Superoxide Dismutase 1 In Vivo Ameliorates Maternal Diabetes Mellitus-Induced Apoptosis and Heart Defects Through Restoration of Impaired Wnt Signaling

A fetal rat model of ventricular noncompaction caused by intrauterine hyperglycemia

BACKGROUND

This study aims to develop a fetal rat model of ventricular noncompaction (NVM) using streptozotocin (STZ)-induced gestational hyperglycemia and compare it with a retinoic acid (RA) model.

METHODS

Female SD rats were categorized into STZ, RA, and normal control (NC) groups. The STZ group was given a high-fat diet pre-pregnancy and 35 mg/kg of 2% STZ postpregnancy. The RA group received a 90 mg/kg dose of RA on day 13 postpregnancy. Embryonic myocardial morphology was analyzed through HE staining, and embryonic cardiomyocyte ultrastructures were studied using electron microscopy. Diagnoses of NVM were based on a ratio of noncompact myocardium (N) to compact myocardium (C) >1.4, accompanied by thick myocardial trabeculae and a thin myocardial compaction layer. Kruskal-Wallis test determined N/C ratio differences among groups.

RESULTS

Both STZ and RA groups displayed significant NVM characteristics. The left ventricular (LV) N/C in the STZ, RA, and NC groups were 1.983 (1.423-3.527), 1.640 (1.197-2.895), and 0.927 (0.806-1.087), respectively, with a statistically significant difference (P<0.001). The right ventricular (RV) N/C in the STZ, RA, and NC groups were 2.097 (1.364-3.081), 1.897 (1.337-2.662), and 0.869 (0.732-1.022), respectively, with a significant difference (P<0.001). Electron microscopy highlighted marked endoplasmic reticulum swelling in embryonic cardiomyocytes from both STZ and RA groups.

CONCLUSION

Our model underscores the pivotal role of an adverse intrauterine developmental environment in the onset of NVM. This insight holds significant implications for future studies exploring the pathogenesis of NVM.

Small Molecule Activators of Mitochondrial Fusion Prevent Congenital Heart Defects Induced by Maternal Diabetes

Most congenital heart defect (CHD) cases are attributed to nongenetic factors; however, the mechanisms underlying nongenetic factor-induced CHDs are elusive. Maternal diabetes is one of the nongenetic factors, and this study aimed to determine whether impaired mitochondrial fusion contributes to maternal diabetes-induced CHDs and if mitochondrial fusion activators, teriflunomide and echinacoside, could reduce CHD incidence in diabetic pregnancy. We demonstrated maternal diabetes-activated FoxO3a increases miR-140 and miR-195, which in turn represses Mfn1 and Mfn2, leading to mitochondrial fusion defects and CHDs. Two mitochondrial fusion activators are effective in preventing CHDs in diabetic pregnancy.

Molecular Pathways and Animal Models of d-Transposition of the Great Arteries

During normal cardiovascular development, the outflow tract becomes septated and rotates so that the separate aorta and pulmonary trunk are correctly aligned with the left and right ventricles, respectively. However, when this process goes wrong, the aorta and pulmonary trunk are incorrectly positioned, resulting in oxygenated blood being directly returned to the lungs, with deoxygenated blood being delivered to the systemic circulation. This is termed transposition of the great arteries (TGA). The precise etiology of TGA is not known, but the use of animal models has elucidated that genes involved in determination of the left- embryonic body axis play key roles. Other factors such as retinoic acid levels are also crucial. This chapter reviews the animal models presenting with TGA that have been generated by genetic manipulation or with exogenous agents.

Epigenetic implications in maternal diabetes and metabolic syndrome-associated risk of orofacial clefts

Orofacial clefts (OFCs) are one of the most common types of structural birth defects. The etiologies are complicated, involving with genetic, epigenetic, and environmental factors. Studies have found that maternal diabetes and metabolic syndrome are associated with a higher risk of OFCs in offspring. Metabolic syndrome is a clustering of several disease risk factors, including hyperglycemia, dyslipidemia, obesity, and hypertension. Metabolic disease during pregnancy can increase risk of adverse outcomes and significantly influence fetal development, including orofacial formation and fusion. An altered metabolic state may contribute to developmental disorders or congenital defects including OFCs, potentially through epigenetic modulations, such as histone modification, DNA methylation, and noncoding RNA expression to alter activities of critical morphogenetic signaling or related developmental genes. This review summarizes the currently available evidence and underlying mechanisms of how the maternal metabolic syndrome is associated with OFCs in mostly human and some animal studies. It may provide a better understanding of the interactions between intrauterine metabolic status and fetal orofacial development which might be applied toward prevention and treatments of OFCs.

Maternal Pre-Existing Diabetes: A Non-Inherited Risk Factor for Congenital Cardiopathies

Congenital heart defects (CHDs) are the most common form of birth defects in humans. They occur in 9 out of 1000 live births and are defined as structural abnormalities of the heart. Understanding CHDs is difficult due to the heterogeneity of the disease and its multifactorial etiology. Advances in genomic sequencing have made it possible to identify the genetic factors involved in CHDs. However, genetic origins have only been found in a minority of CHD cases, suggesting the contribution of non-inherited (environmental) risk factors to the etiology of CHDs. Maternal pregestational diabetes is associated with a three- to five-fold increased risk of congenital cardiopathies, but the underlying molecular mechanisms are incompletely understood. According to current hypotheses, hyperglycemia is the main teratogenic agent in diabetic pregnancies. It is thought to induce cell damage, directly through genetic and epigenetic dysregulations and/or indirectly through production of reactive oxygen species (ROS). The purpose of this review is to summarize key findings on the molecular mechanisms altered in cardiac development during exposure to hyperglycemic conditions in utero. It also presents the various in vivo and in vitro techniques used to experimentally model pregestational diabetes. Finally, new approaches are suggested to broaden our understanding of the subject and develop new prevention strategies.

Calpain inhibition decreases oxidative stress via mitochondrial regulation in a swine model of chronic myocardial ischemia

INTRODUCTION

Calpain overexpression is implicated in mitochondrial damage leading to tissue oxidative stress and myocardial ischemic injury. The aim of this study was to determine the effects of calpain inhibition (CI) on mitochondrial impairment and oxidative stress in a swine model of chronic myocardial ischemia and metabolic syndrome.

METHODS

Yorkshire swine were fed a high-fat diet for 4 weeks to induce metabolic syndrome then underwent placement of an ameroid constrictor to the left circumflex artery. Three weeks later, animals received: no drug (control, "CON"; n= 7); a low-dose calpain inhibitor (0.12 mg/kg; "LCI", n= 7); or high-dose calpain inhibitor (0.25 mg/kg; "HCI", n=7). Treatment continued for 5 weeks, followed by tissue harvest. Cardiac tissue was assayed for protein carbonyl content, as well as antioxidant and mitochondrial protein expression. Reactive oxygen species (ROS) and mitochondrial respiration was measured in H9c2 cells following exposure to normoxia or hypoxia (1%) for 24 h with or without CI.

RESULTS

In ischemic myocardial tissue, CI was associated with decreased total oxidative stress compared to control. CI was also associated with increased expression of mitochondrial proteins superoxide dismutase 1, SDHA, and pyruvate dehydrogenase compared to control. 100 nM of calpain inhibitor decreased ROS levels and respiration in both normoxic and hypoxic H9c2 cardiomyoblasts.

CONCLUSIONS

In the setting of metabolic syndrome, CI improves oxidative stress in chronically ischemic myocardial tissue. Decreased oxidative stress may be via modulation of mitochondrial proteins involved in free radical scavenging and production.

