Current perspectives on the causes of neural tube defects resulting from diabetic pregnancy

MicroRNA-322 overexpression reduces neural tube defects in diabetic pregnancies

BACKGROUND

Hyperglycemia from pregestational diabetes mellitus induces neural tube defects in the developing fetus. Folate supplementation is the only effective way to prevent neural tube defects; however, some cases of neural tube defects are resistant to folate. Excess folate has been linked to higher maternal cancer risk and infant allergy. Therefore, additional interventions are needed. Understanding the mechanisms underlying maternal diabetes mellitus-induced neural tube defects can identify potential targets for preventing such defects. Despite not yet being in clinical use, growing evidence suggests that microRNAs are important intermediates in embryonic development and can serve as both biomarkers and drug targets for disease intervention. Our previous studies showed that maternal diabetes mellitus in vivo activates the inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α) in the developing embryo and that a high glucose condition in vitro reduces microRNA-322 (miR-322) levels. IRE1α is an RNA endonuclease; however, it is unknown whether IRE1α targets and degrades miR-322 specifically or whether miR-322 degradation leads to neural tube defects via apoptosis. We hypothesize that IRE1α can inhibit miR-322 in maternal diabetes mellitus-induced neural tube defects and that restoring miR-322 expression in developing neuroepithelium ameliorates neural tube defects.

OBJECTIVE

This study aimed to identify potential targets for preventing maternal diabetes mellitus-induced neural tube defects and to investigate the roles and relationship of a microRNA and an RNA endonuclease in mouse embryos exposed to maternal diabetes mellitus.

STUDY DESIGN

To determine whether miR-322 reduction is necessary for neural tube defect formation in pregnancies complicated by diabetes mellitus, male mice carrying a transgene expressing miR-322 were mated with nondiabetic or diabetic wide-type female mice to generate embryos with or without miR-322 overexpression. At embryonic day 8.5 when the neural tube is not yet closed, embryos were harvested for the assessment of 3 miR-322 transcripts (primary, precursor, and mature miR-322), tumor necrosis factor receptor-associated factor 3 (TRAF3), and neuroepithelium cell survival. Neural tube defect incidences were determined in embryonic day 10.5 embryos when the neural tube should be closed if there is no neural tube defect formation. To identify which miR-322 transcript is affected by maternal diabetes mellitus and high glucose conditions, 3 miR-322 transcripts were assessed in embryos from dams with or without diabetes mellitus and in C17.2 mouse neural stem cells treated with different concentrations of glucose and at different time points. To determine whether the endonuclease IRE1α targets miR-322, small interfering RNA knockdown of IRE1α or overexpression of inositol-requiring transmembrane kinase/endoribonuclease 1α by DNA plasmid transfection was used to determine the effect of IRE1α deficiency or overexpression on miR-322 expression. RNA immunoprecipitation was performed to reveal the direct targets of inositol-requiring transmembrane kinase/endoribonuclease 1α.

RESULTS

Maternal diabetes mellitus suppressed miR-322 expression in the developing neuroepithelium. Restoring miR-322 expression in the neuroepithelium blocked maternal diabetes mellitus-induced caspase-3 and caspase-8 cleavage and cell apoptosis, leading to a neural tube defect reduction. Reversal of maternal diabetes mellitus-inhibited miR-322 via transgenic overexpression prevented TRAF3 up-regulation in embryos exposed to maternal diabetes mellitus. Activated IRE1α acted as an endonuclease and degraded precursor miR-322, resulting in mature miR-322 reduction.

CONCLUSION

This study supports the crucial role of the IRE1α-microRNA-TRAF3 circuit in the induction of neuroepithelial cell apoptosis and neural tube defect formation in pregnancies complicated by diabetes mellitus and identifies IRE1α and miR-322 as potential targets for preventing maternal diabetes mellitus-induced neural tube defects.

Determinants of neural tube defects among women who gave birth in hospitals in Eastern Ethiopia: evidence from a matched case control study

INTRODUCTION

Neural tube defects (NTDs) are severe birth defects caused by nutritional, genetic or environmental factors. Because NTDs continue to have a significant health and economic impact on children and community at large, it is crucial to investigate potential risk factors in order to develop novel approaches to NTDs prevention. Determinants for the development of NTDs differ by country, region as well as within the country. The objective of this study was to identify the determinants of NTDs among newborns delivered in three hospitals found in eastern Ethiopia.

METHODS

A hospital-based matched case-control study was conducted among 138 cases and 138 control women who delivered in three teaching hospitals in Eastern Ethiopia in 2021. Data were collected using a structured and pre-tested interviewer-administered questionnaire. Cases were mothers who delivered a neonate with any type of NTDs regardless of gestational age or fetal viability, whereas controls were mothers who delivered an apparently healthy newborn. Chi-square was used to assess the significant difference between the two groups. Conditional logistic regression model was used to generate adjusted odds ratio with its corresponding 95% confidence intervals and compare the two groups.

RESULTS

Anencephaly (51.4%) and spinal bifida (34.1%) were the most frequently observed NTDs. None of study participants took preconception folic acid supplementation. Being a non-formal mothers (AOR = 0.34, 95% CI: 0.12-0.92, P = 0.034), rural residence, (AOR = 3.4, 95% CI: 1.18-9.78, P = 0.023), history of spontaneous abortion (AOR = 2.95, 95% CI: 1.15-7.55, P = 0.023), having severe anemia (AOR = 3.4, 95% CI: 1.17-9.87, P = 0.024), history of fever or cold (AOR = 2.75; 95% CI: 1.05-7.15, P = 0.038), and an exposure to various agro-chemicals (AOR = 3.39, 95% CI: 1.11-10.3, P = 0.032) were independent determinants of NTDs.

CONCLUSION AND RECOMMENDATION

In this study, NTDs were associated to several determinant factors in the area, including residential area, history of spontaneous abortion, severe anemia, fever/cold, antibiotic use before or during early pregnancy, and exposure to agrochemicals. Addressing the identified determinants is critical in averting the incidence of NTDs in the study area. Moreover, more research is needed to investigate women's dietary practices as well as the practice of preconception folic acid supplementation for pregnant women in Ethiopia's current health care system.

Spatial transcriptome profiling uncovers metabolic regulation of left-right patterning

Left-right patterning disturbance can cause severe birth defects, but it remains least understood of the three body axes. We uncovered an unexpected role for metabolic regulation in left-right patterning. Analysis of the first spatial transcriptome profile of left-right patterning revealed global activation of glycolysis, accompanied by right-sided expression of Bmp7 and genes regulating insulin growth factor signaling. Cardiomyocyte differentiation was left-biased, which may underlie the specification of heart looping orientation. This is consistent with known Bmp7 stimulation of glycolysis and glycolysis suppression of cardiomyocyte differentiation. Liver/lung laterality may be specified via similar metabolic regulation of endoderm differentiation. Myo1d , found to be left-sided, was shown to regulate gut looping in mice, zebrafish, and human. Together these findings indicate metabolic regulation of left-right patterning. This could underlie high incidence of heterotaxy-related birth defects in maternal diabetes, and the association of PFKP, allosteric enzyme regulating glycolysis, with heterotaxy. This transcriptome dataset will be invaluable for interrogating birth defects involving laterality disturbance.

Production of human spinal-cord organoids recapitulating neural-tube morphogenesis

Human spinal-cord-like tissues induced from human pluripotent stem cells are typically insufficiently mature and do not mimic the morphological features of neurulation. Here, we report a three-dimensional culture system and protocol for the production of human spinal-cord-like organoids (hSCOs) recapitulating the neurulation-like tube-forming morphogenesis of the early spinal cord. The hSCOs exhibited neurulation-like tube-forming morphogenesis, cellular differentiation into the major types of spinal-cord neurons as well as glial cells, and mature synaptic functional activities, among other features of the development of the spinal cord. We used the hSCOs to screen for antiepileptic drugs that can cause neural-tube defects. hSCOs may also facilitate the study of the development of the human spinal cord and the modelling of diseases associated with neural-tube defects.

