Hieronymus A.M. Voorbij

Risk factors for cardiovascular disease in women with a history of pregnancy complicated by preeclampsia or intrauterine growth restriction.

Objective: Women with a history of preeclampsia or intrauterine growth restriction (IUGR) have an increased risk for cardiovascular disease in later life. We determined the presence of traditional and novel risk factors for cardiovascular disease in these women. Methods: We studied 256 women with a history of preeclampsia and 59 women with a history of intrauterine growth restriction. Fifty-three women with a history of uncomplicated pregnancy served as controls. We determined values for blood pressure, body mass index, concentrations of cholesterol, high-density lipoprotein cholesterol, triglycerides and lipoprotein (a), and insulin resistance. Results: Women with a history of preeclampsia exhibited more risk factors for future cardiovascular disease such as dyslipidemia, hypertension, obesity, and increased insulin resistance compared with women with a history of uncomplicated pregnancy. Women with a history of IUGR have higher concentrations of cholesterol and show a tendency to higher BMI, higher triglyceride concentrations, and increased insulin resistance as compared with women with a history of normal pregnancy. Conclusions: Preeclampsia or IUGR may represent an early marker for increased risk for early cardiovascular disease.

PON2 gene variants are associated with clinical manifestations of cardiovascular disease in familial hypercholesterolemia patients

Paraoxonase is an enzyme associated with the high-density lipoprotein (HDL) particle. It catalyses the hydrolysis of organophosphates and protects LDL from oxidative modification in vitro by hydrolyzing lipid peroxides, suggestive of a role for paraoxonase in the development of atherosclerosis. Two frequent mutations at the paraoxonase gene locus (PON1) underlie the leucine (Leu allele) --> methionine (Met allele) and the glutamine(Gln allele) --> arginine(Arg allele) aminoacid substitutions at residues 55 and 192, respectively. These polymorphisms have been associated with increased risk for cardiovascular disease (CVD) in several studies, while others have not found this association. Recently, another member of the PON gene family designated PON2 has been identified. While the PON2 gene product is expressed ubiquitously, its physiological role is unknown. A common polymorphism at codon 311 (Cys-->Ser) in the PON2 gene has been described. In our study we assessed the frequency and genotype distribution of the PON1 and PON2 polymorphisms in 197 patients with familial hypercholesterolemia (FH), to determine the possible association between these mutations and susceptibility for CVD. The FH cohort group was divided into subjects with (n=83) and without (n=114) definite clinical manifestations of CVD (FH-Symptomatic and FH-Asymptomatic respectively). The control population consisted of 201 healthy normolipidemic blood donors. All subjects in this study were of Caucasian background. Genotypes were identified by PCR based analysis. With regard to the PON1 polymorphisms 55 and 192, no different distributions of allele frequencies were found between the groups studied. However, we did show an association between the PON2 311 polymorphism and CVD. The frequencies of PON2 Ser311 carriers (Ser/Ser and Cys/Ser) between FH-Symptomatic and both FH-Asymptomatic and controls did show a significant difference (P=0.01 and P=0.02 respectively). In the FH-Symptomatic population, surprisingly, no subjects were homozygous for PON2 Cys311, whereas in the FH-Asymptomatic population nine persons (7.9%) and in the control group 12 persons (6.0%) were homozygous. Our data indicate that the common PON2 polymorphism is associated with clinical manifestations of CVD in FH patients. While PON2 Ser311 carriers seem to be at risk, subjects with the Cys/Cys311 genotype are likely to be protected against the development of premature CVD.

