L-arginine metabolism in early-onset and late-onset pre-eclamptic pregnancies

Disrupted Balance of the Oxidant-Antioxidant System in the Pathophysiology of Female Reproduction: Oxidative Stress and Adverse Pregnancy Outcomes

The significance of oxidative stress in the pathophysiology of male reproductive processes has been closely studied in the last two decades. Recently, it has become clear that oxidative stress can lead to numerous pathological conditions during female reproductive processes as well, contributing to the development of endometriosis, polycystic ovary syndrome and various forms of infertility. During pregnancy, physiological generation of reactive oxygen species (ROS) occurs in association with several developmental processes including oocyte maturation and implantation. An overproduction of ROS can lead to disturbances in fetal development and increases the risk for missed abortion, intrauterine growth restriction, pre-eclampsia, premature delivery and gestational diabetes. Our review focuses on the etiological role of the disrupted oxidant-antioxidant system during human gestation as it relates to adverse pregnancy outcomes.

Association of Umbilical Cord Serum Oxidative Stress Markers, ADMA and Adiponectin with Adverse Fetal Outcomes in Hypertensive Disorders of Pregnancy

BACKGROUND

Limited studies are available on fetal oxidative stress and endothelial dysfunction and their association with adverse fetal outcomes in hypertensive disorders of pregnancy (HDP). Method: Umbilical cord blood samples were collected at delivery from 134 pregnant women with HDP and 59 controls. Markers of oxidative stress, endothelial dysfunction and inflammation and adipokines were analyzed. Results were correlated with adverse fetal outcomes. Results: Malondialdehyde, total antioxidant status(TAS), ADMA and hsCRP levels were increased in late and early onset preeclampsia. Adiponectin levels were decreased in early onset preeclampsia. High ADMA levels were positively associated with preterm births and fetal mortality and high TAS, protein carbonyl content(PC), ADMA and low adiponectin levels were positively associated with low birth weight babies. Conclusion: Fetal systemic oxidative stress, endothelial dysfunction and inflammation were altered in early and late onset preeclampsia. High TAS, PC and ADMA levels and low adiponectin levels were positively associated with adverse fetal outcomes in HDP.

The Role of L-Arginine-NO System in Female Reproduction: A Narrative Review

Accumulating evidence are available on the involvement of l-arginine-nitric oxide (NO) system in complex biological processes and numerous clinical conditions. Particular attention was made to reveal the association of l-arginine and methylarginines to outcome measures of women undergoing in vitro fertilization (IVF). This review attempts to summarize the expression and function of the essential elements of this system with particular reference to the different stages of female reproduction. A literature search was performed on the PubMed and Google Scholar systems. Publications were selected for evaluation according to the results presented in the Abstract. The regulatory role of NO during the period of folliculogenesis, oocyte maturation, fertilization, embryogenesis, implantation, placentation, pregnancy, and delivery was surveyed. The major aspects of cellular l-arginine uptake via cationic amino acid transporters (CATs), arginine catabolism by nitric oxide synthases (NOSs) to NO and l-citrulline and by arginase to ornithine, and polyamines are presented. The importance of NOS inhibition by methylated arginines and the redox-sensitive elements of the process of NO generation are also shown. The l-arginine-NO system plays a crucial role in all stages of female reproduction. Insufficiently low or excessively high rates of NO generation may have adverse influences on IVF outcome.

Newborn screen metabolic panels reflect the impact of common disorders of pregnancy

BACKGROUND

Hypertensive disorders of pregnancy and maternal diabetes profoundly affect fetal and newborn growth, yet disturbances in intermediate metabolism and relevant mediators of fetal growth alterations remain poorly defined. We sought to determine whether there are distinct newborn screen metabolic patterns among newborns affected by maternal hypertensive disorders or diabetes in utero.

METHODS

A retrospective observational study investigating distinct newborn screen metabolites in conjunction with data linked to birth and hospitalization records in the state of California between 2005 and 2010.

RESULTS

A total of 41,333 maternal-infant dyads were included. Infants of diabetic mothers demonstrated associations with short-chain acylcarnitines and free carnitine. Infants born to mothers with preeclampsia with severe features and chronic hypertension with superimposed preeclampsia had alterations in acetylcarnitine, free carnitine, and ornithine levels. These results were further accentuated by size for gestational age designations.