Time Course Transcriptome Analysis of Spina Bifida Progression in Fetal Rats

A better understanding of the transcriptomic modifications that occur in spina bifida may lead to identify mechanisms involved in the progression of spina bifida in utero and the development of new therapeutic strategies that aid in spinal cord regeneration after surgical interventions. In this study, RNA-sequencing was used to identify differentially expressed genes in fetal spinal cords from rats with retinoic acid-induced spina bifida at E15, E17, and E20. Gene ontology, KEGG, and protein–protein interaction analysis were conducted to predict pathways involved in the evolution of the disease. Approximately 3000, 1000 and 300 genes were differentially expressed compared to the control groups at E15, E17 and E20, respectively. Overall, the results suggest common alterations in certain pathways between gestational time points, such as upregulation in p53 and sonic hedgehog signaling at E15 and E17 and downregulation in the myelin sheath at E17 and E20. However, there were other modifications specific to gestational time points, including skeletal muscle development at E15, downregulated glucose metabolism at E17, and upregulated inflammation at E20. In conclusion, this work provides evidence that gestational age during spina bifida repair may be a significant variable to consider during the development of new regenerative therapeutics approaches.

Severe types of fetopathy are associated with changes in the serological proteome of diabetic mothers

ABSTRACT

Pregestational or gestational diabetes are the main risk factors for diabetic fetopathy. There are no generalized signs of fetopathy before the late gestational age due to insufficient sensitivity of currently employed instrumental methods. In this cross-sectional observational study, we investigated several types of severe diabetic fetopathy (cardiomyopathy, central nervous system defects, and hepatomegaly) established in type 2 diabetic mothers during 30 to 35 gestational weeks and confirmed upon delivery. We examined peripheral blood plasma and determined a small proportion of proteins strongly associated with a specific type of fetopathy or anatomical malfunction. Most of the examined markers participate in critical processes at different stages of embryogenesis and regulate various phases of morphogenesis. Alterations in CDCL5 had a significant impact on mRNA splicing and DNA repair. Patients with central nervous system defects were characterized by the greatest depletion (ca. 7% of the basal level) of DFP3, a neurotrophic factor needed for the proper specialization of oligodendrocytes. Dysregulation of noncanonical wingless-related integration site signaling pathway (Wnt) signaling guided by pigment epithelium-derived factor (PEDF) and disheveled-associated activator of morphogenesis 2 (DAAM2) was also profound. In addition, deficiency in retinoic acid and thyroxine transport was exhibited by the dramatic increase of transthyretin (TTHY). The molecular interplay between the identified serological markers leads to pathologies in fetal development on the background of a diabetic condition. These warning serological markers can be quantitatively examined, and their profile may reflect different severe types of diabetic fetopathy, producing a beneficial effect on the current standard care for pregnant women and infants.

Effect of Corn Silk Aqueous Extract on Brown Adipose Tissue of Embryos and Neonates of Diabetic Pregnant Mice: A Histological Study

Context

Many congenital malformations are seen increasingly, due to diabetic mothers causing a burden on health systems. Corn silk (CS) extract has been used as a natural hypoglycemic treatment. However, its teratogenic safety was not studied.

Aims

Therefore, in this study, we examine the effect of CS aqueous extract on fetuses, offspring of normal and diabetic female mice treated with CS aqueous extract.

Settings and Design

Pregnant female mice were divided into two groups diabetic and nondiabetic. Then, each of these groups was divided into control and treated.

Subjects and Methods

A daily dose of 4 g/kg of CS aqueous extract was given orally to the treated groups, control groups were given distilled water. The collection of samples was at day 16.5 of pregnancy, and neonates. Brown adipose tissue (BAT) in the sections of the preserved sample was examined.

Statistical Analysis Used

BAT areas were measured from 10 samples of each treatment age group in 2 sections. Data were analyzed with one-way ANOVA, then, two-independent sample test (Mann-Whitney) was done to test the significance of differences between groups.

Results

The BAT areas were negatively affected by diabetes and the extract. Both the extract and diabetes caused an increase in fat accumulation in the adipocytes with varying degrees.

Conclusions

This study showed for the first time to our knowledge that the use of CS aqueous extract during pregnancy affected BAT organization and area, and that the used dose did not decrease the malformations caused by diabetes. More studies with different doses should be investigated.

Maternal influences on fetal brain development: The role of nutrition, infection and stress, and the potential for intergenerational consequences

An optimal early life environment is crucial for ensuring ideal neurodevelopmental outcomes. Brain development consists of a finely tuned series of spatially and temporally constrained events, which may be affected by exposure to a sub-optimal intra-uterine environment. Evidence suggests brain development may be particularly vulnerable to factors such as maternal nutrition, infection and stress during pregnancy. In this review, we discuss how maternal factors such as these can affect brain development and outcome in offspring, and we also identify evidence which suggests that the outcome can, in many cases, be stratified by socio-economic status (SES), with individuals in lower brackets typically having a worse outcome. We consider the relevant epidemiological evidence and draw parallels to mechanisms suggested by preclinical work where appropriate. We also discuss possible transgenerational effects of these maternal factors and the potential mechanisms involved. We conclude that modifiable factors such as maternal nutrition, infection and stress are important contributors to atypical brain development and that SES also likely has a key role.

Ceramide: a novel inducer for neural tube defects

BACKGROUND

Circulating plasma ceramides, a class of bioactive sphingolipids, are elevated in metabolic disorders, including obesity. Infants of women with these disorders are at 2- to 3-fold greater risk for developing a neural tube defect (NTD). This study aimed to test the effects of embryonic exposure to C2-ceramides (C2) during neural tube closure. Preliminary data shows an increase in NTDs in chick embryos after C2 exposure, and addresses potential mechanisms.

RESULTS

Cell and embryo models were used to examine redox shifts after ceramide exposure. While undifferentiated P19 cells were resistant to ceramide exposure, neuronally differentiated P19 cells exhibited an oxidizing shift. Consistent with these observations, GSH E _h curves revealed a shift to a more oxidized state in C2 treated embryos without increasing apoptosis or changing Pax3 expression, however cell proliferation was lower. Neural tube defects were observed in 45% of chick embryos exposed to C2, compared to 12% in control embryos.

CONCLUSIONS

C2 exposure during critical developmental stages increased the frequency of NTDs in the avian model. Increased ROS generation in cell culture, along with the more oxidative GSH E _h profiles of C2 exposed cells and embryos, support a model wherein ceramide affects neural tube closure via altered tissue redox environments.

M2-like cells from the macrophage lineage might play a central role in closure of the embryonic neural tube

Herein it is hypothesized that M2-like macrophages or pre-macrophages of fetal origin might play a central role in development and closure of the neural tube. Early in embryonic development, pre-macrophages arise from the fetal yolk sac and track through the bloodstream to reach diverse embryonic tissues, where they mature. Most of these macrophages exhibit an M2-like phenotype. The critical period for neural tube closure is contained within the period of yolk sac-derived pre-macrophage tracking and distribution, which poses a question: might these pre-macrophages or macrophages exert an influence on the closing neural tube? Evidence suggests that perturbations in macrophage polarization or M2 macrophage function might contribute to the failure of neural tube closure associated with diabetes mellitus, one carbon metabolism (including folic acid deficit), inositol, arachidonic acid, and sphingosine-1-phosphate, as well as in the teratogenicity of nitric acid, valproic acid, and fumonisin. The influence of each of these factors is interpreted in light of potential interactions with M2-like macrophages or macrophage progenitors on the developing neural tube. By placing these anti inflammatory macrophages at the center of various epigenetic, neurochemical, and signaling processes suspected to be involved in neural tube closure, potential associations are revealed between macrophages and embryonic structural developmental processes such as collagen and actin dynamics. The choice of this model is also an attempt to explain why some etiologies for failure of neural tube closure are rescued by folic acid, whereas other etiologies are rescued only by formate, inositol, or not at all.