Novel insights into the role of mitochondria in diabetic cardiomyopathy: molecular mechanisms and potential treatments

Diabetic cardiomyopathy describes decreased myocardial function in diabetic patients in the absence of other heart diseases such as myocardial ischemia and hypertension. Recent studies have defined numerous molecular interactions and signaling events that may account for deleterious changes in mitochondrial dynamics and functions influenced by hyperglycemic stress. A metabolic switch from glucose to fatty acid oxidation to fuel ATP synthesis, mitochondrial oxidative injury resulting from increased mitochondrial ROS production and decreased antioxidant capacity, enhanced mitochondrial fission and defective mitochondrial fusion, impaired mitophagy, and blunted mitochondrial biogenesis are major signatures of mitochondrial pathologies during diabetic cardiomyopathy. This review describes the molecular alterations underlying mitochondrial abnormalities associated with hyperglycemia and discusses their influence on cardiomyocyte viability and function. Based on basic research findings and clinical evidence, diabetic treatment standards and their impact on mitochondrial function, as well as mitochondria-targeted therapies of potential benefit for diabetic cardiomyopathy patients, are also summarized.

Functional cargos of exosomes derived from Flk-1+ vascular progenitors enable neurulation and ameliorate embryonic anomalies in diabetic pregnancy

Various types of progenitors initiate individual organ formation and their crosstalk orchestrates morphogenesis for the entire embryo. Here we show that progenitor exosomal communication across embryonic organs occurs in normal development and is altered in embryos of diabetic pregnancy. Endoderm fibroblast growth factor 2 (FGF2) stimulates mesoderm Flk-1+ vascular progenitors to produce exosomes containing the anti-stress protein Survivin. These exosomes act on neural stem cells of the neuroepithelium to facilitate neurulation by inhibiting cellular stress and apoptosis. Maternal diabetes causes Flk-1+ progenitor dysfunction by suppressing FGF2 through DNA hypermethylation. Restoring endoderm FGF2 prevents diabetes-induced survivin reduction in Flk-1+ progenitor exosomes. Transgenic Survivin expression in Flk-1+ progenitors or in utero delivery of survivin-enriched exosomes restores cellular homeostasis and prevents diabetes-induced neural tube defects (NTDs), whereas inhibiting exosome production induces NTDs. Thus, functional inter-organ communication via Flk-1 exosomes is vital for neurulation and its disruption leads to embryonic anomalies.

Congenital Abnormalities in the Infant of a Diabetic Mother

Diabetes mellitus is among the most common chronic diseases worldwide. Infants of diabetic mothers are at increased risk of having congenital abnormalities. Tremendous progress has been achieved in the pregnancy care of diabetic women; however, the risk of birth defects associated with maternal diabetes still exists. These anomalies might arise in many organs and systems of the developing fetus. Many mechanisms have been implicated in the teratogenicity of maternal diabetes and it is critical to achieve good glycemic control before conception in women with diabetes. Neonatal clinicians must be able to identify patients at risk and recognize the signs of diabetic embryopathy. This article presents a review of congenital anomalies associated with maternal diabetes.

Using Innovative Machine Learning Methods to Screen and Identify Predictors of Congenital Heart Diseases

Objective: Congenital heart diseases (CHDs) are associated with an extremely heavy global disease burden as the most common category of birth defects. Genetic and environmental factors have been identified as risk factors of CHDs previously. However, high volume clinical indicators have never been considered when predicting CHDs. This study aimed to predict the occurrence of CHDs by considering thousands of variables from self-reported questionnaires and routinely collected clinical laboratory data using machine learning algorithms.

Methods: We conducted a birth cohort study at one of the largest cardiac centers in China from 2011 to 2017. All fetuses were screened for CHDs using ultrasound and cases were confirmed by at least two pediatric cardiologists using echocardiogram. A total of 1,127 potential predictors were included to predict CHDs. We used the Explainable Boosting Machine (EBM) for prediction and evaluated the model performance using area under the Receive Operating Characteristics (ROC) curves (AUC). The top predictors were selected according to their contributions and predictive values. Thresholds were calculated for the most significant predictors.

Results: Overall, 5,390 mother-child pairs were recruited. Our prediction model achieved an AUC of 76% (69-83%) from out-of-sample predictions. Among the top 35 predictors of CHDs we identified, 34 were from clinical laboratory tests and only one was from the questionnaire (abortion history). Total accuracy, sensitivity, and specificity were 0.65, 0.74, and 0.65, respectively. Maternal serum uric acid (UA), glucose, and coagulation levels were the most consistent and significant predictors of CHDs. According to the thresholds of the predictors identified in our study, which did not reach the current clinical diagnosis criteria, elevated UA (>4.38 mg/dl), shortened activated partial thromboplastin time (<33.33 s), and elevated glucose levels were the most important predictors and were associated with ranges of 1.17-1.54 relative risks of CHDs. We have developed an online predictive tool for CHDs based on our findings that may help screening and prevention of CHDs.

Conclusions: Maternal UA, glucose, and coagulation levels were the most consistent and significant predictors of CHDs. Thresholds below the current clinical definition of “abnormal” for these predictors could be used to help develop CHD screening and prevention strategies.

Impact of maternal hyperglycemia on cardiac development: Insights from animal models

Congenital heart disease (CHD) is the leading cause of birth defect-related death in infants and is a global pediatric health concern. While the genetic causes of CHD have become increasingly recognized with advances in genome sequencing technologies, the etiology for the majority of cases of CHD is unknown. The maternal environment during embryogenesis has a profound impact on cardiac development, and numerous environmental factors are associated with an elevated risk of CHD. Maternal diabetes mellitus (matDM) is associated with up to a fivefold increased risk of having an infant with CHD. The rising prevalence of diabetes mellitus has led to a growing interest in the use of experimental diabetic models to elucidate mechanisms underlying this associated risk for CHD. The purpose of this review is to provide a comprehensive summary of rodent models that are being used to investigate alterations in cardiac developmental pathways when exposed to a maternal diabetic setting and to summarize the key findings from these models. The majority of studies in the field have utilized the chemically induced model of matDM, but recent advances have also been made using diet based and genetic models. Each model provides an opportunity to investigate unique aspects of matDM and is invaluable for a comprehensive understanding of the molecular and cellular mechanisms underlying matDM-associated CHD.

The role of glucose in physiological and pathological heart formation

Cells display distinct metabolic characteristics depending on its differentiation stage. The fuel type of the cells serves not only as a source of energy but also as a driver of differentiation. Glucose, the primary nutrient to the cells, is a critical regulator of rapidly growing embryos. This metabolic change is a consequence as well as a cause of changes in genetic program. Disturbance of fetal glucose metabolism such as in diabetic pregnancy is associated with congenital heart disease. In utero hyperglycemia impacts the left-right axis establishment, migration of cardiac neural crest cells, conotruncal formation and mesenchymal formation of the cardiac cushion during early embryogenesis and causes cardiac hypertrophy in late fetal stages. In this review, we focus on the role of glucose in cardiogenesis and the molecular mechanisms underlying heart diseases associated with hyperglycemia.

The complex role of Wnt ligands in type 2 diabetes mellitus and related complications

Type 2 diabetes mellitus (T2DM) is one of the major chronic diseases, whose prevalence is increasing dramatically worldwide and can lead to a range of serious complications. Wnt ligands (Wnts) and their activating Wnt signalling pathways are closely involved in the regulation of various processes that are important for the occurrence and progression of T2DM and related complications. However, our understanding of their roles in these diseases is quite rudimentary due to the numerous family members of Wnts and conflicting effects via activating the canonical and/or non-canonical Wnt signalling pathways. In this review, we summarize the current findings on the expression pattern and exact role of each human Wnt in T2DM and related complications, including Wnt1, Wnt2, Wnt2b, Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt7b, Wnt8a, Wnt8b, Wnt9a, Wnt9b, Wnt10a, Wnt10b, Wnt11 and Wnt16. Moreover, the role of main antagonists (sFRPs and WIF-1) and coreceptor (LRP6) of Wnts in T2DM and related complications and main challenges in designing Wnt-based therapeutic approaches for these diseases are discussed. We hope a deep understanding of the mechanistic links between Wnt signalling pathways and diabetic-related diseases will ultimately result in a better management of these diseases.

