Neural tube defects, folate, and immune modulation

Altered placental immune cell composition and gene expression with isolated fetal spina bifida

PROBLEM

Fetal spina bifida (SB) is more common in pregnant people with folate deficiency or anomalies of folate metabolism. It is also known that fetuses with SB have a higher risk of low birthweight, a condition that is typically placental-mediated. We therefore hypothesized that fetal SB would associate with altered expression of key placental folate transporters and an increase in Hofbauer cells (HBCs), which are folate-dependent placental macrophages.

METHOD OF STUDY

Folate receptor-α (FRα), proton coupled folate receptor (PCFT), and reduced folate carrier (RFC) protein localization and expression (immunohistochemistry) and HBC phenotypes (HBC abundance and folate receptor-β [FRβ] expression; RNA in situ hybridization) were assessed in placentae from fetuses with SB (cases; n = 12) and in term (n = 10) and gestational age (GA) - and maternal body mass index - matched (n = 12) controls without congenital anomalies.

RESULTS

Cases had a higher proportion of placental villous cells that were HBCs (6.9% vs. 2.4%, p = .0001) and higher average HBC FRβ expression (3.2 mRNA molecules per HBC vs. 2.3, p = .03) than GA-matched controls. HBCs in cases were largely polarized to a regulatory phenotype (median 92.1% of HBCs). In sex-stratified analyses, only male cases had higher HBC levels and HBC FRβ expression than GA-matched controls. There were no differences between groups in the total percent of syncytium and stromal cells that were positive for FRα, PCFT, or RFC protein immunolabeling.

CONCLUSIONS

HBC abundance and FRβ expression by HBCs are increased in placentae of fetuses with SB, suggesting immune-mediated dysregulation in placental phenotype, and could contribute to SB-associated comorbidities.

Fetal spina bifida associates with dysregulation in nutrient-sensitive placental gene networks: Findings from a matched case-control study

To improve outcomes in fetuses with spina bifida (SB), better understanding is needed of the molecular drivers of SB and its comorbidities. Pregnant people carrying a fetus with isolated SB (cases; n = 12) or a fetus with no congenital anomalies (controls; n = 21) were recruited at Mount Sinai Hospital, Toronto, Ontario, Canada. Clinical data and placental samples were collected. Placental transcriptome was sequenced (Clariom D microarray) and a nutrient-focused gene expression analysis pipeline was applied to determine whether fetal SB associates with placental dysfunction. Of the 391 differentially expressed genes (DEGs) in cases, 11% (n = 42) had at least one nutrient cofactor, including B vitamins (n = 7 genes), iron/heme (n = 6), and zinc (n = 11). Cases had dysregulation in genes not previously known to associate with SB, and in placental genes that have known links to SB but have not been previously identified in the placenta. Cases also had downregulated nutrient transport and upregulated branching angiogenesis and immune/inflammatory processes. Five nutrient-dependent transcription regulators, collectively predicted to target 46% of DEGs in cases, were identified and were most commonly dependent on B vitamins (n = 3) and zinc (n = 2). Placental gene expression changes were most acute in cases with poor growth. Placentae from fetuses with SB have dysregulation in several gene networks, including those that are sensitive to multiple micronutrients beyond the well-known folic acid. An improved understanding of placental phenotype in fetuses with SB may help identify novel mechanisms associated with comorbidities in fetuses with SB, and reveal new targets to improve fetal outcomes in this population.

Determinants of neural tube defects among newborns in public referral hospitals in Eastern Ethiopia

BACKGROUND

Neural tube defects (NTDs) are serious brain and spine birth defects. Although NTDs are primarily pregnancy complications, such as abortion and stillbirth, they also contribute to under-five morbidity and mortality, as well as long-term disability and psychological impact. Despite these negative outcomes, the determinants of NTDs are not widely studied in Ethiopia, particularly in the country's east. As a result, we sought to identify the risk factors for NTDs in neonates born in public referral hospitals in eastern Ethiopia.

METHODS

A facility-based unmatched case-control study was carried out at Hiwot Fana Comprehensive Specialized Hospital and Sheik Hassen Yabare Jigjiga University Referral Hospital in Eastern Ethiopia. We included 59 cases identified in the selected facilities between September 10, 2021, and February 5, 2022, and 118 control neonates, with a case-to-control ratio of 1:2. Data were gathered through the use of interviewer-administered questionnaires and medical record review. To identify determinant factors of NTDs, a multivariable logistic regression model was used, which included all predictor variables from the bivariable analysis. The results were reported using an Adjusted Odds Ratio (AOR) with a 95% confidence interval. A p-value of < 0.05 was considered statistically significant.

