Redox modulation of Ca2+ signaling in human endothelial and smooth muscle cells in pre-eclampsia

Catecholamine induces endothelial dysfunction via Angiotensin II and intermediate conductance calcium activated potassium channel

Endothelial dysfunction contributes to the pathogenesis of Takotsubo syndrome (TTS). However, the exact mechanism underlying endothelial dysfunction in the setting of TTS has not been completely clarified. This study aims to investigate the roles of angiotensin II (Ang II) and intermediate-conductance Ca2+-activated K+ (SK4) channels in catecholamine-induced endothelial dysfunction. Human cardiac microvascular endothelial cells (HCMECs) were exposed to 100 µM epinephrine (Epi), mimicking the setting of TTS. Epi treatment increased the ET-1 concentration and reduced NO levels in HCMECs. Importantly, the effects of Epi were found to be mitigated in the presence of Ang II receptor blockers. Furthermore, Ang II mimicked Epi effects on ET-1 and NO production. Additionally, Ang II inhibited tube formation and increased cell apoptosis. The effects of Ang II could be reversed by an SK4 activator NS309 and mimicked by an SK4 channel blocker TRAM-34. Ang II also inhibited the SK4 channel current (ISK4) without affecting its expression level. Ang II could depolarize the cell membrane potential. Ang II promoted ROS release and reduced protein kinase A (PKA) expression. A ROS blocker prevented Ang II effect on ISK4. The PKA activator Sp-8-Br-cAMPS increased SK4 channel currents. Epinephrine enhanced the activity of ACE by activating the α1 receptor/Gq/PKC signal pathway, thereby promoting the secretion of Ang II. The study suggested that high-level catecholamine can increase Ang II release from endothelial cells by α1 receptors/Gq/PKC signal pathway. Ang II can inhibit SK4 channel current by increasing ROS generation and reducing PKA expression, thereby contributing to endothelial dysfunction.

Preeclampsia and Fetal Congenital Heart Defects

Endothelial dysfunction, impaired implantation and placental insufficiency have been identified as mechanisms behind the development of pre-eclampsia, resulting in angiogenic factors' alteration. Angiogenic imbalance is also associated with congenital heart defects, and this common physiologic pathway may explain the association between them and pre-eclampsia. This review aims to understand the physiology shared by these two entities and whether women with pre-eclampsia have an increased risk of fetal congenital heart defects (or the opposite). The present research has highlighted multiple vasculogenic pathways associated with heart defects and preeclampsia, but also epigenetic and environmental factors, contributing both. It is also known that fetuses with a prenatal diagnosis of congenital heart disease have an increased risk of several comorbidities, including intrauterine growth restriction. Moreover, the impact of pre-eclampsia goes beyond pregnancy as it increases the risk for following pregnancies and for diseases later in life in both offspring and mothers. Given the morbidity and mortality associated with these conditions, it is of foremost importance to understand how they are related and its causative mechanisms. This knowledge may allow earlier diagnosis, an adequate surveillance or even the implementation of preventive strategies.

Role of ROS/RNS in Preeclampsia: Are Connexins the Missing Piece?

Preeclampsia is a pregnancy complication that appears after 20 weeks of gestation and is characterized by hypertension and proteinuria, affecting both mother and offspring. The cellular and molecular mechanisms that cause the development of preeclampsia are poorly understood. An important feature of preeclampsia is an increase in oxygen and nitrogen derived free radicals (reactive oxygen species/reactive nitrogen species (ROS/RNS), which seem to be central players setting the development and progression of preeclampsia. Cell-to-cell communication may be disrupted as well. Connexins (Cxs), a family of transmembrane proteins that form hemichannels and gap junction channels (GJCs), are essential in paracrine and autocrine cell communication, allowing the movement of signaling molecules between cells as well as between the cytoplasm and the extracellular media. GJCs and hemichannels are fundamental for communication between endothelial and smooth muscle cells and, therefore, in the control of vascular contraction and relaxation. In systemic vasculature, the activity of GJCs and hemichannels is modulated by ROS and RNS. Cxs participate in the development of the placenta and are expressed in placental vasculature. However, it is unknown whether Cxs are modulated by ROS/RNS in the placenta, or whether this potential modulation contributes to the pathogenesis of preeclampsia. Our review addresses the possible role of Cxs in preeclampsia, and the plausible modulation of Cxs-formed channels by ROS and RNS. We suggest these factors may contribute to the development of preeclampsia.