CONCLUSIONS

Infants of diabetic mothers demonstrate metabolic signs of incomplete beta oxidation and altered lipid metabolism. Infants of mothers with hypertensive disorders of pregnancy carry analyte signals that may reflect oxidative stress via altered nitric oxide signaling. The newborn screen analyte composition is influenced by the presence of these maternal conditions and is further associated with the newborn size designation at birth.

IMPACT

Substantial differences in newborn screen analyte profiles were present based on the presence or absence of maternal diabetes or hypertensive disorder of pregnancy and this finding was further influenced by the newborn size designation at birth. The metabolic health of the newborn can be examined using the newborn screen and is heavily impacted by the condition of the mother during pregnancy. Utilizing the newborn screen to identify newborns affected by common conditions of pregnancy may help relate an infant's underlying biological disposition with their clinical phenotype allowing for greater risk stratification and intervention.

Preeclampsia subtypes: Clinical aspects regarding pathogenesis, signs, and management with special attention to diuretic administration

During normal pregnancy, blood volume increases by nearly two liters. Distinctively, the absence coupled with the extreme extent regarding the volume expansion, are likely accompanied with pathological conditions. Undoubtedly, preeclampsia, defined as the appearance of hypertension and organ deficiency, such as proteinuria during the second half of pregnancy, is not a homogenous disease. Clinically speaking, two main types of preeclampsia can be distinguished, in which a marked difference between them is vascular condition, and consequently, the blood volume. The "classic" preeclampsia, as a two-phase disease, described in the first, latent phase, in which, placenta development is diminished. Agents from this malperfused placenta generate a maternal disease, the second phase, in which endothelial damage leads to hypertension and organ damage due to vasoconstriction and thrombotic microangiopathy. In this hypovolemia-associated condition, decreasing platelet count, signs of hemolysis, renal and liver involvement are characteristic findings; proteinuria is marked and increasing. In the terminal phase, visible edema develops due to increasing capillary transparency, augmenting end-organ damages. "Classic" preeclampsia is a severe and quickly progressing condition with placental insufficiency and consequent fetal growth restriction and oligohydramnios. The outcome of this condition often leads to fetal hypoxia, eclampsia or placental abruption. The management is limited to a diligent prolongation of pregnancy to accomplish improved neonatal pulmonary function, careful diminishing high blood pressure, and delivery induction in due time. The other subtype, associated with relaxed vasculature and high cardiac output, is a maternal disease, in which obesity is an important risk factor since predisposes to enhanced water retention, hypertension, and a weakened endothelial dysfunction. Initially, enhanced water retention leads to lowered extremity edema, which oftentimes progresses to a generalized form and hypertension. In several cases, proteinuria appears most likely due to tissue edema. This condition already fully meets preeclampsia criteria. Laboratory alterations, including proteinuria, are modest and platelet count remains within the normal range. Fetal weight is also normal or frequently over average due to enhanced placental blood supply. It is very likely, further water retention leads to venous congestion, a parenchyma stasis, responsible for ascites, eclampsia, or placental abruption. During the management of this hypervolemia-associated preeclampsia, the administration of diuretic furosemide treatment seemingly offers promise.

Comparison of Diagnostic Values of Maternal Arginine Concentration for Different Pregnancy Complications: A Systematic Review and Meta-Analysis

Abnormal arginine metabolism contributes to the development of intrauterine growth restriction (IUGR), preeclampsia (PE), and gestational diabetes mellitus (GDM), which increase the health burden of mothers and induce adverse birth outcomes. However, associations between maternal arginine concentration and different pregnancy complications have not been systematically compared. The PubMed, ScienceDirect, and Web of Science databases were searched for peer-reviewed publications to evaluate the diagnostic value of plasma arginine concentration in complicated pregnancies. Standardized mean difference (SMD) of the arginine concentration was pooled by a random effects model. The results show that increased maternal arginine concentrations were observed in IUGR (SMD: 0.48; 95% CI: 0.20, 0.76; I² = 47.0%) and GDM (SMD: 0.46; 95% CI: 0.11, 0.81; I² = 82.3%) cases but not in PE patients (SMD: 0.21; 95% CI: −0.04, 0.47; I² = 80.3%) compared with the normal cohorts. Subgroup analyses indicated that the non-fasting circulating arginine concentration in third trimester was increased significantly in GDM and severe IUGR pregnancies, but the change mode was dependent on ethnicity. Additionally, only severe PE persons were accompanied by higher plasma arginine concentrations. These findings suggest that maternal arginine concentration is an important reference for assessing the development of pregnancy complications.

