Altered distribution of plasma platelet-activating factor acetylhydrolase between high-density lipoprotein and low-density lipoprotein in patients with polycystic ovary syndrome

GALNT2 Gene Variant rs4846914 Is Associated with Insulin and Insulin Resistance Depending on BMI in PCOS Patients: a Case-Control Study

GALNT2 is a GalNAc transferase that regulates insulin signaling, lipogenesis, and serum lipid fractions. The objective of this study was to investigate the association of GALNT2 rs2144300 and rs4846914 single nucleotide polymorphisms (SNPs) with the risk of polycystic ovary syndrome (PCOS) and related traits. The two SNPs were genotyped in 616 PCOS patients and 482 control subjects. Genetic associations with related traits were also analyzed. The genotype distributions of the two SNPs in PCOS patients were similar to those of normal controls. However, significant differences were noted across the three groups of genotypes with respect to the examined variables. In the PCOS group, subjects with genotype AA at the rs4846914 SNP exhibited an increased fasting serum insulin and homeostasis model insulin resistance (HOMA-IR) index compared with that of corresponding GG or GA genotype carriers (all P < 0.05). When PCOS patients were further separated into obese and non-obese subgroups, the genotype-related effects on insulin and HOMA-IR were more obvious, and variations in BMI and FSH levels were exclusively observed in obese PCOS subjects (all P < 0.05). In addition, fasting plasma glucose levels were affected by the genotypes of the rs2144300 SNP in normal control women (P < 0.05). rs4846914 and rs2144300 polymorphisms in the GALNT2 gene are associated with insulin and HOMA-IR, BMI, and FSH levels in obese PCOS patients and glucose levels in normal control women, respectively, but not with PCOS. GALNT2 rs4846914 AA carrier status may be associated with insulin resistance and related traits in obese patients.

Effect of the R92H and A379V genotypes of platelet-activating factor acetylhydrolase on its enzyme activity, oxidative stress and metabolic profile in Chinese women with polycystic ovary syndrome

Background

The G994T polymorphism in platelet-activating factor acetylhydrolase (PAF-AH) gene is associated with the risk of polycystic ovary syndrome (PCOS). The aim of this study was to investigate the relationship between R92H and A379V variants of the PAF-AH gene and the risk of PCOS and to evaluate the effects of the genotypes on PAF-AH activities and clinical, metabolic and oxidative stress indexes in Chinese women.

Methods

A total of 862 patients with PCOS based on the Rotterdam consensus criteria and 750 control women from a population of Chinese Han nationality in the Chengdu area were studied from 2006–2015. PAF-AH genotypes were determined by PCR and restriction fragment length polymorphism analysis. Plasma PAF-AH, high-density lipoprotein (HDL)-associated PAF-AH (H-PAF-AH) and apolipoprotein (apo) B-containing lipoprotein-associated PAF-AH (apoB-PAF-AH) activities were measured using the trichloroacetic acid precipitation procedure with PAF C-16 as a substrate. Circulating markers of oxidative stress, including serum total oxidant status, total antioxidant capacity, oxidative stress index and malondialdehyde levels, and clinical and metabolic parameters were also analyzed.

Results

No significant differences were observed in the frequencies of R92H and A379V genotypes and alleles of the PAF-AH gene between PCOS and control groups (P > 0.05). Compared with patients with the 92RR genotype, patients with H allele of R92H (RH + HH genotype) had significantly higher plasma PAF-AH and apoB-PAF-AH activities (P < 0.05) and tended to exhibit increased H-PAF-AH activity (P = 0.063) after adjusted for age and BMI. However, when serum LDL-C, HDL-C, TG and HOMA index were added as covariates, the comparisons no longer remained statistical significance (P > 0.05). There were no significant differences in clinical, hormonal, metabolic and circulating oxidative stress parameters and the frequencies of PAF-AH G449T genotype according to PAF-AH R92H or A379V genotyping in patients with PCOS and control women.

Conclusions

There were no significant associations between R92H and A379V variants of PAF-AH gene and risk of PCOS in Chinese women. The increased plasma PAF-AH and apoB-PAF-AH activities in patients with H allele of R92H are related to the R92 → H variation, changes in plasma lipoprotein levels, insulin resistance, aging, and gaining weight and thus may be involved in the pathogenesis of PCOS and the increased risks of future cardiovascular diseases.

Activity and distribution of plasma platelet-activating factor acetylhydrolase in women with gestational diabetes mellitus and their neonates

BACKGROUND

Abnormal activity and distribution of plasma platelet-activating factor acetylhydrolase (PAF-AH) are associated with chronic inflammatory status. In this study, we investigate the activity and distribution of plasma PAF-AH and their association with metabolic components in mothers with gestational diabetes mellitus (GDM) and in their neonates.

