Gene–gene interactions in the NAMPT pathway, plasma visfatin/NAMPT levels, and antihypertensive therapy responsiveness in hypertensive disorders of pregnancy

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Correlation Analysis of NAMPT rs61330082 Polymorphism in Type 2 Diabetes Mellitus Combined with Hypertension

Introduction

This study aimed to investigate the association of Nicotinamide phosphoribosyl transferase (NAMPT) rs61330082 polymorphism with co-morbid hypertension (HTN) and the progression of hypertension in Chinese patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 453 T2DM patients were genotyped for the polymorphism of rs61330082 using SNP-scan high-throughput technology. These patients were divided into T2DM group (261 patients) and T2DM combined with hypertension group (T2MH, 192 patients). The T2MH group was further categorized into Grade I, Grade II, and Grade III based on the results of the Hypertension Grade Score. Peripheral blood plasma urea, plasma creatinine, renin-angiotensin system (RAS) indexes, and lipid biochemistry indexes were measured in patients and analyzed in relation to NAMTP polymorphisms.

Results

We found that the presence of the NAMPT rs61330082-AA genotype was associated with a significantly increased risk of developing higher-grade hypertension in patients with T2MH. In addition, the A allele of the NAMPT rs61330082 gene displayed more associated in developing a higher grade of hypertension compared to the G allele. Also, the level of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c) increased with hypertension grade in the NAMPT rs61330082-GG genotype.

Conclusion

NAMPT rs61330082 polymorphism was significantly associated with the progression of hypertension grade in T2MH patients and also affected plasma creatinine and LDL-c levels.

Functional polymorphisms of NOS3 and GUCY1A3 affect both nitric oxide formation and association with hypertensive disorders of pregnancy

Impaired nitric oxide (NO) formation may be associated with endothelial dysfunction and increased cardiovascular disease risk in preeclampsia (PE). Functional single-nucleotide polymorphisms (SNPs) of nitric oxide synthase 3 (NOS3) (rs3918226) and guanylate cyclase 1, soluble, alpha 3 (GUCY1A3) (rs7692387) increase susceptibility to the adverse consequences due to inadequate generation of NO by the endothelium. However, no previous study has examined whether these SNPs affect NO formation in healthy pregnancy and in gestational hypertension (GH) and PE. Here, we compared the alleles and genotypes of NOS3 (rs3918226) and GUCY1A3 (rs7692387) SNPs in normotensive pregnant women (NP, n = 153), in GH (n = 96) and PE (n = 163), and examined whether these SNPs affect plasma nitrite concentrations (a marker of NO formation) in these groups. We further examined whether the interaction among SNP genotypes is associated with GH and PE. Genotypes were determined using TaqMan allele discrimination assays, and plasma nitrite concentrations were determined by an ozone-based chemiluminescence assay. Multifactor dimensionality reduction was used to examine the interactions among SNP genotypes. Regarding NOS3 rs3918226, the CT genotype (p = 0.046) and T allele (p = 0.020) were more frequent in NP than in GH, and GH patients carrying the CT+TT genotypes showed lower nitrite concentrations than NP carrying the CT+TT genotypes (p < 0.05). Regarding GUCY1A3 rs7692387, the GA genotype (p = 0.013) and A allele (p = 0.016) were more frequent in PE than in NP, and NP women carrying the GG genotype showed higher nitrite concentrations than GH or PE patients carrying the GG genotype (p < 0.05). However, we found no significant interactions among genotypes for these functional SNPs to be associated with GH or PE. Our novel findings suggest that NOS3 rs3918226 and GUCY1A3 rs7692387 may affect NO formation and association with hypertensive disorders of pregnancy.