Maternal obesity and metabolic disorders associate with congenital heart defects in the offspring: A systematic review

BACKGROUND

Congenital heart defects (CHDs) are the most common congenital malformations. The aetiology of CHDs is complex. Large cohort studies and systematic reviews and meta-analyses based on these have reported an association between higher risk of CHDs in the offspring and individual maternal metabolic disorders such as obesity, diabetes, hypertension, and preeclampsia, all conditions that can be related to insulin resistance or hyperglycaemia. However, the clinical reality is that these conditions often occur simultaneously. The aim of this review is, in consequence, both to evaluate the existing evidence on the association between maternal metabolic disorders, defined as obesity, diabetes, hypertension, preeclampsia, dyslipidaemia and CHDs in the offspring, as well as the significance of combinations, such as metabolic syndrome, as risk factors.

METHODS

A systematic literature search of papers published between January 1, 1990 and January 14, 2021 was conducted using PubMed and Embase. Studies were eligible if they were published in English and were case-control or cohort studies. The exposures of interest were maternal overweight or obesity, hypertension, preeclampsia, diabetes, dyslipidaemia, and/or metabolic syndrome, and the outcome of interest was CHDs in the offspring. Furthermore, the studies were included according to a quality assessment score.

RESULTS

Of the 2,250 identified studies, 32 qualified for inclusion. All but one study investigated only the individual metabolic disorders. Some disorders (obesity, gestational diabetes, and hypertension) increased risk of CHDs marginally whereas pre-gestational diabetes and early-onset preeclampsia were strongly associated with CHDs, without consistent differences between CHD subtypes. A single study suggested a possible additive effect of maternal obesity and gestational diabetes.

CONCLUSIONS

Future studies of the role of aberrations of the glucose-insulin homeostasis in the common aetiology and mechanisms of metabolic disorders, present during pregnancy, and their association, both as single conditions and-particularly-in combination, with CHDs are needed.

Mending a broken heart: In vitro, in vivo and in silico models of congenital heart disease

Birth defects contribute to ∼0.3% of global infant mortality in the first month of life, and congenital heart disease (CHD) is the most common birth defect among newborns worldwide. Despite the significant impact on human health, most treatments available for this heterogenous group of disorders are palliative at best. For this reason, the complex process of cardiogenesis, governed by multiple interlinked and dose-dependent pathways, is well investigated. Tissue, animal and, more recently, computerized models of the developing heart have facilitated important discoveries that are helping us to understand the genetic, epigenetic and mechanobiological contributors to CHD aetiology. In this Review, we discuss the strengths and limitations of different models of normal and abnormal cardiogenesis, ranging from single-cell systems and 3D cardiac organoids, to small and large animals and organ-level computational models. These investigative tools have revealed a diversity of pathogenic mechanisms that contribute to CHD, including genetic pathways, epigenetic regulators and shear wall stresses, paving the way for new strategies for screening and non-surgical treatment of CHD. As we discuss in this Review, one of the most-valuable advances in recent years has been the creation of highly personalized platforms with which to study individual diseases in clinically relevant settings.

ERG1 plays an essential role in rat cardiomyocyte fate decision by mediating AKT signaling

ERG1, a potassium ion channel, is essential for cardiac action potential repolarization phase. However, the role of ERG1 for normal development of the heart is poorly understood. Using the rat embryonic stem cells (rESCs) model, we show that ERG1 is crucial in cardiomyocyte lineage commitment via interactions with Integrin β1. In the mesoderm phase of rESCs, the interaction of ERG1 with Integrin β1 can activate the AKT pathway by recruiting and phosphorylating PI3K p85 and focal adhesion kinase (FAK) to further phosphorylate AKT. Activation of AKT pathway promotes cardiomyocyte differentiation through two different mechanisms, (a) through phosphorylation of GSK3β to upregulate the expression levels of β-catenin and Gata4; (b) through promotion of nuclear translocation of nuclear factor-κB by phosphorylating IKKβ to inhibit cell apoptosis, which occurs due to increased Bcl2 expression. Our study provides solid evidence for a novel role of ERG1 on differentiation of rESCs into cardiomyocytes.

Comprehensive Identification of Key Genes Involved in Development of Diabetes Mellitus-Related Atherogenesis Using Weighted Gene Correlation Network Analysis

Coronary heart disease (CHD) is common in patients with diabetes mellitus (DM), however, the relevant mechanism remains elusive. The whole blood gene expression profiles of healthy control, patients with DM, patients with DM and CHD (DMCHD) were used to performed weight gene correlation network analysis (WGCNA) to identify the gene modules associated with DM-related atherogenesis. The candidate module was significantly involved in immune- and T cell activity-related biological process. GSEA results suggested that lysosome and apoptosis were enriched in DM and DMCHD samples. The protein-protein-KEGG pathway network may reveal the potential transcriptional regulatory network involving in DM-related atherosclerosis. Nineteen genes (RTKN, DCP1B, PDZD4, CACNA2D2, TSEN54, PVRIG, PLEKHF1, NKG7, ZAP70, NUDCD3, SLAMF6, CCDC107, NAG6, ZDHHC14, EOMES, VIL2, WDR54, DMAP1, and PMPCA) were considered as DM-related atherogenesis genes (DRAGs). The Gene Set Variation Analysis (GSVA) score of the DRAG set gradually increased in the control, DM and DMCHD. ROC curve analysis showed that ZAP70, TSEN54, and PLEKHF1 may be potential blood circulation biomarkers for DMCHD in patients with DM. In conclusion, we identified nineteen hallmark genes involving in DM-related atherogenesis and constructed a potential transcriptional regulatory network involving in DM-related atherosclerosis.

Restoring BMP4 expression in vascular endothelial progenitors ameliorates maternal diabetes-induced apoptosis and neural tube defects

During mouse embryonic development, vasculogenesis initially occurs in the yolk sac, preceding neurulation. Our previous studies have demonstrated that maternal diabetes induces embryonic vasculopathy at early embryonic developmental stage by suppressing the expression of vascular growth factors including BMP4 (bone morphogenetic protein 4). This study aimed to determine whether restoring diabetes-inhibited BMP4 expression in Flk-1+ progenitors effectively prevented maternal diabetes-induced embryonic vasculopathy and NTDs. Transgenic (Tg) BMP4 expression in the vascular endothelial growth factor receptor 2 (Flk-1)-positive (Flk-1+) progenitors was achieved by crossing a Floxed BMP4 Tg mouse line with the Flk-1-Cre mouse line. Non-BMP4 Tg and BMP4 Tg embryos were harvested at E8.5 to assess the expression of BMP4, markers of endoplasmic reticulum stress, and expression of the Id genes, direct targets of BMP4; and the presence of cleaved caspase 3 and 8, apoptosis, and Smad signaling. BMP4 Tg overexpression neutralized its down-regulation by maternal diabetes in E8.5 embryos. Maternal diabetes-induced Flk-1+ progenitor apoptosis, impairment of blood island formation, and reduction of Flk-1+ progenitor number and blood vessel density, which were reversed by BMP4 Tg expression. BMP4 Tg expression in Flk-1+ progenitors blocked maternal diabetes-induced vasculopathy in early stage embryos (E7.5-E8.5) and consequently led to amelioration of maternal diabetes-induced neural tube defects (NTDs) at E10.5. BMP4 Tg expression inhibited maternal diabetes-induced endoplasmic reticulum stress and caspase cascade activation in the developing neuroepithelium, and reduced neuroepithelial cell apoptosis. BMP4 Tg expression re-activated Smad1/5/8 phosphorylation and reversed maternal diabetes-suppressed Smad4 expression. BMP4 Tg expression restored Id1 and Smad6 expression inhibited by maternal diabetes. In vitro, recombinant BMP4 protein blocked high glucose-induced Flk-1+ progenitor apoptosis and NTDs. These data demonstrate that BMP4 down-regulation in Flk-1+ progenitors are responsible for diabetes-induced yolk sac vasculopathy, and that restoring BMP4 expression prevents vasculopathy and rescues neuroepithelial cells from cellular organelle stress, leading to NTD reduction.