METHODS

Based on the International Association of Diabetes Pregnancy Study Group criteria, we performed a case-controlled study of 101 women with GDM, 98 women with uncomplicated pregnancies, 142 neonates of mothers with GDM and 121 neonates of mothers with uncomplicated pregnancies. Plasma PAF-AH, high-density lipoprotein (HDL)-associated PAF-AH (H-PAF-AH) and apolipoprotein (apo) B-containing lipoprotein-associated PAF-AH (apoB-PAF-AH) activities were measured using the trichloroacetic acid precipitation procedure with PAF C-16 as a substrate.

RESULTS

The plasma PAF-AH and apoB-PAF-AH activities, triglyceride (TG) levels, atherogenic index and TG/HDL-C ratio were increased, and the H-PAF-AH proportions were decreased in the mothers with GDM compared with the control mothers (p < 0.05). Multivariate regression analyses demonstrated that the apoB and TG levels were significant predictors of plasma PAF-AH or apoB-PAF-AH activities, while the low-density lipoprotein-cholesterol levels, weight gain during pregnancy and age were associated with H-PAF-AH activities. The neonates of mothers with GDM had higher plasma insulin and glucose concentrations (p < 0.05) and tended to exhibit increased serum apoB levels (p = 0.062) compared with the neonates of mothers with uncomplicated pregnancies.

CONCLUSIONS

The mothers with GDM presented with a state of chronic inflammation, and these mothers and their neonates also exhibited unfavourable metabolic profiles in terms of glucose and lipids. Copyright © 2016 John Wiley & Sons, Ltd.

Reassessing lipid metabolism and its potentialities in the prediction of cardiovascular risk

There are numerous particles, enzymes, and mechanisms in the lipid metabolism that are involved in the genesis of cardiovascular disease (CVD). Given its prevalence in populations and its impact on mortality, it is relevant to review the lipid metabolism as it may potentially provide subsidies to better prediction. This article reviews the importance of traditional cardiovascular risk factors and comments on the potential of novel lipid biomarkers involved in the physiopathology of CVD. The Framingham cohorts proved the role of traditional risk factors (physical inactivity, smoking, blood pressure, total cholesterol, LDL-C, HDL-C, plasma glucose) in the prediction of cardiovascular events. However, a significant number of individuals that suffer from a cardiovascular event has few or none of these factors. Such finding indicates the need for new biomarkers able to identify plaques that are more susceptible to rupture. Some of bloodstream biomarkers related to lipid metabolism are modified LDL particles, apolipoprotein AI (apo AI), apolipoprotein B, lipoprotein (a) [Lp (a)], cholesteryl ester transfer protein (CETP), subtypes of LDL and HDL particles, and lipoprotein-associated phospholipase A2 (Lp-PLA2). These factors participate in the atherosclerotic process, and are abnormal in individuals at high risk, or in those who suffered from a cardiovascular event. Lp (a) determination is already employed in clinical practice and should be included as a reference parameter for CVD monitoring. Furthermore, there are expectations for wider use of apo B, non-HDL cholesterol and total cholesterol / HDL-C determination to improve cardiovascular risk assessment.

Antioxidant properties of high-density lipoproteins are impaired in women with polycystic ovary syndrome

OBJECTIVE

To determine the relationships among the inflammatory index, intrinsic oxidation levels, lipid and apolipoprotein (apo)A-I concentrations of high-density lipoprotein (HDL), and polycystic ovary syndrome (PCOS).

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENT(S)

A total of 425 patients with PCOS and 441 control women were included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The HDL inflammatory index (HII) was determined using a cell-free fluorometric assay. Intrinsic HDL oxidation levels, HDL-free cholesterol, HDL-cholesterol ester, HDL-triglyceride, serum apoA-I, and malondialdehyde levels were also measured.

RESULT(S)

The mean HII value and the frequency of HII ≥1 were significantly higher in the PCOS group (0.77 ± 0.54, 27.1%) than in the control group (0.53 ± 0.37, 8.4%). These values were also higher in each of the 4 PCOS phenotypes based on the Rotterdam criteria than in the controls, and higher in patients with hyperandrogenism (HA) + oligo- and/or anovulation (OA) phenotype than in those with OA + polycystic ovary (PCO) phenotype. Furthermore, patients with PCOS with OA + PCO had lower malondialdehyde and intrinsic HDL oxidation levels compared with those with HA. Multivariate regression analysis demonstrated that PCOS, HDL-cholesterol ester, and E2 levels were the main predictors of HII value.