Carpinus turczaninowii Extract May Alleviate High Glucose-Induced Arterial Damage and Inflammation

Hyperglycemia-induced oxidative stress triggers severe vascular damage and induces an inflammatory vascular state, and is, therefore, one of the main causes of atherosclerosis. Recently, interest in the natural compound Carpinus turczaninowii has increased because of its reported antioxidant and anti-inflammatory properties. We investigated whether a C. turczaninowii extract was capable of attenuating high glucose-induced inflammation and arterial damage using human aortic vascular smooth muscle cells (hASMCs). mRNA expression levels of proinflammatory response [interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)], endoplasmic reticulum (ER) stress [CCAAT-enhancer-binding proteins (C/EBP) homologous protein (CHOP)], and adenosine monophosphate (AMP)-protein activated kinase α2 (AMPK α2)], and DNA damage [phosphorylated H2.AX (p-H2.AX)] were measured in hASMCs treated with the C. turczaninowii extracts (1 and 10 μg/mL) after being stimulated by high glucose (25 mM) or not. The C. turczaninowii extract attenuated the increased mRNA expression of IL-6, TNF-α, and CHOP in hASMCs under high glucose conditions. The expression levels of p-H2.AX and AMPK α2 induced by high glucose were also significantly decreased in response to treatment with the C. turczaninowii extract. In addition, 15 types of phenolic compounds including quercetin, myricitrin, and ellagic acid, which exhibit antioxidant and anti-inflammatory properties, were identified in the C. turczaninowii extract through ultra-performance liquid chromatography-quadrupole-time of flight (UPLC-Q-TOF) mass spectrometry. In conclusion, C. turczaninowii may alleviate high glucose-induced inflammation and arterial damage in hASMCs, and may have potential in the treatment of hyperglycemia-induced atherosclerosis.

Redox signaling and unfolded protein response coordinate cell fate decisions under ER stress

Endoplasmic reticulum (ER) is a dynamic organelle orchestrating the folding and post-translational maturation of almost all membrane proteins and most secreted proteins. These proteins synthesized in the ER, need to form disulfide bridge to acquire specific three-dimensional structures for function. The formation of disulfide bridge is mediated via protein disulfide isomerase (PDI) family and other oxidoreductases, which contribute to reactive oxygen species (ROS) generation and consumption in the ER. Therefore, redox regulation of ER is delicate and sensitive to perturbation. Deregulation in ER homeostasis, usually called ER stress, can provoke unfolded protein response (UPR) pathways with an aim to initially restore homeostasis by activating genes involved in protein folding and antioxidative machinery. Over time, however, activated UPR involves a variety of cellular signaling pathways which determine the state and fate of cell in large part (like autophagy, apoptosis, ferroptosis, inflammation, senescence, stemness, and cell cycle, etc.). This review will describe the regulation of UPR from the redox perspective in controlling the cell survival or death, emphasizing the redox modifications of UPR sensors/transducers in the ER.