Pharmacogenomics of Preeclampsia therapies: Current evidence and future challenges for clinical implementation

Preeclampsia is a pregnancy-specific disorder, and it is a leading cause of maternal and perinatal morbidity and mortality. The application of pharmacogenetics to antihypertensive agents and dose selection in women with preeclampsia is still in its infancy. No current prescribing guidelines from the clinical pharmacogenetics implementation consortium (CPIC) exist for preeclampsia. Although more studies on pharmacogenomics are underway, there is some evidence for the pharmacogenomics of preeclampsia therapies, considering both the pharmacokinetic (PK) and pharmacodynamic (PD) properties of drugs used in preeclampsia. It has been revealed that the CYP2D6*10 variant is significantly higher in women with preeclampsia who are non-responsive to labetalol compared to those who are in the responsive group. Various genetic variants of PD targets, i.e., NOS3, MMP9, MMP2, TIMP1, TIMP3, VEGF, and NAMPT, have been investigated to assess the responsiveness of antihypertensive therapies in preeclampsia management, and they indicated that certain genetic variants of MMP9, TIMP1, and NAMPT are more frequently observed in those who are non-responsive to anti-hypertensive therapies compared to those who are responsive. Further, gene-gene interactions have revealed that NAMPT, TIMP1, and MMP2 genotypes are associated with an increased risk of preeclampsia, and they are more frequently observed in the non-responsive subgroup of women with preeclampsia. The current evidence is not rigorous enough for clinical implementation; however, an institutional or regional-based retrospective analysis of audited data may help close the knowledge gap during the transitional period from a traditional approach (a "one-size-fits-all" strategy) to the pharmacogenomics of preeclampsia therapies.

Gene Interactions in Human Disease Studies-Evidence Is Mounting

Despite monumental advances in molecular technology to generate genome sequence data at scale, there is still a considerable proportion of heritability in most complex diseases that remains unexplained. Because many of the discoveries have been single-nucleotide variants with small to moderate effects on disease, the functional implication of many of the variants is still unknown and, thus, we have limited new drug targets and therapeutics. We, and many others, posit that one primary factor that has limited our ability to identify novel drug targets from genome-wide association studies may be due to gene interactions (epistasis), gene-environment interactions, network/pathway effects, or multiomic relationships. We propose that many of these complex models explain much of the underlying genetic architecture of complex disease. In this review, we discuss the evidence from multiple research avenues, ranging from pairs of alleles to multiomic integration studies and pharmacogenomics, that supports the need for further investigation of gene interactions (or epistasis) in genetic and genomic studies of human disease. Our goal is to catalog the mounting evidence for epistasis in genetic studies and the connections between genetic interactions and human health and disease that could enable precision medicine of the future.

ARG2 single-nucleotide polymorphism rs3742879 affects plasma arginase 2 levels, nitric oxide formation and antihypertensive therapy response in preeclampsia

Aim: This work examined whether ARG1 (rs2781659, rs2781667, rs2246012 and rs17599586) and ARG2 (rs3742879 and rs10483801) single-nucleotide polymorphisms (SNPs) are associated with antihypertensive therapy responsiveness in preeclampsia (PE) and their effects on arginase isoforms and nitrite concentrations in responsive and nonresponsive patients. Methods: SNP genotypes were determined by TaqMan assays. Plasma arginase levels were measured by ELISA and nitrite concentrations were measured using an ozone-based chemiluminescence assay. Results: The G allele for ARG2 rs3742879 (A>G) was less frequent in nonresponsive compared with responsive patients (15.5% vs 24.7%) and the G carriers of the nonresponsive subgroup had lower arginase 2 (9.2 ± 7.5 ng/ml vs 19.1 ± 17.3 ng/ml) and higher nitrite concentrations (110.2 ± 52.8 nM vs 78.5 ± 37.9 nM) than carriers of the AA genotype (all p < 0.05). Conclusion: ARG2 SNP rs3742879 is associated with diminished arginase 2 levels and increased nitric oxide formation in nonresponsive PE patients.

