How high-density lipoprotein protects against the effects of lipid peroxidation

Causal association of lipoprotein-associated phospholipids on the risk of sepsis: a Mendelian randomization study

Background

Many previous studies have revealed a close relationship between lipoprotein metabolism and sepsis, but their causal relationship has, until now, remained unclear. Therefore, we performed a two-sample Mendelian randomization analysis to estimate the causal relationship of lipoprotein-associated phospholipids with the risk of sepsis.

Materials and methods

A two-sample Mendelian randomization (MR) analysis was performed to investigate the causal relationship between lipoprotein-associated phospholipids and sepsis based on large-scale genome-wide association study (GWAS) summary statistics. MR analysis was performed using a variety of methods, including inverse variance weighted as the primary method, MR Egger, weighted median, simple mode, and weighted mode as complementary methods. Further sensitivity analyses were used to test the robustness of the data.

Results

After Bonferroni correction, the results of the MR analysis showed that phospholipids in medium high-density lipoprotein (HDL; ORIVW = 0.82, 95% CI 0.71-0.95, P = 0.0075), large HDL (ORIVW = 0.92, 95% CI 0.85-0.98, P = 0.0148), and very large HDL (ORMR Egger = 0.83, 95% CI 0.72-0.95, P = 0.0134) had suggestive causal relationship associations with sepsis. Sensitivity testing confirmed the accuracy of these findings. There was no clear association between other lipoprotein-associated phospholipids and sepsis risk.

Conclusions

Our MR analysis data suggestively showed a correlation between higher levels of HDL-associated phospholipids and reduced risk of sepsis. Further studies are required to determine the underlying mechanisms behind this relationship.

Paraoxonase-1: How a xenobiotic detoxifying enzyme has become an actor in the pathophysiology of infectious diseases and cancer

Both infectious and non-infectious diseases can share common molecular mechanisms, including oxidative stress and inflammation. External factors, such as bacterial or viral infections, excessive calorie intake, inadequate nutrients, or environmental factors, can cause metabolic disorders, resulting in an imbalance between free radical production and natural antioxidant systems. These factors may lead to the production of free radicals that can oxidize lipids, proteins, and nucleic acids, causing metabolic alterations that influence the pathogenesis of the disease. The relationship between oxidation and inflammation is crucial, as they both contribute to the development of cellular pathology. Paraoxonase 1 (PON1) is a vital enzyme in regulating these processes. PON1 is an enzyme that is bound to high-density lipoproteins and protects the organism against oxidative stress and toxic substances. It breaks down lipid peroxides in lipoproteins and cells, enhances the protection of high-density lipoproteins against different infectious agents, and is a critical component of the innate immune system. Impaired PON1 function can affect cellular homeostasis pathways and cause metabolically driven chronic inflammatory states. Therefore, understanding these relationships can help to improve treatments and identify new therapeutic targets. This review also examines the advantages and disadvantages of measuring serum PON1 levels in clinical settings, providing insight into the potential clinical use of this enzyme.

A systematic review and meta-analysis of paraoxonase-1 activity in asthma

Human serum paraoxonase-1 (PON-1) is a critical antioxidant defence system against lipid oxidation. Decreased PON-1 activity has been associated with systemic oxidative stress in several disease states. We conducted a systematic review and meta-analysis of plasma/serum concentrations of PON-1 in asthma, a chronic inflammatory airway disease. The electronic databases PubMed, Web of Science, Scopus and Google Scholar were searched from inception to February 2022. In total, 8 studies in 355 asthmatic patients and 289 healthy controls were included in the meta-analysis. Serum PON-1 concentrations were significantly lower in asthmatic patients (SMD = −1.58, 95% CI −2.53 to −0.63; p = 0.001). The pooled SMD values were not substantially altered in sensitivity analysis. There was no publication bias. There were non-significant differences in PON-1 concentrations in patients with severe vs. mild-to-moderate asthma (SMD =  − 0.39, 95% CI − 1.00 to 0.22, p = 0.21). Our meta-analysis has shown that serum PON-1 concentrations are significantly lower in patients with asthma, suggesting the presence of an impaired antioxidant defense in this group.

Evaluation of lipoprotein (a) [Lp(a)] and lipid abnormalities in patients with newly detected hypertension and its association with severity of hypertension

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Evaluation of the relationship between serum paraoxonase-1 activity and superovulation response/embryo yield in Holstein cows

In this study, the effect of serum paraoxonase-1 (PON-1) activity on superovulation response and embryo yield was evaluated. The study material comprised 50 Holstein cows aged 3-4 years on postpartum day 90-120 with a body condition score of 3-3.25. A progesterone-based estrus synchronization protocol was initially administered to the selected donors. For this purpose, progesterone source was inserted intravaginally (day 0) and gonadotropin-releasing hormone injection was performed (day 6). Seven days after the insertion of progesterone device, follicle-stimulating hormone injections (total dose of 500 µg in decreasing doses for 4 days) were administered for superovulation. On the morning of the ninth day, prostaglandin (PG) F2α was administered, and the progesterone device was removed from the vagina in the evening on the same day. Two days after PGF2α administration, fixed-time artificial insemination was performed in the morning and in the evening. On the day of artificial insemination, blood samples were taken from the donors to determine the serum PON-1 activity. Uterine flushing was performed seven days after insemination. The results revealed that the serum PON-1 activity (mean ± SD, 562.71 ± 140.23 U/l) of the cows that responded to superovulation (donors with total corpus luteum count of ≥3 in both ovaries) was higher than those (389.91 ± 80.51 U/l) that did not (P<0.05). On the day of insemination, a positive correlation was determined between serum PON-1 activity and the counts of total corpus luteum (r=0.398), total oocyte/embryo (r=0.468), transferable embryo (r=0.453), and Code I embryos (r=0.315, P<0.05). Unlike the Code I embryos, there was no significant correlation between serum PON-1 activity and the number of Code III embryos. Moreover, no significant difference in the number of Code III embryos between the two PON-1 groups was observed. However, embryo yield and quality were found to have increased with increased PON-1 activity. Therefore, it was concluded that serum PON-1 activity may be associated with superovulation response, embryo yield and quality in donor cows.

The relationship between measures of obesity and atherogenic lipids among Nigerians with hypertension

Aim

This study aimed to determine the relationship between measures of obesity and serum lipid levels among hypertensive patients.

Methods

This was a cross-sectional study in which participants newly diagnosed with hypertension formed the study population. A range of demographic and anthropometric data was obtained, including weight, height, and waist and hip circumference. Fasting serum lipids were also measured, including total cholesterol, high density lipoprotein cholesterol (HDL-C) and triglycerides (TG). Low density lipoprotein cholesterol (LDL-C) was calculated using Friedewald formula. Statistical analysis was then carried out to determine the relationship between anthropometric indices and lipid profile levels.