Embryonic cell migratory capacity is impaired upon exposure to glucose in vivo and in vitro

BACKGROUND

Impairments in cell migration during vertebrate gastrulation lead to structural birth defects, such as heart defects and neural tube defects. These defects are more frequent in progeny from diabetic pregnancies, and we have recently provided evidence that maternal diabetes leads to impaired migration of embryonic mesodermal cells in a mouse model of diabetic pregnancy.

METHODS

We here report the isolation of primary cell lines from normal and diabetes-exposed embryos of the nonobese diabetic mouse strain, and characterization of their energy metabolism and expression of nutrient transporter genes by quantitative real-time PCR.

RESULTS

Expression levels of several genes in the glucose transporter and fatty acid transporter gene families were altered in diabetes-exposed cells. Notably, primary cells from embryos with prior in vivo exposure to maternal diabetes exhibited reduced capacity for cell migration in vitro.

CONCLUSIONS

Primary cells isolated from diabetes-exposed embryos retained a "memory" of their in vivo exposure, manifesting in cell migration impairment. Thus, we have successfully established an in vitro experimental model for the mesoderm migration defects observed in diabetes-exposed mouse embryos.

Whole exome sequencing identifies novel predisposing genes in neural tube defects

BACKGROUND

Neural tube defects (NTD) are among the most common defects affecting 1:1000 births. They are caused by a failure of neural tube closure during development. Their clinical presentation is diverse and dependent on the site and severity of the original defect on the embryonic axis. The etiology of NTD is multifactorial involving environmental factors and genetic variants that remain largely unknown.

METHODS

We have conducted a whole exome sequencing (WES) study in five new NTD families and pooled the results with WES data from three NTD families and 43 trios that were previously investigated by our group. We analyzed the data using biased candidate gene and unbiased gene burden approaches.

RESULTS

We identified four novel loss-of-function variants in three genes, MTHFR, DLC1, and ITGB1, previously associated with NTD. Notably, DLC1 carried two protein truncating variants in two independent cases. We also demonstrated an enrichment of variants in MYO1E involved in cytoskeletal remodeling. This enrichment reached borderline significance in a replication cohort supporting the association of this new candidate gene to NTD.

CONCLUSION

These data provide some key insights into the pathogenic mechanisms of human NTD and demonstrate the power of next-generation sequencing in deciphering the genetics of this complex trait.

Mitochondrial dysfunction is implicated in retinoic acid-induced spina bifida aperta in rat fetuses

Neural tube defects (NTDs) are the most common and severe congenital malformations, which result from failure of the neural tube to close during embryonic development. The etiology of NTDs is complex, caused by interactions between genetic defects and environmental factors, but the exact mechanisms of this disease are still not fully understood. We herein employ a Seahorse Bioscience microplate-based extracellular flux (XF) analyzer to determine mitochondrial function and quantify respiratory coupling to various bioenergetic functions using specific pharmacological inhibitors of bioenergetic pathways. We demonstrate that changes in coupling between ATP turnover and proton leak are correlated with NTDs. Further, we determined that the ATP content and oxidative stress levels in posterior spinal cords of rat embryos with NTDs between E11 and E14 was lower than that of normal controls. The present study reveals that mitochondrial dysfunction is associated with all-trans retinoic acid (atRA)-induced NTDs in rat embryos. Oxidative stress results from decreased antioxidant enzyme activity. This study provides a novel viewpoint for exploring the embryonic pathogenesis of atRA-induced NTDs.

Advanced glycation end products induce neural tube defects through elevating oxidative stress in mice

Our previous study showed an association between advanced glycation end products (AGEs) and neural tube defects (NTDs). To understand the molecular mechanisms underlying the effect of AGEs on neural tube development, C57BL/6 female mice were fed for 4 weeks with commercial food containing 3% advanced glycation end product bovine serum albumin (AGE-BSA) or 3% bovine serum albumin (BSA) as a control. After mating mice, oxidative stress markers including malondialdehyde and H₂O₂ were measured at embryonic day 7.5 (E7.5) of gestation, and the level of intracellular reactive oxygen species (ROS) in embryonic cells was determined at E8.5. In addition to evaluating NTDs, an enzyme-linked immunosorbent assay was used to determine the effect of embryonic protein administration on the N-(carboxymethyl) lysine reactivity of acid and carboxyethyl lysine antibodies at E10.5. The results showed a remarkable increase in the incidence of NTDs at E10.5 in embryos of mice fed with AGE-BSA (no hyperglycemia) compared with control mice. Moreover, embryonic protein administration resulted in a noticeable increase in the reactivity of N-(carboxymethyl) lysine and N(ε)-(carboxyethyl) lysine antibodies. Malondialdehyde and H₂O₂ levels in embryonic cells were increased at E7.5, followed by increased intracellular ROS levels at E8.5. Vitamin E supplementation could partially recover these phenomena. Collectively, these results suggest that AGE-BSA could induce NTDs in the absence of hyperglycemia by an underlying mechanism that is at least partially associated with its capacity to increase embryonic oxidative stress levels.

Oxidative stress-induced miR-27a targets the redox gene nuclear factor erythroid 2-related factor 2 in diabetic embryopathy

BACKGROUND

Maternal diabetes induces neural tube defects, and oxidative stress is a causal factor for maternal diabetes-induced neural tube defects. The redox gene nuclear factor erythroid 2-related factor 2 is the master regulator of the cellular antioxidant system.

OBJECTIVE

In this study, we aimed to determine whether maternal diabetes inhibits nuclear factor erythroid 2-related factor 2 expression and nuclear factor erythroid 2-related factor 2-controlled antioxidant genes through the redox-sensitive miR-27a.

STUDY DESIGN

We used a well-established type 1 diabetic embryopathy mouse model induced by streptozotocin for our in vivo studies. Embryos at embryonic day 8.5 were harvested for analysis of nuclear factor erythroid 2-related factor 2, nuclear factor erythroid 2-related factor 2-controlled antioxidant genes, and miR-27a expression. To determine if mitigating oxidative stress inhibits the increase of miR-27a and the decrease of nuclear factor erythroid 2-related factor 2 expression, we induced diabetic embryopathy in superoxide dismutase 2 (mitochondrial-associated antioxidant gene)-overexpressing mice. This model exhibits reduced mitochondria reactive oxygen species even in the presence of hyperglycemia. To investigate the causal relationship between miR-27a and nuclear factor erythroid 2-related factor 2 in vitro, we examined C17.2 neural stem cells under normal and high-glucose conditions.

RESULTS

We observed that the messenger RNA and protein levels of nuclear factor erythroid 2-related factor 2 were significantly decreased in embryos on embryonic day 8.5 from diabetic dams compared to those from nondiabetic dams. High-glucose also significantly decreased nuclear factor erythroid 2-related factor 2 expression in a dose- and time-dependent manner in cultured neural stem cells. Our data revealed that miR-27a was up-regulated in embryos on embryonic day 8.5 exposed to diabetes, and that high glucose increased miR-27a levels in a dose- and time-dependent manner in cultured neural stem cells. In addition, we found that a miR-27a inhibitor abrogated the inhibitory effect of high glucose on nuclear factor erythroid 2-related factor 2 expression, and a miR-27a mimic suppressed nuclear factor erythroid 2-related factor 2 expression in cultured neural stem cells. Furthermore, our data indicated that the nuclear factor erythroid 2-related factor 2-controlled antioxidant enzymes glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit, and glutathione S-transferase A1 were down-regulated by maternal diabetes in embryos on embryonic day 8.5 and high glucose in cultured neural stem cells. Inhibiting miR-27a restored expression of glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit, and glutathione S-transferase A1. Overexpressing superoxide dismutase 2 reversed the maternal diabetes-induced increase of miR-27a and suppression of nuclear factor erythroid 2-related factor 2 and nuclear factor erythroid 2-related factor 2-controlled antioxidant enzymes.