Nampt promotes fibroblast extracellular matrix degradation in stress urinary incontinence by inhibiting autophagy

Stress urinary incontinence (SUI) is defined as involuntary urinary leakage happening in exertion. Nicotinamide phosphoribosyltransferase (Nampt) is seldom researched in the pathogenesis of SUI. Accordingly, the current study set out to elucidate the role of Nampt in SUI progression. Firstly, we determined Nampt expression patterns in SUI patients and rat models. In addition, fibroblasts were obtained from the anterior vaginal wall tissues of non-SUI patients and subjected to treatment with different concentrations of interleukin-1β (IL-1β), followed by quantification of Nampt expressions in fibroblasts. Subsequently, an appropriate concentration of IL-1β was selected to treat anterior vaginal wall fibroblasts. Nampt was further silenced in IL-1β-treated fibroblasts to assess the role of Nampt in autophagy and extracellular matrix (ECM) degradation. Lastly, functional rescue assays were carried out to inhibit autophagy and evaluate the role of autophagy in the mechanism of Nampt modulating IL-1β-treated fibroblast ECM degradation. It was found that Nampt was highly-expressed in SUI patients and rat models and IL-1β-treated fibroblasts. On the other hand, Nampt silencing was found to suppress ECM degradation and promote SUI fibroblast autophagy. Additionally, inhibition of autophagy attenuated the inhibitory effects of Nampt silencing on SUI fibroblast ECM degradation. Collectively, our findings revealed that Nampt was over-expressed in SUI, whereas Nampt silencing enhanced SUI fibroblast autophagy, and thereby inhibited ECM degradation.

Comprehensive analyses of DNA methylation of the TIMP3 promoter in placentas from early-onset and late-onset preeclampsia

Preeclampsia (PE) is classified into late-onset (LOPE) or early-onset (EOPE) according to gestational age of onset (≥34 or <34 weeks, respectively), and into preterm and term (delivery at <37 or ≥37 weeks, respectively). An imbalanced expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) impairs proper placentation in PE, and DNA methylation (DNAm) may affect their expression. We performed comprehensive analyses of DNAm and TIMP3 expression in placentas from PE reclassified into EOPE, LOPE, and term PE. We identified significant differentially methylated probes at the TIMP3 promoter in PE (28), EOPE (38), LOPE (20), and term PE (4) compared to controls, and in EOPE vs. LOPE (8). Moreover, we found a hypomethylation >70% in all groups (except EOPE vs. LOPE) and an increased TIMP3 expression in corresponding placental samples from PE, EOPE and LOPE compared to controls (p<0.05). Our findings highlight the role of DNAm of the TIMP3 promoter region regarding an epigenetic mechanism in PE.

Gene-gene interactions in the protein kinase C/endothelial nitric oxide synthase axis impact the hypotensive effects of propofol

Anaesthesia with propofol is frequently associated with hypotension, which is at least partially attributable to increased nitric oxide (NO) formation derived from the activation of protein kinase C (PKC)/endothelial NO synthase (NOS3) axis. In this cross-sectional study, we tested whether PRKCA (which encodes PKCα) polymorphisms, or haplotypes, and interactions among PRKCA and NOS3 polymorphisms affect the hypotensive responses to propofol. We collected venous blood samples from 164 patients before and 10 min after propofol administration. Genotypes were determined by PCR and haplotype frequencies were estimated. Nitrite and NO_x (nitrites+nitrates) levels were measured by using an ozone-based chemiluminescence assay and the Griess reaction, respectively. We used multifactor dimensionality reduction to test interactions among PRKCA and NOS3 polymorphisms. Propofol promoted enhanced blood pressure-lowering effects and increased nitrite levels in subjects carrying GA + AA genotypes for the rs16960228 and TC + CC genotypes for the rs1010544 PRKCA polymorphisms, and the CCG haplotype. Moreover, genotypes for the rs1010544 PRKCA polymorphism were associated with higher or lower blood pressure decreases in response to propofol depending on the genotypes for the rs2070744 NOS3 polymorphism. Our findings suggest that PRKCA genotypes and haplotypes impact the hypotensive responses to propofol, possibly by modifying NO bioavailability, and that PRKCA-NOS3 interactions modify the blood pressure-lowering effects of propofol.