Results

The study population consisted of 124 male and 290 female subjects with a mean age of 66±16.95 years (range, 30-100 years). The female subjects were older than the male subjects (p=0.020). Our analysis showed that 85%, 58.5% and 30.7% of the study population had abnormal waist circumference (WC), abnormal waist-hip ratio (WHR) and a body mass index (BMI) >25 kg/m2, respectively. Decreased HDL-C (70.1%) was the commonest lipid abnormality detected, followed by elevated LDL (6.0%). None of the anthropometric indices were independent predictors of abnormal lipid levels. However, advanced age and female sex were independent predictors for at least one serum lipid abnormality.

Conclusion

None of the measures of obesity could independently predict abnormal lipid levels in individuals newly diagnosed with hypertension. However, female sex, advanced age and systolic blood pressure were independently associated with abnormal serum lipids. Encouraging regular exercise, and the possible addition of statins, may be beneficial in addressing both obesity and dyslipidaemia.

Effect of low high-density lipoprotein levels on mortality of septic patients: A systematic review and meta-analysis of cohort studies

BACKGROUND

An increase in high-density lipoprotein (HDL) is well associated with a decreased cardiovascular risk, especially atherosclerosis. Recent studies suggest that lower levels of HDL may also be associated with an increased risk of sepsis and an increased rate of mortality in septic patients. However, this conclusion remains controversial.

METHODS

MEDLINE, EMBASE, and CENTRAL databases were searched from inception to September 30, 2019. All studies were conducted to evaluate the correlation of lipoprotein levels and the risk and outcomes of sepsis in adult patients. The primary outcomes were the risk and mortality of sepsis.

RESULTS

Seven studies comprising 791 patients were included. Lower levels of HDL had no marked relevance with the risk of sepsis (odds radio [OR] for each 1 mg/dL increase, 0.94; 95% CI 0.86-1.02; P=0.078), whereas lower HDL levels were related to an increased mortality rate in septic patients (OR for below about median HDL levels, 2.00; 95% CI 1.23-3.24; P=0.005).

CONCLUSION

This meta-analysis did not reveal a significant association between lower HDL levels and an increase in the risk of sepsis, whereas it showed that lower HDL levels are associated with a higher mortality rate in septic adult patients. These findings suggest that HDL may be considered as a promising factor for the prevention and treatment of sepsis in the future.

Paraoxonase 3: Structure and Its Role in Pathophysiology of Coronary Artery Disease

Spanning three decades in research, Paraoxonases (PON1) carried potential of dealing with neurotoxicity of organophosphates entering the circulation and preventing cholinergic crisis. In the past few years, the Paraoxonase multigene family (PON1, PON2, PON3) has been shown to play an important role in pathogenesis of cardiovascular disorders including coronary artery disease (CAD). The PON genes are clustered in tandem on the long arm of human chromosome 7 (q21, 22). All of them have been shown to act as antioxidants. Of them, PON3 is the least studied member as its exact physiological substrate is still not clear. This has further led to limitation in our understanding of its role in pathogenesis of CAD and development of the potential therapeutic agents which might modulate its activity, expression in circulation and tissues. In the present review, we discuss the structure and activity of human PON3 enzyme and its Single nucleotide variants that could potentially lead to new clinical strategies in prevention and treatment of CAD.

Paraoxonases (PON) 1, 2, and 3 Polymorphisms and PON-1 Activities in Patients with Sickle Cell Disease

(1) Background: Oxidative stress, chronic inflammation, vasoocclusion, and free iron are all features present in sickle cell disease. Paraoxonases (PON) are a family (PON-1, PON-2, PON-3) of antioxidant enzymes with anti-inflammatory action. Here, for the first time, we described PON-1 activities and PON-1, PON-2, PON-3 polymorphisms in patients with sickle cell disease, homozygous for HbSS, compared with healthy controls. (2) Methods: The groups were matched for age and gender. PON-1 activities (arylesterase and paraoxonase) were determined by enzymatic hydrolysis of phenylcetate and paraoxon, respectively. Polymorphisms were determined by Restriction Fragment Length Polymorphism- Polymerase Chain Reaction (RFLP-PCR). (3) Results: Plasma cholesterol and fractions, ApoA1 and ApoB levels were all decreased in sickle cell disease patients, while anti-oxidized low-density lipoprotein (LDL) antibodies and C-reactive protein were increased. Serum arylesterase activity was lower in sickle cell disease patients when compared with healthy controls. In patients, paraoxonase activity was higher in those with PON-1 RR Q192R polymorphism. In these patients, the increase of serum iron and ferritin levels and transferrin saturation were less pronounced than those observed in patients with QQ or QR polymorphism. No differences were observed with PON-1 L55M, and PON-2 and PON-3 polymorphisms. Multivariate regression analysis showed that transferrin and ferritin concentrations correlated with arylesterase and paraoxonase activities. (4) Conclusions: Both transferrin and ferritin were the main predictors of decreased arylesterase and paraoxonase activities in patients with sickle cell disease. LDL oxidation increased, and RR PON-1 Q192R polymorphism is likely to be a protective factor against oxidative damage in these patients.

Paraoxonase 1 in bovine milk and blood as marker of subclinical mastitis caused by Staphylococcus aureus

The aim of this study was to determine serum lipid values and parameters of oxidative stress in blood and milk of cows with subclinical mastitis (SCM) caused by Staphylococcus aureus and to establish association between these parameters. The study was performed on total of 104 cows assigned into control group of healthy animals (n = 12) and two groups of cows with SCM, either SCM₁ group (n = 37) with ˂ 1000 CFU/mL of S. aureus or SCM₂ group (n = 55) with ≥1000 CFU/mL of causative agent in milk. Significantly lower serum concentrations of high density lipoprotein-cholesterol (HDLC) in SCM₂ group and higher low density lipoprotein-cholesterol (LDL-C) in both SCM groups were recorded. Significantly lower paraoxonase-1 (PON1) activity and higher lipid hydroperoxides (LOOH) concentration in blood and milk were recorded in both groups of SCM cows vs control. In blood serum of cows from SCM₂ group significantly higher concentrations of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), but significantly lower total antioxidative capacity (TAC) were obtained. In milk serum of SCM cows were detected significantly higher concentrations of H₂O₂ and MDA, but significantly lower TAC vs control. There was a significant positive correlation between PON1 in serum with HDLC, but negative correlation with LDL-C and LOOH. In milk, PON1 negatively correlated with LOOH and somatic cell counts (SCC). Strong positive correlation was obtained between PON1 in blood and milk. Oxidative stress and inflammatory reaction induced by SCM significantly lowered PON1 activity in blood and milk of affected cows.

Halofuginone protects HUVECs from H2O2-induced injury by modulating VEGF/JNK signaling pathway

BACKGROUND

Halofuginone, which is the main active ingredient of Dichroa fabrifuga, was used to inhibit the synthesis of type I collagen and played increasingly important roles in tumor therapy. This study aims to investigate the protective effects of halofuginone on human umbilical vein endothelial cells (HUVECs) from H2O2-induced apoptosis and oxidative stress.