In ovo hyperglycemia causes congenital limb defects in chicken embryos via disruption of cell proliferation and apoptosis

While the correlation between diabetes during pregnancy and birth defects is well-established, how hyperglycemia causes developmental abnormalities remains unclear. In this study, we developed a novel "hyperglycemic" chicken embryonic model by administrating various doses of glucose to fertilized eggs at embryonic stages HH16 or HH24. When the embryos were collected at HH35, the LD50 was 1.57 g/Kg under HH16 treatment and 0.93 g/Kg under HH24 treatment, indicating that "hyperglycemic" environments can be lethal for the embryos. When exposed to a dose equal to or higher than 1 g/Kg glucose at HH16 or HH24, more than 40% of the surviving chicken embryos displayed heart defects and/or limb defects. The limb defects were associated with proliferation defects of both the wing and leg buds indicated by reduced numbers of p-H3S10 labeled cells. These limb defects were also associated with ectopic apoptosis in the leg bud and expression changes of key apoptotic genes. Furthermore, glucose treatment induced decreased expression of genes involved in Shh-signaling, chondrogenesis, and digit patterning in the limb bud. In summary, our data demonstrated that a high-glucose environment induces congenital heart and limb defects associated with disrupted cell proliferation and apoptosis, possibly through depressed Shh-signaling.

Maternal Obesity and Diabetes Mellitus as Risk Factors for Congenital Heart Disease in the Offspring

Congenital heart disease (CHD) is the most common anatomical malformation occurring live‐born infants and an increasing cause of morbidity and mortality across the lifespan and throughout the world. Population‐based observations have long described associations between maternal cardiometabolic disorders and the risk of CHD in the offspring. Here we review the epidemiological evidence and clinical observations relating maternal obesity and diabetes mellitus to the risk of CHD offspring with particular attention to mechanistic models of maternal‐fetal risk transmission and first trimester disturbances of fetal cardiac development. A deeper understanding of maternal risk factors holds the potential to improve both prenatal detection of CHD by identifying at‐risk pregnancies, along with primary prevention of disease by improving preconception and prenatal treatment of at‐risk mothers.

Lactobacillus plantarum And Inulin: Therapeutic Agents to Enhance Cardiac Ob Receptor Expression and Suppress Cardiac Apoptosis in Type 2 Diabetic Rats

BACKGROUND

T2DM may cause increased levels of oxidative stress and cardiac apoptosis through elevated blood glucose. The present study investigated the effects of Lactobacillus plantarum (L. plantarum) as a probiotic strain and inulin as a prebiotic supplement on cardiac oxidative stress and apoptotic markers in type 2 diabetes mellitus (T2DM) rats.

METHODS

A high-fat diet and a low dose of streptozotocin were used to induce type 2 diabetes. The rats were divided into six groups which were supplemented with L. plantarum, inulin, or their combination for 8 weeks.

RESULTS

The results showed improved activity of cardiac antioxidant parameters including total antioxidant capacity (TAC), superoxide dismutase (SOD), and glutathione peroxidase (GPx) (P < 0.001, P < 0.01, and P < 0.01, respectively) and decreased level of cardiac malondialdehyde (MDA) concentration (P < 0.05). These changes were accompanied with increased protein expression of cardiac obesity receptor (Ob-R) (P = 0.05) and reduced apoptotic markers such as tumor necrosis factor-alpha (TNF-α), Fas ligand (FasL), and caspase proteins (P < 0.001, P = 0.003, and P < 0.01, respectively) in T2DM rats after concurrent L. plantarum and inulin supplementation. Moreover, a remarkable correlation of cardiac Ob-R and oxidative stress parameters with cardiac apoptotic markers was observed (P < 0.01).

CONCLUSION

The concurrent use of L. plantarum and inulin seems to be beneficial, as they can lead to decreased heart complications of T2DM via reducing cardiac apoptotic markers.

In utero exposure to maternal diabetes impairs nephron progenitor differentiation

The incidence of diabetes mellitus has significantly increased among women of childbearing age, and it has been shown that prenatal exposure to maternal diabetes increases the risk of associated congenital anomalies of the kidney. Congenital anomalies of the kidney are among the leading causes of chronic kidney disease in children. To better understand the effect of maternal diabetes on kidney development, we analyzed wild-type offspring (DM_Exp) of diabetic Ins2+/C96Y mice (Akita mice). DM_Exp mice at postnatal day 34 have a reduction of ~20% in the total nephron number compared with controls, using the gold standard physical dissector/fractionator method. At the molecular level, the expression of the nephron progenitor markers sine oculis homeobox homolog 2 and Cited1 was increased in DM_Exp kidneys at postnatal day 2. Conversely, the number of early developing nephrons was diminished in DM_Exp kidneys. This was associated with decreased expression of the intracellular domain of Notch1 and the canonical Wnt target lymphoid enhancer binding factor 1. Together, these data suggest that the diabetic intrauterine environment impairs the differentiation of nephron progenitors into nephrons, possibly by perturbing the Notch and Wnt/β-catenin signaling pathways.

Say NO to ROS: Their Roles in Embryonic Heart Development and Pathogenesis of Congenital Heart Defects in Maternal Diabetes

Congenital heart defects (CHDs) are the most prevalent and serious birth defect, occurring in 1% of all live births. Pregestational maternal diabetes is a known risk factor for the development of CHDs, elevating the risk in the child by more than four-fold. As the prevalence of diabetes rapidly rises among women of childbearing age, there is a need to investigate the mechanisms and potential preventative strategies for these defects. In experimental animal models of pregestational diabetes induced-CHDs, upwards of 50% of offspring display congenital malformations of the heart, including septal, valvular, and outflow tract defects. Specifically, the imbalance of nitric oxide (NO) and reactive oxygen species (ROS) signaling is a major driver of the development of CHDs in offspring of mice with pregestational diabetes. NO from endothelial nitric oxide synthase (eNOS) is crucial to cardiogenesis, regulating various cellular and molecular processes. In fact, deficiency in eNOS results in CHDs and coronary artery malformation. Embryonic hearts from diabetic dams exhibit eNOS uncoupling and oxidative stress. Maternal treatment with sapropterin, a cofactor of eNOS, and antioxidants such as N-acetylcysteine, vitamin E, and glutathione as well as maternal exercise have been shown to improve eNOS function, reduce oxidative stress, and lower the incidence CHDs in the offspring of mice with pregestational diabetes. This review summarizes recent data on pregestational diabetes-induced CHDs, and offers insights into the important roles of NO and ROS in embryonic heart development and pathogenesis of CHDs in maternal diabetes.

Maternal hyperglycemia and fetal cardiac development: Clinical impact and underlying mechanisms

Congenital heart disease (CHD) is the most common type of birth defect and is both a significant pediatric and adult health problem, in light of a growing population of survivors. The etiology of CHD has been considered to be multifactorial with genetic and environmental factors playing important roles. The combination of advances in cardiac developmental biology, which have resulted in the elucidation of molecular pathways regulating normal cardiac morphogenesis, and genome sequencing technology have allowed the discovery of numerous genetic contributors of CHD ranging from chromosomal abnormalities to single gene variants. Conversely, mechanistic details of the contribution of environmental factors to CHD remain unknown. Maternal diabetes mellitus (matDM) is a well-established and increasingly prevalent environmental risk factor for CHD, but the underlying etiologic mechanisms by which pregestational matDM increases the vulnerability of embryos to cardiac malformations remains largely elusive. Here, we will briefly discuss the multifactorial etiology of CHD with a focus on the epidemiologic link between matDM and CHD. We will describe the animal models used to study the underlying mechanisms between matDM and CHD and review the numerous cellular and molecular pathways affected by maternal hyperglycemia in the developing heart. Last, we discuss how this increased understanding may open the door for the development of novel prevention strategies to reduce the incidence of CHD in this high-risk population.