RESULTS

In total, 59 cases of NTDs were identified out of 2915 live birth total births registered in the two hospitals, making the incidence of NTDs 202.4/10,000 births. In the final model analysis, determinant factors such as gender of newborn [AOR = 2.97; 95%CI(1.27, 6.92)], having no history of antenatal care[AOR = 4.45;95%CI(1.30,15.20)], having a poor food consumption score (AOR = 3.38;95% CI;1.06,10.72), having history of monotonous diet consumption (AOR = 4.80; 95%CI: 1.09, 9.08; P = 0.038), and coffee consumption of three or more cups per day during pregnancy (AOR = 3.84:95% CI: 1.23, 11.97) were statistically associated with NTDs.

CONCLUSION

Modifiable and non-modifiable determinants were identified as major contributors of neural tube defect in this study. Early screening, dietary intervention counseling to increase consumption of a healthy diet, coffee consumption reduction, and pre-pregnancy supplementation programs should be developed to reduce NTDs in Ethiopia.

Identification of novel nutrient-sensitive gene regulatory networks in amniocytes from fetuses with spina bifida

Neural tube defects (NTDs) remain among the most common congenital anomalies. Contributing risk factors include genetics and nutrient deficiencies, however, a comprehensive assessment of nutrient-gene interactions in NTDs is lacking. We applied a nutrient-focused gene expression analysis pipeline to identify nutrient-sensitive gene regulatory networks in amniocyte gene expression data (GSE4182) from fetuses with NTDs (cases; n = 3) and fetuses with no congenital anomalies (controls; n = 5). Differentially expressed genes (DEGs) were screened for having nutrient cofactors. Nutrient-dependent transcriptional regulators (TRs) that regulated DEGs, and nutrient-sensitive miRNAs with a previous link to NTDs, were identified. Of the 880 DEGs in cases, 10% had at least one nutrient cofactor. DEG regulatory network analysis revealed that 39% and 52% of DEGs in cases were regulated by 22 nutrient-sensitive miRNAs and 10 nutrient-dependent TRs, respectively. Zinc- and B vitamin-dependent gene regulatory networks (Zinc: 10 TRs targeting 50.6% of DEGs; B vitamins: 4 TRs targeting 37.7% of DEGs, 9 miRNAs targeting 17.6% of DEGs) were dysregulated in cases. We identified novel, nutrient-sensitive gene regulatory networks not previously linked to NTDs, which may indicate new targets to explore for NTD prevention or to optimise fetal development.

Systems biology analysis of human genomes points to key pathways conferring spina bifida risk

Genetic investigations of most structural birth defects, including spina bifida (SB), congenital heart disease, and craniofacial anomalies, have been underpowered for genome-wide association studies because of their rarity, genetic heterogeneity, incomplete penetrance, and environmental influences. Our systems biology strategy to investigate SB predisposition controls for population stratification and avoids much of the bias inherent in candidate gene searches that are pervasive in the field. We examine both protein coding and noncoding regions of whole genomes to analyze sequence variants, collapsed by gene or regulatory region, and apply machine learning, gene enrichment, and pathway analyses to elucidate molecular pathways and genes contributing to human SB.

Spina bifida (SB) is a debilitating birth defect caused by multiple gene and environment interactions. Though SB shows non-Mendelian inheritance, genetic factors contribute to an estimated 70% of cases. Nevertheless, identifying human mutations conferring SB risk is challenging due to its relative rarity, genetic heterogeneity, incomplete penetrance, and environmental influences that hamper genome-wide association studies approaches to untargeted discovery. Thus, SB genetic studies may suffer from population substructure and/or selection bias introduced by typical candidate gene searches. We report a population based, ancestry-matched whole-genome sequence analysis of SB genetic predisposition using a systems biology strategy to interrogate 298 case-control subject genomes (149 pairs). Genes that were enriched in likely gene disrupting (LGD), rare protein-coding variants were subjected to machine learning analysis to identify genes in which LGD variants occur with a different frequency in cases versus controls and so discriminate between these groups. Those genes with high discriminatory potential for SB significantly enriched pathways pertaining to carbon metabolism, inflammation, innate immunity, cytoskeletal regulation, and essential transcriptional regulation consistent with their having impact on the pathogenesis of human SB. Additionally, an interrogation of conserved noncoding sequences identified robust variant enrichment in regulatory regions of several transcription factors critical to embryonic development. This genome-wide perspective offers an effective approach to the interrogation of coding and noncoding sequence variant contributions to rare complex genetic disorders.