METHODS

Propidium iodide and Annexin-V double staining assay was used to measure the apoptosis. Cell viability assay, the measurements of reactive oxygen species (ROS) parameters malondialdehyde and superoxide dismutase, western-blot assays, and quantitative PCR were used to elucidate the effects and mechanisms of halofuginone in protecting H2O2-induced injury.

RESULTS

The results showed that halofuginone counteracted H2O2-induced cell viability decline and PCNA downregulation. Furthermore, halofuginone decreased ROS levels and protected HUVECs from H2O2-induced apoptosis. In detail, it showed that H2O2 induced a transient activation of Mitogen-activated protein kinases members ERK1/2 and p38, whereas induced a sustained activation of c-Jun N-terminal kinase (JNK), which play dominant roles in triggering apoptosis. Inhibition of JNK activation also inhibited H2O2-mediated apoptosis. Finally, it was shown that halofuginone upregulated VEGF expressions, which functioned by inhibiting sustained JNK activation, thus protecting HUVECs.

CONCLUSION

Halofuginone has powerful effects in protecting HUVECs from H2O2-induced apoptosis, via upregulating VEGF and inhibiting overactivated JNK phosphorylation. Halofuginone might be a promising preventive drug for cardiovascular diseases.

HDL cholesterol: reappraisal of its clinical relevance

Background

While several lines of evidence prove that elevated concentrations of low-density lipoproteins (LDL) causally contribute to the development of atherosclerosis and its clinical consequences, high-density lipoproteins are still widely believed to exert atheroprotective effects. Hence, HDL cholesterol (HDL-C) is in general still considered as “good cholesterol”. Recent research, however, suggests that this might not always be the case and that a fundamental reassessment of the clinical significance of HDL-C is warranted.

Method

This review article is based on a selective literature review.

Results

In individuals without a history of cardiovascular events, low concentrations of HDL-C are inversely associated with the risk of future cardiovascular events. This relationship may, however, not apply to patients with metabolic disorders or manifest cardiovascular disease. The classical function of HDL is to mobilise cholesterol from extrahepatic tissues for delivery to the liver for excretion. These roles in cholesterol metabolism as well as many other biological functions of HDL particles are dependent on the number as well as protein and lipid composition of HDL particles. They are poorly reflected by the HDL-C concentration. HDL can even exert negative vascular effects, if its composition is pathologically altered. High serum HDL-C is therefore no longer regarded protective. In line with this, recent pharmacological approaches to raise HDL-C concentration have not been able to show reductions of cardiovascular outcomes.

Conclusion

In contrast to LDL cholesterol (LDL-C), HDL-C correlates with cardiovascular risk only in healthy individuals. The calculation of the ratio of LDL-C to HDL-C is not useful for all patients. Low HDL-C should prompt examination of additional metabolic and inflammatory pathologies. An increase in HDL-C through lifestyle change (smoking cessation, physical exercise) has positive effects and is recommended. However, HDL-C is currently not a valid target for drug therapy.

The Search for Dietary Supplements to Elevate or Activate Circulating Paraoxonases

Low levels of paraoxonase 1 (PON1) have been associated with the development of several pathological conditions, whereas high levels have been shown to be anti-atherosclerotic in mouse models. These findings suggest that PON1 could be a good surrogate biomarker. The other members of the family, namely PON2 and PON3, the role of which has been much less studied, deserve more attention. This paper provides a systematic review of current evidence concerning dietary supplements in that regard. Preliminary studies indicate that the response to dietary supplements may have a nutrigenetic aspect that will need to be considered in large population studies or in clinical trials. A wide range of plant preparations have been found to have a positive action, with pomegranate and some of its components being the best characterized and Aronia melanocarpa one of the most active. Flavonoids are found in the composition of all active extracts, with catechins and genistein being the most promising agents for increasing PON1 activity. However, some caveats regarding the dose, length of treatment, bioavailability, and stability of these compounds in formulations still need to be addressed. Once these issues have been resolved, these compounds could be included as nutraceuticals and functional foods capable of increasing PON1 activity, thereby helping with the long-term prevention of atherosclerosis and other chronic ailments.

An intensive lifestyle intervention reduces circulating oxidised low-density lipoprotein and increases human paraoxonase activity in obese subjects

OBJECTIVE

Obesity has a great impact on cardiovascular morbidity and mortality, the treatment of this pathological state is important given the significant health consequences. Lifestyle and behaviour changes play a significant role in weight management. The purpose of this study was to investigate the impact of an intensive multidisciplinary lifestyle intervention on well-known atherogenic factors in a group of overweight and obese subjects.

METHODS

A total of 44 people with overweight/obesity underwent a lifestyle intervention based on nutritional education, psychological support and a 3-month exercise training program with a frequency of twice a week. Several anthropometric and biochemical parameters were measured before and after the lifestyle intervention.

RESULTS

Lifestyle intervention led to a significant reduction in metabolic profile including body mass index (BMI), waist circumference, systolic and diastolic blood pressure, plasma glucose, and plasma triglycerides. These reductions were also accompanied by a significant increase in maximal oxygen consumption and muscle strength. Furthermore, paraoxonase and lactonase activities and the concentration of Apoliproteins A1 (APO A1) were significantly increased and the serum levels of oxLDL reduced without any changes in the circulating levels of LDL and HDL.

CONCLUSION

In conclusion, our study suggests that an intensive lifestyle intervention in obese subjects promotes a series of beneficial antiatherogenic changes which included increased enzyme activites of paraoxonase and lactonase, concentration of Apoliproteins A1 and decreased circulating levels of oxLDL.

[Clinical importance of HDL cholesterol]

BACKROUND

Each year 16-17 million determinations of high-density lipoprotein cholesterol (HDL-C) are conducted and interpreted in Germany. Recently acquired data have led to a fundamental reassessment of the clinical significance of HDL-C.

METHOD

This review article is based on a selective literature search.

RESULTS

Low HDL‑C levels usually indicate an increased cardiovascular risk, particularly in primary prevention but the epidemiological relationship between HDL‑C and the risk is complex. The HDL plays a role in the back transport and excretion of cholesterol; however, the biological functions of HDL are dependent on the protein and lipid composition, which is not reflected by the HDL‑C concentration. If the composition of HDL is pathologically altered it can also exert negative vascular effects.

CONCLUSION

Compared with low-density lipoprotein cholesterol (LDL-C), HDL‑C is of secondary importance for cardiovascular risk stratification and the calculation of the LDL-C:HDL‑C ratio is not useful for all patients. Low HDL‑C levels should prompt a search for additional metabolic and inflammatory pathologies. An increase in HDL‑C through lifestyle changes (e.g. smoking cessation and physical exercise) has positive effects and is recommended; however, HDL‑C is currently not a valid target for drug therapy.