Paraoxonase gene polymorphisms are associated with carotid arterial wall thickness in subjects with familial hypercholesterolemia

Human serum paraoxonase (PON) is a high density lipoprotein (HDL) associated enzyme capable of hydrolyzing lipid peroxides in vitro. PON has recently attracted attention as a protective factor against oxidative modification of LDL and may therefore play an important role in the prevention of the atherosclerotic process. Two frequent mutations at the paraoxonase gene locus (PON1) are the leucine (L allele)-->methionine (M allele) and the glutamine (Q allele)-->arginine (R allele) substitutions at residues 55 and 192, respectively. We have examined the influence of these two polymorphisms on carotid atherosclerosis in familial hypercholesterolemia (FH) patients. The allele frequencies of these two polymorphisms were determined by PCR and restriction fragment analysis, for both the FH population and healthy controls. High resolution B-mode ultrasound was used to assess intima-media wall thickness (IMT) of the carotid artery. No differences were found in allele frequencies between the FH and the control population. In FH patients, the LL, LM and MM genotypes at position 55 occurred in 86 (46.0%), 78 (41.7%) and 23 (12.3%) subjects, respectively, whereas the QQ, QR and RR genotypes at position 192 were found in 90 (48.1%), 79 (42.2%) and 18 (9.6%) individuals. When both polymorphisms were considered separately, no different carotid IMTs were found between the genotype groups. However, our data did show a significant association between the various genotypes of the combined polymorphisms at position 55 and 192 of PON1 and the carotid artery IMT in FH subjects. Subjects with the homozygous wildtype LL/QQ for paraoxonase had the highest mean carotid IMTs when compared to other genotypes, combined. Multiple regression analysis demonstrated age (beta=0.34, P<0.0001), total plasma cholesterol (beta=0.17, P=0. 0109) and the LL/QQ genotype of the PON1 gene (beta=0.22, P=0.0018) to be significant risk factors for carotid atherosclerosis in subjects with FH. The LL/QQ genotype could explain 5.3% of total variance of carotid IMT. In conclusion, this is the first study to report an independent association between the combined PON1 polymorphism genotypes and carotid wall thickness. The homozygous wildtype LL/QQ for PON1 may represent an additional risk factor for carotid atherosclerosis in subjects with FH.

Serum Ferritin Is a Risk Factor for Stroke in Postmenopausal Women

Background and Purpose— Iron is an essential element for the human body. It has, however, been suggested that excessive iron stores may increase the risk of vascular disease. So far, epidemiologic studies on stroke are sparse. Methods— We studied the association between iron status and stroke risk in a population-based cohort of 11 471 Dutch postmenopausal women between 49 and 70 years of age. Women were included between 1993 and 1997 and followed up until January 1, 2000, for cerebrovascular events. We conducted a case-cohort study by using all stroke cases (n=63) and a random sample of the baseline cohort (n=1134). Serum ferritin, serum iron, and transferrin saturation were measured as markers of iron status. A weighted Cox proportional-hazards model was used to estimate crude and multivariate-adjusted hazard ratios for tertiles of different iron parameters in relation to stroke. Results— In a multivariate model, the highest tertile of serum ferritin concentration was associated with an increased risk of stroke (hazard ratio [HR], 1.45; 95% confidence interval [CI], 0.87 to 2.42) compared with the lowest tertile. For ischemic stroke, the increase was more pronounced (HR, 2.23; 95% CI, 1.05 to 4.73) and reached statistical significance. Conclusions— Neither serum iron nor transferrin saturation was associated with an increased stroke risk. However, higher serum ferritin concentrations in postmenopausal women are associated with an increased risk of ischemic stroke.

Non–Transferrin-Bound Iron and Risk of Coronary Heart Disease in Postmenopausal Women