Biology of Perseverative Negative Thinking: The Role of Timing and Folate Intake

Past-oriented rumination and future-oriented worry are two aspects of perseverative negative thinking related to the neuroticism endophenotype and associated with depression and anxiety. Our present aim was to investigate the genomic background of these two aspects of perseverative negative thinking within separate groups of individuals with suboptimal versus optimal folate intake. We conducted a genome-wide association study in the UK Biobank database (n = 72,621) on the "rumination" and "worry" items of the Eysenck Personality Inventory Neuroticism scale in these separate groups. Optimal folate intake was related to lower worry, but unrelated to rumination. In contrast, genetic associations for worry did not implicate specific biological processes, while past-oriented rumination had a more specific genetic background, emphasizing its endophenotypic nature. Furthermore, biological pathways leading to rumination appeared to differ according to folate intake: purinergic signaling and circadian regulator gene ARNTL emerged in the whole sample, blastocyst development, DNA replication, and C-C chemokines in the suboptimal folate group, and prostaglandin response and K+ channel subunit gene KCNH3 in the optimal folate group. Our results point to possible benefits of folate in anxiety disorders, and to the importance of simultaneously taking into account genetic and environmental factors to determine personalized intervention in polygenic and multifactorial disorders.

The prevalence and distribution of sternalis muscle: a meta-analysis of published literature of the last two hundred years

The sternalis muscle (SM) is an anatomical variant that lies subcutaneously and is superficial to the pectoralis major muscle or sternum. The present meta-analysis was conducted to analyze the prevalence, anatomical features, and variance of the SM in different population. In total, 98 studies were included for this meta-analysis. Eighty-two studies dealt with adult subjects, and sixteen studies with fetuses. The worldwide prevalence of SM was observed to be 6% or 0.06 [0.05-0.7, 95% CI] in 27,470 adults, whereas it was 0.29 [0.20-0.39, 95% CI] in 673 fetuses. In 259 anencephalic fetuses, the prevalence was 44% or 0.44 [0.26-0.63, 95% CI], while the same in 414 fetuses without anencephaly was 16% or 0.16 [0.06-0.27, 95% CI]. The reported prevalence rate in Asian mongoloid population (9.1% = 0.091) was three times that of the Asian Caucasian population (3.33% = 0.0333). The prevalence in European descent was 3.93%. Interestingly, the reported prevalence rates in North and South American populations were 3.44% and 3.66%, almost being equivalent. The cadaveric investigations revealed that the SM had an overall prevalence of 5.96% in adults based on 76 studies, which was higher than other modalities of investigations. The multi-detector computerized tomography (MDCT) had shown the prevalence of approximately 4.33%. The same was reported in surgical studies and mammographic studies as 0.47% and 0.02%, respectively. The SM is not an unusual variant of the chest wall musculature. MDCT could be a new method to precisely demonstrate the morphology, course, and size of the SM in vivo.

Complement factors and alpha-fetoprotein as biomarkers for noninvasive prenatal diagnosis of neural tube defects

Neural tube defects (NTDs) are serious congenital malformations. In this study, we aimed to identify more specific and sensitive maternal serum biomarkers for noninvasive NTD screenings. We collected serum from 37 pregnant women carrying fetuses with NTDs and 38 pregnant women carrying normal fetuses. Isobaric tags for relative and absolute quantitation were conducted for differential proteomic analysis, and an enzyme-linked immunosorbent assay was used to validate the results. We then used a support vector machine (SVM) classifier to establish a disease prediction model for NTD diagnosis. We identified 113 differentially expressed proteins; of these, 23 were either up- or downregulated 1.5-fold or more, including five complement proteins (C1QA, C1S, C1R, C9, and C3); C3 and C9 were downregulated significantly in NTD groups. The accuracy rate of the SVM model of the complement factors (including C1QA, C1S, and C3) was 62.5%, with 60% sensitivity and 67% specificity, while the accuracy rate of the SVM model of alpha-fetoprotein (AFP, an established biomarker for NTDs) was 62.5%, with 75% sensitivity and 50% specificity. Combination of the complement factor and AFP data resulted in the SVM model accuracy of 75%, and receiver operating characteristic curve analysis showed 75% sensitivity and 75% specificity. These data suggest that a disease prediction model based on combined complement factor and AFP data could serve as a more accurate method of noninvasive prenatal NTD diagnosis.