Placental Ischemia Says "NO" to Proper NOS-Mediated Control of Vascular Tone and Blood Pressure in Preeclampsia

In this review, we first provide a brief overview of the nitric oxide synthase (NOS) isoforms and biochemistry. This is followed by describing what is known about NOS-mediated blood pressure control during normal pregnancy. Circulating nitric oxide (NO) bioavailability has been assessed by measuring its metabolites, nitrite (NO₂) and/or nitrate (NO₃), and shown to rise throughout normal pregnancy in humans and rats and decline postpartum. In contrast, placental malperfusion/ischemia leads to systemic reductions in NO bioavailability leading to maternal endothelial and vascular dysfunction with subsequent development of hypertension in PE. We end this article by describing emergent risk factors for placental malperfusion and ischemic disease and discussing strategies to target the NOS system therapeutically to increase NO bioavailability in preeclamptic patients. Throughout this discussion, we highlight the critical importance that experimental animal studies have played in our current understanding of NOS biology in normal pregnancy and their use in finding novel ways to preserve this signaling pathway to prevent the development, treat symptoms, or reduce the severity of PE.

Longitudinal Changes of One-Carbon Metabolites and Amino Acid Concentrations during Pregnancy in the Women First Maternal Nutrition Trial

BACKGROUND

Maternal dietary restriction and supplementation of one-carbon (1C) metabolites can impact offspring growth and DNA methylation. However, longitudinal research of 1C metabolite and amino acid (AA) concentrations over the reproductive cycle of human pregnancy is limited.

OBJECTIVE

To investigate longitudinal 1C metabolite and AA concentrations prior to and during pregnancy and the effects of a small-quantity lipid-based nutrition supplement (LNS) containing >20 micronutrients and prepregnancy BMI (ppBMI).

METHODS

This study was an ancillary study of the Women First Trial (NCT01883193, clinicaltrials.gov) focused on a subset of Guatemalan women (n = 134), 49% of whom entered pregnancy with a BMI ≥25 kg/m2. Ninety-five women received LNS during pregnancy (+LNS group), while the remainder did not (-LNS group). A subset of women from the Pakistan study site (n = 179) were used as a replication cohort, 124 of whom received LNS. Maternal blood was longitudinally collected on dried blood spot (DBS) cards at preconception, and at 12 and 34 wk gestation. A targeted metabolomics assay was performed on DBS samples at each time point using LC-MS/MS. Longitudinal analyses were performed using linear mixed modeling to investigate the influence of time, LNS, and ppBMI.

RESULTS

Concentrations of 23 of 27 metabolites, including betaine, choline, and serine, changed from preconception across gestation after application of a Bonferroni multiple testing correction (P < 0.00185). Sixteen of those metabolites showed similar changes in the replication cohort. Asymmetric and symmetric dimethylarginine were decreased by LNS in the participants from Guatemala. Only tyrosine was statistically associated with ppBMI at both study sites.

CONCLUSIONS

Time influenced most 1C metabolite and AA concentrations with a high degree of similarity between the 2 diverse study populations. These patterns were not significantly altered by LNS consumption or ppBMI. Future investigations will focus on 1C metabolite changes associated with infant outcomes, including DNA methylation. This trial was registered at clinicaltrials.gov as NCT01883193.

Altered methylation and expression patterns of genes regulating placental nitric oxide pathway in patients with severe preeclampsia