Comparison of lipid profile parameters and oxidized low-density lipoprotein between normal and preeclamptic pregnancies in a tertiary care hospital in Nepal

Introduction

Preeclampsia is a pregnancy-specific complication that significantly contributes to maternal and perinatal morbidity and mortality worldwide, even more so in developing countries such as Nepal. The potential contribution of dyslipidemia and elevated levels of oxidized low-density lipoprotein (oxLDL) in the pathogenesis of preeclamptic pregnancies has been observed in several studies. The aim of this study was to compare the maternal lipid profile parameters and particularly oxLDL between preeclamptic and healthy pregnancies and also correlate oxLDL with other lipid profile parameters.

Patients and methods

A total of 54 preeclamptic women were selected as cases for this cross-sectional study. Age and gestational week-matched 60 pregnant women were enrolled as controls. Preeclampsia was defined as per Australasian Society Consensus Statement research definition. The serum lipid parameters were measured using automated enzymatic systems and a competitive enzyme-linked immunosorbent assay was used to determine oxLDL concentrations in the serum. Student’s t-test was used to compare oxLDL levels between preeclamptic and healthy pregnancies, and Pearson’s correlation analysis was carried out to assess the relation between oxLDL and other variables.

Results

The mean values of serum total cholesterol, triglyceride, non-high-density lipoprotein-cholesterol (non-HDL-c) and oxLDL were significantly higher in the preeclamptic cases (P<0.01). However, the levels of low-density lipoprotein cholesterol (LDL-c and HDL-c) did not significantly differ between the two groups. oxLDL had a significant positive correlation (P<0.01) with total cholesterol, triglyceride, LDL-c and non-HDL-c, and a negative correlation with HDL-c.

Conclusion

The atherogenic type of dyslipidemia and high oxLDL levels are associated with preeclamptic pregnancies. The lipid parameters, however, seem to be poor markers of the severity of preeclampsia. Further prospective studies are needed to see if the observed dyslipidemia has a causal role in preeclampsia and imparts a long-term cardiovascular risk.

Alteration of hepatic cells glucose metabolism as a non-cholinergic detoxication mechanism in counteracting diazinon-induced oxidative stress

The aim of this study was to evaluate effects of acute exposure to various doses of diazinon, a widely used synthetic organophosphorus (OP) insecticide on plasma glucose, hepatic cells key enzymes of glycogenolysis and gluconeogenesis, and oxidative stress in rats. Diazinon was administered by gavage at doses of 15, 30 and 60 mg/kg. The liver was perfused and removed under anaesthesia. The activities of glycogen phosphorylase (GP), phosphoenolpyruvate carboxykinase (PEPCK), thiobarbituric acid reactive substances (TBARS) and total antioxidant capacity (TAC) were analysed in liver homogenate. Administration of diazinon (15, 30 and 60 mg/kg) increased plasma glucose concentrations by 101.43% (P=0.001), 103.68% (P=0.000) and 160.65% (P=0.000) of control, respectively. Diazinon (15, 30 and 60 mg/kg) increased hepatic GP activity by 43.5% (P=0.05), 70.3% (P=0.00) and 117.2% (P=0.02) of control, respectively. In addition, diazinon (30 and 60 mg/kg) increased hepatic PEPCK by 77.3% (P=0.000) and 93.5% (P=0.000) of control, respectively. Diazinon (30 and 60 mg/kg) decreased liver TAC by 38% (P=0.046) and 48% (P=0.000) of control, respectively. Also diazinon (30 and 60 mg/kg) increased hepatic cell liver lipid peroxidation by 77% (P=0.05) and 280% (P=0.000) of control. The correlations between plasma glucose and hepatic cells TBARS (r2=0.537, P=0.02), between plasma glucose and ChE activity (r2=0.81, P=0.049) and between plasma glucose and hepatic cells GP activity (r2=0.833, P=0.04) were significant. It is concluded that the liver cells are a site of toxic action of diazinon. Diazinon increases glucose release from liver into blood through activation of glycogenolysis and gluconeogenesis as a detoxication non-cholinergic mechanism to overwhelm diazinon-induced toxic stress. The results are in accordance with the hypothesis that OPs are a predisposing factor of diabetes.

Dysfunctional High-Density Lipoprotein: An Innovative Target for Proteomics and Lipidomics

High-Density Lipoprotein-Cholesterol (HDL-C) is regarded as an important protective factor against cardiovascular disease, with abundant evidence of an inverse relationship between its serum levels and risk of cardiovascular disease, as well as various antiatherogenic, antioxidant, and anti-inflammatory properties. Nevertheless, observations of hereditary syndromes featuring scant HDL-C concentration in absence of premature atherosclerotic disease suggest HDL-C levels may not be the best predictor of cardiovascular disease. Indeed, the beneficial effects of HDL may not depend solely on their concentration, but also on their quality. Distinct subfractions of this lipoprotein appear to be constituted by specific protein-lipid conglomerates necessary for different physiologic and pathophysiologic functions. However, in a chronic inflammatory microenvironment, diverse components of the HDL proteome and lipid core suffer alterations, which propel a shift towards a dysfunctional state, where HDL-C becomes proatherogenic, prooxidant, and proinflammatory. This heterogeneity highlights the need for further specialized molecular studies in this aspect, in order to achieve a better understanding of this dysfunctional state; with an emphasis on the potential role for proteomics and lipidomics as valuable methods in the search of novel therapeutic approaches for cardiovascular disease.

Cholesteryl Ester Transfer Protein Inhibitors - Future Soon to be REVEALed

Reduction of the remaining residual cardiovascular risk is a clinical unmet need currently being addressed through a combination of further reduction of plasma concentrations of low-density lipoproteins (LDLs) and increasing plasma concentrations of high-density lipoproteins (HDLs). This brief review sets out the so-called HDL hypothesis and summarises the clinical results of the family of drugs, which function to raise plasma HDL concentration through inhibition of cholesteryl ester transfer proteins (CEPT).

Plasma paraoxonase, oxidative status level, and their relationship with asthma control test in children with asthma

BACKGROUND

Assessment of asthma with a control test has been suggested as a relevant approach in recent years. However, no biomarker of systemic inflammation has been included in the assessment of asthma control.

OBJECTIVE

To evaluate plasma paraoxonase (PON1), total oxidant status (TOS), and total antioxidant status (TAS) levels in children with asthma according to the disease control, and the performance in the identification of uncontrolled patients.

