in the present study when they satisfied the following previously described criteria (9): 1) lack of abnormalities in carbohydrate metabolism, and 2) normal thyroid, renal, and hepatic functions evaluated by different biochemical parameters and clinical examination. Special care was taken to avoid subjects with additional causes of dyslipidemia such as tobacco consumption, excessive ethanol intake, therapy

Results

In this study, we evaluated PON1 and PAF-AH activities in patients with low HDL-C levels (n = 24) associated (subgroup 1, n = 12) or not (subgroup 2, n = 12) with hypertriglyceridemia. Patients were compared with healthy normolipemic control subjects (n = 12).

Lipoprotein profiles of studied subjects are shown in Table 1. Briefly, HDL-C and triglyceride levels emerged from selection criteria and the constitution of each group. Reduction in HDL-C levels observed in the hypoalphalipoproteinemic

Discussion

In this study we found that PON1 activities were significantly reduced in the hypoalphalipoproteinemic group in comparison with control subjects. Accordingly, James et al. (16) showed that PON1 activity and plasma concentration were reduced in different HDL genetically deficient states. On the other hand, in patients with normal HDL-C levels and even with diabetes PON1 activity was not different from control subjects (17).

When hypoalphalipoproteinemic patients were divided into two subgroups,

Acknowledgements

This work was supported by a grant from the Universidad de Buenos Aires (TB089) and by a Ramón Carrillo-Arturo Oñativ Fellowship from the Argentine National Ministry of Health.

References (31)

M.J Caslake et al.
Lipoprotein-associated phospholipase A2, platelet-activating factor acetylhydrolase: a potential new risk factor for coronary artery disease
Atherosclerosis
(2000)
K Karasawa et al.
Plasma platelet activating factor-acetylhydrolase (PAF-AH)
Prog Lipid Res
(2003)
B Lamarche et al.
HDL metabolism in hypertriglyceridemic states: an overview
Clin Chim Acta
(1999)
C.E Furlong et al.
Spectrophotometric assays for the enzymatic hydrolysis of the active metabolites of clorpyrifos and parathion by plasma paraoxonase/arylesterase
Anal Biochem
(1989)
M.L Blank et al.
Inactivation of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine by a plasma acetylhydrolase: higher activities in hypertensive rats
Biochem Biophys Res Commun
(1983)
R.W James et al.
Modulated serum activities and concentrations of paraoxonase in high density lipoprotein deficiency states
Atherosclerosis
(1998)
A Graham et al.
Evidence for a paraoxonase-independent inhibition of low-density lipoprotein oxidation by high-density lipoprotein
Atherosclerosis
(1997)
R Zech et al.
Lipoproteins and hydrolysis of organophosphorus compounds
Chem Biol Interact
(1993)
S.A.P Karabina et al.
PAF-acetylhydrolase activity on Lp(a) before and during Cu²⁺-induced oxidative modification in vitro
Atherosclerosis
(1996)
M Macknes et al.
The role of high density lipoprotein and lipid-soluble antioxidant vitamins in inhibiting low density lipoprotein oxidation
Biochem J
(1993)

A.D Watson et al.

Protective effect of high density lipoprotein associated paraoxonase

J Clin Invest

(1995)

M Navab et al.

High density associated enzymes: their role in vascular biology

Curr Opin Lipidol

(1998)

M.I Mackness et al.

Paraoxonase and coronary heart disease

Curr Opin Lipidol

(1998)

B Mackness et al.

Paraoxonase status in coronary heart disease. Are activity and concentration more important than genotype?

Arterioscler Thromb Vasc Biol

(2001)

N Ferré et al.

Regulation of serum paraoxonase activity by genetic, nutritional, and lifestyle factors in the general population

Clin Chem

(2003)

Cited by (35)