NAMPT single-nucleotide polymorphism rs1319501 and visfatin/NAMPT affect nitric oxide formation, sFlt-1 and antihypertensive therapy response in preeclampsia

Aim: We examined the relationships between visfatin/NAMPT and nitrite concentrations (a marker of nitric oxide [NO] formation) or sFlt-1 levels in 205 patients with preeclampsia (PE) responsive or nonresponsive to antihypertensive therapy, and whether NAMPT SNPs rs1319501 and rs3801266 affect nitrite concentrations in PE and 206 healthy pregnant women. Patients & methods: Circulating visfatin/NAMPT and sFlt-1 levels were measured by ELISA, and nitrite concentrations by using an ozone-based chemiluminescence assay. Results: In nonresponsive PE patients, visfatin/NAMPT levels were inversely related to nitrite concentrations and positively related to sFlt-1 levels. NAMPT SNP rs1319501 affected nitrite concentrations in nonresponsive PE patients and was tightly linked with NAMPT functional SNPs in Europeans. Conclusion: NAMPT SNP rs1319501 and visfatin/NAMPT affect NO formation, sFlt-1 levels and antihypertensive therapy response in PE.

Mutations of mtDNA in some Vascular and Metabolic Diseases

BACKGROUND

The present review article considers some chronic diseases of vascular and metabolic genesis, the causes of which may be mitochondrial dysfunction. Very often, in the long course of the disease, complications may occur, leading to myocardial infarction or ischemic stroke and, as a result, death. In particular, a large percentage of human deaths nowadays belongs to cardiovascular diseases, such as coronary heart disease (CHD), arterial hypertension, cardiomyopathies, and type 2 diabetes mellitus.

OBJECTIVE

The aim of the present review was the analysis of literature sources, devoted to an investigation of a link of mitochondrial DNA mutations with chronic diseases of vascular and metabolic genesis.

RESULTS

The analysis of literature indicates the association of the mitochondrial genome mutations with coronary heart disease, type 2 diabetes mellitus, hypertension, and various types of cardiomyopathies.

CONCLUSION

The detected mutations can be used to analyze the predisposition to chronic diseases of vascular and metabolic genesis. They can also be used to create molecular-cell models necessary to evaluate the effectiveness of drugs developed for the treatment of these pathologies. MtDNA mutations associated with the absence of diseases of vascular and metabolic genesis could be potential candidates for gene therapy of the said diseases.

Different profiles of circulating arginase 2 in subtypes of preeclampsia pregnant women

BACKGROUND AND AIMS

Preeclampsia (PE) is a gestational hypertensive disease responsible for high maternal and fetal morbidity and mortality. The increase in blood pressure is associated with a decrease in the bioavailability of nitric oxide (NO). Arginase interferes with NO production consuming L-arginine, a substrate required by endothelial NO synthase to NO formation. No previous study has quantified the circulating levels of the two arginase isoforms (arginase 1 and arginase 2) in the plasma of pregnant women with PE. Therefore, our objective is to evaluate these plasma levels in healthy pregnant women and PE with or without severe features and who respond or not to antihypertensive therapy.

METHODS

We compared 29 healthy pregnant women with 56 pregnant women with PE, who were also divided into with severe features (n = 24) or without severe features (n = 32) and into responsive (n = 29) or nonresponsive to antihypertensive therapy (n = 27). We quantified the plasmatic expression of arginase 1 and arginase 2 by ELISA kits.

RESULTS

While similar levels of arginase 1 were found among groups, lower arginase 2 plasma levels were found in PE without severe features and responsive to antihypertensive drugs when compared to healthy pregnant women. There was no difference between arginase 2 levels in PE with severe features and nonresponsive group when compared to healthy pregnant women.

CONCLUSION

This shows different circulation profiles of arginase 2 among groups, suggesting the existence of mechanisms of arginase 2 modulation in pregnant women with PE associated with the severity of the disease and responsiveness to antihypertensive treatment.