Mouse Models of Neural Tube Defects

During embryonic development, the central nervous system forms as the neural plate and then rolls into a tube in a complex morphogenetic process known as neurulation. Neural tube defects (NTDs) occur when neurulation fails and are among the most common structural birth defects in humans. The frequency of NTDs varies greatly anywhere from 0.5 to 10 in 1000 live births, depending on the genetic background of the population, as well as a variety of environmental factors. The prognosis varies depending on the size and placement of the lesion and ranges from death to severe or moderate disability, and some NTDs are asymptomatic. This chapter reviews how mouse models have contributed to the elucidation of the genetic, molecular, and cellular basis of neural tube closure, as well as to our understanding of the causes and prevention of this devastating birth defect.

Maternal genetic markers for risk of celiac disease and their potential association with neural tube defects in offspring

Background

We examined the association between the maternal genotype for celiac disease‐associated variants and risk of neural tube defects (NTDs).

Methods

We conducted a case–control study, using data from the National Birth Defects Prevention Study. We evaluated 667 cases (women with an offspring with NTD) and 743 controls (women with an offspring without a birth defect). We classified women as having low, intermediate, or high risk of celiac disease based on human leukocyte antigen (HLA) variants. We used logistic regression to assess the relationship between HLA celiac risk group (low, intermediate, high) and risk of NTDs. Fifteen non‐HLA variants (identified from genome‐wide association studies of celiac disease) were individually evaluated and modeled additively.

Results

There was no association between HLA celiac risk group and NTDs (intermediate vs. low risk: aOR, 1.0; 95% CI, 0.8–1.3; high vs. low risk: aOR, 0.8; 95% CI, 0.5–1.3). Of the fifteen non‐HLA variants, we observed five significant associations after accounting for multiple comparisons. Three negative associations were observed with rs10903122, rs13314993, rs13151961 (aOR range: 0.69–0.81), and two positive associations were observed with rs13003464 and rs11221332 (aOR range: 1.27–1.73).

Conclusion

If confirmed, our results suggest that the maternal variants related to celiac disease may be involved in the risk of NTDs.

Prepregnancy asthma and the subsequent risk of central nervous system defects in offspring

BACKGROUND

The relationship between childhood asthma and central nervous system defects in offspring is poorly understood. We assessed if childhood asthma was associated with the risk of having an infant with neural tube or other nervous system defects compared with asthma during pregnancy.

METHODS

We analyzed a longitudinal cohort of 128,060 women who were 5 years or less at study entry and later delivered an infant in Quebec, Canada (1989-2014). We identified women hospitalized for asthma before pregnancy, including childhood and adolescence, and determined if asthma was present during pregnancy based on obstetric records. Main outcomes were neural tube and non-neural tube defects in pregnancy. We used log-binomial regression models to determine risk ratios (RR) and 95% confidence intervals (CI) for the association between asthma and risk of nervous system defects, adjusting for patient characteristics.

RESULTS

Asthma was associated with a greater risk of neural tube defects in offspring (RR 2.39, 95% CI 1.03-5.53) compared with no asthma, but not non-neural tube defects (RR 1.10, 95% CI 0.71-1.71). Women whose asthma resolved before pregnancy had a greater risk of neural tube defects (RR 3.43, 95% CI 1.35-8.69), while women with asthma during pregnancy were at greater risk of non-neural tube defects, especially microcephaly (RR 2.80, 95% CI 1.23-6.40).

CONCLUSIONS

Asthma that resolved before pregnancy was associated with an increased risk of neural tube defects in offspring but not non-neural tube defects. Further investigation is needed to determine the pathophysiology connecting childhood asthma with nervous system defects in offspring.

Does arsenic increase the risk of neural tube defects among a highly exposed population? A new case-control study in Bangladesh

BACKGROUND

Neural tube defects are debilitating birth defects that occur when the developing neural plate fails to close in early gestation. Arsenic induces neural tube defects in animal models, but whether environmental arsenic exposure increases risk of neural tube defects in humans is unknown.

METHODS

We describe a new case-control study in Bangladesh, a country currently experiencing an epidemic of arsenic poisoning through contaminated drinking water. We plan to understand how arsenic influences risk of neural tube defects in humans through mechanisms that include disruption of maternal glucose and folate metabolism, as well as epigenetic effects. We also investigate whether sweat chloride concentration, a potential new biomarker for arsenic toxicity, can be used to identify women at higher risk for having a child affected by neural tube defect. We will collect dural tissue from cases, obtained at the time of surgical closure of the defect, and believe investigation of these samples will provide insight into the epigenetic mechanisms by which prenatal arsenic exposure affects the developing nervous system.