Activity of Lipoprotein-Associated Enzymes in Argentinean Indigenous Children Living at Different Altitudes
2019, Archives of Medical Research
Citation Excerpt :
Additionally, impairment of PON1 activity observed in our study could also be a consequence of the above-mentioned probable HDL-triglyceride enrichment. Accordingly, we previously found that PON1 activity was lower in hypertriglyceridemic subjects (42). As a result, SAC children would present HDL particles altered in their composition and antioxidant activity.
High altitude is associated with hypobaric hypoxia, and metabolic modifications. In particular, alterations to lipoprotein-associated enzymes have been reported under hypoxia.
To determine the association between paraoxonase 1 (PON-1) and Cholesteryl-ester transfer protein (CETP) activities and altitude in two groups of Argentinean Indigenous schoolchildren living at different altitudes.
A cross-sectional study compared 151 schoolchildren from San Antonio de los Cobres (SAC), 3,750 m, with 175 schoolchildren from Chicoana (CH), 1,400 m. Anthropometric data, lipids, apolipoprotein (apo) A-I, apo B, plus PON-1 and CETP activities were determined.
The prevalence of overweight/obesity was significantly lower in SAC than in CH. Z- BMI (0.3 vs 0.7), Apo A-I/Apo B (1.67 vs. 1.85) and PON-1 (170 vs. 243 nmol/mL.min) were significantly lower in SAC than in CH, respectively. Total cholesterol (156 vs 144 mg/dL), triglycerides (TG) (119 vs. 94 mg/dL), apo A-I (133 vs. 128 mg/dL), apo B (84 vs. 73 mg/dL), hematocrit (48 vs. 41%), transferrin (295 vs. 260 mg/dL) and CETP (181 vs. 150%/mL.h) were significantly higher in SAC than in CH. There was a significant univariate association between altitude and transferrin (r0.38), hematocrit (r0.75), TG (r0.24), apo B (r0.29), PON-1 (r-0.40), and CETP (r0.37). Multiple linear regression analyses showed that altitude was significantly associated with children's TG (β = 0.28, R² = 0.14), HDL-C (β = ‒0.27; R² = 0.23), apo B (β = 0.32; R² = 0.14), CETP (β = 0.38; R² = 0.15) and PON-1 (β = ‒0.36; R² = 0.16), adjusted for age, gender and BMI.
SAC children presented a more atherogenic lipid profile, plus lower PON1 and higher CETP activities, than CH children.
HDL-associated enzymes and proteins in hemodialysis patients
2012, Clinical Biochemistry
To evaluate HDL-associated proteins and enzymes and their relation with lipoprotein profile and inflammatory markers in chronic renal patients on hemodialysis.
We studied 53 patients under hemodialysis and 32 healthy subjects as controls. We compared plasma lipids, Apoprotein-AI and hs-CRP, as a marker of chronic inflammation. We evaluated proteins and enzymes associated to HDL, involved in several points of lipoprotein metabolism: CETP, paraoxonase and LpPLA2 activities. Hepatic lipase was measured in postheparin plasma.
Patients showed higher triglycerides and lower LDL-, HDL- and total-cholesterol than controls (p < 0.05). Also, in comparison with controls, Apoprotein-AI, paraoxonase and hepatic lipase were lower, while CETP was higher (p < 0.03). LpPLA2 did not show changes between groups.
Beyond plasma lipid-lipoprotein profile, other factors could contribute to induce a pro-oxidative and pro-inflammatory status. The protective role of HDL does not only depend on its concentration, but also on its functionality.
Nanotechnology for synthetic high-density lipoproteins
2010, Trends in Molecular Medicine
Citation Excerpt :
Furthermore, esterification of HDL-bound cholesterol, which ensures that a free cholesterol gradient is maintained between cells and HDL for RCT, occurs at different rates for different sizes of HDL [19,29]. There is also evidence that large cholesterol rich HDL particles, such as HDL2 (Figure 1), have higher levels of antioxidant activity, another of the atheroprotective properties of HDL [30]. These findings demonstrate the importance of size and composition in the ability of HDL to protect against atherosclerosis and the notion that the most effective HDL therapeutic would ideally increase the amount of those HDL species that are most atheroprotective.
Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high-density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD.
High-density lipoprotein therapeutics and cardiovascular prevention
2010, Journal of Clinical Lipidology
Citation Excerpt :
Compositional methods study the presence or absence of particular HDL particles containing different proteins or lipids. Much work has been devoted to well-known HDL enzymes such as PAF-AH, LCAT, and PON-1.38–40 A recent “shotgun proteomics” analysis of HDL from patients with coronary artery disease (CAD) revealed several clues to protein peculiarities that can be exploited in specific tests, if validated.
The field of cardiovascular prevention has long anticipated the evolution of high-density lipoprotein (HDL) therapy from unproven metabolic tweaking to pillar of risk reduction on par with low-density lipoprotein control. However, the convincing epidemiologic data linking HDL cholesterol (HDL-C) and cardiovascular disease risk in an inverse correlation has not yet translated into clinical trial evidence supporting linearity between HDL-C increases and risk reduction, or identifying obvious goals of therapy. Although HDL-C-increasing lifestyle maneuvers and established HDL drugs such as niacin and fibrates are likely to protect the vasculature, the negative results obtained in trials of a cholesteryl ester transfer protein inhibitor remind us that HDL-C increases are not always beneficial. It is becoming clear that a functional HDL is a more desirable target than simply increasing HDL-C levels. The larger objective of improving HDL functionality (with or without HDL-C level changes) is bound to become the guiding principle for pharmaceutical research in this area. Several new compounds currently being tested bridge the classical aim of increasing HDL-C levels with the novel target of improving HDL function.
Single intravenous injection of plasmid DNA encoding human paraoxonase-1 inhibits hyperlipidemia in rats
2010, Biochemical and Biophysical Research Communications
Paraoxonase-1 (PON1, EC 3.1.8.1) is a high-density lipoprotein (HDL)-associated antioxidant enzyme, and its activity correlates negatively with the level of plasma low-density lipoprotein cholesterol (LDL-C) and triglyceridemia (TG). In this study, we examined the therapeutic effect of plasmid DNA containing the human PON1 gene (pcDNA/PON1) in hyperlipidemic model rats. The rats were fed a high-fat and high-cholesterol diet for 25 days to produce a hyperlipidemic animal model. Single intravenous injection of pcDNA/PON1 into model rats prevented dyslipidemia and hepatic lipid accumulation. The mechanisms of pcDNA/PON1 in treating hyperlipidemia were associated with increases of serum antioxidant PON1 and SOD activities, and with reduction of the levels of total cholesterol (TC), LDL-C and TG. The results suggest the potential therapeutic effect of pcDNA/PON1 on hyperlipidemia.
Low adiponectin levels in primary hypertriglyceridemic male patients
2009, Nutrition, Metabolism and Cardiovascular Diseases
Citation Excerpt :
In this study, we showed that adiponectin levels were significantly decreased in male patients with primary hypertriglyceridemia. Given that adiponectin is an antiatherogenic and antiinflammatory adipokine [17], the alteration described here adds to the different modifications already reported in hypertriglyceridemic patients that contribute to understanding the relationship between high triglyceride levels and atherosclerosis [18–20]. Most studies reported in the literature have been carried out in patients with obesity [4], the metabolic syndrome [7], type 2 diabetes [5] and in HIV patients under treatment with highly active antiretrovirals (HAART) [21], and the reduction observed in adiponectin concentration was associated with insulin resistance, hypertriglyceridemia and fat distribution.
Adiponectin is an adipokine highly and specifically expressed by adipose cells with antiatherogenic and antiinflammatory activities. The aim of the present study was to evaluate plasma adiponectin concentration in patients with primary hypertriglyceridemia and its relationship with metabolic parameters.
Male patients with primary hypertriglyceridemia and without the metabolic syndrome (n = 22) were compared with normotriglyceridemic individuals (n = 25). Plasma adiponectin concentration was measured by standardised enzyme-linked immunosorbent assay. Body mass index, waist circumference, glucose, insulin and non-esterified fatty acid levels, lipoprotein profile, and CETP activity were evaluated. Adiponectin levels were significantly decreased in hypertriglyceridemic patients in comparison with normotriglyceridemic subjects (4292 ± 1717 vs. 6939 ± 3249 ng/ml, p < 0.005, respectively). Adiponectin was negatively associated with glucose (r = − 0.44, p < 0.01), insulin (r = − 0.37, p < 0.01), HOMA (r = − 0.40, p < 0.01), triglycerides (r = − 0.36, p < 0.01), VLDL-C (r = − 0.34, p < 0.05), and CETP (r = − 0.47, p < 0.001). Positive and significant correlations were observed with QUICKI (r = 0.49, p < 0.001) and HDL-C (r = 0.33, p < 0.05). In the multiple linear regression analysis, considering waist circumference, QUICKI, Log-triglycerides, HDL-C, and CETP as independent variables, Log-adiponectin showed a positive correlation with QUICKI, with an r² = 0.229 and p < 0.001. Therefore, the independent variable QUICKI explained the 23% of the variance in Log-adiponectin concentration.
We found low adiponectin levels in a population of primary hypertriglyceridemic men without the metabolic syndrome and an independent relationship between adiponectin concentration and insulin resistance. A reduction in insulin sensitivity and its impact on adiponectin concentration could be linked to high non-esterified fatty acid levels, increased triglyceride synthesis in the liver and impaired catabolism of triglyceride-rich lipoproteins.

