Placental expression of endothelial and inducible nitric oxide synthase and nitric oxide levels in patients with HELLP syndrome

HELLP Syndrome and Differential Diagnosis with Other Thrombotic Microangiopathies in Pregnancy

Thrombotic microangiopathies (TMAs) comprise a distinct group of diseases with different manifestations that can occur in both pediatric and adult patients. They can be hereditary or acquired, with subtle onset or a rapidly progressive course, and they are particularly known for their morbidity and mortality. Pregnancy is a high-risk time for the development of several types of thrombotic microangiopathies. The three major syndromes are hemolysis, elevated liver function tests, and low platelets (HELLP); hemolytic uremic syndrome (HUS); and thrombotic thrombocytopenic purpura (TTP). Because of their rarity, clinical information and therapeutic results related to these conditions are often obtained from case reports, small series, registries, and reviews. The collection of individual observations, the evolution of diagnostic laboratories that have identified autoimmune and/or genetic abnormalities using von Willebrand factor post-secretion processing or genetic-functional alterations in the regulation of alternative complement pathways in some of these TMAs, and, most importantly, the introduction of advanced treatments, have enabled the preservation of affected organs and improved survival rates. Although TMAs may show different etiopathogenesis routes, they all show the presence of pathological lesions, which are characterized by endothelial damage and the formation of thrombi rich in platelets at the microvascular level, as a common denominator, and thrombotic damage to microcirculation pathways induces "mechanical" (microangiopathic) hemolytic anemia, the consumption of platelets, and ischemic organ damage. In this review, we highlight the current knowledge about the diagnosis and management of these complications during pregnancy.

Circulating miRNAs and Preeclampsia: From Implantation to Epigenetics

In this review, we comprehensively present the literature on circulating microRNAs (miRNAs) associated with preeclampsia, a pregnancy-specific disease considered the primary reason for maternal and fetal mortality and morbidity. miRNAs are single-stranded non-coding RNAs, 20-24 nt long, which control mRNA expression. Changes in miRNA expression can induce a variation in the relative mRNA level and influence cellular homeostasis, and the strong presence of miRNAs in all body fluids has made them useful biomarkers of several diseases. Preeclampsia is a multifactorial disease, but the etiopathogenesis remains unclear. The functions of trophoblasts, including differentiation, proliferation, migration, invasion and apoptosis, are essential for a successful pregnancy. During the early stages of placental development, trophoblasts are strictly regulated by several molecular pathways; however, an imbalance in these molecular pathways can lead to severe placental lesions and pregnancy complications. We then discuss the role of miRNAs in trophoblast invasion and in the pathogenesis, diagnosis and prediction of preeclampsia. We also discuss the potential role of miRNAs from an epigenetic perspective with possible future therapeutic implications.

Evidence of Nitric Oxide Impairment During Hypertensive Pregnancies

Hypertensive disorders of pregnancy complicate up to 10% of pregnancies worldwide, and they can be classified into (1) gestational hypertension, (2) preeclampsia, (3) chronic hypertension and (4) chronic hypertension with preeclampsia. Nitric oxide (NO) plays an essential role in the haemodynamic adaptations observed during pregnancy. It has been shown that the nitric oxide pathway's dysfunction during pregnancy is associated with placental- and vascular-related diseases such as hypertensive disorders of pregnancy. This review aims to present a brief definition of hypertensive disorders of pregnancy and physiological maternal cardiovascular adaptations during pregnancy. We also detail how NO signalling is altered in the (a) systemic vasculature, (b) uterine artery/spiral arteries, (c) implantation and (d) placenta of hypertensive disorders during pregnancy. We conclude by summarizing the anti-hypertensive therapy of hypertensive disorders of pregnancy as a specific management strategy.

Vasomotor tone-associated factors and pregnancy outcomes of women who undergo in vitro fertilization

Vasomotor tone-associated factors play important roles in normal pregnancy, but their roles in the pregnancy outcome of women who undergo in vitro fertilization and embryo transfer (IVF-ET) remain unclear. A total of 82 infertile women who underwent successful IVF-ET were enrolled, including 18 pregnancy losses, 11 complications, and 53 normal deliveries. The serum NO and iNOS levels were significantly higher in the pregnancy loss group and significantly lower in the complication group than in the normal delivery group (p < 0.05). Significantly increased ET-1 and decreased PGI2 were found in both the pregnancy loss and complication groups compared with those in the normal delivery group (p < 0.05). NO, iNOS, and ET-1 are risk factors and PGI2 is a protective factor for pregnancy loss. ET-1 + PGI2 (AUC, 0.897; sensitivity, 90.6%; specificity, 83.3%) showed a relatively good predictive value for pregnancy loss following IVF-ET.

The role of hepatic sinusoidal obstruction in the pathogenesis of the hepatic involvement in HELLP syndrome: Exploring the literature

AIM

This study aims to determine, based on existing data, whether the mechanism resulting in liver dysfunction in HELLP syndrome resembles that in Sinusoidal Obstruction Syndrome (SOS).