CONCLUSION

These studies explore mechanisms by which arsenic may increase risk of neural tube defects in humans and use a unique population with high arsenic exposure to test hypotheses. If successful, these studies may assist countries with high arsenic exposure such as Bangladesh to identify populations at high risk of neural tube defects, as well as direct development of novel screening strategies for maternal risk.Birth Defects Research 109:92-98, 2017.© 2016 The Authors Birth Defects Research Published by Wiley Periodicals, Inc.

Valproic Acid in Women and Girls of Childbearing Age

PURPOSE OF REVIEW

The aim of this paper is to evaluate recent literature on valproic acid (VPA) in women and girls of childbearing age and to emphasize new findings.

RECENT FINDINGS

Recent research confirms VPAs teratogenicity and risk of hormone disruption. VPA exposure in utero increases the risk for a variety of major congenital malformations (MCMs), reduced IQ and behavioral problems. In girls and women, VPA increases the risk of hormone abnormalities, obesity, and polycystic ovarian syndrome (PCOS). Despite guidelines recommending caution, VPA use continues to be prescribed to reproductive-aged women and girls. Despite significant and well-documented risk, adherence to guidelines in VPA use in reproductive-aged girls and women remains low.

Folate receptors and neural tube closure

Neural tube defects (NTD) are among the most common human congenital malformations, affecting 0.5-8.0/1000 of live births. Human clinical trials have shown that periconceptional folate supplementation significantly decreases the occurrence of NTD in offspring. However, the mechanism by which folate acts on NTD remains largely unknown. Folate receptor (Folr) is one of the three membrane proteins that mediate cellular uptake of folates. Recent studies suggest that mouse Folr1 (formerly referred to as Fbp1) is essential for neural tube closure. Therefore, we examined spatial and temporal expression patterns of Folr1 in developing mouse embryos, showing a close association between Folr1 and anterior neural tube closure. Transient transgenic analysis was performed using lacZ as a reporter; we identified a 1.1-kb enhancer that directs lacZ expression in the neural tube and optic vesicle in a manner that is similar to endogenous Folr1. The 1.1-kb enhancer sequences were highly conserved between humans and mice, suggesting that human FOLR1 is associated with anterior neural tube closure in humans. Several experimental studies in mice and human epidemiological and genetics studies have suggested that folate receptor abnormalities are involved in a portion of human NTDs, although the solo defect of FOLR1 did not cause NTD.

Primary Prevention of Congenital Anomalies: Special Focus on Environmental Chemicals and other Toxicants, Maternal Health and Health Services and Infectious Diseases

Congenital anomalies (CA) represent an important fraction of rare diseases, due to the critical role of non-genetic factors in their pathogenesis. CA are the main group of rare diseases in which primary prevention measures will have a beneficial impact. Indeed, since 2013 the European Union has endorsed a body of evidence-based recommendations for CA primary prevention; the recommendations aim at facilitating the inclusion of primary prevention actions the National Rare Disease Plans of EU Member States and encompass different public health fields, from environment through to maternal diseases and lifestyles.The chapter overviews and discusses the assessment of main risk factors for CA, such as environmental toxicants, maternal health and lifestyles and infections, with a special attention to issues that are emerging or need more knowledge.Overall, the availability of CA registries is important for estimating the health burden of CA, identifying possible hotspots, assessing the impact of interventions and addressing further, fit-to-purpose research.The integration of relevant public health actions that are already in place (e.g., control of noxious chemicals, vaccination programmes, public health services addressing chronic maternal conditions) can increase the affordability and sustainability of CA primary prevention. In developing countries with less primary prevention in place and limited overall resources, a first recognition phase may be pivotal in order to identify priority targets. In the meanwhile, policy makers should be made aware that primary prevention of RD supports publicly endorsed societal values like the knowledge-based promotion of health, empowerment, equity and social inclusiveness.

Folic acid supplementation improves cognitive function by reducing the levels of peripheral inflammatory cytokines in elderly Chinese subjects with MCI