Background— Epidemiological studies aimed at correlating coronary heart disease (CHD) with serum ferritin levels have thus far yielded inconsistent results. We hypothesized that a labile iron component associated with non–transferrin-bound iron (NTBI) that appears in individuals with overt or cryptic iron overload might be more suitable for establishing correlations with CHD. Methods and Results— We investigated the relation of NTBI, serum iron, transferrin saturation, and serum ferritin with risk of CHD and acute myocardial infarction (AMI). The cohort used comprised a population-based sample of 11 471 postmenopausal women aged 49 to 70 years at enrollment in 1993 to 1997. During a median follow-up of 4.3 years (quartile limits Q1 to Q3: 3.3 to 5.4), 185 CHD events were identified, including 66 AMI events. We conducted a case-cohort study using all CHD cases and a random sample from the baseline cohort (n=1134). A weighted Cox proportional hazards model was used to estimate hazard ratios for tertiles of iron variables in relation to CHD and AMI. Adjusted hazard ratios of women in the highest NTBI tertile (range 0.38 to 3.51) compared with the lowest (range −2.06 to −0.32) were 0.84 (95% confidence interval 0.61 to 1.16) for CHD and 0.47 (95% confidence interval 0.31 to 0.71) for AMI. The results were similar for serum iron, transferrin saturation, and serum ferritin. Conclusions— Our results show no excess risk of CHD or AMI within the highest NTBI tertile compared with the lowest but rather seem to demonstrate a decreased risk. Additional studies are warranted to confirm our findings.

Maternal TLR4 and NOD2 gene variants, pro-inflammatory phenotype and susceptibility to early-onset preeclampsia and HELLP syndrome

Background Altered maternal inflammatory responses play a role in the development of preeclampsia and the hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome. We examined whether allelic variants of the innate immune receptors Toll-like receptor 4 (TLR4) and nucleotide-binding oligomerization domain 2 (NOD2), that impair the inflammatory response to endotoxin, are related to preeclampsia and HELLP syndrome. Methods and Findings We determined five common mutations in TLR4 (D299G and T399I) and NOD2 (R702W, G908R and L1007fs) in 340 primiparous women with a history of early-onset preeclampsia, of whom 177 women developed HELLP syndrome and in 113 women with a history of only uneventful pregnancies as controls. In addition, we assessed plasma levels of pro-inflammatory biomarkers C-reactive protein, interleukin-6, soluble intercellular adhesion molecule-1, fibrinogen and von Willebrand factor in a subset of 214 women included at least six months after delivery. After adjustment for maternal age and chronic hypertension, attenuating allelic variants of TLR4 were more common in women with a history of early-onset preeclampsia than in controls (OR 2.9 [95% CI 1.2–6.7]). Highest frequencies for TLR4 variants were observed in women who developed HELLP syndrome (adjusted OR 4.1 [95% CI 1.7–9.8]). In addition, high levels of interleukin-6 and fibrinogen were associated with a history of early-onset preeclampsia. Combined positivity for any of the TLR4 and NOD2 allelic variants and high levels of interleukin-6 was 6.9-fold more common in women with a history of early-onset preeclampsia (95% CI 2.1–23.2) compared to controls. Conclusions We observed an association of common TLR4 and NOD2 gene variants, and pro-inflammatory phenotype with a history of early-onset preeclampsia and HELLP syndrome. These findings suggest involvement of the maternal innate immune system in severe hypertensive disorders of pregnancy.

Ischemia modified albumin in normal pregnancy and preeclampsia.

Objective. Ischemia-modified albumin (IMA) has emerged as a new biomarker of myocardial ischemia. Currently, no information is available on maternal IMA levels during normal and complicated pregnancy. Preeclampsia is associated with ischemia and increased formation of free radicals in the placenta. We therefore hypothesized that production of IMA may occur in women with preeclampsia. Methods. Serum IMA and albumin concentrations were assessed in 12 patients with preeclampsia, 12 normal pregnant controls, and 12 nonpregnant controls. IMA levels were compared between groups and corrected for albumin by multivariate regression analysis. Results. Mean IMA levels were elevated in normal pregnant controls (107.3 U/mL; 95% CI, 102.5 to 112.01), compared with nonpregnant controls (94.5 U/mL; CI, 89.4 to 99.6; p = 0.015). In patients with preeclampsia, IMA levels were similar to those in normal pregnant controls (109.7 U/mL; CI, 102.2 to 117.2; p = 0.65). Also, no difference in IMA levels was observed between women with preeclampsia who delivered small-for-gestational-age (SGA) infants (99.0 U/mL; CI, 87.9 to 110.1; p = 0.13) and women with preeclampsia but without SGA. Conclusion. Serum IMA, which has been advocated as a clinical marker of cardiac ischemia, appears to be elevated during normal pregnancy. We found no significant relationship between IMA levels and preeclampsia, in women with or without SGA infants.

