Serum angiotensin-converting enzyme activity in pregnancy-induced hypertension

Increased angiotensin II coupled with decreased Adra1a expression enhances cardiac hypertrophy in pregnancy-associated hypertensive mice

Cardiac hypertrophy is a crucial risk factor for hypertensive disorders during pregnancy, but its progression during pregnancy remains unclear. We previously showed cardiac hypertrophy in a pregnancy-associated hypertensive (PAH) mouse model, in which an increase in angiotensin II (Ang II) levels was induced by human renin and human angiotensinogen, depending on pregnancy conditions. Here, to elucidate the factors involved in the progression of cardiac hypertrophy, we performed a comprehensive analysis of changes in gene expression in the hearts of PAH mice and compared them with those in control mice. We found that alpha-1A adrenergic receptor (Adra1a) mRNA levels in the heart were significantly reduced under PAH conditions, whereas the renin-angiotensin system was upregulated. Furthermore, we found that Adra1a-deficient PAH mice exhibited more severe cardiac hypertrophy than PAH mice. Our study suggests that Adra1a levels are regulated by renin-angiotensin system and that changes in Adra1a expression are involved in progressive cardiac hypertrophy in PAH mice.

The effect of age on blood pressure response by 4-week treatment perindopril: A pooled sex-specific analysis of the EUROPA, PROGRESS, and ADVANCE trials

Previous studies showed that postmenopausal women are more likely to have poorly controlled hypertension than men of the same age. Whether this is caused by inadequate treatment or poor response to antihypertensive agents remains unknown. The aim of this study is to analyze treatment response to the most potent renin angiotensin aldosterone system (RAAS) inhibitor perindopril in different age categories in women and men. Individual patient data were used from the combined European Trial on Reduction of Cardiac Events With Perindopril (EUROPA), Perindopril Protection Against Recurrent Stroke Study (PROGRESS), and Action in Diabetes and Vascular disease: Preterax and Diamicron‐MR Controlled Evaluation (ADVANCE) trials, which include patients with vascular disease (n = 29,463). We studied the relative and absolute changes in systolic blood pressure (SBP) and diastolic blood pressure (DBP) during a 4‐week run‐in phase in which all patients were treated with the perindopril‐based treatment in different age categories. In total, 8366 women and 21,097 men were included in the analysis. Women greater than 65 years of age showed a significantly smaller blood pressure reduction after perindopril treatment (2.8 mmHg [95% confidence interval {CI} = 0.1–5.5] less reduction compared to women ≤45 years, p = 0.039). In men, the SBP reduction after perindopril in patients greater than 55–65 and greater than 65 years was lower compared to the age category less than or equal to 45 years (adjusted mean difference >55–65: 2.8 mmHg [95% CI = 1.8–3.7], p < 0.001, >65: 3.7 mmHg [95% CI = 2.7–4.7], p < 0.001). A trend of less blood pressure reduction was seen with ageing in both men and women (p < 0.001). To conclude, we observed that in both women and men the perindopril leads to less SBP reduction with increasing age, whereas the DBP reduction increases with age. More research is needed to determine whether it would be beneficial to use age‐adjusted perindopril dosages.

Lack of change in serum angiotensin-converting enzyme activity during the menstrual cycle

Introduction. The Deletion (D) rather than Insertion (I) variant of the angiotensin-converting enzyme (ACE) gene is associated with higher circulating ACE activity. Meanwhile, coronary risk rises with the menstrual nadir in oestrogen levels, exogenous oestrogen reduces serum ACE activity (with a greater reduction the higher the baseline ACE activity), and pharmacological reduction in ACE activity is cardioprotective. Alterations in coronary risk associated with the menstrual cycle may thus be mediated through (genotype-dependent) changes in ACE activity. We have examined this hypothesis.

Materials and methods. Twenty-three healthy female subjects (12 II, 11 DD genotype) were studied. None were taking oral contraceptive agents. Blood was assayed for oestrogen, follicle stimulating hormone (FSH), luteinising hormone (LH), progesterone and ACE activity every three days throughout their menstrual cycle. Results ACE activity was unrelated to oestrogen, FSH or LH during the menstrual cycle, irrespective of ACE genotype.

Conclusions. The increase in myocardial ischaemia during low oestrogen phases of the menstrual cycle does not appear mediated through a fall in serum ACE activity.

The influence of mode of delivery and ACE genotype on serum angiotensin converting enzyme (ACE) activity in the mother and infant at term

OBJECTIVE

Angiotensin converting enzyme (ACE) and its genotype have been shown to play a role in the pathophysiology of pregnancy complications such as pre-eclampsia and intrauterine growth restriction and possibly in adult onset chronic diseases. The physiological changes of ACE and the influence of its genotype during the intrapartum period are not well known. Hence the aim of this study was to assess serum ACE activity and its genotype in mothers and infants at term in relation to labour and mode of delivery.