BACKGROUND

HELLP syndrome is a serious pregnancy disorder with high maternal and perinatal morbidity and mortality rates. Because of poor insight in its pathophysiology, particularly that of the liver involvement, clinical management is limited to symptomatic treatment, often followed by termination of pregnancy. SOS is a rare, potentially life-threatening complication of radio and/ or chemotherapy in the preparation of hematopoietic cell transplantation. The etiology of liver dysfunction in SOS is - unlike that in HELLP syndrome - better-understood and seems to be initiated by direct toxic damage and demise of endothelial cells, causing hepatic sinusoidal obstruction and ischemia.

METHODS

We searched Pubmed, Embase and Cochrane for reports on the etiology of HELLP and SOS. This yielded 73 articles, with 14 additional reports from the references listed in these articles.

RESULTS

The dysfunctional placenta in women developing HELLP initiates a cascade of events that eventually results in liver dysfunction. The placenta releases, besides anti-angiogenetic factors, also necrotic debris and cell-free DNA, a mixture that not only induces systemic endothelial dysfunction as in preeclampsia, but also a systemic inflammatory response. The latter aggravates the endothelio-toxic effects in the systemic cardiovascular bed, amplifying the already increased pro-thrombotic conditions. Particularly in microcirculations with extremely low shear forces, such as in the hepatic sinusoids, this will facilitate microthrombi formation and fibrin deposition eventually resulting in obstruction of the sinusoids similar as in SOS. The latter causes ischemic damage and progressive demise of hepatocytes.

CONCLUSION

The available information supports the concept that the liver damage in HELLP and SOS results from sinusoidal ischemia, presumably resulting from partially overlapping pathophysiological mechanisms.

Nitric oxide synthase and VEGF expression in full-term placentas of obese women

An adequate placental vascularization allows the proper development of the fetus and it is crucial for the gestational success. A number of factors regulate angiogenesis, including vascular endothelial growth factor (VEGF), which induces the synthesis of nitric oxide (NO), a potent vasodilator produced by three different nitric oxide synthase (NOS) isoforms. NO is essential to maintain a low vascular resistance in the fetoplacental circulation, although at high concentrations, it may combine with excess superoxide to produce peroxynitrite, which reacts with proteins giving rise to nitrotyrosine. Since obesity, whose incidence is increasing worldwide, is characterized by a low-grade inflammatory state and increased levels of oxidative and nitrative stress, both affecting placental function, our aim was to evaluate the expression of VEGF, eNOS, and iNOS in full-term placentas obtained from normal weight and pre-pregnancy obese women by means of immunohistochemistry and real-time PCR. Moreover, we assessed the NO levels and the nitrotyrosine immunoexpression in the same sample groups. Our results show a significantly higher immunohistochemical expression of VEGF and eNOS in the endothelium of placentas from obese women than in controls, whereas the immunoexpression of iNOS was comparable in the two groups. These data agree with those of the gene expression analysis, thus suggesting the possible existence of a compensatory mechanism for changes in placental blood flow associated with obesity. As concerns nitrotyrosine and NO levels, we observed a significant increase in placental tissue from obese women which may contribute to the development of metabolic and cardiovascular diseases both in the mother and the offspring.

Attenuation of oxidative stress and hypertension in an animal model of HELLP syndrome

HELLP (hemolysis elevated liver enzyme low platelet) syndrome is associated with hypertension, inflammation, oxidative stress and endothelial activation. The objective of this study was to determine if oxygen scavenging or endothelin A receptor antagonism improved hypertension and oxidative stress. sFlt-1 and sEndoglin were infused via mini-osmotic pump into normal pregnant rats (NP) on gestational day 12 to create HELLP syndrome. On gestational day 18 arterial catheters were inserted and on gestational day 19 mean arterial pressure was analyzed in rats; serum, urine and tissues were collected for molecular analysis. HELLP rats had significantly increased MAP compared to control normal pregnant rats (P < 0.0005). Endothelin A receptor antagonism via ABT-627 and Tempol, superoxide dismutase mimetic, were administered to a subset of normal pregnant and HELLP rats beginning on gestational day 13 and attenuated mean arterial pressure in HELLP rats (P < 0.05; P < 0.005). There were no statistically significant differences in mean arterial pressure between NP+ET_A Receptor or NP+Tempol treated rats and NP rats (P = 0.22). Endothelin A receptor blockade significantly decreased HELLP induced isoprostane excretion (P < 0.0005), placental and hepatic reactive oxygen species (P < 0.05; P < 0.0005) and increased placental total antioxidant capacity (P < 0.005) compared to untreated HELLP rats. Similar results in isoprostane (P < 0.005), hepatic reactive oxygen species (P < 0.05) and placental total antioxidant capacity (P < 0.05) were seen in HELLP rats treated with Tempol or Endothelin A receptor antagonist vs. untreated HELLP rats. These data demonstrated a role for oxidative stress in contributing to the hypertension, placental and liver damage that is seen in HELLP syndrome.