CONCLUSION

Our study demonstrates that maternal diabetes-induced oxidative stress increases miR-27a, which, in turn, suppresses nuclear factor erythroid 2-related factor 2 and its responsive antioxidant enzymes, resulting in diabetic embryopathy.

Apoptosis, Expression of PAX3 and P53, and Caspase Signal in Fetuses with Neural Tube Defects

BACKGROUND

Neural tube defects (NTDs) are among the most common and severe congenital malformations of the central nervous system. Animal studies have shown that apoptosis is involved in the development of NTDs. However, little evidence is available from human studies. We aim to examine the level of apoptosis and expression of apoptosis-regulating proteins of human terminated fetuses.

METHODS

A total of 37 NTD cases and 21 controls from pregnancy terminations were recruited. Tissues of the central nervous system were obtained through autopsy. Apoptosis of neuroepithelial cells was examined by terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling (TUNEL) assay. Expression of PAX3, p53, and caspase 3/8/9 in central nervous tissue was measured using Western blotting.

RESULTS

More TUNEL-positive apoptosis cells were observed in the central nervous tissue of NTD cases than those of controls (p < 0.05). In spinal cord tissue, lower PAX3 expression, higher p53 expression, and increased levels of cleaved caspase 3(17kD) and cleaved caspase 8 (18kD) were found in anencephaly cases but not in spina bifida cases when compared with controls. In brain tissue, levels of PAX3 were significantly reduced in both encephalocele and spina bifida subtypes; the expression levels of cleaved caspase 3(17 kD) of encephalocele cases and cleaved caspase 8(47/45 kD) in spina bifida cases were higher than in controls; no difference was found in the expression of p53 or caspase 9 between NTDs and controls.

CONCLUSION

These findings provide some evidence that excessive apoptosis in fetal central nervous tissues may be associated with the development of human NTDs. Birth Defects Research 109:1596-1604, 2017. © 2017 Wiley Periodicals, Inc.

Lower Plasma Ghrelin Levels are Found in Women with Diabetes-Complicated Pregnancies

OBJECTIVE

To evaluate the associations of glycemic control and gestational age with ghrelin and proinsulin levels in cord blood and mothers' peripheral blood during pregnancy.

METHODS

This is a cross-sectional comparative study of twenty-four pregnant women with gestational diabetes (GD), 18 with type 2 diabetes mellitus (T2DM), and 36 without diabetes, as well as their neonates. Levels of proinsulin, ghrelin, and glycated hemoglobin A1c (HbA1c) were measured from maternal blood during the last week before caesarian delivery and in neonatal umbilical cord blood samples.

RESULTS

Mothers with GD and T2DM had significantly lower ghrelin levels compared to the healthy mothers (p<0.001). Maternal proinsulin was lower in women with GD than in women without diabetes (p<0.001). Proinsulin was significantly elevated in the neonates of women with GD and in women with HbA1c ≥6.5% (p<0.001). However, maternal ghrelin levels were higher (p=0.031) and neonate proinsulin levels lower in the pre-term offspring of mothers with GD (p=0.033). There was a negative correlation between HbA1c levels and birth weight (r=-0.407, p<0.001).

CONCLUSION

Ghrelin levels were lower in pregnant women with diabetes, although pre-term birth appeared to reverse this trend in GD. Proinsulin levels were also low in pregnant women with diabetes and even lower in pre-term vs. at-term births. Both ghrelin and proinsulin levels were lower in pregnant women with diabetes and HbA1c of <6.5%. Thus, ghrelin participates in the adaptation to the caloric imbalance of diabetic pregnancy and may play a similar role in pregnancy-related complications, since high ghrelin concentrations may be necessary for normal fetal development.

Effect of maternal diabetes on gliogensis in neonatal rat hippocampus

Background:

Diabetes in pregnancy is a common metabolic disorder associated with various adverse outcomes in the offspring including impairments in attention and memory and alterations in social behavior. Glial cells are proven to have a critical role in normal function of neurons, and alteration in their activity could contribute to disturbance in the brain function. The aim of this study was to investigate the effect of maternal diabetes on hippocampal mRNA expression and distribution pattern of glial fibrillary acidic protein (GFAP) immunoreactive glial cells in the dentate gyrus (DG) of rat neonate at postnatal day 14 (P14).

Materials and Methods:

Wistar female rats were randomly allocated in control, diabetic, and insulin-treated diabetic groups. Diabetes was induced by injection of streptozotocin from 4 weeks before gestation until parturition. After delivery, the male offspring was euthanized at P14.

Results:

Our results showed a significant higher level of hippocampal GFAP expression and an increase in the mean number of GFAP positive cells in the DG of diabetic group offspring (P < 0.05). We also found an insignificant up-regulation in the expression of GFAP and the mean number of positive cells in the insulin-treated diabetic group neonates as compared to control group (P > 0.05).

Conclusion:

The present study revealed that diabetes during pregnancy strongly increased the glial cells production in the developing rat hippocampus.

Effect of Hyperglycemia on Gene Expression during Early Organogenesis in Mice

Background

Cardiovascular and neural malformations are common sequels of diabetic pregnancies, but the underlying molecular mechanisms remain unknown. We hypothesized that maternal hyperglycemia would affect the embryos most shortly after the glucose-sensitive time window at embryonic day (ED) 7.5 in mice.

Methods

Mice were made diabetic with streptozotocin, treated with slow-release insulin implants and mated. Pregnancy aggravated hyperglycemia. Gene expression profiles were determined in ED8.5 and ED9.5 embryos from diabetic and control mice using Serial Analysis of Gene Expression and deep sequencing.

Results

Maternal hyperglycemia induced differential regulation of 1,024 and 2,148 unique functional genes on ED8.5 and ED9.5, respectively, mostly in downward direction. Pathway analysis showed that ED8.5 embryos suffered mainly from impaired cell proliferation, and ED9.5 embryos from impaired cytoskeletal remodeling and oxidative phosphorylation (all P ≤ E-5). A query of the Mouse Genome Database showed that 20–25% of the differentially expressed genes were caused by cardiovascular and/or neural malformations, if deficient. Despite high glucose levels in embryos with maternal hyperglycemia and a ~150-fold higher rate of ATP production from glycolysis than from oxidative phosphorylation on ED9.5, ATP production from both glycolysis and oxidative phosphorylation was reduced to ~70% of controls, implying a shortage of energy production in hyperglycemic embryos.

Conclusion

Maternal hyperglycemia suppressed cell proliferation during gastrulation and cytoskeletal remodeling during early organogenesis. 20–25% of the genes that were differentially regulated by hyperglycemia were associated with relevant congenital malformations. Unexpectedly, maternal hyperglycemia also endangered the energy supply of the embryo by suppressing its glycolytic capacity.

Elevated body mass index and decreased diet quality among women and risk of birth defects in their offspring

BACKGROUND

We examined whether risks of 32 birth defects were higher than expected in the presence of overweight or obese body mass index (BMI) and low diet quality, based on estimating individual and joint effects of these factors and calculating relative excess risk due to interaction.

METHODS

Analyses included mothers of 20,250 cases with birth defects and 8617 population-based controls without birth defects born from 1997 to 2009 and interviewed for the National Birth Defects Prevention Study. We used logistic regression to generate adjusted odds ratios (AORs) reflecting the combined effects of BMI and diet quality. We focused analyses on 16 birth defects (n = 11,868 cases, 8617 controls) for which initial results suggested an association with BMI or diet quality.