Pre-eclampsia is a common pregnancy disorder syndrome whose molecular mechanism is not clear. Nitric oxide (NO) is a key regulator of placentation. Reduction of NO has previously been associated with endothelial dysfunction in pre-eclamptic women. Therefore, we measured expression and methylation of some placental genes that were involved in NO pathway like named ARG II, PRMT1 and DDAH2 in pre-eclampsia and normal pregnancies in order to determine whether impairment of expression of these genes in the pre-eclamptic placenta could contribute to development of disease. ARG II, PRMT1 expressions as well as DDAH2 expression and methylation, in placentas collected from 59 patients with preeclampsia and 40 normotensive pregnancies were measured using real-time PCR and methylation specific PCR, respectively. The relationship among ARG II, PRMT1 and DDAH2 expressions was analyzed statistically. ARG II expression was increased, PRMT1 expression was not significantly changed. DDAH2 expression was decreased and qualitative methylation patterns were 32/59 and 21/40 in placentas from patients with pre-eclampsia compared with control group, respectively. The alterations in ARG II and DDAH2 expressions in pre-eclampsia patients maybe correlated with decreased eNOS expression. These findings indicate that ARG II and DDAH2 may be involved in pre-eclampsia pathogenesis and could be potential therapeutic targets for this disease.

Maternal allergy as an isolated risk factor for early-onset preeclampsia: An epidemiological study

Immunological mechanisms underlying the development of preeclampsia are well known, but no association to allergy has yet been demonstrated. The aim of this study was to assess the correlation between maternal pre-gestational allergy, and early-onset and late-onset preeclampsia, respectively. It was a retrospective cohort study including all women giving birth in the Norwegian cities of Stavanger (1996-2014) and Bergen (2009-2014). Pre-gestational asthma, allergy, other known risk factors for preeclampsia, maternal age and parity were obtained from the electronic medical record system. The main outcome variables were early-onset and late-onset preeclampsia (before and after 34 completed weeks of gestation, respectively). We used multinomial logistic regression to estimate odds ratios (OR) with 95% confidence intervals (95% CI) for early and late-onset preeclampsia in women with pre-gestational allergy when compared to women without allergy, adjusting for covariates. Predicted probabilities for the outcomes were also calculated. Of the 110 064 included pregnancies, 2 799 developed late-onset preeclampsia (2.5%) and 348 developed early-onset preeclampsia (0.3%). Pre-gestational allergy increased the risk of early-onset preeclampsia (OR 1.7, 95% CI 1.3-2.4), and reduced the risk of late-onset preeclampsia (OR 0.8, 95% CI 0.7-0.9). These findings add valuable information on preeclampsia as an immunological complication of pregnancy and corroborate the understanding of early- and late-onset preeclampsia as two different entities.

Is the serum l-arginine level during early pregnancy a predictor of pregnancy-induced hypertension?

The objective of this study was to determine the concentration of serum l-arginine in healthy pregnant women and infant cord blood and to compare them with those in patients with pregnancy-induced hypertension (PIH). The serum concentration of l-arginine in normal pregnant women at early gestation (n = 186) was determined and analyzed based on maternal factors such as the age, pre-pregnancy body mass index (BMI), smoking and alcohol habits before pregnancy. Similarly, the concentration of cord blood of the newborns (n = 142) was also analyzed. These values were compared with those in the PIH group (n = 21). The potential risk factors for PIH were also estimated. The serum concentration of l-arginine at early gestation in normal pregnant women (88.65 ± 19.96 µM) was not affected by the maternal age and BMI before pregnancy. A lower l-arginine concentration at early gestation (<70 µM) significantly elevated PIH risk [adjusted odds ratio (OR) = 4.26, 95% CI 1.29-14.50]. In addition, either women with large body mass before pregnancy (BMI>25 kg/m(2)) or primipara women also showed a significant association with PIH risk [adjusted OR = 10.55 (2.95-40.68); 5.25 (1.72-19.15), respectively]. In conclusion, a lower l-arginine concentration at early gestation, overweight before pregnancy (BMI>25 kg/m(2)) and primipara could predict to the development of PIH.

Plasma levels of dimethylarginines in preterm very low birth weight neonates: its relation with perinatal factors and short-term outcome

Endogenously produced inhibitors of nitric oxide (NO) synthase, in particular asymmetric dimethylarginine (ADMA), are currently considered of importance in various disease states characterized by reduced NO availability. We investigated the association between plasma levels of ADMA, symmetric dimethylarginine (SDMA), l-arginine, and citrulline and perinatal factors and outcome in 130 preterm (gestational age ≤30 weeks) very low birth weight (VLBW, <1500 g) infants. Plasma samples were collected 6–12 h after birth. We did not find significant correlations between ADMA, SDMA, l-arginine, and citrulline levels and gestational age or birth weight. However, the arginine:ADMA ratio (AAR, a better indicator of NO availability than either arginine or ADMA separately) was positively correlated with gestational age. ADMA and arginine levels were not significantly different between males and females but males showed a negative correlation between ADMA levels and gestational age. Perinatal factors such as preeclampsia, chrorioamnionitis, prolonged rupture of membranes, or form of delivery did not significantly alter dimethylarginine levels or AAR. In contrast, the AAR was significantly reduced in the infants with respiratory distress, mechanical ventilation, and systemic hypotension Therefore, our data suggest that altered NO availability may play a role in the respiratory and cardiovascular adaptation in preterm VLBW infants.