STUDY DESIGN

A cross sectional study of 99 women who laboured and 27 women who delivered by elective caesarean section after 36 completed weeks gestation with uncomplicated pregnancies. Venous cord bloods were obtained immediately after delivery of the placenta for serum ACE activity, ACE genotype and acid-base status. Maternal venous samples were obtained just after delivery for analysis of ACE activity and ACE genotype. Univariate analyses were performed using parametric tests for normally distributed data and nonparametric tests for the data that were not normally distributed. A multiple regression model was developed to adjust for potential confounding factors.

RESULTS

The umbilical venous ACE activity was similar for infants delivered following labour compared to those delivered by elective caesarean section, 47.2 U/L (35-64) versus 40.1 U/L (31-60) (adjusted p=0.21). Maternal ACE activities were 28.9 U/L (22-35) and 32.1 U/L (22-40) respectively (adjusted p=0.17). The ACE activity in infants was higher than that of mothers 46 U/L versus 22 U/L, respectively (p= or <0.001). Neither the mode of delivery nor the presence of suspected fetal compromise influenced maternal or infant ACE activity. There was no influence of the infants' genotype on ACE activity in relation to mode of delivery. The DD genotype was associated with higher ACE activity in mothers (p=0.001) but not in infants (p=0.56).

CONCLUSIONS

This study shows that intrapartum events do not affect ACE activity. These results will enhance our ability to investigate the role of ACE and its genotype in abnormal fetal growth and in subsequent adult onset chronic disease.

ACE gene is associated with Alzheimer's disease and atrophy of hippocampus and amygdala

Despite biological support for a role of angiotensin converting enzyme (ACE) in Alzheimer's disease (AD), studies assessing the ACE I/D polymorphism in AD are conflicting. We re-evaluated this association in the Rotterdam Study, a population-based cohort study. The mechanism of association was further explored by adjusting for vascular factors, and by analysing atrophy, white matter lesions and infarcts on MRI in non-demented individuals. Genotypes were available for 6488 participants. During average follow-up of 6 years 250 subjects developed AD. MRI data were available for 494 non-demented participants. Homozygosity for the I-allele conferred a slightly increased risk of AD compared to carrying a D-allele (RR 1.12 (95% CI 0.99-1.25)). This increase was only significant in women, and independent of vascular factors (RR 1.39 (95% CI 1.14-1.69)). Non-demented women with the II genotype had smaller hippocampal and amygdalar volumes. Vascular pathology was not significantly associated with ACE. This suggests a modest but significant increase in risk of AD and early AD pathology in women homozygous for the ACE I-allele independent of vascular factors.

Associations of polymorphisms of the angiotensinogen M235 polymorphism and angiotensin-converting-enzyme intron 16 insertion/deletion polymorphism with preeclampsia in Korean women

OBJECTIVE

The contribution of genetic factors to preeclampsia has been well documented. However, there has not been any study done on the association between preeclampsia and the angiotensinogen (AGT) M235T polymorphism and angiotensin-converting-enzyme (ACE) intron 16 insertion/deletion (I/D) polymorphism among Korean preeclampsia women. We performed a hospital-based case-control study on Korean women to investigate the association between preeclampsia and the angiotensinogen M235T polymorphism and also to determine the association between preeclampsia and the angiotensin-converting-enzyme intron 16 polymorphism.

METHODS

DNA was extracted from whole blood of 104 preeclampsia patients and 114 healthy pregnant women. All samples were genotyped for all the polymorphisms using amplification after PCR of known allelic variants. Results were analyzed with the chi-square test, Student's t-test, and logistic regression.

RESULTS

18 of 50 women with preeclampsia (36.0%) in nulliparous women and 15 of 37 women with preeclampsia (40.5%) in parous women were homozygous for methionine (M235) to threonine (T235) substitution at residue 235 of AGT gene, versus 12 of 38 women in nulliparous control women and 18 of 50 women in parous control women. There was no association between the AGT M235T polymorphism and preeclampsia according to age. Fourteen of 55 women with preeclampsia (25.5%) in nulliparous women and 11 of 39 women with preeclampsia (28.2%) in parous women were homozygous for the D allele of the ACE intron 16, versus 9 of 52 women in nulliparous control women and 16 of 53 women in parous control women. No association was demonstrated between D allele of ACE intron 16 and preeclampsia according to age. There were significant differences in birth weight and delivery weeks between controls and preeclampsia patients (P < 0.001). There were no significant differences in age and nulliparity between controls and preeclampsia patients.

CONCLUSION

The result indicates that the AGT M235T polymorphism and the ACE intron 16 polymorphism play no significant role in preeclampsia observed in Korean women.