RESULTS

Relative to the reference group (normal weight women with not low diet quality, i.e., >lowest quartile), AORs for low diet quality among normal weight women tended to be >1, and AORs for overweight and obese women tended to be stronger among women who had low diet quality than not low diet quality. For 9/16 birth defects, AORs for obese women who had low diet quality-the group we hypothesized to have highest risk-were higher than other stratum-specific AORs. Most relative excess risk due to interactions were positive but small (<0.5), with confidence intervals that included zero.

CONCLUSION

These findings provide evidence for the hypothesis of highest birth defect risks among offspring to women who are obese and have low diet quality but insufficient evidence for an interaction of these factors in their contribution to risk.

Diabetes in Pregnancy Adversely Affects the Expression of Glycogen Synthase Kinase-3β in the Hippocampus of Rat Neonates

Diabetes during pregnancy causes a wide range of neurodevelopmental and neurocognitive abnormalities in offspring. Glycogen synthase kinase-3 (GSK-3) is widely expressed during brain development and regulates multiple cellular processes, and its dysregulation is implicated in the pathogenesis of diverse neurodegenerative and psychological diseases. This study was designed to examine the effects of maternal diabetes on GSK-3β messenger RNA (mRNA) expression and phosphorylation in the developing rat hippocampus. Female rats were maintained diabetic from a week before pregnancy through parturition, and male offspring was killed immediately after birth. We found a significant bilateral upregulation of GSK-3β mRNA expression in the hippocampus of pups born to diabetic mothers at P0, compared to controls. Moreover, at the same time point, there was a marked bilateral increase in the phosphorylation level of GSK-3β in the diabetic group. Unlike phosphorylation levels, there was a significant upregulation in hippocampal GSK-3β mRNA expression in the insulin-treated group, when compared to controls. The present study revealed that diabetes during pregnancy strongly influences the regulation of GSK-3β in the right/left developing hippocampi. These dysregulations may be part of the cascade of events through which diabetes during pregnancy affects the newborn's hippocampal structure and function.

Markers of macromolecular oxidative damage in maternal serum and risk of neural tube defects in offspring

Neural tube defects (NTDs) are among the most common and severe congenital malformations. To examine the association between markers of macromolecular oxidative damage and risk of NTDs, we measured levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), protein carbonyl (PC), and 8-iso-prostaglandin F2α (8-iso-PGF2α) in maternal serum samples of 117 women with NTD-affected pregnancies and 121 women with healthy term newborns. We found higher levels of 8-OHdG and PC in the NTD group than in the control group; however, we did not observe a statistically significant difference in 8-iso-PGF2α levels between the NTD and the control groups. NTD risk increased with increasing quartiles of 8-OHdG [odds ratio (OR)=1.17; 95% confidence interval (CI) 0.39-3.51; OR=2.19; 95% CI, 0.68-7.01; OR=3.70; 95% CI, 1.30-10.51, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.009], and with increasing quartiles of PC (OR=2.26; 95% CI, 0.66-7.69; OR=3.86; 95% CI, 1.17-12.80; OR=5.98; 95% CI, 1.82-19.66, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.002]. Serum levels of 8-OHdG were higher in women who did not take folic acid supplements during the periconceptional period. These results suggest that oxidative stress is present in women carrying pregnancies affected by NTDs.

Maternal serum AGEs levels in pregnancies associated with neural tube defects

Advanced glycation end products (AGEs) plays an important role in diabetic embryopathy. AGE-mediated DNA damage could be a significant factor in the teratogenicity. The aim of the present study was to evaluate the association between the AGEs level and neural tube defects (NTDs) occurrence risk. Forty-eight mothers with NTD-affected pregnancies and 50 normal mothers were selected in this study. Blood were collected from the mothers and were assayed for serum AGEs, malondiadehyde (MDA) and hemoglobin A1c (HbA1c). Data were analyzed by logistic regression method. The study indicated that there were significant but modest lower prevalence for cases mothers on age, BMI and glucose levels compared with controls. NTD-affected mothers were significantly more likely to have higher AGEs levels (5.6±0.48 AU vs. 4.6±0.68 AU ρ<0.01) than controls. The AGEs levels were not correlated with MDA and HbA1c in NTDs mothers (r(2)=0.0006 p=0.8691 and r(2)=0.001 p=0.8172, respectively). The conclusion is that AGEs might be associated with NTDs occurrence.

Genetic evidence in planar cell polarity signaling pathway in human neural tube defects

Neural tube defects (NTDs) are a group of birth anomalies having a profound physical, emotional, and financial effects on families and communities. Their etiology is complex, involving environmental and genetic factors that interact to modulate the incidence and severity of the developing phenotype. The planar cell polarity (PCP) pathway controls the process of convergent extension (CE) during gastrulation and neural tube closure and has been implicated in the pathogenesis of NTDs in animal models and human cohorts. This review summarizes the cumulative results of recent studies on PCP signaling pathway and human NTDs. These results demonstrate that PCP gene alterations contribute to the etiology of human NTDs.

The effects of induced type-I diabetes on developmental regulation of insulin & insulin like growth factor-1 (IGF-1) receptors in the cerebellum of rat neonates

Diabetes during pregnancy impairs brain development in offspring, leading to behavioral problems, motor dysfunction and learning deficits. Insulin and insulin-like growth factor-1 (IGF-1) are important regulators of developmental and cognitive functions in the central nervous system. Aim of the present study was to examine the effects of maternal diabetes on insulin receptor (InsR) and IGF-1 receptor (IGF-1R) expression in the developing rat cerebellum. Wistar female rats were maintained diabetic from a week before pregnancy through parturition and male offspring was killed at P0, P7, and P14, an active neurogenesis period in brain development equivalent to the third trimester in human. The expression of InsR and IGF-1R in cerebelli was evaluated using real-time PCR and western blot analysis. We found a significant upregulation of both IGF-1R and InsR transcripts in cerebellum of pups born to diabetic mothers at P0, compared to controls. However, at the same time point, the results of western blot analysis revealed only a slight change in their protein levels. In contrast to InsR, which does not show any difference, there was a markedly reduction in cerebellar expression of IGF-1R mRNA and protein level in the diabetic group of newborns at P7. Moreover, 2 weeks after birth, mRNA expression and protein levels of both InsR and IGF-1R in cerebellum of the diabetic group was significantly downregulated. Compared to controls, we did not find any difference in cerebellar InsR or IGF-1R mRNA and protein levels in the insulin treated group. The present study revealed that diabetes during pregnancy strongly influences the regulation of both InsR and IGF-1R in the developing cerebellum. Furthermore, optimal maternal glycaemia control by insulin administration normalized these effects.

The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida

OBJECTIVE

The purpose of this study was to investigate the relationship between spina bifida and 2 established risk factors (pregestational diabetes mellitus and obesity) in both the presence and absence of the recommended daily folic acid intake in the periconceptional period.

STUDY DESIGN

Cases of spina bifida (n = 1154) and control subjects (n = 9439) from the Slone Epidemiology Center Birth Defects Study (1976-2011) were included. Information on preexisting diabetes mellitus (collected 1976-2011) and obesity (collected 1993-2011), defined as a body mass index of ≥30 kg/m(2), was collected through interviews that were conducted within 6 months of delivery. Periconceptional folic acid intake was calculated with both dietary and supplement information. Mothers were classified as consuming more or less than 400 μg/day of folic acid; food folate was included at a 30% discount for its lower bioavailability. Logistic regression models that were adjusted for maternal age, race, education, and study site were used to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for the joint effects of low folic acid intake coupled with diabetes mellitus or obesity.