Global DNA methylation in placental tissues from pregnant with preeclampsia: A systematic review and pathway analysis

Pre-eclampsia (PE) is the major cause of fetal and maternal mortality and can be classified according to gestational age of onset into early-onset (EOPE, <34 weeks of gestation) and late- (LOPE, ≥34 weeks of gestation). DNA methylation (DNAm) may help to understand the abnormal placentation in PE. Therefore, we performed a systematic review to assess the role of global DNAm on pathophysiology of PE, focused on fetal and maternal tissues of placenta from pregnant with PE, including EOPE and LOPE. We searched the databases EMBASE, Medline/PubMed, Cochrane Central Register of Controlled Trials, Scopus, Lilacs, Scielo and Google Scholar, and followed the MOOSE guidelines. Moreover, we performed pathway analysis with the overlapping genes from the included studies. Twelve out of 24 included studies in the qualitative analysis considered the classification into EOPE and LOPE. We did not found heterogeneity in the criteria used for diagnosis of PE, and a few studies evaluated whether confounding factors would influence placental DNAm. Fourteen out of 24 included studies showed hypomethylation in placental tissue from pregnant with PE compared to controls. The differences in DNAm are specific to genes or differentially methylated regions, and more evident in EOPE and preterm PE compared to controls, rather than LOPE and term PE. The overlapping genes from included studies revealed pathways relevant to pathophysiology of PE. Our findings highlighted the heterogeneous results of the included studies, mainly focused on North America and China. Replication studies in different populations should use the same placental tissues, techniques to assess DNAm and pipelines for bioinformatic analysis.

Can adipokine visfatin be a novel marker of pregnancy-related disorders in women with obesity?

Overweight and obesity have become a dangerous disease requiring multiple interventions, treatment and preventions. In women of reproductive age, obesity is one of the most common medical conditions. Among others, obese state is characterized by low-grade systemic inflammation and enhanced oxidative stress. Increased maternal body mass index might amplify inflammation and reactive oxygen species production, which is associated with unfavourable clinical outcomes that affect both mother and child. Intrauterine growth retardation, preeclampsia, or gestational diabetes mellitus are examples of the hampered maternal and foetoplacental unit interactions. Visfatin is the obesity-related adipokine produced mainly by the visceral adipose tissue. Visfatin affects glucose homeostasis, as well as the regulation of genes related to oxidative stress and inflammatory response. Here, we review visfatin interactions in pregnancy-related disorders linked to obesity. We highlight the possible predictive and prognostic value of visfatin in diagnostic strategies on gravidas with obesity.

Interaction Between NOS3 and HMOX1 on Antihypertensive Drug Responsiveness in Preeclampsia

OBJECTIVE

 We examined the interaction of polymorphisms in the genes heme oxygenase-1 (HMOX1) and nitric oxide synthase (NOS3) in patients with preeclampsia (PE) as well as the responsiveness to methyldopa and to total antihypertensive therapy.

METHODS

 The genes HMOX1 (rs2071746, A/T) and NOS3 (rs1799983, G/T) were genotyped using TaqMan allele discrimination assays (Applied Biosystems, Foster City, CA, USA ), and the levels of enzyme heme oxygenase-1 (HO-1) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

 We found interactions between genotypes of the HMOX-1 and NOS3 genes and responsiveness to methyldopa and that PE genotyped as AT presents lower levels of protein HO-1 compared with AA.

CONCLUSION

 We found interactions between the HMOX-1 and NOS3 genes and responsiveness to methyldopa and that the HMOX1 polymorphism affects the levels of enzyme HO-1 in responsiveness to methyldopa and to total antihypertensive therapy. These data suggest impact of the combination of these two polymorphisms on antihypertensive responsiveness in PE.