Integrated Network Pharmacology and Metabolomics Analysis of the Therapeutic Effects of Zi Dian Fang on Immune Thrombocytopenic Purpura

Current hormone-based treatments for immune thrombocytopenic purpura (ITP) are associated with potentially serious adverse reactions. Zi Dian Fang (ZDF) is a multi-target Traditional Chinese Medicine (TCM) used to treat both the symptoms and root causes of ITP, with fewer side effects than hormone-based treatments. This study analysis of the therapeutic effects of ZDF on ITP from three aspects: platelet proliferation, immunoregulation, and inflammation. After detection of 52 chemical constituents of ZDF by UPLC-Q-TOF/MS, The main targets and pathways affected by ZDF were screened by network pharmacology and verified by Western blot and ELISA. Meanwhile, metabolomics analysis were applied to a mouse model of ITP to identify and screen endogenous terminal metabolites differentially regulated by ZDF. Integrated network pharmacology and metabolomics analysis of the therapeutic effects of ZDF on ITP may be as follows: ZDF counteracts ITP symptoms mainly by inhibiting Ras/MAPKs (Ras/Mitogen-activated protein kinases) pathway, and the expression of upstream protein (Ras) and downstream protein (p-ERK, p-JNK, p-p38) were inhibited, which affects the content of effect index associated with proliferation (Thrombopoietin, TPO; Granulocyte-macrophage colony stimulating factor, GM-CSF), inflammation (Tumor necrosis factor-α, TNF-α; Interleukin-6, IL-6), immune (Interleukin-2, IL-2; Interferon-gamma, IFN-γ; Interleukin-4, IL-4), so that the body’s arginine, Δ¹²-prostaglandin j2 (Δ¹²-PGJ2), 9-cis-Retinoic Acid, sphingosine-1-phosphate (S1P), oleic acid amide and other 12 endogenous metabolites significantly changes. Considering the established safety profile, the present study suggests ZDF may be a useful alternative to hormone-based therapies for the treatment of ITP.

Placental expression of endothelial and inducible nitric oxide synthase and NO metabolism in gestational hypertension: a case-control study

OBJECTIVE

Hypertension is one of the most common medical disorders in pregnancy and a role of nitric oxide (NO) metabolism has been described. Thus, the present work aimed at determining placental gene expression of eNOS and iNOS, to measure NO and ONOO(-) levels in patients with gestational hypertension (GH).

METHODS

Fifteen patients with GH and 15 healthy pregnant controls were enrolled in the study. Placental tissue was taken immediately after delivery and was stored at -80 °C until analysis. A piece of frozen tissue was homogenized in the appropriate buffer. Total RNA was extracted and was reverse transcribed to obtain complementary DNA that was used for real-time PCR for iNOS and eNOS expression, whereas NO and ONOO(-) production were measured by commercially available kits.

RESULTS

Placental eNOS and iNOS mRNA levels were significantly reduced in GH when compared to controls. NO and ONOO(-) production were both significantly higher in GH than controls.

CONCLUSIONS

The reduced eNOS and iNOS gene expression in women with GH reinforces the hypothesis that the mechanisms involving NO pathways, may promote oxidative damage, by contributing to the reduced blood flow and increased resistance in the feto-maternal circulation and suggests the use of NO modulators as useful tools in GH management.

Nitroso-redox balance and mitochondrial homeostasis are regulated by STOX1, a pre-eclampsia-associated gene

AIMS

Storkhead box 1 (STOX1) is a winged-helix transcription factor that is implicated in the genetic forms of a high-prevalence human gestational disease, pre-eclampsia. STOX1 overexpression confers pre-eclampsia-like transcriptomic features to trophoblastic cell lines and pre-eclampsia symptoms to pregnant mice. The aim of this work was to evaluate the impact of STOX1 on free radical equilibrium and mitochondrial function, both in vitro and in vivo.

RESULTS

Transcriptome analysis of STOX1-transgenic versus nontransgenic placentas at 16.5 days of gestation revealed alterations of mitochondria-related pathways. Placentas overexpressing STOX1 displayed altered mitochondrial mass and were severely biased toward protein nitration, indicating nitroso-redox imbalance in vivo. Trophoblast cells overexpressing STOX1 displayed an increased mitochondrial activity at 20% O2 and in hypoxia, despite reduction of the mitochondrial mass in the former. STOX1 overexpression is, therefore, associated with hyperactive mitochondria, resulting in increased free radical production. Moreover, nitric oxide (NO) production pathways were activated, resulting in peroxynitrite formation. At low oxygen pressure, STOX1 overexpression switched the free radical balance from reactive oxygen species (ROS) to reactive nitrogen species (RNS) in the placenta as well as in a trophoblast cell line.

INNOVATION

In pre-eclamptic placentas, NO interacts with ROS and generates peroxynitrite and nitrated proteins as end products. This process will deprive the maternal organism of NO, a crucial vasodilator molecule.

CONCLUSION

Our data posit STOX1 as a genetic switch in the ROS/RNS balance and suggest an explanation for elevated blood pressure in pre-eclampsia.