The association between preeclampsia and angiotensin-converting enzyme insertion/deletion polymorphism

BACKGROUND

Plasma and tissue angiotensin-converting enzyme (ACE) activities are believed to be under genetic control. Increased ACE activity due to the deletion polymorphism of the ACE gene is associated with a wide variety of diseases that exhibit endothelial disturbances. Available reports suggest that the incidence of ACE gene deletion polymorphism associated with preeclampsia varies depending on the study population and geographic location. In this study, we examined the insertion/deletion genotype distribution and the activity of ACE in preeclamptic pregnants.

METHODS

Ninety-five preeclamptic and 50 normotensive pregnant patients, both in their third trimester, as well as 39 healthy nonpregnant individuals were included in the study. Gene polymorphism was studied by the polymerase chain reaction followed by the agarose electrophoresis. Pearson's chi(2) test was used for the statistical evaluation of the allele frequency, and Student's t-test for the ACE activity.

RESULTS

The presence of D allele was found to be associated with preeclampsia (p<0.05, odds ratio=1.53; df=1; 95% CI=1.007-2.338). The influence of allelic distribution on the enzyme activity was observed in the preeclamptics bearing II genotype, who exhibited significantly lower activity of ACE than that of the patients with the other genotypes (p<0.05).

CONCLUSION

We found an association between the genotype II and low ACE activity in preeclamptic women and an association between D allele frequency and preeclampsia. Pregnancy alone did not have an effect on the ACE activity.

Molecular epidemiology of preeclampsia

Numerous articles have been published that address the possible genetic influences on the development of preeclampsia (PE). However, to our knowledge, a complete review of the results has not yet been completed. We undertook a MEDLINE search to identify English-language articles published after January 1, 1990 that examined the possible role of specific genes in the etiology of PE. After a brief introduction and a concise review of the prevailing etiologic hypotheses, we have categorized the candidate genes into six categories, based on their hypothesized role in PE etiology. The purpose of this paper is to review the literature, comment on its quality, and provide a reference for researchers interested in the molecular epidemiology of preeclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to list the prevailing etiologic hypotheses of preeclampsia, to outline the published data on possible genetic influence on the development of preeclampsia, and to clearly state the definition of preeclampsia.

Estrogen regulation of angiotensin-converting enzyme mRNA

Estrogen replacement therapy is cardioprotective in postmenopausal women; however, the precise molecular mechanisms for this modulation are not fully elucidated. We previously showed that chronic estrogen replacement therapy reduced angiotensin-converting enzyme (ACE) activity in tissue extracts and serum with an associated reduction in plasma angiotensin II. A reverse transcriptase-polymerase chain reaction assay was developed to determine whether estrogen treatment regulates tissue ACE mRNA concentration. Total RNA was isolated from kidney cortex, kidney medulla, lung, and aorta of ovariectomized Sprague-Dawley rats after 21 days of chronic 17beta-estradiol replacement therapy (5 mg pellet per rat SC) or placebo. A marked decrease in densitometric intensity ratios of amplified ACE cDNA to elongation factor-1alpha control cDNA was observed in all tissues from placebo-treated rats compared with the estradiol-treated rats (renal cortex: 0.29+/-0.04 versus 0.14+/-0.02; renal medulla: 0. 37+/-0.04 versus 0.24+/-0.03; lung: 4.49+/-0.37 versus 2.49+/-0.59; and aorta: 0.41+/-0.04 versus 0.29+/-0.02; all P<0.05). A comparable reduction in ACE activity was detected in tissue extracts from kidney cortex, kidney medulla, and lung of hormone-treated animals. Incubation of purified rat lung ACE with 1 or 10 micromol/L 17beta-estradiol had no effect on enzyme activity. These results suggest that estrogen treatment regulates tissue ACE activity by reducing ACE mRNA concentrations. Thus, the beneficial cardiovascular effects of estrogen may be mediated in part by downregulation of ACE with a consequent reduction in the circulating levels of the vasoconstrictor angiotensin II, a decrease in the metabolism of the vasodilator bradykinin, and an increase in the production of the vasorelaxant angiotensin-(1-7).

Teratogen update: angiotensin-converting enzyme inhibitors

Occasionally there is a drug whose record in pregnancy is so frequently associated with adverse outcome of so specific a pattern that it becomes clear that its use must be restricted before scientific proof from epidemiological studies is obtained. I believe this to be the case with the drug class of ACEIs. There are mammalian models suggesting substantial fetotoxicity in a dose-related fashion. There is a strong and consistent pattern to the reported cases of ACEI-related adverse outcomes: the syndrome of oligohydramnios-anuria, neonatal hypotension, renal dysplasia, and hypocalvaria is too specific in association with the use of these drugs to be ignored. There is a very plausible biologic mechanism to explain the relationship. The features of ACEI fetopathy suggest that the underlying pathogenetic mechanism is fetal hypotension, which may also result from other exposures. Thus, while the fetopathy may not be truly specific to ACEIs, they are particularly liable to produce adverse fetal renal effects with their sequels (anuria-oligohydramnios, pulmonary hypoplasia, growth restriction) and hypocalvaria.