Glomerular mesangial cell and podocyte injuries in diabetic nephropathy

Diabetic nephropathy is one of the leading causes of end-stage renal disease and creates heavy healthcare burdens globally. Dysfunction of mesangial cells and podocytes contributes to diabetic nephropathy. Dysregulation of signaling involved in renal development and regeneration may cause diabetic kidney damages. Growing evidences suggest the importance of dysregulated dickkopf-1 (DKK1)/Wnt/ β-catenin signaling pathways in the pathogenesis of diabetic glomerular injuries. The inhibition of Wnt signaling in injured mesangial cells is likely attributed to the high glucose-induced Ras/Rac1 dependent superoxide formation. When DKK1, the cellular inhibitor of Wnt signaling, binds to the Kremen-2 receptor, depositions of extracellular matrix increase in the mesangium of diabetic kidneys. Additionally, reactivation of Notch-1 signaling has been implicated in podocytopathy during diabetic proteinuria development. Knocking down Notch-1 alleviates vascular endothelial growth factor (VEGF) expression, nephrin repression and proteinuria in diabetic kidneys. It is also found that epigenetic modulations by histone deacetylase 4 (HDAC4) and miR-29a could lead to diabetic nephropathy. High glucose increases the expression of HDAC4, which causes deacetylation with subsequent ubiquitination of nephrin. Overexpression of miR-29a in diabetic transgenic mice would decrease the expression of HDAC4 and stabilize nephrin. Surprisingly, reprogramming or reactivation of signaling involved in renal development or regeneration often brings about diabetic glomerular sclerosis in mesangial cells and podocytes. Better knowledge about modifications of embryonic stem cell signaling will have a chance to implement strategically focused pharmacological research programs aiming to the development of new drugs for diabetic kidney injuries.

The copper-zinc superoxide dismutase activity in selected diseases

Copper-zinc superoxide dismutase (Cu,Zn-SOD) plays a protective role in various types of tissue protecting them from oxidative damage. Alterations in Cu,Zn-SOD (SOD1 and SOD3) activity and its expression have been observed in pathological occurrences most prevalent in modern society, including inflammatory bowel disease, obesity and its implications-diabetes and hypertension, and chronic obstructive pulmonary disease. Moreover, several SOD1 and SOD3 gene polymorphisms have been associated with the risk of developing a particular type of disease, or its exacerbation. This article features recent observations in this topic, aiming to show the importance of proper gene sequence and activity of Cu,Zn-SOD in the aforementioned diseases.

Oxidative Stress Induces an Interactive Decline in Wnt and Nrf2 Signaling in Degenerating Retinal Pigment Epithelium

AIMS

Cells have evolved a highly sophisticated web of cytoprotective systems to neutralize unwanted oxidative stress, but are challenged by unique modern day stresses such as cigarette smoking and ingestion of a high-fat diet (HFD). Age-related disease, such as age-related macular degeneration (AMD), the most common cause of blindness among the elderly in Western societies, develops in part, when oxidative stress overwhelms cytoprotective systems to injure tissue. Since most studies focus on the protection by a single protective system, the aim of this study was to investigate the impact of more than one cytoprotective system against oxidative stress.

RESULTS

Wingless (Wnt) and nuclear factor-erythroid 2-related factor 2 (Nrf2), two fundamental signaling systems that are vital to cell survival, decline after mice are exposed to chronic cigarette smoke and HFD, two established AMD risk factors, in a bidirectional feedback loop through phosphorylated glycogen synthase kinase 3 beta. Decreased Wnt and Nrf2 signaling leads to retinal pigment epithelial dysfunction and apoptosis, and a phenotype that is strikingly similar to geographic atrophy (GA), an advanced form of AMD with no effective treatment.

INNOVATION

This study is the first to show that chronic oxidative stress from common modern day environmental exposures reduces two fundamental and vital cytoprotective networks in a bidirectional feedback loop, and their decline leads to advanced disease phenotype.

CONCLUSION

Our data offer new insights into how combined modern oxidative stresses of cigarette smoking and HFD contribute to GA through an interactive decline in Wnt and Nrf2 signaling. Antioxid. Redox Signal. 29, 389-407.

[Research advances in the mechanism of congenital heart disease induced by pregestational diabetes mellitus]

Congenital heart disease (CHD) is the most common birth defect at present and has a complex etiology which involves the combined effect of genetic and environmental factors. Pregestational diabetes mellitus is significantly associated with the development of CHD, but the detailed mechanism remains unknown. This article reviews the research advances in the molecular mechanism of CHD caused by pregestational diabetes mellitus.

Epigenetic mechanisms underlying maternal diabetes-associated risk of congenital heart disease

Birth defects are the leading cause of infant mortality, and they are caused by a combination of genetic and environmental factors. Environmental risk factors may contribute to birth defects in genetically susceptible infants by altering critical molecular pathways during embryogenesis, but experimental evidence for gene-environment interactions is limited. Fetal hyperglycemia associated with maternal diabetes results in a 5-fold increased risk of congenital heart disease (CHD), but the molecular basis for this correlation is unknown. Here, we show that the effects of maternal hyperglycemia on cardiac development are sensitized by haploinsufficiency of Notch1, a key transcriptional regulator known to cause CHD. Using ATAC-seq, we found that hyperglycemia decreased chromatin accessibility at the endothelial NO synthase (Nos3) locus, resulting in reduced NO synthesis. Transcription of Jarid2, a regulator of histone methyltransferase complexes, was increased in response to reduced NO, and this upregulation directly resulted in inhibition of Notch1 expression to levels below a threshold necessary for normal heart development. We extended these findings using a Drosophila maternal diabetic model that revealed the evolutionary conservation of this interaction and the Jarid2-mediated mechanism. These findings identify a gene-environment interaction between maternal hyperglycemia and Notch signaling and support a model in which environmental factors cause birth defects in genetically susceptible infants.

Pregestational type 2 diabetes mellitus induces cardiac hypertrophy in the murine embryo through cardiac remodeling and fibrosis

BACKGROUND

Cardiac hypertrophy is highly prevalent in patients with type 2 diabetes mellitus. Experimental evidence has implied that pregnant women with type 2 diabetes mellitus and their children are at an increased risk of cardiovascular diseases. Our previous mouse model study revealed that maternal type 2 diabetes mellitus induces structural heart defects in their offspring.

OBJECTIVE

This study aims to determine whether maternal type 2 diabetes mellitus induces embryonic heart hypertrophy in a murine model of diabetic embryopathy.

STUDY DESIGN

The type 2 diabetes mellitus embryopathy model was established by feeding 4-week-old female C57BL/6J mice with a high-fat diet for 15 weeks. Cardiac hypertrophy in embryos at embryonic day 17.5 was characterized by measuring heart size and thickness of the right and left ventricle walls and the interventricular septum, as well as the expression of β-myosin heavy chain, atrial natriuretic peptide, insulin-like growth factor-1, desmin, and adrenomedullin. Cardiac remodeling was determined by collagen synthesis and fibronectin synthesis. Fibrosis was evaluated by Masson staining and determining the expression of connective tissue growth factor, osteopontin, and galectin-3 genes. Cell apoptosis also was measured in the developing heart.

RESULTS

The thicknesses of the left ventricle walls and the interventricular septum of embryonic hearts exposed to maternal diabetes were significantly thicker than those in the nondiabetic group. Maternal diabetes significantly increased β-myosin heavy chain, atrial natriuretic peptide, insulin-like growth factor-1, and desmin expression, but decreased expression of adrenomedullin. Moreover, collagen synthesis was significantly elevated, whereas fibronectin synthesis was suppressed, in embryonic hearts from diabetic dams, suggesting that cardiac remodeling is a contributing factor to cardiac hypertrophy. The cardiac fibrosis marker, galectin-3, was induced by maternal diabetes. Furthermore, maternal type 2 diabetes mellitus activated the proapoptotic c-Jun-N-terminal kinase 1/2 stress signaling and triggered cell apoptosis by increasing the number of terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling-positive cells (10.4 ± 2.2% of the type 2 diabetes mellitus group vs 3.8 ± 0.7% of the nondiabetic group, P < .05).

CONCLUSION

Maternal type 2 diabetes mellitus induces cardiac hypertrophy in embryonic hearts. Adverse cardiac remodeling, including elevated collagen synthesis, suppressed fibronectin synthesis, profibrosis, and apoptosis, is implicated as the etiology of cardiac hypertrophy.