RESULTS

Case mothers were more likely to have diabetes mellitus or be obese (0.7% and 19.0%, respectively) than control mothers (0.4% and 10.8%, respectively). The joint effect of diabetes mellitus and lower folic acid intake on spina bifida was larger (aOR, 3.95; 95% CI, 1.56-10.00) than that of diabetes mellitus and higher folic acid intake (aOR, 1.31; 95% CI, 0.17-10.30). Folic acid intake made little difference on the association between obesity and spina bifida.

CONCLUSION

Our findings suggest that folic acid further attenuates, although does not eliminate, the risk of spina bifida that is associated with diabetes mellitus than the risk with obesity.

Analysis of epigenetic factors in mouse embryonic neural stem cells exposed to hyperglycemia

BACKGROUND

Maternal diabetes alters gene expression leading to neural tube defects (NTDs) in the developing brain. The mechanistic pathways that deregulate the gene expression remain unknown. It is hypothesized that exposure of neural stem cells (NSCs) to high glucose/hyperglycemia results in activation of epigenetic mechanisms which alter gene expression and cell fate during brain development.

METHODS AND FINDINGS

NSCs were isolated from normal pregnancy and streptozotocin induced-diabetic pregnancy and cultured in physiological glucose. In order to examine hyperglycemia induced epigenetic changes in NSCs, chromatin reorganization, global histone status at lysine 9 residue of histone H3 (acetylation and trimethylation) and global DNA methylation were examined and found to be altered by hyperglycemia. In NSCs, hyperglycemia increased the expression of Dcx (Doublecortin) and Pafah1b1 (Platelet activating factor acetyl hydrolase, isoform 1b, subunit 1) proteins concomitant with decreased expression of four microRNAs (mmu-miR-200a, mmu-miR-200b, mmu-miR-466a-3p and mmu-miR-466 d-3p) predicted to target these genes. Knockdown of specific microRNAs in NSCs resulted in increased expression of Dcx and Pafah1b1 proteins confirming target prediction and altered NSC fate by increasing the expression of neuronal and glial lineage markers.

CONCLUSION/INTERPRETATION

This study revealed that hyperglycemia alters the epigenetic mechanisms in NSCs, resulting in altered expression of some development control genes which may form the basis for the NTDs. Since epigenetic changes are reversible, they may be valuable therapeutic targets in order to improve fetal outcomes in diabetic pregnancy.

New concepts in diabetic embryopathy

Diabetes mellitus is responsible for nearly 10% of fetal anomalies in diabetic pregnancies. Although aggressive perinatal care and glycemic control are available in developed countries, the birth defect rate in diabetic pregnancies remains higher than that in the general population. Major cellular activities (ie, proliferation and apoptosis) and intracellular metabolic conditions (ie, nitrosative, oxidative, and endoplasmic reticulum stress) have been shown to be associated with diabetic embryopathy using animal models. Translating advances made in animal studies into clinical applications in humans requires collaborative efforts across the basic research, preclinical, and clinical communities.

Magnetic resonance imaging in the prenatal diagnosis of neural tube defects

OBJECTIVE

To assess the role of magnetic resonance imaging (MRI) in the prenatal diagnosis of neural tube defects (NTDs).

BACKGROUND

NTDs comprise a heterogeneous group of congenital anomalies that derive from the failure of the neural tube to close. Advances in ultrasonography and MRI have considerably improved the diagnosis and treatment of NTDs both before and after birth. Ultrasonography is the first technique in the morphological study of the fetus, and it often makes it possible to detect or suspect NTDs. Fetal MRI is a complementary technique that makes it possible to clear up uncertain ultrasonographic findings and to detect associated anomalies that might go undetected at ultrasonography. The progressive incorporation of intrauterine treatments makes an accurate diagnosis of NTDs essential to ensure optimal perinatal management. The ability of fetal MRI to detect complex anomalies that affect different organs has been widely reported, and it can be undertaken whenever NTDs are suspected.

CONCLUSION

We describe the normal appearance of fetal neural tube on MRI, and we discuss the most common anomalies involving the structures and the role of fetal MRI in their assessment.

KEY POINTS

• To learn about the normal anatomy of the neural tube on MRI • To recognise the MR appearance of neural tube defects • To understand the value of MRI in assessing NTDs.

Neural tube defects and their significance in clinical dentistry: a mini review

Neural tube defects are common congenital malformations that could be apparent at birth or manifested in later stages of life. Morbidity is high in anencephaly, whereas in spina bifida, there are neurological and motor disorders. These defects deserve paramount importance in clinical dentistry. Latex allergy, dental caries, difficulty in mouth opening, and sitting in a dental chair are common problems. There is a high risk of anaphylactic response during anaesthesia. There could be associated craniosynostosis causing maxillary deficiency, and malformed sella turcica might be seen. An association of the defects has been linked with orofacial clefts and Down syndrome.

The effects of maternal diabetes on expression of insulin-like growth factor-1 and insulin receptors in male developing rat hippocampus

Diabetes during pregnancy causes neurodevelopmental and neurocognitive abnormalities in offspring. Insulin and insulin-like growth factor-1 (IGF-1) are important regulators of developmental and cognitive functions in the central nervous system. We examined the effects of maternal diabetes on insulin-like growth factor-1 receptor (IGF-1R) and insulin receptor (InsR) expression in the developing rat hippocampus. Female rats were maintained diabetic from a week before pregnancy through parturition and male offspring was killed at P0, P7, and P14. We found a significant bilateral upregulation of both IGF-1R and InsR transcripts in the hippocampus of pups born to diabetic mothers at P0, as compared to controls. However, at the same time point, the results of western blot analysis revealed only a slight change in their protein levels. At P7, there was a marked bilateral reduction in mRNA expression and protein levels of IGF-1R, although not of InsR in the diabetic group. We also found a downregulation in IGF1-R transcripts, especially in left hippocampus of the diabetic group at P14. Moreover, at the same time point, InsR expression was significantly decreased in both hippocampi of diabetic newborns. When compared with controls, we did not find any difference in hippocampal IGF-1R or InsR mRNA and protein levels in the insulin-treated group. The present study revealed that diabetes during pregnancy strongly influences the regulation of both IGF-1R and InsR in the right/left developing hippocampi. Furthermore, the rigid control of maternal glycaemia by insulin administration normalized these effects.

Reduced risks of neural tube defects and orofacial clefts with higher diet quality

OBJECTIVE

To examine whether better maternal diet quality was associated with reduced risk for selected birth defects.

DESIGN

A multicenter, population-based case-control study, the National Birth Defects Prevention Study.

SETTING

Ten participating centers in the United States.

PARTICIPANTS

Eligible subjects' estimated due dates were from October 1997 through December 2005. Telephone interviews were conducted with 72% of case and 67% of control mothers. Analyses included 936 cases with neural tube defects (NTDs), 2475 with orofacial clefts, and 6147 nonmalformed controls.

MAIN EXPOSURES

Food-frequency data were used to calculate the Mediterranean Diet Score (MDS) and Diet Quality Index (DQI), modeled after existing indices.

MAIN OUTCOME MEASURE

Adjusted odds ratios (ORs).

RESULTS

After covariate adjustment, increasing diet quality based on either index was associated with reduced risks for the birth defects studied. The strongest association was between anencephaly and DQI; the OR for highest vs lowest quartile was 0.49 (95% CI, 0.31-0.75). The ORs for cleft lip with or without cleft palate and cleft palate and DQI were also notable (0.66 [95% CI, 0.54-0.81] and 0.74 [95%CI, 0.56-0.96], respectively).

CONCLUSIONS

Healthier maternal dietary patterns, as measured by diet quality scores, were associated with reduced risks of NTDs and clefts. These results suggest that dietary approaches could lead to further reduction in risks of major birth defects and complement existing efforts to fortify foods and encourage periconceptional multivitamin use.