METHODS

Stable asthmatic children (n=85) and healthy controls (n=55) were recruited for this study. Blood samples were collected for plasma PON1, TOS, and TAS measurements. Any contributing factors that may affect plasma PON1, TAS, and TOS levels were excluded from both groups. The diagnostic potential of these measures was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

Comparing the asthmatic children with the control group, plasma TAS and TOS levels were significantly higher (TAS; 6.9 ± 2.1, 1.05 ± 0.32, P<0.001, and TOS; 12.5 ± 3.4, 5.5 ± 3.8, P<0.001, respectively) and PON1 level was significantly lower (156.5 ± 55, 298.6 ± 87.6, respectively, P<0.001) in the asthmatic group than controls. In ROC analysis, PON1 presented an AUC 0.679 and TOS presented an AUC 0.645 for the identification of uncontrolled asthma, respectively. Asthma Control Test (ACT) presented an AUC of 0.972 for the identification of uncontrolled asthma.

CONCLUSION

PON1 and TOS levels may be systemic markers of uncontrolled asthma in children. Combined use of these two biomarkers with asthma control test may identify patients with uncontrolled asthma in children.

Paraoxonases and chemokine (C-C motif) ligand-2 in noncommunicable diseases

Oxidative stress and inflammation underpin most diseases; their mechanisms are inextricably linked. Chronic inflammation is associated with oxidation, anti-inflammatory cascades are linked to decreased oxidation, increased oxidative stress triggers inflammation, and redox balance inhibits the inflammatory cellular response. Whether or not oxidative stress and inflammation represent the cause or consequence of cellular pathology, they contribute significantly to the pathogenesis of noncommunicable diseases (NCD). The incidence of obesity and other related metabolic disturbances are increasing, as are age-related diseases due to a progressively aging population. Relationships between oxidative stress, inflammatory signaling, and metabolism are, in the broad sense of energy transformation, being increasingly recognized as part of the problem in NCD. In this chapter, we summarize the pathologic consequences of an imbalance between circulating and cellular paraoxonases, the system for scavenging excessive reactive oxygen species and circulating chemokines. They act as inducers of migration and infiltration of immune cells in target tissues as well as in the pathogenesis of disease that perturbs normal metabolic function. This disruption involves pathways controlling lipid and glucose homeostasis as well as metabolically driven chronic inflammatory states that encompass several response pathways. Dysfunction in the endoplasmic reticulum and/or mitochondria represents an important feature of chronic disease linked to oxidation and inflammation seen as self-reinforcing in NCD. Therefore, correct management requires a thorough understanding of these relationships and precise interpretation of laboratory test results.

Influence of apolipoprotein E, age and aortic site on calcium phosphate induced abdominal aortic aneurysm in mice

OBJECTIVE

To assess relevant features of abdominal aortic aneurysms (AAA) induced by calcium phosphate within a mouse model. Specifically we investigated: (1) whether apolipoprotein E deficiency and older age promoted AAA formation, and (2) whether the local application of calcium phosphate affected the size of distant aortic segments.

METHODS

AAA was induced by application of calcium phosphate to the infra-renal aortas of 3 and 7 month old male mice. AAA induction was assessed by calculating expansion of the infra-renal aortic diameter over 1-4 weeks. Aortic samples were assessed to quantify calcification, macrophages infiltration, elastic lamellar degradation and apoptosis. Blood pressure was measured by the tail cuff method, and plasma concentrations of total cholesterol, low density lipoprotein and very low density lipoprotein cholesterol, and pro-inflammatory cytokines were measured using commercially available kits. The maximum diameters of the aortic arch, thoracic and supra-renal aorta at sacrifice were measured by morphometry and the mean maximal diameter of these three aortic segments was calculated.

RESULTS

The median expansion of the infra-renal aorta 2 weeks after AAA induction was significantly greater in apolipoprotein E deficient (ApoE(-/-)) mice than in age- and gender-matched wild type controls [275.8% (IQR 193.8%-348.5%) versus 94.7% (IQR 47.8%-163.4%), P = 0.02]. The greater aortic expansion in ApoE(-/-) mice was associated with aortic calcification, macrophage infiltration, elastic lamellar degradation and apoptosis of cells in the media and adventitia. The plasma low density lipoprotein/very low density lipoprotein cholesterol concentrations 2 weeks after AAA induction were positively correlated with the expansion of the infra-renal aorta induced by calcium phosphate. The median expansion of the infra-renal aorta 2 weeks after AAA induction was similar in 3 and 7 month old wild type mice. The local administration of calcium phosphate was associated with an increase in the mean maximal diameter of distant aortic segments, but not associated with changes in the concentrations of pro-inflammatory markers in either the plasma or the spleen.

CONCLUSION

This study suggests that apolipoprotein E deficiency, but not age, predisposes to AAA induced within the calcium phosphate model. Increased AAA expansion in ApoE(-/-) mice was associated with calcification, macrophage infiltration, elastic lamellar degradation, and cell apoptosis. Local application of calcium phosphate also promoted dilation of distant aortic segments.

Paraoxonase (PON1) activity in patients with subclinical thoracic aortic atherosclerosis

High density lipoprotein (HDL), a powerful antioxidant, protects low density lipoprotein (LDL) particles against oxidative stress. By limiting LDL oxidation, HDL plays an important role in preventing atherosclerosis (AS). The antioxidant effect of HDL is mostly associated with the paraoxonase (PON1) activity. It has been known that increased aortic intima-media thickness (IMT) is an earlier marker AS than carotid IMT. We aimed to investigate the association between thoracic aortic IMT and serum PON1 activity. We studied 133 patients (mean age: 46.3 ± 8 years) who underwent transesophageal echocardiography (TEE) for various indications. The measurements of thoracic aortic IMT by TEE are classified into four grades (1, 2, 3 and 4). Serum PON1 activity was measured spectrophotometrically. Oxidative and anti-oxidative status was evaluated by measuring serum lipid hydroperoxide (LOOH), total anti-oxidant status (TAS). Serum PON1 activity was progressively decreasing from grade 1 IMT to grade 4 IMT (p < 0.001). However, serum LOOH was significantly lower and TAS was significantly higher in patients with grade 1 when compared with other grades. In multiple linear regression analysis, IMT was independently correlated with PON1 activity (β = -0.495, p < 0.001), TAS level (β = -196, p < 0.009), age (β = 0.145, p = 0.029) and LDL cholesterol level (β = 0.169, p = 0.009). Decreased PON1 activity was independently associated with the extent of thoracic AS. PON1 activity may play a role in pathogenesis of thoracic AS besides age, TAS and LDL cholesterol levels.

Serum lipid profile and correlates in newly presenting Nigerians with arterial hypertension

Background

Arterial hypertension and dyslipidemia are modifiable cardiovascular risk factors. The multiplicative effect of these risk factors may worsen the atherogenic index of an individual. The objective of this study was to determine the pattern and prevalence of dyslipidemia in newly presenting Nigerians with arterial hypertension, as well as determine some of its correlates.

Methods

This cross-sectional study compared 115 newly presenting, age- and sex-matched individuals with arterial hypertension with 115 normotensive individuals. Fasting lipids, total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and fasting plasma glucose were estimated.

