The pathogenesis of diabetes-associated congenital malformations

Maternal fasting glucose levels throughout the pregnancy and risk of adverse birth outcomes in newborns: a birth cohort study in Foshan city, Southern China

OBJECTIVE

We aimed to investigate the associations between maternal fasting plasma glucose (FPG) levels and glycemic fluctuations during different trimesters and adverse birth outcomes among newborns.

METHODS

This cohort study used data from 63 213 pregnant women and their offspring in Foshan city from November 2015 to January 2019. Associations between maternal FPG and glycemic fluctuations during different trimesters and adverse birth outcomes [congenital heart defect (CHD), macrosomia, small/large for gestational age (SGA/LGA), and preterm birth (PTB)] in newborns were estimated using mixed-effects logistic regression models.

RESULTS

A total of 45 516 participants accepted at least one FPG test throughout pregnancy, and 7852 of whom had glycemic trajectory data. In the adjusted model, higher maternal FPG throughout the pregnancy was associated with an increased risk of adverse birth outcomes (except for SGA). Each 1 mmol/L increase in maternal FPG during trimester 1 was associated with higher odds of CHD (OR = 1.14 (95% CI: 1.02, 1.26)). The same increase in maternal FPG during trimester 3 was associated with a higher risk of PTB (OR = 1.05 (95% CI: 1.01, 1.10)). Increment of maternal FPG during trimester 2 and trimester 3 was associated with a higher risk of macrosomia and LGA. Increase in FPG throughout the pregnancy was associated with slightly lower odds of SGA. Similar results were observed when analyzing the associations between glycemic fluctuations during different trimesters and adverse birth outcomes.

CONCLUSIONS

Our findings indicate higher maternal FPG levels during different trimesters were associated with different adverse birth outcomes, which suggests the importance of glycemic management throughout the pregnancy.

Association of Maternal Prepregnancy Diabetes and Gestational Diabetes Mellitus With Congenital Anomalies of the Newborn

OBJECTIVE

To examine the association of maternal prepregnancy diabetes, gestational diabetes mellitus (GDM), and 12 subtypes of congenital anomalies of the newborn.

RESEARCH DESIGN AND METHODS

We included 29,211,974 live births with maternal age ranging from 18 to 49 years old documented in the National Vital Statistics System in the U.S. from 2011 to 2018. Information on prepregnancy diabetes, GDM, and congenital anomalies was retrieved from birth certificates. Log-binomial regression was used to estimate risk ratios (RRs) and 95% CIs for congenital anomalies overall and by subtypes.

RESULTS

Of the 29,211,974 live births, there were 90,061 infants who had congenital anomalies identified at birth. The adjusted RRs of congenital anomalies at birth were 2.44 (95% CI 2.33-2.55) for prepregnancy diabetes and 1.28 (95% CI 1.24-1.31) for GDM. The associations were generally consistent across subgroups by maternal age, race/ethnicity, prepregnancy obesity status, and infant sex. For specific subtypes of congenital anomalies, maternal prepregnancy diabetes or GDM was associated with an increased risk of most subtypes. For example, the adjusted RRs of cyanotic congenital heart disease were 4.61 (95% CI 4.28-4.96) for prepregnancy diabetes and 1.50 (95% CI 1.43-1.58) for GDM; the adjusted RRs of hypospadias were 1.88 (95% CI 1.67-2.12) for prepregnancy diabetes and 1.29 (95% CI 1.21-1.36) for GDM.

CONCLUSIONS

Prepregnancy diabetes and, to a lesser extent, GDM were associated with several subtypes of congenital anomalies of the newborn. These findings suggest potential benefits of preconception counseling in women with preexisting diabetes or at risk for GDM for the prevention of congenital anomalies.

New development of the yolk sac theory in diabetic embryopathy: molecular mechanism and link to structural birth defects

Maternal diabetes mellitus is a significant risk factor for structural birth defects, including congenital heart defects and neural tube defects. With the rising prevalence of type 2 diabetes mellitus and obesity in women of childbearing age, diabetes mellitus-induced birth defects have become an increasingly significant public health problem. Maternal diabetes mellitus in vivo and high glucose in vitro induce yolk sac injuries by damaging the morphologic condition of cells and altering the dynamics of organelles. The yolk sac vascular system is the first system to develop during embryogenesis; therefore, it is the most sensitive to hyperglycemia. The consequences of yolk sac injuries include impairment of nutrient transportation because of vasculopathy. Although the functional relationship between yolk sac vasculopathy and structural birth defects has not yet been established, a recent study reveals that the quality of yolk sac vasculature is related inversely to embryonic malformation rates. Studies in animal models have uncovered key molecular intermediates of diabetic yolk sac vasculopathy, which include hypoxia-inducible factor-1α, apoptosis signal-regulating kinase 1, and its inhibitor thioredoxin-1, c-Jun-N-terminal kinases, nitric oxide, and nitric oxide synthase. Yolk sac vasculopathy is also associated with abnormalities in arachidonic acid and myo-inositol. Dietary supplementation with fatty acids that restore lipid levels in the yolk sac lead to a reduction in diabetes mellitus-induced malformations. Although the role of the human yolk in embryogenesis is less extensive than in rodents, nevertheless, human embryonic vasculogenesis is affected negatively by maternal diabetes mellitus. Mechanistic studies have identified potential therapeutic targets for future intervention against yolk sac vasculopathy, birth defects, and other complications associated with diabetic pregnancies.