CONCLUSION(S)

The impairment of HDL antioxidant/anti-inflammatory function in PCOS is related to HA status, increased oxidative stress, and abnormalities in HDL components and thus may contribute to PCOS pathogenesis and increase the risks of future cardiovascular diseases.

Naturally Occurring Missense Mutation in Plasma PAF-AH Among the Japanese Population

A single nucleotide polymorphism in the plasma PAF-AH enzyme, i.e., G994T, which causes the substitution of Val at amino acid 279 with Phe (V279F), has been found in the Japanese population. This enzyme preferentially degrades oxidatively modulated or truncated phospholipids; therefore, it has been suggested that this enzyme may prevent the accumulation of proinflammatory and proatherogenic oxidized phospholipids. This hypothesis is supported by the higher prevalence of the V279F mutation in patients with asthmatic and atherosclerotic diseases, as compared with healthy controls. This mutation is rare in the Caucasian population. The plasma PAF-AH mass and enzyme activity are distributed over a wide range in the plasma and they are positively correlated with low-density lipoprotein (LDL) cholesterol. However, several clinical studies in the Caucasian population have suggested that this enzyme has the opposite role. This enzyme plays an active role in the development and progression of atherosclerosis via proinflammatory and proatherogenic lysophosphatidylcholine and oxidized fatty acids produced through the oxidation of LDL by this enzyme. Thus, plasma PAF-AH is a unique enzyme with dual roles in human inflammatory diseases. In this chapter, on the basis of recent findings we describe the association between a naturally occurring missense mutation in plasma PAF-AH and human diseases especially including atherosclerosis and asthma.

Effects of apolipoprotein E genotypes on metabolic profile and oxidative stress in southwest Chinese women with polycystic ovary syndrome

OBJECTIVE

Apolipoprotein (APO) E genetic polymorphism plays an important role in lipid and lipoprotein metabolism, and has been shown to be associated with the risk of metabolic and cardio-cerebrovascular diseases and late-onset Alzheimer's disease. It is not clear, however, whether there are any relationships between the APOE genotypes and PCOS in Chinese women. The aim of this study was to investigate the relationship between APOE genotypes and the risk of polycystic ovary syndrome (PCOS) and to evaluate the effects of the genotypes on metabolic profile and oxidative stress in south-west Chinese women.

STUDY DESIGN

A total of 625 patients with PCOS based on the Rotterdam consensus criteria and 514 control women from a population of Chinese Han nationality in the Chengdu area were studied during 2006-2012. APOE genotypes were determined by PCR and restriction fragment length polymorphism analysis. Clinical and metabolic parameters, serum malondialdehyde concentration, and total antioxidant capacity were analyzed.

RESULTS

No significant differences were found in the frequencies of APOE genotypes (E2/2, E2/3, E2/4, E3/3, E3/4, E4/4) and alleles (ε2, ε3, ε4) between PCOS and control groups. Compared with ε3 homozygotes (APOE3/3), however, ε2 carriers (APOE2/2+APOE2/3+APOE2/4) had significantly higher body mass index, waist circumference and waist-to-hip ratio, a more adverse glucose and insulin metabolic profile, lower high density lipoprotein (HDL)-cholesterol (C) and APOA1 levels, higher triglyceride (TG)/HDL-C ratio and prevalence of metabolic syndrome (MS), whereas ε4 carriers (APOE3/4+APOE4/4) had higher total cholesterol (TC) and low density lipoprotein (LDL)-C levels in patients with PCOS.

CONCLUSIONS

In a cohort of south-west Chinese women, there were no significant associations between any APOE genotype and PCOS. The APOE ε2 allele seems to be related to abdominal obesity, insulin resistance and MS in PCOS women.

Maternal and fetal plasma platelet-activating factor acetylhydrolase activity and distribution in pre-eclampsia

BACKGROUND

Distribution of platelet-activating factor acetylhydrolase (PAF-AH) in lipoproteins plays important roles in the onset of inflammation and atherosclerosis. We hypothesized that women with pre-eclampsia (PE), showing signs of inflammation and oxidative stress, and their fetuses have aberrations of PAF-AH activity and distribution.

METHODS

Maternal and fetal plasma PAF-AH activity, high-density lipoprotein (HDL)-associated PAF-AH (H-PAF-AH) and low-density lipoprotein (LDL)-associated PAF-AH (L-PAF-AH) were examined in women with PE (n = 127) and in women with uncomplicated pregnancies (n = 88).