This study aimed to evaluate whether folic acid supplementation would improve cognitive performance by reducing serum inflammatory cytokine concentrations. This RCT was performed in Tianjin, China. Participants with mild cognitive impairment (MCI) were randomly assigned to the folic acid (400 μg/day) or conventional treatment groups. Neuropsychological tests were administered, and folate, homocysteine, vitamin B₁₂, IL-6, TNF-α, Aβ-42, and Aβ-40 were measured at baseline and at 6- and 12-month time points.152 participants (folic acid: 77, conventional: 75) completed the trial. Significant improvements in folate (ηp² = 0.703, P = 0.011), homocysteine (ηp² = 0.644, P = 0.009), Aβ-42 (ηp² = 0.687, P = 0.013), peripheral IL-6 (ηp² = 0.477, P = 0.025), TNF-α (ηp² = 0.709, P = 0.009) levels were observed in folic acid group compared with conventional group. Folic acid supplementation improved the Full Scale Intelligence Quotient (P = 0.028; effect size d = 0.153), Information (P = 0.031; d = 0.157) and Digit Span (P = 0.009; d = 0.172) scores at 12 months compared with conventional treatment. Based on these findings, daily oral administration of a 400-μg folic acid supplement to MCI subjects for 12 months can significantly improve cognitive performance and reduce peripheral inflammatory cytokine levels.

A review of fundamental principles for animal models of DOHaD research: an Australian perspective

Epidemiology formed the basis of ‘the Barker hypothesis’, the concept of ‘developmental programming’ and today’s discipline of the Developmental Origins of Health and Disease (DOHaD). Animal experimentation provided proof of the underlying concepts, and continues to generate knowledge of underlying mechanisms. Interventions in humans, based on DOHaD principles, will be informed by experiments in animals. As knowledge in this discipline has accumulated, from studies of humans and other animals, the complexity of interactions between genome, environment and epigenetics, has been revealed. The vast nature of programming stimuli and breadth of effects is becoming known. As a result of our accumulating knowledge we now appreciate the impact of many variables that contribute to programmed outcomes. To guide further animal research in this field, the Australia and New Zealand DOHaD society (ANZ DOHaD) Animals Models of DOHaD Research Working Group convened at the 2nd Annual ANZ DOHaD Congress in Melbourne, Australia in April 2015. This review summarizes the contributions of animal research to the understanding of DOHaD, and makes recommendations for the design and conduct of animal experiments to maximize relevance, reproducibility and translation of knowledge into improving health and well-being.

Autoantibodies against homocysteinylated protein in a mouse model of folate deficiency-induced neural tube defects

BACKGROUND

Periconceptional supplementation with folic acid results in a significant reduction in the incidence of neural tube defects (NTDs). Nonetheless, NTDs remain a leading cause of perinatal morbidity and mortality worldwide, and the mechanism(s) by which folate exerts its protective effects are unknown. Homocysteine is an amino acid that accumulates under conditions of folate-deficiency, and is suggested as a risk factor for NTDs. One proposed mechanism of homocysteine toxicity is its accumulation into proteins in a process termed homocysteinylation.

METHODS & RESULTS

Herein, we used a folate-deficient diet in pregnant mice to demonstrate that there is: (i) a significant inverse correlation between maternal serum folate levels and serum homocysteine; (ii) a significant positive correlation between serum homocysteine levels and titers of autoantibodies against homocysteinylated protein; and (iii) a significant increase in congenital malformations and NTDs in mice deficient in serum folate. Furthermore, in mice administered the folate-deplete diet before conception, supplementation with folic acid during the gestational period completely rescued the embryos from congenital defects, and resulted in homocysteinylated protein titers at term that are comparable to that of mice administered a folate-replete diet throughout both the pre- and postconception period. These results demonstrate that a low-folate diet that induces NTDs also increases protein homocysteinylation and the subsequent generation of autoantibodies against homocysteinylated proteins.

CONCLUSION

These data support the hypotheses that homocysteinylation results in neo-self antigen formation under conditions of maternal folate deficiency, and that this process is reversible with folic acid supplementation.

Abnormal O-GlcNAcylation of Pax3 Occurring from Hyperglycemia-Induced Neural Tube Defects Is Ameliorated by Carnosine But Not Folic Acid in Chicken Embryos

Neural tube defects (NTDs) are among the most common of the embryonic abnormalities associated with hyperglycemic gestation. In this study, the molecular mechanisms of embryonic neurogenesis influenced by hyperglycemia was investigated using chicken embryo models. High-concentration glucose was administered into chicken eggs and resulted in increased plasma and brain tissue glucose, and suppressed expression of glucose transporters (GLUTs). The rate of NTD positively correlated with hyperglycemia. Furthermore, abnormally increased O-GlcNAcylation, a nutritionally responsive modification, of the key neural tube marker Pax3 protein led to the loss of this protein. This loss was not observed in a folate-deficiency NTD induced by methotrexate. Carnosine, an endogenous dipeptide, showed significant recovery effects on neural tube development. In contrast, folic acid, a well-known periconceptional agent, surprisingly showed relatively minimal effect. Higher expression levels of the Pax3 protein were found in the carnosine-treated groups, while lower expression levels were found in folic acid groups. Furthermore, the abnormal O-GlcNAcylation of the Pax3 protein was restored by carnosine. These results suggest new insights into using endogenous nutrients for the protection of embryonic neurodevelopment affected by diabetes gestation. The abnormal excessive O-GlcNAcylation of Pax3 may be responsible for the neural tube defects associated with hyperglycemia.