Roles of planar cell polarity pathways in the development of neural [correction of neutral] tube defects

Neural tube defects (NTDs) are the second most common birth defect in humans. Despite many advances in the understanding of NTDs and the identification of many genes related to NTDs, the fundamental etiology for the majority of cases of NTDs remains unclear. Planar cell polarity (PCP) signaling pathway, which is important for polarized cell movement (such as cell migration) and organ morphogenesis through the activation of cytoskeletal pathways, has been shown to play multiple roles during neural tube closure. The disrupted function of PCP pathway is connected with some NTDs. Here, we summarize our current understanding of how PCP factors affect the pathogenesis of NTDs.

Genetic basis of susceptibility to teratogen induced birth defects

Birth defects remain the leading cause of infant death in US. The field of teratology has been focused on the causes and underlying mechanisms of birth defects for decades, yet our understanding of these critical issues remain unacceptably vague. Conclusions from years of animal and human studies made it clear that the vast majority of birth defects have multifactorial origins, with contributions from environmental and genetic factors. The environment comprises not only of the physical, biological, and chemical external environment surrounding the pregnant woman, but it also includes the internal environment of the woman's body that interact with the developing embryo in a complex fashion. The importance of maternal and embryonic genetic factors consisting of countless genetic variants/mutations that exist within every individual contribute to birth defect susceptibility is only now being more fully appreciated. This great complexity of the genome and its diversity within individuals and populations seems to be the principal reason why the same teratogenic exposure can induce severe malformation in one embryo, while fail to do so to other exposed embryos. As the interaction between genetic and environmental factors has long been recognized as the first "Principle of Teratology" by Wilson and Warkany [1965. Teratology: Principles and techniques. Chicago: University of Chicago Press], it is only recently that the appropriate investigative tools have been developed with which to fully investigate this fundamental principle. The introduction of high throughput technologies like whole genome sequencing or genome-wide association studies are promising to deliver an enormous amount of new data that will shed light on the genomic factors that contribute susceptibility to environmental teratogens. In this review, we attempt to summarize the epidemiological and experimental literature concerning birth defects whose phenotypic expression can be clearly related to the interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. © 2011 Wiley-Liss, Inc.

Human neural tube defects: genetic causes and prevention

Neural tube defects (NTDs) are severe congenital malformations affecting 1-2 in 1,000 live births, whose etiology is multifactorial, involving environmental and genetic factors. NTDs arise as consequence of the failure of fusion of the neural tube early during embryogenesis. NTDs' pathogenesis has been linked to genes involved in folate metabolism, consistent with an epidemiologic evidence that 70% of NTDs can be prevented by maternal periconceptional supplementation. However, polymorphisms in such genes are not linked in all populations, suggesting that other genetic factors and environmental factors could be involved. Animal models have provided crucial mechanistic information and possible candidate genes to explain susceptibility to NTDs. A crucial role has been assigned to the planar cell polarity (PCP) pathway, a highly conserved, non-canonical Wnt-frizzled-dishevelled signaling cascade that plays a key role in establishing and maintaining polarity in the plane of the epithelium and in the process of convergent extension during gastrulation and neurulation in vertebrates. The Loop-tail (Lp) mouse that develops craniorachischisis carry missense mutations in the PCP core gene Vangl2, that is the mammalian homolog of the Drosophila Strabismus/Van gogh (Stbm/Vang). The presence of mutations in human VANGL1 and VANGL2 genes encourages us to extend the investigation to other PCP genes that, with VANGL, play an essential role in neurulation during development.

Long term maintenance of neural tube defects prevention in a high prevalence state

OBJECTIVE

To assess the efficacy of folic acid (FA) supplementation and fortification in preventing neural tube defects (NTDs) in a high prevalence region of the United States.

STUDY DESIGN

Active and passive surveillance methods were used to identify all fetuses/infants affected with an NTD in South Carolina. Prevalence rates were compared with FA intake to determine the effects of increased intake on NTD occurrence and recurrence.

RESULTS

From 1992 to 2009, 916 NTD cases occurred in South Carolina, with isolated defects comprising 79% of cases. The NTD rate decreased 58% during this period. There was one NTD-affected pregnancy in 418 subsequent pregnancies (0.2%) in mothers with earlier NTD-affected pregnancies who consumed periconceptional FA supplements, and there were 4 NTDs in 66 pregnancies (6.1%) in which the mother did not take FA supplements. FA supplementation increased from 8% to 35% from 1992 to 2007, and knowledge of the protective benefits of FA increased from 8% to 65% in women of childbearing age.

CONCLUSIONS

Increased periconceptional intake of FA appeared to reduce NTDs in a high-prevalence region. The rate of spina bifida and anencephaly in South Carolina is now essentially the same (0.69 cases per 1000 live births and fetal deaths) as the 1998 to 2005 US rate (0.69).

Maternal periconceptional factors affect the risk of spina bifida-affected pregnancies: an Italian case-control study

PURPOSE

Neural tube defects, including spina bifida and anencephaly, are the second most common birth defects with an incidence in Italy of 0.4-1/1,000. Information on factors playing a role in the pathogenesis of spina bifida is based on populations with different exposures, lifestyle, social and cultural habits compared to Italian people. Our objective was to fill this gap by using data from a case-control interview study carried out at the G. Gaslini Children's Hospital, Genoa, from 2000 to 2008.

METHODS

We surveyed questionnaires from 133 case mothers and 273 control women providing information on periconceptional risk factors. Univariate and multivariate logistic regression analyses were used to estimate risks by odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

Univariate results suggest that birth order, low maternal educational level, age, smoking habits, alcohol consumption, high caffeine intake, lack of folate supplementation, low and high calorie diet, occasional consumption of fruit and vegetables, high emotional stress, and environmental pollution are associated with an increased spina bifida risk. Nevertheless, high caffeine intake (OR = 10.82; 95% CI, 3.78-31), low calorie diet (OR = 5.15; 95%CI, 1.79-14), occasional consumption of fruit and vegetables (OR = 3.38; 95% CI, 1.67-6.82), alcohol consumption (OR = 3.05; 95% CI, 1.24-7.50) and, above all, lack of folate supplementation at any time of pregnancy (OR = 20.54; 95% CI, 5.41-77) mainly determined spina bifida risk in the multivariate analysis.

CONCLUSION

Our findings point out that a common underlying mechanism, a disturbed folate/homocysteine metabolism, may be causative for the burden of spina bifida in the Italian population.

Craniorachischisis and omphalocele in a stillborn cynomolgus monkey (Macaca fascicularis)

Nonhuman primates have been a common animal model to evaluate experimentally induced malformations. Reports on spontaneous malformations are important in determining the background incidence of congenital anomalies in specific species and in evaluating experimental results. Here we report on a stillborn cynomolgus monkey (Macaca fascicularis) with multiple congenital anomalies from the colony maintained at the Southwest National Primate Research Center at the Texas Biomedical Research Institute, San Antonio, Texas. Physical findings included low birth weight, craniorachischisis, facial abnormalities, omphalocele, malrotation of the gut with areas of atresia and intussusception, a Meckel diverticulum, arthrogryposis, patent ductus arteriosus, and patent foramen ovale. The macaque had normal male external genitalia, but undescended testes. Gestational age was unknown but was estimated from measurements of the limbs and other developmental criteria. Although cytogenetic analysis was not possible due to the tissues being in an advanced state of decomposition, array Comparative Genomic Hybridization analysis using human bacterial artificial chromosome clones was successful in effectively eliminating aneuploidy or any copy number changes greater than approximately 3-5 Mb as a cause of the malformations. Further evaluation of the animal included extensive imaging of the skeletal and neural tissue defects. The animal's congenital anomalies are discussed in relation to the current hypotheses attempting to explain the frequent association of neural tube defects with other abnormalities.