RESULTS

The neonates of women with severe PE (n = 42) had significantly higher plasma PAF-AH, L-PAF-AH activities, and ratio of L-PAF-AH to H-PAF-AH activities than the neonates of women with normal pregnancies (n = 83). The mothers with severe PE (n = 106) and their neonates presented a significantly higher atherogenic index (AI) and triglyceride (TG)/HDL cholesterol (C) ratio than the control mothers and their neonates. The ratio of L-PAF-AH to H-PAF-AH activities correlated positively with TG levels, TG/HDL(C) ratio, and AI and negatively with HDL(C) levels in the neonates of women with PE.

CONCLUSION

The neonates of women with severe PE presented with a chronic inflammation status, increased oxidative stress, and unfavorable lipid changes, which may potentially link to related complications responsible for oxidative stress and inflammation in later life.

Utility of Lp-PLA2 in lipid-lowering therapy

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a vascular-specific inflammatory marker. It is so named because of its association with low-density lipoprotein in plasma. Atherosclerosis is an inflammatory disease. Lp-PLA2 is recognized as a risk marker in primary or secondary prevention of atherosclerosis. Elevated Lp-PLA2 levels are associated with the increased risk for cardiovascular events, even after multivariable adjustment for traditional risk factors. Patients with dyslipidemia are shown to benefit largely from the modification of Lp-PLA2. The degree of coronary artery disease (0-, 1-, 2-, or 3-vessel disease) and plasma low-density lipoprotein cholesterol significantly correlated to Lp-PLA2 levels. The low biologic fluctuation and high vascular specificity of Lp-PLA2 make it possible to use a single measurement in clinical decision making, and it also permits clinicians to follow the Lp-PLA2 marker serially. Simvastatin significantly reduces macrophage content, lipid retention, and the intima to media ratio but increased the content of smooth muscle cells in atherosclerotic lesions. Statin treatment markedly reduced Lp-PLA2 in both plasma and atherosclerotic plaques with attenuation of the local inflammatory response and improved plaque stability due to reduced inflammation and decreased apoptosis of macrophages. Darapladib, an inhibitor of Lp-PLA2 when added to lipid-lowering therapy such as statins, offers great benefit in the reduction of plaque formation. This article explores the atherosclerotic process at molecular level, role of Lp-PLA2 in atherosclerosis, the effect of lipid-lowering drugs on Lp-PLA2, effect of direct Lp-PLA2 inhibitor darapladib in the atherosclerosis process, the therapeutic implications of Lp-PLA2 as risk marker, and finally the net effect on plaque stabilization.

Evidence for association between paraoxonase 1 gene polymorphisms and polycystic ovarian syndrome in southwest Chinese women

OBJECTIVE

The aim of this study was to investigate the relationship between 192Q/R and 55L/M polymorphisms of paraoxonase 1 (PON1) gene and polycystic ovarian syndrome (PCOS) in Chinese women.

DESIGN

A case-control study.

METHODS

A total of 1113 subjects (610 patients with PCOS and 503 control women) from a population of Chinese Han nationality in Chengdu area were included in this study. PON1 genotypes were studied using PCR and restriction fragment length polymorphism analysis. Clinical and metabolic parameters were analyzed.

RESULTS

The frequencies of PON1 192RR genotype and R allele were significantly higher in patients with PCOS than in control women (44.6 vs 36.4%, 0.667 vs 0.610 respectively). The 192RR genotype remained a significant predictor for PCOS (odds ratio (RR/QR)(+)(QQ): 1.656, 95% confidence interval: 1.156-2.371) in prognostic models including age, body mass index, insulin resistance index, triglyceride, HDL, and LDL as covariates. Compared with patients with QQ genotype, patients with RR or QR genotype had significantly higher waist circumference and fasting insulin and triglyceride levels, patients with RR genotype had significantly higher waist-to-hip ratio, and patients with QR genotype had significantly higher homeostasis model assessment of insulin resistance. Such relationships were not detected in the control women. No significant differences were found in the frequencies of PON1 55L/M genotype and allele between PCOS and control groups.

CONCLUSIONS

The 192Q/R, but not 55L/M, polymorphism in PON1 gene is associated with the risk of PCOS in south-west Chinese women.