Diabetes-induced effects on cardiomyocytes in chick embryonic heart micromass and mouse embryonic D3 differentiated stem cells

Diabetes mellitus during pregnancy is a considerable medical challenge, since it is related to ‎augmented morbidity and mortality concerns for both the fetus ‎and the pregnant woman. Records show that the etiology of diabetic ‎embryopathy is complicated, as many teratological factors might be involved ‎in the mechanisms of diabetes mellitus-induced congenital malformation. ‎In this study, the potential cardiotoxic effect of hyperglycemia with hyperketonemia was investigated by using two in vitro models; primary chick embryonic cardiomyocytes and stem cell derived cardiomyocytes, where adverse effects were recorded in both systems. The cells were evaluated by changes in beating activity, cell activity, protein content, ROS production, DNA damage and differentiating stem cell migration. The diabetic formulae used produced an increase in DNA damage and a decline in cell migration in mouse embryonic stem cells. These results provide an additional insight into adverse effects during gestational diabetes mellitus and a recommendation for expectant mothers and maternity staff to monitor glycaemic levels months ahead of conception. This study also supports the recommendation of using antioxidants during pregnancy to prevent DNA damage by the production of ROS, which might result in heart defects as well as other developmental anomalies.

Deregulated Cardiac Specific MicroRNAs in Postnatal Heart Growth

The heart is recognized as an organ that is terminally differentiated by adulthood. However, during the process of human development, the heart is the first organ with function in the embryo and grows rapidly during the postnatal period. MicroRNAs (miRNAs, miRs), as regulators of gene expression, play important roles during the development of multiple systems. However, the role of miRNAs in postnatal heart growth is still unclear. In this study, by using qRT-PCR, we compared the expression of seven cardiac- or muscle-specific miRNAs that may be related to heart development in heart tissue from mice at postnatal days 0, 3, 8, and 14. Four miRNAs-miR-1a-3p, miR-133b-3p, miR-208b-3p, and miR-206-3p-were significantly decreased while miR-208a-3p was upregulated during the postnatal heart growth period. Based on these results, GeneSpring GX was used to predict potential downstream targets by performing a 3-way comparison of predictions from the miRWalk, PITA, and microRNAorg databases. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to identify potential functional annotations and signaling pathways related to postnatal heart growth. This study describes expression changes of cardiac- and muscle-specific miRNAs during postnatal heart growth and may provide new therapeutic targets for cardiovascular diseases.

Maternal diabetes and high glucose in vitro trigger Sca1+ cardiac progenitor cell apoptosis through FoxO3a

Recent controversies surrounding the authenticity of c-kit⁺ cardiac progenitor cells significantly push back the advance in regenerative therapies for cardiovascular diseases. There is an urgent need for research in characterizing alternative types of cardiac progenitor cells. Towards this goal, in the present study, we determined the effect of maternal diabetes on Sca1⁺ cardiac progenitor cells. Maternal diabetes induced caspase 3-dependent apoptosis in Sca1⁺ cardiac progenitor cells derived from embryonic day 17.5 (E17.5). Similarly, high glucose in vitro but not the glucose osmotic control mannitol triggered Sca1⁺ cardiac progenitor cell apoptosis in a dose- and time-dependent manner. Both maternal diabetes and high glucose in vitro activated the pro-apoptotic transcription factor, Forkhead O 3a (FoxO3a) via dephosphorylation at threonine 32 (Thr-32) residue. foxo3a gene deletion abolished maternal diabetes-induced Sca1⁺ cardiac progenitor cell apoptosis. The dominant negative FoxO3a mutant without the transactivation domain from the C terminus blocked high glucose-induced Sca1⁺ cardiac progenitor cell apoptosis, whereas the constitutively active FoxO3a mutant with the three phosphorylation sites, Thr-32, Ser-253, and Ser-315, being replaced by alanine residues mimicked the pro-apoptotic effect of high glucose. Thus, maternal diabetes and high glucose in vitro may limit the regenerative potential of Sca1⁺ cardiac progenitor cells by inducing apoptosis through FoxO3a activation. These findings will serve as the guide in optimizing the autologous therapy using Sca1⁺ cardiac progenitor cells in cardiac defect babies born exposed to maternal diabetes.

The impaired myocardial ischemic tolerance in adult offspring of diabetic pregnancy is restored by maternal melatonin treatment

Diabetic pregnancy, with ever increasing prevalence, adversely affects embryogenesis and increases vasculometabolic disorder risks in adult offspring. However, it remains poorly understood whether maternal diabetes increases the offspring's susceptibility to heart injuries in adulthood. In this study, we observed that cardiac function and structure were comparable between adult offspring born to diabetic mice and their counterparts born to nondiabetic mice at baseline. However, in response to myocardial ischemia/reperfusion (MIR), diabetic mother offspring exhibited augmented infarct size, cardiac dysfunction, and myocardial apoptosis compared with control, in association with exaggerated activation of mitochondria- and endoplasmic reticulum (ER) stress-mediated apoptosis pathways and oxidative stress. Molecular analysis showed that the impaired myocardial ischemic tolerance in diabetic mother offspring was mainly attributable to blunted cardiac insulin receptor substrate (IRS)-1/Akt signaling. Furthermore, the effect of maternal melatonin administration on offspring's response to MIR was determined, and the results indicated that melatonin treatment in diabetic dams during pregnancy significantly improved the tolerance to MIR injury in their offspring, via restoring cardiac IRS-1/Akt signaling. Taken together, these data suggest that maternal diabetes predisposes offspring to augmented MIR injury in adulthood, and maternal melatonin supplementation during diabetic pregnancy may hold promise for improving myocardial ischemic tolerance in the offspring.

microRNA expression profiling and functional annotation analysis of their targets modulated by oxidative stress during embryonic heart development in diabetic mice

Maternal pregestational diabetes mellitus (PGDM) induces congenital heart defects (CHDs). The molecular mechanism underlying PGDM-induced CHDs is unknown. microRNAs (miRNAs), small non-coding RNAs, repress gene expression at the posttranscriptional level and play important roles in heart development. We performed a global miRNA profiling study to assist in revealing potential miRNAs modulated by PGDM and possible developmental pathways regulated by miRNAs during heart development. A total of 149 mapped miRNAs in the developing heart were significantly altered by PGDM. Bioinformatics analysis showed that the majority of the 2111 potential miRNA target genes were associated with cardiac development-related pathways including STAT3 and IGF-1 and transcription factors (Cited2, Zeb2, Mef2c, Smad4 and Ets1). Overexpression of the antioxidant enzyme, superoxide dismutase 1, reversed PGDM-altered miRNAs, suggesting that oxidative stress is responsible for dysregulation of miRNAs. Thus, our study provides the foundation for further investigation of a miRNA-dependent mechanism underlying PGDM-induced CHDs.

The green tea polyphenol EGCG alleviates maternal diabetes-induced neural tube defects by inhibiting DNA hypermethylation

BACKGROUND

Maternal diabetes increases the risk of neural tube defects in offspring. Our previous study demonstrated that the green tea polyphenol, Epigallocatechin gallate, inhibits high glucose-induced neural tube defects in cultured embryos. However, the therapeutic effect of Epigallocatechin gallate on maternal diabetes-induced neural tube defects is still unclear.

OBJECTIVE

We aimed to examine whether Epigallocatechin gallate treatment can reduce maternal diabetes-induced DNA methylation and neural tube defects.

STUDY DESIGN

Nondiabetic and diabetic pregnant mice at embryonic day 5.5 were given drinking water with or without 1 or 10 μM Epigallocatechin gallate. At embryonic day 8.75, embryos were dissected from the visceral yolk sac for the measurement of the levels and activity of DNA methyltransferases, the levels of global DNA methylation, and methylation in the CpG islands of neural tube closure essential gene promoters. embryonic day 10.5 embryos were examined for neural tube defect incidence.