Patient report: sacral agenesis with hypopituitarism

We report an association of sacral agenesis and hypopituitarism in a child born of a diabetic mother. The child presented with short stature and evaluation revealed sacral agenesis, growth hormone deficiency (GHD) and adrenal insufficiency. This association might be important as short stature in children with sacral agenesis is usually attributed to mechanical factors. Early detection of GHD and treatment might help the child in gaining height.

Animal models in diabetes and pregnancy

The worldwide increase in the incidence of diabetes, the increase in type 2 diabetes in women at reproductive ages, and the cross-generation of the intrauterine programming of type 2 diabetes are the bases for the growing interest in the use of experimental diabetic models in order to gain insight into the mechanisms of induction of developmental alterations in maternal diabetes. In this scenario, experimental models that present the most common features of diabetes in pregnancy are highly required. Several important aspects of human diabetic pregnancies such as the increased rates of spontaneous abortions, malformations, fetoplacental impairments, and offspring diseases in later life can be approached by using the appropriate animal models. The purpose of this review is to give a practical and critical guide into the most frequently used experimental models in diabetes and pregnancy, discuss their advantages and limitations, and describe the aspects of diabetes and pregnancy for which these models are thought to be adequate. This review provides a comprehensive view and an extensive analysis of the different models and phenotypes addressed in diabetic animals throughout pregnancy. The review includes an analysis of the surgical, chemical-induced, and genetic experimental models of diabetes and an evaluation of their use to analyze early pregnancy defects, induction of congenital malformations, placental and fetal alterations, and the intrauterine programming of metabolic diseases in the offspring's later life.

Cardiac malformations and alteration of TGFbeta signaling system in diabetic embryopathy

BACKGROUND

Cardiovascular defects are the most common anomalies in diabetic embryopathy. The mechanisms underlying the manifestation of the defects remain to be addressed.

METHODS

Female mice were administered streptozotocin to induce diabetes. Embryos from euglycemic (control) and hyperglycemic groups were examined for morphological and histological evaluation of malformations. Cell proliferation and programmed cell death (apoptosis) were assessed using mitotic markers (BrdU and Ki67) and TUNEL assay, respectively. Expression of eight four genes in the TGFbeta signaling system was analyzed using real-time RT-PCR.

RESULTS

Structural abnormalities were observed in the heart and neural tube in diabetic groups, with significantly higher malformation rates than in control groups. Moreover, malformation rates in the heart were higher than those in the neural tube. Cardiac abnormalities including dilated heart tube, smaller ventricles, conotruncal stenosis, and abnormal heart looping were seen during early morphogenesis prior to cardiac septation [embryonic day (E) 9.5-11.5]. Histological examinations showed hypoplastic myocardium and endocardial cushions. After cardiac septation (E15.5), ventricular septal defects were observed, which were manifested in the non-muscular portion of the septum. Significant decreases in cell proliferation with no differences in apoptosis were observed in the myocardium and endocardial cushions in diabetic compared to control groups. Factors in the TGFbeta signaling that regulate heart development were downregulated by maternal diabetes.

CONCLUSIONS

Maternal diabetes causes malformations in the heart of the embryo. The heart is more susceptible to maternal diabetic insults than the neural tube. Malformations in the heart prior to septation are associated with decreased cell proliferation, but not increased apoptosis. The TGFbeta signaling is involved in cardiac malformations in diabetic embryopathy.

Alx3-deficient mice exhibit folic acid-resistant craniofacial midline and neural tube closure defects

Neural tube closure defects are among the most frequent congenital malformations in humans. Supplemental maternal intake of folic acid before and during pregnancy reduces their incidence significantly, but the mechanism underlying this preventive effect is unknown. As a number of genes that cause neural tube closure defects encode transcriptional regulators in mice, one possibility is that folic acid could induce the expression of transcription factors to compensate for the primary genetic defect. We report that folic acid is required in mouse embryos for the specific expression of the homeodomain gene Alx3 in the head mesenchyme, an important tissue for cranial neural tube closure. Alx3-deficient mice exhibit increased failure of cranial neural tube closure and increased cell death in the craniofacial region, two effects that are also observed in wild type embryos developing in the absence of folic acid. Folic acid cannot prevent these defects in Alx3-deficient embryos, indicating that one mechanism of folic acid action is through induced expression of Alx3. Thus, Alx3 emerges as a candidate gene for human neural tube defects and reveals the existence of induced transcription factor gene expression as a previously unknown mechanism by which folic acid prevents neural tube closure defects.

High-resolution 1H NMR spectroscopic investigation of a chick embryo model of neural tube development

High-field (1)H nuclear magnetic resonance (NMR) spectroscopy together with cryogenic probe capabilities have been applied to obtain metabolic profiles of chick embryos and to determine the suitability of the platform for profiling such mass-limited samples. Metabolic profiles were generated for both pooled and single embryo samples at early stages of neural development, using both 600 and 800 MHz (1)H NMR spectrometer platforms. High-resolution metabolic profiles, representing metabolites from many chemical classes, including triglycerides, organic acids, carbohydrates, amino acids and nucleosides, were rapidly acquired. Neural tube defects (NTDs) are severe congenital malformations, and evidence exists for prevention of NTDs by periconceptional supplementation of the diet with folate. The molecular basis for the protective ability of folate in prevention of NTDs is not clear, although the involvement of methylation has been postulated. Thus, the metabolic profiles of chick embryos following inhibition of enzymes of the methylation cycle and the effect of their action on neural tube closure were investigated. The embryos were profiled at early stages of development, and closure of the neural tube was followed via digital imaging. Metabolic profiles of embryo samples representing both neural tube closure and the neural tube remaining open were discriminated; glucose levels were found to be significantly higher in methylation-inhibited samples. The application of a non-targeted metabolic profiling approach for the study of a chick embryo model of NTDs is novel and presents the exciting potential to provide metabolic insight necessary to elucidate the complex interplay of one-carbon moiety metabolism and NTDs.

Importance of gene-environment interactions in the etiology of selected birth defects

It is generally understood that both genetic and environmental factors contribute to the highly complex etiology of structural birth defects, including neural tube defects, oral clefts and congenital heart defects, by disrupting highly regulated embryonic developmental processes. The intrauterine environment of the developing embryo/fetus is determined by maternal factors such as health/disease status, lifestyle, medication, exposure to environmental teratogens, as well as the maternal genotype. Certain genetic characteristics of the embryo/fetus also predispose it to developmental abnormalities. Epidemiologic and animal studies conducted over the last few decades have suggested that the interplay between genes and environmental factors underlies the etiological heterogeneity of these defects. It is now widely believed that the study of gene-environment interactions will lead to better understanding of the biological mechanisms and pathological processes that contribute to the development of complex birth defects. It is only through such an understanding that more efficient measures will be developed to prevent these severe, costly and often deadly defects. In this review, we attempt to summarize the complex clinical and experimental literature on current hypotheses of interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. These include maternal folate nutritional status, maternal diabetes/obesity-related conditions, and maternal exposure to selected medications and environmental contaminants. Our goal is to highlight the potential gene-environment interactions affecting early embryogenesis that deserve comprehensive study.

Folic acid, methylation and neural tube closure in humans

This review provides a brief description of folate use and folic acid metabolism in relation to neural tube defect (NTD) risk. First, a meta-analysis of reduction in NTD recurrence and occurrence risk with periconceptional folic acid supplementation is presented. Second, an overview of the complex folate metabolism is given. Third, SNPs for genes involved in folate and homocysteine metabolism that have been studied in relation to NTD riskare discussed. Fourth, the questions whether folate receptor autoantibodies or hampered methylation are mechanisms underlying NTDs are briefly discussed.