Genetic Variants in Preeclampsia: Lessons From Studies in Latin-American Populations

Placental vascularization is a tightly regulated physiological process in which the maternal immune system plays a fundamental role. Vascularization of the maternal-placental interface involves a wide range of mechanisms primarily orchestrated by the fetal extravillous trophoblast and maternal immune cells. In a healthy pregnancy, an immune cross-talk between the mother and fetal cells results in the secretion of immunomodulatory mediators, apoptosis of specific cells, cellular differentiation/proliferation, angiogenesis, and vasculogenesis, altogether favoring a suitable microenvironment for the developing embryo. In the context of vasculopathy underlying common pregnancy disorders, it is believed that inefficient invasion of extravillous trophoblast cells in the endometrium leads to a poor placental blood supply, which, in turn, leads to decreased secretion of angiogenic factors, hypoxia, and inflammation commonly associated with preterm delivery, intrauterine growth restriction, and preeclampsia. In this review, we will focus on studies published by Latin American research groups, providing an extensive review of the role of genetic variants from candidate genes involved in a broad spectrum of biological processes underlying the pathophysiology of preeclampsia. In addition, we will discuss how these studies contribute to fill gaps in the current understanding of preeclampsia. Finally, we discuss some trending topics from important fields associated with pregnancy vascular disorders (e.g., epigenetics, transplantation biology, and non-coding RNAs) and underscore their possible implications in the pathophysiology of preeclampsia. As a result, these efforts are expected to give an overview of the extent of scientific research produced in Latin America and encourage multicentric collaborations by highlighted regional research groups involved in preeclampsia investigation.

Pharmacogenetic relevance of endothelial nitric oxide synthase polymorphisms and gene interactions

Endothelial nitric oxide synthase (NOS3) is a key enzyme responsible for nitric oxide (NO) generation in the vascular endothelium. Endothelial dysfunction is characterized by reduced NO production, and is a hallmark of cardiovascular diseases. Drugs with cardiovascular action may activate NOS3 and result in NO release and vasodilation. Moreover, genetic variations affect NOS3 expression and activity, and may partially explain the variability in the responses to cardiovascular drugs. We reviewed NO signaling and genetic effects on NO formation, and the effects of NOS3 polymorphisms, haplotypes and gene-gene interactions within NO signaling pathways on the responses to cardiovascular drugs. We discuss the role of rare NOS3 variants and further gene-gene interactions analysis for the development of novel therapies for cardiovascular diseases.

Associations of polymorphisms of CYP2D6 and CYP2C9 with early onset severe pre-eclampsia and response to labetalol therapy

PURPOSE

Early onset preeclampsia (PPE) contributes to life-threatening maternal complications and fetal demise. Pharmacogenomics is a precision medicine, and metabolizing enzymes responsive to antihypertensive remains understudied. The aim of this study was to evaluate the associations of polymorphisms of cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) and cytochrome P450, family 2, subfamily C, polypeptide 9 (CYP2C9) with PPE and the relationship among CYP2D6, CYP2C9 polymorphisms and response to labetalol therapy.

METHODS

Totally 105 gravidas diagnosed with PPE (case) and 103 healthy gravidas (control) were recruited between August 2013 and July 2016. Labetalol was given to control blood pressures (BP) with PPE. If labetalol administration alone did not exceed the mean dose and effectively controlled the BP, it would be considered to be valid (n = 75). Genotype and allele frequencies of CYP2C9 gene (rs1057910 and rs4918758) and CYP2D6 gene (rs1065852, rs28371725, rs35742686, and rs3892097) were analyzed by TaqMan PCR. Differences in the genotype and allele frequencies were compared between case-control groups, and the responsive and nonresponsive to labetalol in PPE.