Alterations in antioxidant system, mitochondrial biogenesis and autophagy in preeclamptic myometrium

Preeclampsia is a pregnancy complication which causes significant maternal and fetal morbidity and mortality worldwide. Although intensive research has been performed in the last 40 years, the pathology of preeclampsia is still poorly understood. The present work is a comparative study of the myometrium of women with normal pregnancy, and those with late- and early-onset preeclampsia (n = 10 for each group). We observed significant changes in the levels of antioxidant enzymes, markers of mitochondrial biogenesis and autophagy proteins in preeclamptic myometrium. Levels of superoxide dismutase 1 and catalase were lower in both preeclamptic groups than the control group. In late-onset preeclampsia, expression levels of essential mitochondria-related proteins VDAC1, TFAM, hexokinase 1, PGC-1α and PGC-1β, and autophagy marker LC3A, were significantly elevated. In the myometrium of the early-onset preeclampsia group OPA1 and Bcl-2 were up-regulated compared to those of the control (p < 0.05). These findings suggest that crucial molecular changes in the maternal myometrium occur with the development of preeclampsia.

Altered Endothelial Nitric Oxide Signaling as a Paradigm for Maternal Vascular Maladaptation in Preeclampsia

PURPOSE OF REVIEW

The goal of this review is to present the newest insights into what we view as a central failure of cardiovascular adaptation in preeclampsia (PE) by focusing on one clinically significant manifestation of maternal endothelial dysfunction: nitric oxide signaling. The etiology, symptoms, and current theories of the PE syndrome are described first, followed by a review of the available evidence, and underlying causes of reduced endothelial nitric oxide (NO) signaling in PE.

RECENT FINDINGS

PE maladaptations include, but are not limited to, altered physiological stimulatory inputs (e.g., estrogen; VEGF/PlGF; shear stress) and substrates (L-Arg; ADMA), augmented placental secretion of anti-angiogenic and inflammatory factors such as sFlt-1 and Eng, changes in eNOS (polymorphisms, expression), and reduced bioavailability of NO secondary to oxidative stress. PE is a complex obstetrical syndrome that is associated with maternal vascular dysfunction. Diminished peripheral endothelial vasodilator influence in general, and of NO signaling specifically, are key in driving disease progression and severity.

Effects of Hyperglycemia on Vascular Smooth Muscle Ca2+ Signaling

Diabetes is a complex disease that is characterized with hyperglycemia, dyslipidemia, and insulin resistance. These pathologies are associated with significant cardiovascular implications that affect both the macro- and microvasculature. It is therefore important to understand the effects of various pathologies associated with diabetes on the vasculature. Here we directly test the effects of hyperglycemia on vascular smooth muscle (VSM) Ca²⁺ signaling in an isolated in vitro system using the A7r5 rat aortic cell line as a model. We find that prolonged exposure of A7r5 cells to hyperglycemia (weeks) is associated with changes to Ca²⁺ signaling, including most prominently an inhibition of the passive ER Ca²⁺ leak and the sarcoplasmic reticulum Ca²⁺-ATPase (SERCA). To translate these findings to the in vivo condition, we used primary VSM cells from normal and diabetic subjects and find that only the inhibition of the ER Ca²⁺ leaks replicates in cells from diabetic donors. These results show that prolonged hyperglycemia in isolation alters the Ca²⁺ signaling machinery in VSM cells. However, these alterations are not readily translatable to the whole organism situation where alterations to the Ca²⁺ signaling machinery are different.

Keap1-Nrf2 regulated redox signaling in utero: Priming of disease susceptibility in offspring

Intrauterine exposure to gestational diabetes, pre-eclampsia or intrauterine growth restriction alters the redox status of the developing fetus. Such pregnancy-related diseases in most cases do not have a readily identifiable genetic cause, and epigenetic 'priming' mechanisms in utero may predispose both mother and child to later-life onset of cardiovascular and metabolic diseases. The concept of 'fetal programing' or 'developmental priming' and its association with an increased risk of disease in childhood or adulthood has been reviewed extensively. This review focuses on adaptive changes in the in utero redox environment during normal pregnancy and the consequences of alterations in redox control associated with pregnancies characterized by oxidative stress. We evaluate the evidence that the Keap1-Nrf2 pathway is important for protecting the fetus against adverse conditions in utero and may itself be subject to epigenetic priming, potentially contributing to an increased risk of vascular disease and insulin resistance in later life.