"Platelet-associated regulatory system (PARS)" with particular reference to female reproduction

Background

Blood platelets play an essential role in hemostasis, thrombosis and coagulation of blood. Beyond these classic functions their involvement in inflammatory, neoplastic and immune processes was also investigated. It is well known, that platelets have an armament of soluble molecules, factors, mediators, chemokines, cytokines and neurotransmitters in their granules, and have multiple adhesion molecules and receptors on their surface.

Methods

Selected relevant literature and own views and experiences as clinical observations have been used.

Results

Considering that platelets are indispensable in numerous homeostatic endocrine functions, it is reasonable to suppose that a platelet-associated regulatory system (PARS) may exist; internal or external triggers and/or stimuli may complement and connect regulatory pathways aimed towards target tissues and/or cells. The signal (PAF, or other tissue/cell specific factors) comes from the stimulated (by the e.g., hypophyseal hormones, bacteria, external factors, etc.) organs or cells, and activates platelets. Platelet activation means their aggregation, sludge formation, furthermore the release of the for-mentioned biologically very powerful factors, which can locally amplify and deepen the tissue specific cell reactions. If this process is impaired or inhibited for any reason, the specifically stimulated organ shows hypofunction. When PARS is upregulated, organ hyperfunction may occur that culminate in severe diseases.

Conclusion

Based on clinical and experimental evidences we propose that platelets modulate the function of hypothalamo-hypophyseal-ovarian system. Specifically, hypothalamic GnRH releases FSH from the anterior pituitary, which induces and stimulates follicular and oocyte maturation and steroid hormone secretion in the ovary. At the same time follicular cells enhance PAF production. Through these pathways activated platelets are accumulated in the follicular vessels surrounding the follicle and due to its released soluble molecules (factors, mediators, chemokines, cytokines, neurotransmitters) locally increase oocyte maturation and hormone secretion. Therefore we suggest that platelets are not only a small participant but may be the conductor or active mediator of this complex regulatory system which has several unrevealed mechanisms. In other words platelets are corpuscular messengers, or are more than a member of the family providing hemostasis.

Acute nitric oxide synthase inhibition and endothelin-1-dependent arterial pressure elevation

Key evidence that endogenous nitric oxide (NO) inhibits the continuous, endothelin (ET)-1-mediated drive to elevate arterial pressure includes demonstrations that ET-1 mediates a significant component of the pressure elevated by acute exposure to NO synthase (NOS) inhibitors. This review examines the characteristics of this pressure elevation in order to elucidate potential mechanisms associated with the negative regulation of ET-1 by NO and, thereby, provide potential insight into the vascular pathophysiology underlying NO dysregulation. We surmise that the magnitude of the ET-1-dependent component of the NOS inhibitor-elevated pressure is (1) independent of underlying arterial pressure and other pressor pathways activated by the NOS inhibitors and (2) dependent on relatively higher NOS inhibitor dose, release of stored and de novo synthesized ET-1, and ET_A receptor-mediated increased vascular resistance. Major implications of these conclusions include: (1) the marked variation of the ET-1-dependent component, i.e., from 0 to 100% of the pressure elevation, reflects the NO-ET-1 regulatory pathway. Thus, NOS inhibitor-mediated, ET-1-dependent pressure elevation in vascular pathophysiologies is an indicator of the level of compromised/enhanced function of this pathway; (2) NO is a more potent inhibitor of ET-1-mediated elevated arterial pressure than other pressor pathways, due in part to inhibition of intravascular pressure-independent release of ET-1. Thus, the ET-1-dependent component of pressure elevation in vascular pathophysiologies associated with NO dysregulation is of greater magnitude at higher levels of compromised NO.