Genetic and environmental determinants of the PON‐1 phenotype

Background  Paraoxonase (PON‐1) is a high‐density lipoprotein (HDL)‐associated enzyme that may protect against cardiovascular disease (CVD), because it hydrolyses oxidized phospholipids of low‐density lipoprotein (LDL) and therefore prevents the detrimental effects on the arterial wall. The current report describes the determinants of PON‐1 bioavailability and activity.

Paraoxonase (PON1) and the risk for coronary heart disease and myocardial infarction in a general population of Dutch women

There is strong evidence from both animal- and in vitro-models that paraoxonase (PON1) is involved in the onset of cardiovascular disease. In humans there is no consensus on this issue and therefore we investigated the effect of PON1 genotype and activity on the incidence of coronary heart disease (CHD) and acute myocardial infarction (AMI) in a large prospective cohort of 17,357 middle-aged women. We applied a case-cohort design using the CHD (n=211) and AMI cases (n=71) and a random sample from the baseline cohort (n=1527). A weighted Cox proportional hazards model was used to estimate age- and multivariate-adjusted hazard ratios (HR) for the PON1 genetic variants (192Q > R and -107C > T) and tertiles of the PON1 arylesterase- and paraoxonase activities. Neither the PON1 genetic variants, nor the PON1 activities affected the incidence of CHD in general, but, an increased paraoxonase activity was associated with a higher risk of AMI: the second and third tertile HR were 1.31 and 2.07, respectively (P-trend=0.029, multivariate model). In the subgroup of never-smokers, paraoxonase activity was associated with an increased risk for AMI: the second and third tertile HR were 4.1 and 4.7, respectively (P-trend=0.009, multivariate model). Additionally, when compared to the lowest paraoxonase tertile in never-smokers, the highest paraoxonase tertile in current-smokers showed a 19.2-fold higher risk for AMI (95%CI: 5.3-69.5, P < 0.0001, multivariate model). In conclusion, this study shows that in middle-aged women paraoxonase activity was associated with an increased risk for AMI and that the risk was modified by the effects of smoking.

High levels of urinary F2-isoprostanes predict cardiovascular mortality in postmenopausal women

BACKGROUND F2-isoprostanes are prostaglandin-like compounds formed via arachidonic acid oxidation during oxidative stress. OBJECTIVE To study the relation between urinary concentrations of 8-iso-prostaglandin F2α (8-iso PGF2α) and mortality due to cardiovascular disease (CVD) in a nested case-cohort design. METHODS Follow-up duration of this prospective study among postmenopausal women was 18 years. Cases included 141 women who died of coronary heart disease and 109 women who died of stroke, whereas controls were a random cohort sample of 142 women. The concentration of 8-iso PGF2α was determined with liquid chromatography/tandem mass spectrometry in urine samples collected at baseline. RESULTS Smokers had 34.8% higher urinary 8-iso PGF2α concentrations than nonsmokers (P < 0.001). High levels of urinary 8-iso PGF2α were associated with increased incidence of fatal CVD. Women who were in the highest quartile of urinary 8-iso PGF2α levels had, independently of age, an odds ratio of 1.8 (95% confidence interval, 1.1-3.1, P < 0.05) for CVD mortality. Further adjustment by systolic blood pressure, history of CVD, diabetes, smoking, and body mass index did not attenuate this association. CONCLUSION Women with high levels of urinary 8-iso PGF2α had an 80% increased risk of dying of coronary heart disease or stroke, supporting involvement of oxidative stress in the pathophysiology of cardiovascular disease.