Results

Patients with arterial hypertension had higher body mass index (t=7.64; P=0.000), TC (t=2.95; P=0.006), and HDL-C (t=−5.18; P=0.000). The most common dyslipidemia was low HDL-C, found in both the hypertensive (44.3%) and normotensive (20.9%) patients. The prevalence of dyslipidemia in hypertensives and controls was 64% and 39%, respectively. In hypertensive patients, TC correlated positively to diastolic blood pressure (r=0.218; P=0.0019). Other positive correlates include LDL-C and age (r=0.217; P=0.020) and fasting plasma glucose (r=0.202; P=0.030) and body mass index (r=0.209; P=0.025). Among normotensive controls, TC correlated positively with LDL-C (r=0.63; P=0.000) but correlated negatively with tri glycerides (r=−0.30; P=0.001).

Conclusion

Lipid abnormalities are common in newly presenting Nigerians with arterial hypertension. Screening of these risk factors, promotion of healthy lifestyle, and the institution of therapy is desirable to reduce their multiplicative effects.

Total serum oxidant/antioxidant status and arylesterase activity in recurrent aphthous stomatitis

Background

Recurrent aphthous stomatitis (RAS) is a chronic relapsing inflammatory disorder of the oral mucosa with unknown etiology. Oxidative stress (OS) is suggested to play a main role in the etiopathogenesis in RAS.

Objective

In this study, we hypothesize that a systemic OS is present in patients with RAS.

Methods

Forty-four patients with active RAS lesions and 38 healthy controls were being included in the study. Serum total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), and paraoxonase 1 arylesterase (ARES) activity were being determined.

Results

RAS patients had significantly lower TAS levels and higher TOS and OSI values than controls. The patients had a lower ARES activity when compared to healthy controls. No correlations were observed between OS parameters and age, gender, duration of disease or frequency of RAS attacks per month.

Conclusion

A systemic OS is determined with an imbalance in oxidant/antioxidant status and lower ARES activity in RAS. Systemic OS may have an important role in the pathogenesis of RAS formation.

Plasma paraoxonase activity and oxidative stress and their relationship to disease severity in children with allergic rhinitis

BACKGROUND

Oxidative stress may play a role in the pathophysiology of several diseases including allergic rhinitis (AR). In children with AR an antioxidant enzyme paraoxonase (PON1) has not been previously investigated. The aim of this study was to investigate plasma PON1 activity and plasma total oxidant status (TOS), which are in the form of plasma reactive oxidants, and their association with severity of disease in house-mite-sensitive children with AR.

METHODS

This study included 66 children with persistent AR and 40 healthy controls aged between 7 and 12 years old. Plasma PON1, TOS, and total serum immunoglobulin E (IgE) were measured. The nasal symptom scores and body mass index were evaluated at the time of blood collection.

RESULTS

Mean serum PON1 levels were significantly lower and, TOS levels were higher in the patient group than in the control group (p ≤ 0.001 and p ≤ 0.002, respectively). A significant negative correlation was observed between serum levels of PON1 and nasal symptom scores. However, serum levels of TOS were correlated with nasal symptom scores positively. There were no correlations between levels of total IgE and levels of PON1 and TOS levels.

CONCLUSION

Plasma PON1 and TOS levels may serve as predictors of disease severity in children with AR and both of them appear to be attractive candidates for modulating inflammation in AR.

Paraoxonase 1 activities and genetic variation in childhood obesity

Changes in paraoxonase 1 (PON1) activities have been observed in a variety of diseases involving oxidative stress, such as CVD. However, its role in obesity has not been fully established. In the present study, we aimed (1) to genotype sixteen PON1 SNP, (2) to measure serum PON1 activities and (3) to correlate these findings with the incidence of childhood obesity and related traits. We conducted a case–control study of 189 normal-weight and 179 obese prepubertal children, and we measured four different PON1 activities: lactonase; paraoxonase; arylesterase; diazoxonase. Although none of these activities was significantly different between the obese and normal-weight children, lactonase activity was found to be positively correlated with HDL-cholesterol and ApoA1 levels and negatively correlated with myeloperoxidase and fatty acid-binding protein 4 levels. Among the sixteen genotyped PON1 SNP, only the intronic SNP rs854566 exhibited a significant association with obesity (OR 0·61, 95 % CI 0·41, 0·91; P= 0·016). This genetic variant was also associated with increased diazoxonase, lactonase and arylesterase activities and decreased paraoxonase activity. Other genetic variants exhibited different association patterns with serum activities based on their location within the PON1 gene, and SNP that were located within the promoter were strongly associated with lactonase, arylesterase and diazoxonase activities. The functional variant Q192R exhibited the greatest effect on paraoxonase activity (P= 5·88 × 10− 42). In conclusion, SNP rs854566 was negatively associated with childhood obesity and with increased serum PON1 activities in prepubertal children. We determined that lactonase is a reliable indicator of PON1 activities and should be included in future studies of PON1 function.

Associations of PON1 and genetic ancestry with obesity in early childhood

Obesity in children has become an epidemic in the U.S. and is particularly prominent in minority populations such as Mexican-Americans. In addition to physical activity and diet, genetics also plays a role in obesity etiology. A few studies in adults and adolescents suggest a link between obesity and paraoxonase 1 (PON1), a multifunctional enzyme that can metabolize organophosphate pesticides and also has antioxidant properties. We determined PON1₁₉₂ genotype and arylesterase levels (ARYase, measure of PON1 enzyme quantity), to characterize the relationship between PON1 and obesity in young Mexican-American children (n = 373) living in an agricultural community in California. Since PON1 polymorphisms and obesity both vary between ethnic groups, we estimated proportional genetic ancestry using 106 ancestral informative markers (AIMs). Among children, PON1₁₉₂ allele frequencies were 0.5 for both alleles, and the prevalence of obesity was high (15% and 33% at ages two and five, respectively). The average proportion of European, African, and Native American ancestry was 0.40, 0.09, and 0.51, yet there was wide inter-individual variation. We found a significantly higher odds of obesity (9.3 and 2.5- fold) in PON1_192QQ children compared to PON1_192RR children at ages two and five, respectively. Similar relationships were seen with BMI Z-scores at age two and waist circumference at age five. After adjusting for genetic ancestry in models of PON1 and BMI Z-score, effect estimates for PON1₁₉₂ genotype changed 15% and 9% among two and five year old children, respectively, providing evidence of genetic confounding by population stratification. However even after adjustment for genetic ancestry, the trend of increased BMI Z-scores with increased number of PON1₁₉₂ Q alleles remained. Our findings suggest that PON1 may play a role in obesity independent of genetic ancestry and that studies of PON1 and health outcomes, especially in admixed populations, should account for differences due to population stratification.