RESULTS

Out of six variants, only CC and CT genotypes of the CYP2D6 variants (rs28371725) in PPE were significantly higher than those in the control group [18.1% (19/105) vs 14.6% (15/103); 56.2% (59/105) vs 42.7% (44/103); χ2 = 6.707]. However, there were no differences in maternal age, diastolic pressure, BMI, BW, serum triglyceride, and creatinine were observed among women with CC, CT, or TT genotype of CYP2D6 gene rs28371725 in the experimental group (all P > 0.05). Compared with the gravidas with CT or TT genotype of CYP2D6 gene rs28371725, those with CC genotype had longer gestational age [(32.5 ± 2.1) vs (29.5 ± 1.8) and (29.8 ± 2.2) weeks] and higher plasma albumin [(27.2 ± 9.3) vs (20.3 ± 10.4) and (22.5 ± 7.4) g/L], but lower systolic pressure and 24 h urine protein (LSD test, all P < 0.05). The G allele frequency in CYP2D6 gene rs1065852 nonresponsive to labetalol group was higher than that in responsive labetalol group [93.3% (56/60) vs 76.0% (114/150), χ2 = 8.351, P = 0.004].

CONCLUSIONS

The polymorphism of CYP2D6 gene rs28371725 may be associated with PPE, and the allele of G in CYP2D6 gene rs1065852 may be associated with the efficacy of labetalol in treatment of PPE.

Pharmacogenomics of Hypertension and Preeclampsia: Focus on Gene-Gene Interactions

Hypertension is a leading cause of cardiovascular mortality, but only about half of patients on antihypertensive therapy achieve blood pressure control. Preeclampsia is defined as pregnancy-induced hypertension and proteinuria, and is associated with increased maternal and perinatal mortality and morbidity. Similarly, a large number of patients with preeclampsia are non-responsive to antihypertensive therapy. Pharmacogenomics may help to guide the personalized treatment for non-responsive hypertensive patients. There is evidence for the association of genetic variants with variable response to the most commonly used antihypertensive drugs. However, further replication is needed to confirm these associations in different populations. The failure to replicate findings from single-locus association studies has prompted the search for novel statistical methods for data analysis, which are required to detect the complex effects from multiple genes to drug response phenotypes. Notably, gene–gene interaction analyses have been applied to pharmacogenetic studies, including antihypertensive drug response. In this perspective article, we present advances of considering the interactions among genetic polymorphisms of different candidate genes within pathways relevant to antihypertensive drug response, and we highlight recent findings related to gene–gene interactions on pharmacogenetics of hypertension and preeclampsia. Finally, we discuss the future directions that are needed to unravel additional genes and variants involved in the responsiveness to antihypertensive drugs.

Gene-Gene Interactions Among PRKCA, NOS3 and BDKRB2 Polymorphisms Affect the Antihypertensive Effects of Enalapril

Protein kinase C (PKC) signalling is critically involved in the control of blood pressure. Angiotensin-converting enzyme inhibitors (ACEi) affect PKC expression and activity, which are partially associated with the responses to ACEi. We examined whether PRKCA (protein kinase C, alpha) polymorphisms (rs887797 C>T, rs1010544 T>C and rs16960228 G>A), or haplotypes, and gene-gene interactions within the ACEi pathway affect the antihypertensive responses in 104 hypertensive patients treated with enalapril as monotherapy. Patients were classified as poor responders (PR) or good responders (GR) to enalapril if their changes in mean arterial pressure were lower or higher than the median value, respectively. Multi-factor dimensionality reduction was used to characterize interactions among PRKCA, NOS3 (nitric oxide synthase 3) and BDKRB2 (bradykinin receptor B2) polymorphisms. The TC+CC genotypes for the rs1010544 polymorphism were more frequent in GR than in PR (p = 0.037). Conversely, the GA+AA genotypes for the rs16960228 polymorphism, and the CTA haplotype, were more frequent in PR than in GR (p = 0.040 and p = 0.008, respectively). Moreover, the GG genotype for the PRKCA rs16960228 polymorphism was associated with PR or GR depending on the genotypes for the rs2070744 (NOS3) and rs1799722 (BDKRB2) polymorphisms (p = 0.012). Our results suggest that PRKCA polymorphisms and gene-gene interactions within the ACEi pathway affect the antihypertensive responses to enalapril.