Decoding the oxidative stress hypothesis in diabetic embryopathy through proapoptotic kinase signaling

Maternal diabetes-induced birth defects occur in 6-10% of babies born to mothers with pregestational diabetes, representing a significant maternal-fetal health problem. Currently, these congenital malformations represent a significant maternal-fetal medicine issue, but are likely to create an even greater public health threat as 3 million women of reproductive age (19-44 years) have diabetes in the United States alone, and this number is expected to double by 2030. Neural tube defects (NTDs) and congenital heart defects are the most common types of birth defects associated with maternal diabetes. Animal studies have revealed that embryos under hyperglycemic conditions exhibit high levels of oxidative stress resulting from enhanced production of reactive oxygen species and impaired antioxidant capability. Oxidative stress activates a set of proapoptotic kinase signaling intermediates leading to abnormal cell death in the embryonic neural tube, which causes NTD formation. Work in animal models also has revealed that maternal diabetes triggers a series of signaling intermediates: protein kinase C (PKC) isoforms, PKCα, βII and δ; apoptosis signal-regulating kinase 1; c-Jun-N-terminal kinase (JNK)1/2; caspase; and apoptosis. Specifically, maternal diabetes in rodent models activates the proapoptotic unfolded protein response and endoplasmic reticulum (ER) stress. A reciprocal causation between JNK1/2 activation and ER stress exists in diabetic embryopathy. Molecular studies further demonstrate that deletion of the genes for Prkc, Ask1, Jnk1, or Jnk2 abolishes maternal diabetes-induced neural progenitor apoptosis and ameliorates NTD formation. Similar preventive effects are also observed when apoptosis signal-regulating kinase 1, JNK1/2, or ER stress is inhibited. Cell membrane stabilizers and antioxidant supplements are also effective in prevention of diabetes-induced birth defects. Mechanistic studies have revealed important insights into our understanding the cause of diabetic embryopathy and have provided a basis for future interventions against birth defects or other pregnancy complications associated with maternal diabetes. The knowledge of a molecular pathway map identified in animal studies has created unique opportunities to identify molecular targets for therapeutic intervention.

A novel association of biventricular cardiac noncompaction and diabetic embryopathy: case report and review of the literature

Diabetic embryopathy refers to a constellation of congenital malformations arising in the setting of poorly controlled maternal diabetes mellitus. Cardiac abnormalities are the most frequently observed findings, with a 5-fold risk over normal pregnancies. Although a diverse spectrum of cardiac defects has been documented, cardiac noncompaction morphology has not been associated with this syndrome. In this report, we describe a novel case of biventricular cardiac noncompaction in a neonate of a diabetic mother. The patient was a late preterm female with right anotia, caudal dysgenesis, multiple cardiac septal and aortic arch defects, and biventricular cardiac noncompaction. Examination of both ventricles demonstrated spongy myocardium with increased myocardial trabeculation greater than 50% left ventricular thickness and greater than 75% right ventricular thickness, with hypoplasia of the bilateral papillary muscles, consistent with noncompaction morphology. Review of the literature highlights the importance of gene expression and epigenomic regulation in cardiac embryogenesis.

Use of a murine embryonic stem cell line that is sensitive to high glucose environment to model neural tube development in diabetic pregnancy

BACKGROUND

Neural tube defects (NTDs) are significantly increased by maternal diabetes. Embryonic stem cells (ESC) that can differentiate into neuroepithelium and can sense supraphysiological glucose concentrations would be very valuable to simulate the effects of maternal diabetes on molecular and cellular processes during neural tube formation.

METHODS

LG-ESC, a recently established ESC line that expresses the glucose transporter, Scl2a2, and is sensitive to elevated glucose concentrations, were grown for up to 8 days in a three-dimensional culture to form neural cysts. We tested whether high glucose media inhibits expression of Pax3, a gene that is required for neural tube closure and whose expression is inhibited in embryos of diabetic mice, and inhibits formation of neural cysts.

RESULTS

Pax3 expression was detected after 4 days of culture and increased with time. Pax3 expression was inhibited by high glucose media, but not if cells had been cultured in low glucose media for the first 4 days of culture. Pax7, which is also expressed in dorsal neural tube, was not detected. Pax6, which is expressed in the ventral neural tube, was detected only after 8 days of culture, but was not inhibited by high glucose. High glucose media did not inhibit formation of neural cysts.