Potential Role of Placental Klotho in the Pathogenesis of Preeclampsia

The aim of this study was to analyze the placental expression and allele status of promoter region of Klotho in association with preeclampsia, which represents the most common hypertensive disease of pregnancy. Klotho mRNA and protein levels were determined using real-time PCR and Western blot, respectively, in placental tissue samples obtained from 34 patients affected with preeclampsia and 34 controls. A PCR-based genotyping analysis was carried out in the promoter region of Klotho gene. Moreover, expression levels of pluripotency markers, Nanog and Oct4, and telomere length were assessed using real-time PCR. Klotho mRNA and protein levels were reduced in preeclamptic placentas compared with controls. -744delA single-nucleotide polymorphism was significantly associated with preeclampsia. In pathological placentas, there was a downregulation of pluripotency markers and a reduced telomere length. This study is the first to evaluate the placental expression level of Klotho in association with preeclampsia. Further analyses will clarify its role in the pathogenesis of this pregnancy hypertensive disorder.

L-arginine-nitric oxide pathway and oxidative stress in plasma and platelets of patients with pre-eclampsia

Pre-eclampsia (PE), a syndrome of pregnancy-induced hypertension, continues to be a leading cause of maternal and fetal morbidity and mortality. The aim of this study was to investigate whether changes in oxidative status are correlated with alterations in the L-arginine-nitric oxide pathway and platelet aggregation in PE. Plasma and platelets from women with PE (n=24) or normotensive pregnancy (NP, n=27) recruited in the third trimester of gestation were used to measure oxidative damage assessed by protein carbonyl content, antioxidant activities of superoxide dismutase (SOD), catalase (CAT) and nitrite levels. Transport of L-[(3)H]-arginine, as well as the activities of the nitric oxide (NO) synthase (eNOS and inducible NO synthase (iNOS)) and platelet aggregation, were also evaluated. Plasma nitrite levels and the activities of SOD and CAT were reduced in PE (5.2±2.7, 3.4±0.8, 0.3±0.4, respectively, P<0.05) compared with NP (8.7±2.3, 6.7±3.1, 1.0±0.5, respectively), whereas protein carbonyl content and L-arginine levels were not significantly different between PE and NP groups. In platelets, L-arginine transport was reduced in PE (19.2±10.5, P<0.05) compared with NP (62.0±31.1), whereas the NOS activity, eNOS and iNOS expression, nitrite levels and platelet aggregation were unaffected. Protein carbonyl content was increased, and CAT activity was reduced in platelets from PE (0.03±0.02, 0.55±0.30, respectively, P<0.05), compared with NP (0.005±0.005, 1.01±0.36, respectively). The data suggest that a systemic impairment of antioxidant defense mechanisms is associated with decreased plasma nitrite levels, which may contribute to hypertension in PE. Oxidative stress may contribute to the reduced influx of L-arginine in platelets. Compensatory mechanisms may contribute to the maintenance of NO production and its modulatory role on platelet function.

Elevated amniotic fluid F₂-isoprostane: a potential predictive marker for preeclampsia

In the complex mechanism of preeclampsia, oxidative stress is an important pathogenic factor, and F₂-isoprostane is a marker of oxidative stress and lipid peroxidation. The objective of this study was to identify if the amniotic fluid (AF) levels of F₂-isoprostanes were elevated in women who later developed preeclampsia. In this study, we analyzed AF F₂-isoprostane concentrations with enzyme immunoassay (EIA), and the EIA results could be validated by quantitative mass spectrometry. The mean AF concentration of F₂-isoprostanes was significantly higher in pregnancies with subsequent development of preeclampsia (123.1 ± 57.6 pg/ml, n = 85) than in controls (73.8 ± 36.6 pg/ml, n = 85). The AF elevation of F₂-isoprostanes was even higher in the preeclampsia with intrauterine growth restriction group (138.3 ± 65.2 pg/ml, n = 39). The area under the curve of the receiver operating characteristics analysis for AF F₂-isoprostanes assay was 0.81, supporting its potential as a biomarker for preeclampsia. These results indicate that oxidative stress existed before the onset of clinical preeclampsia, further suggesting that the elevation of AF F₂-isoprostanes may be used as a guide for antioxidant supplementation to reduce the risk and/or severity of preeclampsia.