Serum lipid profile of newly diagnosed hypertensive patients in nnewi, South-East Nigeria

Abnormalities in serum lipid and lipoprotein levels are recognized major modifiable cardiovascular disease and essential hypertension risk factors. The objective of this study was to examine the serum lipid patterns of newly diagnosed hypertensive patients attending a tertiary healthcare centre in South East Nigeria. Methods. Two hundred and fifty newly diagnosed adult hypertensive patients and an equal number of age- and sex-matched controls without hypertension were consecutively recruited from the Medical and General Outpatient Clinics of Nnamdi Azikiwe University Teaching Hospital, Nnewi. Result. 126 males and 124 females were in each of the two groups. Mean age was comparable in both groups. Hypertensives had significantly higher mean systolic blood pressure, diastolic blood pressure, body mass index, waist circumference, waist-hip ratio, and fasting blood sugar than the controls. The mean TC, TG, and LDL-C were significantly higher among the hypertensives. The mean HDL-C was comparable; P = 0.8. Among the hypertensive subjects, there was statistically significant positive correlation between BMI and TC; LDL-C and TG; WC and TG; FBS and TC; LDL-C and TG. HDL-C showed a statistically significant inverse correlation with WHR in hypertensives. Conclusion. This study showed that lipid abnormalities are highly prevalent among newly diagnosed hypertensives in South-East Nigeria.

High-density lipoprotein prevents SAA-induced production of TNF-α in THP-1 monocytic cells and peripheral blood mononuclear cells

In this study, we evaluated whether human serum and lipoproteins, especially high-density lipoprotein (HDL), affected serum amyloid A (SAA)-induced cytokine release. We verified the effects of SAA on THP-1 cells in serum-free medium compared to medium containing human serum or lipoprotein-deficient serum. SAA-induced tumour necrosis factor-alpha (TNF-α) production was higher in the medium containing lipoprotein-deficient serum than in the medium containing normal human serum. The addition of HDL inhibited the SAA-induced TNF-α release in a dose-dependent manner. This inhibitory effect was specific for HDL and was not affected by low-density lipoprotein or very low-density lipoprotein. In human peripheral blood mononuclear cells, the inhibitory effect of HDL on TNF-α production induced by SAA was less pronounced. However, this effect was significant when HDL was added to lipoprotein-deficient medium. In addition, a similar inhibitory effect was observed for interleukin-1 beta release. These findings confirm the important role of HDL and support our previous hypothesis that HDL inhibits the effects of SAA during SAA transport in the bloodstream. Moreover, the HDL-induced reduction in the proinflammatory activity of SAA emphasizes the involvement of SAA in diseases, such as atherosclerosis, that are characterized by low levels of HDL.

Elevation of plasma high-density lipoproteins inhibits development of experimental abdominal aortic aneurysms

OBJECTIVE

Patients with abdominal aortic aneurysms have lower concentrations of high-density lipoproteins (HDLs), leading us to investigate whether increasing plasma HDLs could influence aneurysm formation.

METHODS AND RESULTS

Using the angiotensin II-induced hypercholesterolemic and the CaCl(2)-induced normocholesterolemic mouse model of AAA, we investigated the hypothesis that elevation of HDLs inhibits AAA. HDLs elevated before or at the time of AAA induction reduced AAA formation in both models but had no effect on early ruptures. Analysis of protein lysates from specific aortic segments demonstrated site-specific effects of HDLs on early signal transduction and cellular attrition. We found that HDLs reduced extracellular signal related kinases 1/2 activation in the suprarenal segment, while having no effect on p38 mitogen-associated protein kinase activation in any aortic segment and inhibiting c-Jun N-terminal kinase activation in all aortic segments. In addition, HDL elevation inhibited angiotensin II-induced apoptosis while inducing autophagy in the suprarenal segment of the aorta. Using Illumina gene array profiling we investigated the ability of HDL to modulate basal suprarenal aortic gene expression.

CONCLUSIONS

Increasing plasma HDLs inhibit experimental AAA formation, independent of hypercholesterolemia via reduced extracellular signal related kinases 1/2 activation and alteration of the balance of cellular attrition. HDLs modulate genes involved in matrix remodelling, cell migration, and proliferation.

HDL functionality

PURPOSE OF REVIEW

HDL cholesterol concentration is inversely correlated with cardiovascular disease and has a wide range of functions involved in many systems. The purpose of this review is to summarize HDL functionality, its relevance to atherosclerosis and factors affecting HDL functions.

RECENT FINDINGS

The contribution of HDL to reverse cholesterol transport may not be as great as first envisaged. However, it still plays an important role in cholesterol efflux from peripheral tissues. The capacity of HDL to promote cellular cholesterol efflux in an ex-vivo model has been reported to correlate more closely with carotid intima-media thickness than HDL cholesterol concentration. Recently, a variety of other functions of HDL have been described including antimicrobial, antioxidant, antiglycation, anti-inflammatory, nitric oxide--inducing, antithrombotic and antiatherogenic activity and immune modulation as well as a potential role in glucose homeostasis, diabetes pathophysiology and complications.

SUMMARY

HDL has a wide range of functions some of which are independent of its cholesterol content. Its cargo of apolipoproteins, various proteins and phospholipids contributes most to its various functions. These functions are affected by a number of genetic, physiological and pathological factors.

The Past and Present of Paraoxonase Enzyme: Its Role in the Cardiovascular System and Some Diseases

Although paraoxonase is synthesized in many tissues including the heart, colon, kidneys, lungs, small intestines and brain, its major locus of synthesis is the liver. PON1 is in close association with apolipoproteins and protects LDL against oxidation. It was reported that PON1 quantities dropped to 40 times lower than normal in cardiovascular diseases and diseases like diabetes, ulcerative colitis, Crohn's disease, chronic renal failure, SLE, Behcet's disease, cancer, hepatitis B, obesity, metabolic syndrome, Alzheimer's and dementia. It is speculated that the concerning decline in serum PON1 amount results from single nucleotide polymorphism in the coding (Q192R, L55M) and promoter (T-108C) sites of the PON1 gene. Additionally, circulating amounts of PON1 are affected by vitamins, antioxidants, fatty acids, dietary factors, drugs, age and lifestyle. This collection attempts to review and examine the past and present studies of paraoxonase and its relation with the cardiovascular system and some relevant diseases.

PON gene polymorphisms and ischaemic stroke: a systematic review and meta analysis

BACKGROUND

Paraoxonase is known to play an important role in the pathophysiology of atherosclerosis. Genetic variants of the paraoxonase gene have been implicated as risk factors for atherosclerotic diseases such as coronary artery disease, but individual genetic association studies examining the relationship between the paraoxonase gene polymorphisms and ischaemic stroke have yielded inconsistent results.

AIM

This study aimed to evaluate the association between the paraoxonase gene variants and ischaemic stroke using systematic review with meta-analysis.

METHODS

Relevant studies were identified by searching English and Chinese databases extensively. Allele and genotype frequencies for each included study were extracted. The odds ratio was calculated using a random-effects or fixed-effects model. A Q statistic was used to evaluate homogeneity, and Egger's test and funnel plot were used to assess publication bias.