Mono-2-ethylhexyl phthalate (MEHP) alters histiotrophic nutrition pathways and epigenetic processes in the developing conceptus

Histiotrophic nutrition pathways (HNPs) are processes by which the organogenesis-stage conceptus obtains nutrients, amino acids, vitamins and cofactors required for protein biosynthesis and metabolic activities. Nutrients are captured from the maternal milieu as whole proteins and cargoes via receptor-mediated endocytosis in the visceral yolk sac (VYS), degraded by lysosomal proteolysis and delivered to the developing embryo (EMB). Several nutrients obtained by HNPs are required substrates for one-carbon (C1) metabolism and supply methyl groups required for epigenetic processes, including DNA and histone methylation. Increased availability of methyl donors has been associated with reduced risk for neural tube defects (NTDs). Here, we show that mono-2-ethylhexyl phthalate (MEHP) treatment (100 or 250μM) alters HNPs, C1 metabolism and epigenetic programming in the organogenesis-stage conceptus. Specifically, 3-h MEHP treatment of mouse EMBs in whole culture resulted in dose-dependent reduction of HNP activity in the conceptus. To observe nutrient consequences of decreased HNP function, C1 components and substrates and epigenetic outcomes were quantified at 24h. Treatment with 100-μM MEHP resulted in decreased dietary methyl donor concentrations, while treatment with 100- or 250-μM MEHP resulted in dose-dependent elevated C1 products and substrates. In MEHP-treated EMBs with NTDs, H3K4 methylation was significantly increased, while no effects were seen in treated VYS. DNA methylation was reduced in MEHP-treated EMB with and without NTDs. This research suggests that environmental toxicants such as MEHP decrease embryonic nutrition in a time-dependent manner and that epigenetic consequences of HNP disruption may be exacerbated in EMB with NTDs.

Brief report: complement C5a promotes human embryonic stem cell pluripotency in the absence of FGF2

The complement activation product, C5a, is a pivotal member of the innate immune response; however, a diverse number of nonimmune functions are now being ascribed to C5a signaling, including roles during embryonic development. Here, we identify the expression of the C5a precursor protein, C5, as well as the C5a receptors, C5aR and C5L2, in both human embryonic stem cells and human-induced pluripotent stem cells. We show that administration of a physiologically relevant dose of purified human C5a (1 nM) stimulates activation of ERK1/2 and AKT signaling pathways, and is able to promote maintenance of the pluripotent state in the absence of FGF2. C5a also reduced cell loss following dissociation of human pluripotent stem cells. Our results reveal that complement C5a signaling supports human stem cell pluripotency and survival, and thus may play a key role in shaping early human embryonic development.

Co-ordinated expression of innate immune molecules during mouse neurulation

The innate immune system is the first line of defence against pathogens and infection. Recently, it has become apparent that many innate immune factors have roles outside of immunity and there is growing evidence that these factors play important functional roles during the development of a range of model organisms. Several studies have documented developmental expression of individual factors of the toll-like receptor and complement systems, and we recently demonstrated a key role for complement C5a receptor (C5aR1) signalling in neural tube closure in mice. Despite these emerging studies, a comprehensive expression analysis of these molecules in embryonic development is lacking. In the current study, we therefore, examined the expression of key innate immune factors in the early development period of neurulation (7.5-10.5dpc) in mice. We found that complement factor genes were differentially expressed during this period of murine development. Interestingly, the expression patterns we identified preclude activation of the classical and alternative pathways and formation of the membrane attack complex. Additionally, several other classes of innate immune molecules were expressed during the period of neurulation, including toll-like receptors (TLR-2, -3, -4 and -9), receptor for advanced glycation end-products (RAGE), and their signalling adapters (TRAF-4, TRAF-6, TAK-1 and MyD88). Taken together, this study highlights a number of innate immune factors as potential novel players in early embryonic development.