Impact of dietary soy isoflavones in pregnancy on fetal programming of endothelial function in offspring

Epidemiological evidence suggests that soy-based diets containing phytoestrogens (isoflavones) afford protection against cardiovascular diseases (CVDs); however, supplementation trials have largely reported only marginal health benefits. The molecular mechanisms by which the isoflavones genistein, daidzein, and equol afford protection against oxidative stress remain to be investigated in large scale clinical trials. Isoflavones are transferred across the placenta in both rodents and humans, yet there is limited information on their actions in pregnancy and the developmental origins of disease. Our studies established that feeding a soy isoflavone-rich diet during pregnancy, weaning, and postweaning affords cardiovascular protection in aged male rats. Notably, rats exposed to a soy isoflavone-deficient diet throughout pregnancy and adult life exhibited increased oxidative stress, diminished antioxidant enzyme and eNOS levels, endothelial dysfunction, and elevated blood pressure in vivo. The beneficial effects of refeeding isoflavones to isoflavone-deficient rats include an increased production of nitric oxide and EDHF, an upregulation of antioxidant defense enzymes and lowering of blood pressure in vivo. This review focuses on the role that isoflavones in the fetal circulation may play during fetal development in affording protection against CVD in the offspring via their ability to activate eNOS, EDHF, and redox-sensitive gene expression.

Nitric oxide signaling in brain function, dysfunction, and dementia

Nitric oxide (NO) is an important signaling molecule that is widely used in the nervous system. With recognition of its roles in synaptic plasticity (long-term potentiation, LTP; long-term depression, LTD) and elucidation of calcium-dependent, NMDAR-mediated activation of neuronal nitric oxide synthase (nNOS), numerous molecular and pharmacological tools have been used to explore the physiology and pathological consequences for nitrergic signaling. In this review, the authors summarize the current understanding of this subtle signaling pathway, discuss the evidence for nitrergic modulation of ion channels and homeostatic modulation of intrinsic excitability, and speculate about the pathological consequences of spillover between different nitrergic compartments in contributing to aberrant signaling in neurodegenerative disorders. Accumulating evidence points to various ion channels and particularly voltage-gated potassium channels as signaling targets, whereby NO mediates activity-dependent control of intrinsic neuronal excitability; such changes could underlie broader mechanisms of synaptic plasticity across neuronal networks. In addition, the inability to constrain NO diffusion suggests that spillover from endothelium (eNOS) and/or immune compartments (iNOS) into the nervous system provides potential pathological sources of NO and where control failure in these other systems could have broader neurological implications. Abnormal NO signaling could therefore contribute to a variety of neurodegenerative pathologies such as stroke/excitotoxicity, Alzheimer's disease, multiple sclerosis, and Parkinson's disease.

Pathological aspects of lipid peroxidation

Lipid peroxidation (LPO) product accumulation in human tissues is a major cause of tissular and cellular dysfunction that plays a major role in ageing and most age-related and oxidative stress-related diseases. The current evidence for the implication of LPO in pathological processes is discussed in this review. New data and literature review are provided evaluating the role of LPO in the pathophysiology of ageing and classically oxidative stress-linked diseases, such as neurodegenerative diseases, diabetes and atherosclerosis (the main cause of cardiovascular complications). Striking evidences implicating LPO in foetal vascular dysfunction occurring in pre-eclampsia, in renal and liver diseases, as well as their role as cause and consequence to cancer development are addressed.