View all citing articles on Scopus

View full text

Original articleParaoxonase 1 and platelet-activating factor acetylhydrolase activities in patients with low hdl-cholesterol levels with or without primary hypertriglyceridemia

Abstract

Background

Methods

Results

Conclusions

Introduction

Section snippets

Subjects

Results

Discussion

Acknowledgements

Atherosclerosis

Prog Lipid Res

Clin Chim Acta

Anal Biochem

Biochem Biophys Res Commun

Atherosclerosis

Atherosclerosis

Chem Biol Interact

Atherosclerosis

The role of high density lipoprotein and lipid-soluble antioxidant vitamins in inhibiting low density lipoprotein oxidation

Biochem J

Protective effect of high density lipoprotein associated paraoxonase

J Clin Invest

High density associated enzymes: their role in vascular biology

Curr Opin Lipidol

Paraoxonase and coronary heart disease

Curr Opin Lipidol

Paraoxonase status in coronary heart disease. Are activity and concentration more important than genotype?

Arterioscler Thromb Vasc Biol

Regulation of serum paraoxonase activity by genetic, nutritional, and lifestyle factors in the general population

Clin Chem

Original article
Paraoxonase 1 and platelet-activating factor acetylhydrolase activities in patients with low hdl-cholesterol levels with or without primary hypertriglyceridemia