RESULTS

Epigallocatechin gallate treatment did not affect embryonic development because embryos from nondiabetic dams treated with Epigallocatechin gallate did not exhibit any neural tube defects. Treatment with 1 μM Epigallocatechin gallate did not reduce maternal diabetes-induced neural tube defects significantly. Embryos from diabetic dams treated with 10 μM Epigallocatechin gallate had a significantly lower neural tube defect incidence compared with that of embryos without Epigallocatechin gallate treatment. Epigallocatechin gallate reduced neural tube defect rates from 29.5% to 2%, an incidence that is comparable with that of embryos from nondiabetic dams. Ten micromoles of Epigallocatechin gallate treatment blocked maternal diabetes-increased DNA methyltransferases 3a and 3b expression and their activities, leading to the suppression of global DNA hypermethylation. Additionally, 10 μM Epigallocatechin gallate abrogated maternal diabetes-increased DNA methylation in the CpG islands of neural tube closure essential genes, including Grhl3, Pax3, and Tulp3.

CONCLUSION

Epigallocatechin gallate reduces maternal diabetes-induced neural tube defects formation and blocks the enhanced expression and activity of DNA methyltransferases, leading to the suppression of DNA hypermethylation and the restoration of neural tube closure essential gene expression. These observations suggest that Epigallocatechin gallate supplements could mitigate the teratogenic effects of hyperglycemia on the developing embryo and prevent diabetes-induced neural tube defects.

Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis

BACKGROUND

Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects remain largely unknown.

OBJECTIVE

We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects.

STUDY DESIGN

A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination.

RESULTS

Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin protein; endoplasmic reticulum chaperone gene expression; and XBP1 messenger RNA splicing, as well as increased cleaved caspase 3 and 8 in embryonic hearts. Furthermore, maternal type 2 diabetes mellitus triggered excessive apoptosis in ventricular myocardium, endocardial cushion, and outflow tract of the embryonic heart.

CONCLUSION

Similar to those observations in type 1 diabetic embryopathy, maternal type 2 diabetes mellitus causes heart defects in the developing embryo manifested with oxidative stress, endoplasmic reticulum stress, and excessive apoptosis in heart cells.

Superoxide dismutase 2 overexpression alleviates maternal diabetes-induced neural tube defects, restores mitochondrial function and suppresses cellular stress in diabetic embryopathy

Pregestational diabetes disrupts neurulation leading to neural tube defects (NTDs). Oxidative stress resulting from reactive oxygen species (ROS) plays a central role in the induction of NTD formation in diabetic pregnancies. We aimed to determine whether mitochondrial dysfunction increases ROS production leading to oxidative stress and diabetic embryopathy. Overexpression of the mitochondrion-specific antioxidant enzyme superoxide dismutase 2 (SOD2) in a transgenic (Tg) mouse model significantly reduced maternal diabetes-induced NTDs. SOD2 overexpression abrogated maternal diabetes-induced mitochondrial dysfunction by inhibiting mitochondrial translocation of the pro-apoptotic Bcl-2 family members, reducing the number of defective mitochondria in neuroepithelial cells, and decreasing mitochondrial membrane potential. Furthermore, SOD2 overexpression blocked maternal diabetes-increased ROS production by diminishing dihydroethidium staining signals in the developing neuroepithelium, and reducing the levels of nitrotyrosine-modified proteins and lipid hydroperoxide level in neurulation stage embryos. SOD2 overexpression also abolished maternal diabetes-induced endoplasmic reticulum stress. Finally, caspase-dependent neuroepithelial cell apoptosis enhanced by oxidative stress was significantly reduced by SOD2 overexpression. Thus, our findings support the hypothesis that mitochondrial dysfunction in the developing neuroepithelium enhances ROS production, which leads to oxidative stress and endoplasmic reticulum (ER) stress. SOD2 overexpression blocks maternal diabetes-induced oxidative stress and ER stress, and reduces the incidence of NTDs in embryos exposed to maternal diabetes.

High glucose-induced oxidative stress represses sirtuin deacetylase expression and increases histone acetylation leading to neural tube defects

Aberrant epigenetic modifications are implicated in maternal diabetes-induced neural tube defects (NTDs). Because cellular stress plays a causal role in diabetic embryopathy, we investigated the possible role of the stress-resistant sirtuin (SIRT) family histone deacetylases. Among the seven sirtuins (SIRT1-7), pre-gestational maternal diabetes in vivo or high glucose in vitro significantly reduced the expression of SIRT 2 and SIRT6 in the embryo or neural stem cells, respectively. The down-regulation of SIRT2 and SIRT6 was reversed by superoxide dismutase 1 (SOD1) over-expression in the in vivo mouse model of diabetic embryopathy and the SOD mimetic, tempol and cell permeable SOD, PEGSOD in neural stem cell cultures. 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a superoxide generating agent, mimicked high glucose-suppressed SIRT2 and SIRT6 expression. The acetylation of histone 3 at lysine residues 56 (H3K56), H3K14, H3K9, and H3K27, putative substrates of SIRT2 and SIRT6, was increased by maternal diabetes in vivo or high glucose in vitro, and these increases were blocked by SOD1 over-expression or tempol treatment. SIRT2 or SIRT6 over-expression abrogated high glucose-suppressed SIRT2 or SIRT6 expression, and prevented the increase in acetylation of their histone substrates. The potent sirtuin activator (SRT1720) blocked high glucose-increased histone acetylation and NTD formation, whereas the combination of a pharmacological SIRT2 inhibitor and a pan SIRT inhibitor mimicked the effect of high glucose on increased histone acetylation and NTD induction. Thus, diabetes in vivo or high glucose in vitro suppresses SIRT2 and SIRT6 expression through oxidative stress, and sirtuin down-regulation-induced histone acetylation may be involved in diabetes-induced NTDs. The mechanism underlying pre-gestational diabetes-induced neural tube defects (NTDs) is still elusive. Our study unravels a new epigenetic mechanism in which maternal diabetes-induced oxidative stress represses sirtuin deacetylase 2 (SIRT2) and 6 (SIRT6) expression leading to histone acetylation and gene expression. SIRT down-regulation mediates the teratogenicity of diabetes leading to (NTD) formation. The study provides a mechanistic basis for the development of natural antioxidants and SIRT activators as therapeutics for diabetic embryopathy.

High glucose suppresses embryonic stem cell differentiation into neural lineage cells

Abnormal neurogenesis occurs during embryonic development in human diabetic pregnancies and in animal models of diabetic embryopathy. Our previous studies in a mouse model of diabetic embryopathy have implicated that high glucose of maternal diabetes delays neurogenesis in the developing neuroepithelium leading to neural tube defects. However, the underlying process in high glucose-impaired neurogenesis is uncharacterized. Neurogenesis from embryonic stem (ES) cells provides a valuable model for understanding the abnormal neural lineage development under high glucose conditions. ES cells are commonly generated and maintained in high glucose (approximately 25 mM glucose). Here, the mouse ES cell line, E14, was gradually adapted to and maintained in low glucose (5 mM), and became a glucose responsive E14 (GR-E14) line. High glucose induced the endoplasmic reticulum stress marker, CHOP, in GR-E14 cells. Under low glucose conditions, the GR-E14 cells retained their pluripotency and capability to differentiate into neural lineage cells. GR-E14 cell differentiation into neural stem cells (Sox1 and nestin positive cells) was inhibited by high glucose. Neuron (Tuj1 positive cells) and glia (GFAP positive cells) differentiation from GR-E14 cells was also suppressed by high glucose. In addition, high glucose delayed GR-E14 differentiation into neural crest cells by decreasing neural crest markers, paired box 3 (Pax3) and paired box 7 (Pax7). Thus, high glucose impairs ES cell differentiation into neural lineage cells. The low glucose adapted and high glucose responsive GR-E14 cell line is a useful in vitro model for assessing the adverse effect of high glucose on the development of the central nervous system.