Apolipoprotein E-containing HDL-associated platelet-activating factor acetylhydrolase activities and malondialdehyde concentrations in patients with PCOS

PAF and PAF-like oxidized phospholipids hydrolysed by platelet-activating factor (PAF) acetylhydrolase (AH) are potent lipid mediators involved in inflammation and atherosclerosis. Apolipoprotein (apo) E-containing high-density lipoprotein (HDL) has antioxidant, anti-inflammatory and anti-atherogenic properties. The study investigated apoE-containing HDL-associated PAF-AH (HDL-PAF-AH) and total (apoE-containing+apoE-poor) HDL-PAF-AH activities as well as malondialdehyde (MDA) concentration in 291 patients with polycystic ovary syndrome (PCOS) using the Rotterdam consensus criteria and 281 control women. Compared with the control women, patients with hyperandrogenism+oligo/anovulation+polycystic ovaries (PCO) or hyperandrogenism+PCO had lower total, apoE-containing and apoE-poor HDL-PAF-AH activities, while those with oligo/anovulation+PCO showed decreased total and apoE-poor HDL-PAF-AH activities. Other factors including insulin resistance and obesity in PCOS had the adverse effects associated with the HDL-PAF-AH activities. Serum MDA concentration was associated with PCOS, hyperandrogenism, insulin resistance and hypertriglyceridaemia in patients with PCOS. Decreased total and apoE-containing HDL-PAF-AH activities and increased serum MDA concentration may contribute to the pathogenesis of PCOS and potentially link to related complications responsible for oxidative stress and inflammation such as an increased risk for type 2 diabetes mellitus and/or future cardiovascular diseases in PCOS patients.

The role of low-grade inflammation in the polycystic ovary syndrome

PCOS is not only the most frequent cause of oligomenorrhea in young women, but also a metabolic disorder characterized by insulin resistance, glucose intolerance, dyslipidemia, and obesity, especially the visceral phenotype. PCOS represents a broad spectrum of endocrine and metabolic alterations which change with age and with increasing adiposity. In fact, during adolescence and youth the predominant clinical manifestations of PCOS are menstrual abnormalities, hirsutism and acne, whereas in peri-menopausal and post-menopausal periods metabolic disorders and an increased risk for cardiovascular diseases prevail. The pathogenetic links between PCOS and metabolic or cardiovascular complications are still debated. However, recent evidence has been focused on a condition of low-grade chronic inflammation as a potential cause of the long-term consequence of the syndrome. In this review we describe the state of low-grade inflammation observed in PCOS. In addition, we hypothesize the potential mechanisms responsible for the generation of this inflammatory state and the role played by low-grade inflammation in linking hyperandrogenism and insulin resistance with the metabolic and cardiovascular long-term complications of the syndrome.

Identification of the G994T polymorphism in exon 9 of plasma platelet-activating factor acetylhydrolase gene as a risk factor for polycystic ovary syndrome

BACKGROUND

Low-grade chronic inflammation and greater risks of cardiovascular diseases are often present in patients with polycystic ovary syndrome (PCOS). Platelet-activating factor (PAF) acetylhydrolase (PAF-AH) hydrolyzes and inactivates PAF and PAF-like oxidized phospholipids that are potent lipid mediators involved in inflammation and atherosclerosis. Deficiency of this enzyme is caused by a missense mutation (G994 --> T) in exon 9 of the plasma PAF-AH gene. The aim of the study was to investigate a possible association of this polymorphism with the risk of PCOS and to evaluate the effects of the genotype on the activity and distribution of PAFAH in Chinese patients.

METHODS

A total of 661 subjects (346 patients with PCOS and 315 healthy control women) from a population of Chinese Han nationality in Chengdu area were included in this study. PAFAH G994T genotype was studied using PCR and restriction fragment length polymorphism analysis. Total plasma PAF-AH, high-density lipoprotein (HDL)-associated PAF-AH (H-PAF-AH) and low-density lipoprotein (LDL)-associated PAF-AH (L-PAF-AH) activities were measured by the trichloroacetic acid precipitation procedure using [(3)H-acetyl] PAF and PAF C-16 as a substrate.

RESULTS

The prevalence of the mutant genotype (GT + TT) was significantly more frequent in patients with PCOS than in control subjects (12.7 versus 6.0%, P = 0.003). Genotype (GT + TT) remained a significant predictor for PCOS (P = 0.020) in prognostic models including age, body mass index, insulin resistance index, triglyceride, HDL and LDL as covariates. There was a significant difference in plasma PAF-AH, L-PAF-AH and H-PAF-AH activities between GG and GT genotypes in both the patient and control groups. The ratio of L-PAF-AH to H-PAF-AH activities was significantly higher after adjustment for multiple variables in patients with GT genotype compared with patients with GG genotype (P = 0.003). There were no significant differences in clinical, biochemical and metabolic parameters according to PAFAH G994T genotyping in patients with PCOS and control women.

CONCLUSIONS

The G994T polymorphism in PAFAH gene may be one of the genetic determinants for PCOS in Chinese Han women.