Primary prevention of congenital anomalies: recommendable, feasible and achievable

Primary prevention of congenital anomalies was identified as an important action in the field of rare diseases by the European Commission in 2008, but it was not included in the Council Recommendation on an action in the field of rare diseases in 2009. However, primary prevention of congenital anomalies is feasible because scientific evidence points to several risk factors (e.g., obesity, infectious and toxic agents) and protective factors (e.g., folic acid supplementation and glycemic control in diabetic women). Evidence-based community actions targeting fertile women can be envisaged, such as risk-benefit evaluation protocols on therapies for chronic diseases, vaccination policies, regulations on workplace and environmental exposures as well as the empowerment of women in their lifestyle choices. A primary prevention plan can identify priority targets, exploit and integrate ongoing actions and optimize the use of resources, thus reducing the health burden for the new generation. The EUROCAT-EUROPLAN recommendations for the primary prevention of congenital anomalies endorsed in 2013 by the European Union Committee of Experts on Rare Diseases present an array of feasible and evidence-based measures from which national plans can adopt and implement actions based on country priorities. Primary prevention of congenital anomalies can be achieved here and now and should be an integral part of national plans on rare diseases.

Update on epigenetics in allergic disease

Chronic inflammatory diseases, including allergies and asthma, are the result of complex gene-environment interactions. One of the most challenging questions in this regard relates to the biochemical mechanism of how exogenous environmental trigger factors modulate and modify gene expression, subsequently leading to the development of chronic inflammatory conditions. Epigenetics comprises the umbrella of biochemical reactions and mechanisms, such as DNA methylation and chromatin modifications on histones and other structures. Recently, several lifestyle and environmental factors have been investigated in terms of such biochemical interactions with the gene expression-regulating machinery: allergens; microbes and microbial compounds; dietary factors, including vitamin B12, folic acid, and fish oil; obesity; and stress. This article aims to update recent developments in this context with an emphasis on allergy and asthma research.

The application of a chemical determination of N-homocysteinylation levels in developing mouse embryos: implication for folate responsive birth defects

Elevated homocysteine levels have long been associated with various disease states, including cardiovascular disease and birth defects, including neural tube defects (NTDs). One hypothesis regarding the strong correlation between these various disorders and high levels of homocysteine is that a reactive form of this small molecule can attach to mammalian proteins in a phenomenon known as homocysteinylation. These posttranslational modifications may become antigenic or may even directly disrupt certain protein function. It remains to be determined whether dietary influences that can cause globally increased levels of circulating homocysteine confer negative effects maternally, or may otherwise negatively and materially impact the metabolic balance in developing embryos. Herein we present the application of a chemical method of determination of N-homocysteinylation to a set of neural tube closure stage mouse embryos and their mothers. We explore the uses of this newly described technique to investigate levels of maternal and embryonic N-homocysteinylation using dietary manipulations of one-carbon metabolism with two known folate-responsive NTD mouse models. The data presented reveal that although diet appeared to have significant effects on the maternal metabolic status, those effects did not directly correlate to the embryonic folate or N-homocysteinylation status. Our studies indicate that maternal diet and embryonic genotype most significantly affected the embryonic developmental outcome.

Association between maternal single nucleotide polymorphisms in genes regulating glucose metabolism and risk for neural tube defects in offspring

BACKGROUND

Maternal pregestational hyperglycemia, diabetes, and obesity are well-established risk factors for neural tube defects (NTDs). As a common underlying mechanism, the imbalance of glucose homeostasis is directly related to the development of NTDs. Polymorphisms in genes regulating glucose metabolism in women may impact their chance of having an NTD-affected pregnancy.

METHODS

We conducted a two-stage case-control study to investigate the association between maternal genetic variants in genes regulating glucose metabolism and risk for NTDs. The cases were 547 women who gave birth to a child with an NTD (anencephaly, spina bifida, or encephalocele); the controls were 543 women who gave birth to a full-term healthy infant. In the first stage, 12 single nucleotide polymorphisms were genotyped in 160 cases and 162 controls. In the second stage, five single nucleotide polymorphisms found in the first stage and potentially associated with NTD risk were genotyped for validation, in an additional 387 cases and 381 controls.

RESULTS

Combined analysis of data from the two stages showed an association between maternal AA genotype of GCKR rs780094 and increased risk for total NTDs [odds ratio, 1.73; 95% confidence interval, 1.16-2.59) and spina bifida subtype [odds ratio, 1.83; 95% confidence interval, 1.16-2.88). No association was found between the other four single nucleotide polymorphisms (LEPR rs1137100, HK1 rs748235, HHEX rs5015480, KCNQ1 rs2237892) and NTD risk.

CONCLUSION

The AA genotype in maternal GCKR rs780094 is associated with an increased risk for NTDs and spina bifida in the Chinese population.