RESULTS

A total of 28 studies were included and identified for the current meta-analysis. It was found that the R allele or RR genotype of paraoxonase 1 Q192R polymorphism had an increased risk for ischaemic stroke in the general population (192R allele: odds ratio: 1·21, 95% confidence interval: 1·08-1·35, P = 0·0009 and 192RR genotype: odds ratio: 1·25, 95% confidence interval: 1·06-1·49, P = 0·009 in general population, respectively), but there was no significant association between other genetic variants of paraoxonase gene and ischaemic stroke.

CONCLUSIONS

Existing evidence indicates that the Q192R polymorphism (the R allele and RR genotype) is associated with an increased risk of ischaemic stroke in the general population. Future studies with larger sample sizes will be necessary to confirm the present results.

PPARs in Regulation of Paraoxonases: Control of Oxidative Stress and Inflammation Pathways

The paraoxonase (PON) group of enzymes, composed of PON1, PON2, and PON3, play an important role in decreasing oxidative stress by degrading lipid peroxides. PON1 synthesis is upregulated by PPAR. Several pharmacological compounds (acting as antioxidants and, hence, atheroprotective) stimulate both PPAR activity and PON1 expression. Recent evidence suggests that PON1 and the monocyte chemoattractant protein-1 (MCP-1) are involved in coordinating the inflammatory response in damaged tissues; PPAR may be central in the regulation of these biochemical pathways. This article reviews the state of knowledge on PON1 biochemistry and function, the influence of genetic variation, and the regulation of PON1 expression by pharmaceutical compounds that increase PPAR activity. We also describe recent lines of evidence suggesting links between PON1 and MCP-1 and how their production may be regulated by PPAR.

Serum PON-1 activity but not Q192R polymorphism is related to the extent of atherosclerosis

AIM

Paraoxonase-1 (PON1) is an antioxidant enzyme located in high density lipoprotein (HDL). PON1 was defined as a protective factor against atherosclerosis. The aim of this study was to investigate the possible relationship between serum paraoxonase (PONase), homocysteine thiolactonase (HTase) activities and PON1 Q192R polymorphism, and the extent and severity of atherosclerosis.

METHODS

Blood specimens were collected from 142 individuals who had no coronary artery lesions angiographically (control group) and 128 individuals who had angiographically documented coronary artery disease of several degrees (patient group). The extent and severity of arterial lesions were evaluated by the Gensini scoring system. PONase and HTase activities were measured in serum using a spectrophotometric method. PON1 Q192R polymorphism was evaluated using PCR-RFLP after DNA isolation from blood.

RESULTS

Serum PONase and HTase activities were significantly lower in the patient group than in healthy controls (135.7±56.0U/mL vs 153.8±62.0U/mL, p< 0.05; 36.0±6.1 U/mL vs 43.0±4.04 U/mL, p< 0.01; respectively). In the patient group, there was a negative correlation between PONase, HTase activities and the Gensini score (r=-0.168, p= 0.039; r=-0.164, p= 0.006, respectively). In both groups, there was no significant difference in the distribution of PON1 Q192R polymorphism. In the patient group, the distribution of Gensini scores according to genotypes was not significant.

CONCLUSION

It has been concluded that serum PONase and HTase activities might be a more relevant marker than PON1 genotype in evaluating the extent and severity of atherosclerosis.

Susceptibility of LDL and its subfractions to glycation

PURPOSE OF REVIEW

To highlight the potential importance of glycation as an atherogenic modification of LDL, factors determining glycated apolipoprotein B in vivo and susceptibility of LDL to glycation in vitro. We also discuss the distribution of glycated apolipoprotein B across different LDL subfractions in healthy controls, patients with type 2 diabetes and metabolic syndrome.

RECENT FINDINGS

Small, dense LDL, which is known to be most closely associated with atherogenesis, is more preferentially glycated in vivo and more susceptible to glycation in vitro than more buoyant LDL. Glycation and oxidation of LDL appear to be intimately linked. In patients with type 2 diabetes, plasma glycated apolipoprotein B correlated with small, dense LDL apolipoprotein B, but not with HbA1c. Glycated apolipoprotein B is significantly lower in statin-treated type 2 diabetes compared with those not on statins.

SUMMARY

Glycation of LDL occurs chiefly because of the nonenzymatic reaction of glucose and its metabolites with the free amino groups of lysine of which apolipoprotein B is rich. Higher concentrations of glycated LDL are present in diabetes than in nondiabetic individuals and metabolic syndrome. Even in nondiabetic individuals, however, there is generally more circulating glycated LDL than oxidatively modified LDL. Probably, oxidation and glycation of LDL are partially interdependent and indisputably coexist, and both prevent LDL receptor-mediated uptake and promote macrophage scavenger receptor-mediated LDL uptake. The recognition that LDL glycation is at least as important as oxidation in atherogenesis may lead to improvements in our understanding of its mechanism and how to prevent it.

Paraoxonase 1 (PON1) polymorphisms, haplotypes and activity in predicting cad risk in North-West Indian Punjabis

BACKGROUND

Human serum paraoxonase-1 (PON1) prevents oxidation of low density lipoprotein cholesterol (LDL-C) and hydrolyzes the oxidized form, therefore preventing the development of atherosclerosis. The polymorphisms of PON1 gene are known to affect the PON1 activity and thereby coronary artery disease (CAD) risk. As studies are lacking in North-West Indian Punjabi's, a distinct ethnic group with high incidence of CAD, we determined PON1 activity, genotypes and haplotypes in this population and correlated them with the risk of CAD.

METHODOLOGY/PRINCIPAL FINDINGS

350 angiographically proven (≥ 70% stenosis) CAD patients and 300 healthy controls were investigated. PON1 activity was determined towards paraoxon (Paraoxonase; PONase) and phenylacetate (Arylesterase; AREase) substrates. In addition, genotyping was carried out by using multiplex PCR, allele specific oligonucleotide -PCR and PCR-RFLP methods and haplotyping was determined by PHASE software. The serum PONase and AREase activities were significantly lower in CAD patients as compared to the controls. All studied polymorphisms except L55M had significant effect on PONase activity. However AREase activity was not affected by them. In a logistic regression model, after adjustment for the conventional risk factors for CAD, QR (OR: 2.73 (1.57-4.72)) and RR (OR, 16.24 (6.41-41.14)) genotypes of Q192R polymorphism and GG (OR: 2.07 (1.02-4.21)) genotype of -162A/G polymorphism had significantly higher CAD risk. Haplotypes L-T-G-Q-C (OR: 3.25 (1.72-6.16)) and L-T-G-R-G (OR: 2.82 (1.01-7.80)) were also significantly associated with CAD.

CONCLUSIONS

In conclusion this study shows that CAD patients had lower PONase and AREase activities as compared to the controls. The coding Q192R polymorphism, promoter -162A/G polymorphism and L-T-G-Q-C and L-T-G-R-G haplotypes are all independently associated with CAD.