The Nrf2 Activator Vinylsulfone Reduces High Glucose-Induced Neural Tube Defects by Suppressing Cellular Stress and Apoptosis

The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway is one of the primary pathways responsible for the cellular defense system against oxidative stress. Oxidative stress-induced apoptosis is a causal event in diabetic embryopathy. Thus, the Nrf2 pathway may play an important role in the induction of diabetic embryopathy. In the present study, we investigated the potentially protective effect of the Nrf2 activator, vinylsulfone, on high glucose-induced cellular stress, apoptosis, and neural tube defects (NTDs). Embryonic day 8.5 (E8.5) whole mouse embryos were cultured in normal (5 mmol/L) or high (16.7 mmol/L) glucose conditions, with or without vinylsulfone. At a concentration of 10 μmol/L, vinylsulfone had an inhibitory effect on high glucose-induced NTD formation, but it was not significant. At a concentration of 20 μmol/L, vinylsulfone significantly reduced high glucose-induced NTDs. In addition, 20 μmol/L vinylsulfone abrogated the high glucose-induced oxidative stress markers lipid hydroperoxide (LPO), 4-hydroxynonenal (4-HNE), and nitrotyrosine-modified proteins. The high glucose-induced endoplasmic reticulum (ER) stress biomarkers were also suppressed by 20 μmol/L vinylsulfone through the inhibition of phosphorylated protein kinase RNA-like ER kinase (PERK), inositol requiring protein 1α (IRE1a), eukaryotic initiation factor 2α (eIF2a), upregulated C/EBP-homologous protein (CHOP), binding immunoglobulin protein (BiP), and x-box binding protein 1 (XBP1) messenger RNA splicing. Furthermore, 20 μmol/L vinylsulfone abolished caspase 3 and caspase 8 cleavage, markers of apoptosis, in embryos cultured under high glucose conditions. The Nrf2 activator, vinylsulfone, is protective against high glucose-induced cellular stress, caspase activation, and subsequent NTD formation. Our data suggest that vinylsulfone supplementation is a potential therapy for diabetes-associated neurodevelopmental defects.

Endothelial Dysfunction in Human Diabetes Is Mediated by Wnt5a-JNK Signaling

OBJECTIVE

Endothelial dysfunction is linked to insulin resistance, inflammatory activation, and increased cardiovascular risk in diabetes mellitus; however, the mechanisms remain incompletely understood. Recent studies have identified proinflammatory signaling of wingless-type family member (Wnt) 5a through c-jun N-terminal kinase (JNK) as a regulator of metabolic dysfunction with potential relevance to vascular function. We sought to gain evidence that increased activation of Wnt5a-JNK signaling contributes to impaired endothelial function in patients with diabetes mellitus.

APPROACH AND RESULTS

We measured flow-mediated dilation of the brachial artery and characterized freshly isolated endothelial cells by protein expression, eNOS activation, and nitric oxide production in 85 subjects with type 2 diabetes mellitus (n=42) and age- and sex-matched nondiabetic controls (n=43) and in human aortic endothelial cells treated with Wnt5a. Endothelial cells from patients with diabetes mellitus displayed 1.3-fold higher Wnt5a levels (P=0.01) along with 1.4-fold higher JNK activation (P<0.01) without a difference in total JNK levels. Higher JNK activation was associated with lower flow-mediated dilation, consistent with endothelial dysfunction (r=0.53, P=0.02). Inhibition of Wnt5a and JNK signaling restored insulin and A23187-mediated eNOS activation and improved nitric oxide production in endothelial cells from patients with diabetes mellitus. In endothelial cells from nondiabetic controls, rWnt5a treatment inhibited eNOS activation replicating the diabetic endothelial phenotype. In human aortic endothelial cells, Wnt5a-induced impairment of eNOS activation and nitric oxide production was reversed by Wnt5a and JNK inhibition.

CONCLUSIONS

Our findings demonstrate that noncanonical Wnt5a signaling and JNK activity contribute to vascular insulin resistance and endothelial dysfunction and may represent a novel therapeutic opportunity to protect the vasculature in patients with diabetes mellitus.

MiR-17 Downregulation by High Glucose Stabilizes Thioredoxin-Interacting Protein and Removes Thioredoxin Inhibition on ASK1 Leading to Apoptosis

Pregestational diabetes significantly increases the risk of neural tube defects (NTDs). Maternal diabetes activates an Apoptosis Signal-regulating Kinase 1 (ASK1)-initiated pathway, which triggers neural stem cell apoptosis of the developing neuroepithelium leading to NTD formation. How high glucose of diabetes activates ASK1 is still unclear. In this study, we investigated the mechanism underlying high glucose-induced ASK1 activation. High glucose suppressed miR-17 expression, which led to an increase in its target gene Txnip (Thioredoxin-interacting protein). High glucose-increased Txnip enhanced its binding to the ASK1 inhibitor, thioredoxin (Trx), and thereby sequestered Trx from the Trx-ASK1 complex. High glucose-induced ASK1 activation and consequent apoptosis were abrogated by either the miR-17 mimic or Txnip siRNA knockdown. In contrast, the miR-17 inhibitor or Txnip ectopic overexpression mimicked the stimulative effect of high glucose on ASK1 and apoptosis. Thus, our study demonstrated that miR-17 repression mediates the pro-apoptotic effect of high glucose, and revealed a new mechanism underlying ASK1 activation, in which decreased miR-17 removes Trx inhibition on ASK1 through Txnip.

Punicalagin exerts protective effect against high glucose-induced cellular stress and neural tube defects

Maternal diabetes-induced birth defects remain a significant health problem. Studying the effect of natural compounds with antioxidant properties and minimal toxicities on diabetic embryopathy may lead to the development of new and safe dietary supplements. Punicalagin is a primary polyphenol found in pomegranate juice, which possesses antioxidant, anti-inflammatory and anti-tumorigenic properties, suggesting a protective effect of punicalagin on diabetic embryopathy. Here, we examined whether punicalagin could reduce high glucose-induced neural tube defects (NTDs), and if this rescue occurs through blockage of cellular stress and caspase activation. Embryonic day 8.5 (E8.5) mouse embryos were cultured for 24 or 36 h with normal (5 mM) glucose or high glucose (16.7 mM), in presence or absence of 10 or 20 μM punicalagin. 10 μM punicalagin slightly reduced NTD formation under high glucose conditions; however, 20 μM punicalagin significantly inhibited high glucose-induced NTD formation. Punicalagin suppressed high glucose-induced lipid peroxidation marker 4-hydroxynonenal, nitrotyrosine-modified proteins, and lipid peroxides. Moreover, punicalagin abrogated endoplasmic reticulum stress by inhibiting phosphorylated protein kinase ribonucleic acid (RNA)-like ER kinase (p-PERK), phosphorylated inositol-requiring protein-1α (p-IRE1α), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), C/EBP-homologous protein (CHOP), binding immunoglobulin protein (BiP) and x-box binding protein 1 (XBP1) mRNA splicing. Additionally, punicalagin suppressed high glucose-induced caspase 3 and caspase 8 cleavage. Punicalagin reduces high glucose-induced NTD formation by blocking cellular stress and caspase activation. These observations suggest punicalagin supplements could mitigate the teratogenic effects of hyperglycemia in the developing embryo, and possibly prevent diabetes-induced NTDs.

Maternal diabetes triggers DNA damage and DNA damage response in neurulation stage embryos through oxidative stress

DNA damage and DNA damage response (DDR) in neurulation stage embryos under maternal diabetes conditions are not well understood. The purpose of this study was to investigate whether maternal diabetes and high glucose in vitro induce DNA damage and DDR in the developing embryo through oxidative stress. In vivo experiments were conducted by mating superoxide dismutase 1 (SOD1) transgenic male mice with wild-type (WT) female mice with or without diabetes. Embryonic day 8.75 (E8.75) embryos were tested for the DNA damage markers, phosphorylated histone H2A.X (p-H2A.X) and DDR signaling intermediates, including phosphorylated checkpoint 1 (p-Chk1), phosphorylated checkpoint 2 (p-Chk2), and p53. Levels of the same DNA damage markers and DDR signaling intermediates were also determined in the mouse C17.2 neural stem cell line. Maternal diabetes and high glucose in vitro significantly increased the levels of p-H2A.X. Levels of p-Chk1, p-Chk2, and p53, were elevated under both maternal diabetic and high glucose conditions. SOD1 overexpression blocked maternal diabetes-induced DNA damage and DDR in vivo. Tempol, a SOD1 mimetic, diminished high glucose-induced DNA damage and DDR in vitro. In conclusion, maternal diabetes and high glucose in vitro induce DNA damage and activates DDR through oxidative stress, which may contribute to the pathogenesis of diabetes-associated embryopathy.