CONCLUSION

LG-ESC can be used as a model of embryonic exposure to a diabetic environment during neural tube development. While high glucose exposure inhibits expression of a gene required for neural tube closure, it may not inhibit all of the processes involved in formation of a neural tube-like structure.

Diabetes and hypertension increase the placental and transcellular permeation of the lipophilic drug diazepam in pregnant women

Background

Previous studies carried out in our laboratories have demonstrated impaired drug permeation in diabetic animals. In this study the permeation of diazepam (after a single dose of 5 mg/day, administered intramuscularly) will be investigated in diabetic and hypertensive pregnant women.

Methods

A total 75 pregnant women were divided into three groups: group 1 (healthy control, n = 31), group 2 (diabetic, n = 14) and group 3 (hypertensive, n = 30). Two sets of diazepam plasma concentrations were collected and measured (after the administration of the same dose of diazepam), before, during and after delivery. The first set of blood samples was taken from the mother (maternal venous plasma). The second set of samples was taken from the fetus (fetal umbilical venous and arterial plasma). In order to assess the effect of diabetes and hypertension on diazepam placental-permeation, the ratios of fetal to maternal blood concentrations were determined. Differences were considered statistically significant if p ≤ 0.05.

Results

The diabetes and hypertension groups have 2-fold increase in the fetal umbilical-venous concentrations, compared to the maternal venous concentrations. Feto: maternal plasma-concentrations ratios were higher in diabetes (2.01 ± 1.10) and hypertension (2.26 ± 1.23) groups compared with control (1.30 ± 0.48) while, there was no difference in ratios between the diabetes and hypertension groups. Umbilical-cord arterial: venous ratios (within each group) were similar among all groups (control: 0.97 ± 0.32; hypertension: 1.08 ± 0.60 and diabetes: 1.02 ± 0.77).

Conclusions

On line with our previous findings which demonstrate disturbed transcellular trafficking of lipophilic drugs in diabetes, this study shows significant increase in diazepam placental-permeation in diabetic and hypertensive pregnant women suggesting poor transcellular control of drug permeation and flux, and bigger exposure of the fetus to drug-placental transport.

Zinc supplementation prevents cardiomyocyte apoptosis and congenital heart defects in embryos of diabetic mice

Oxidative stress induced by maternal diabetes plays an important role in the development of cardiac malformations. Zinc (Zn) supplementation of animals and humans has been shown to ameliorate oxidative stress induced by diabetic cardiomyopathy. However, the role of Zn in the prevention of oxidative stress induced by diabetic cardiac embryopathy remains unknown. We analyzed the preventive role of Zn in diabetic cardiac embryopathy by both in vivo and in vitro studies. In vivo study revealed a significant decrease in lipid peroxidation, superoxide ions, and oxidized glutathione and an increase in reduced glutathione, nitric oxide, and superoxide dismutase in the developing heart at embryonic days (E) 13.5 and 15.5 in the Zn-supplemented diabetic group when compared to the diabetic group. In addition, significantly down-regulated protein and mRNA expression of metallothionein (MT) in the developing heart of embryos from diabetic group was rescued by Zn supplement. Further, the nuclear microscopy results showed that trace elements such as phosphorus, calcium, and Zn levels were significantly increased (P<0.001), whereas the iron level was significantly decreased (P<0.05) in the developing heart of embryos from the Zn-supplemented diabetic group. In vitro study showed a significant increase in cellular apoptosis and the generation of reactive oxygen species (ROS) in H9c2 (rat embryonic cardiomyoblast) cells exposed to high glucose concentrations. Supplementation with Zn significantly decreased apoptosis and reduced the levels of ROS. In summary, oxidative stress induced by maternal diabetes could play a role in the development and progression of cardiac embryopathy, and Zn supplementation could be a potential therapy for diabetic cardiac embryopathy.

Responses of the embryonic epigenome to maternal diabetes

Maternal diabetes and obesity are independent risk factors for neural tube defects, although it is unclear whether the effects are mediated by common pathogenic mechanisms. In this manuscript, we report a genome-wide survey of histone acetylation in neurulation stage embryos from mouse pregnancies with different metabolic conditions: maternal diabetes, and maternal consumption of a high fat content diet. We find that maternal diabetes, and independently, exposure to high-fat diet, are associated with increases and decreases of H3 and H4 histone acetylation in the embryo. Intriguingly, changes of H3K27 acetylation marks are significantly enriched near genes known to cause neural tube defects in mouse mutants. These data suggest that epigenetic changes in response to diet and metabolic condition may contribute to increased risk for neural tube defects in diabetic and obese pregnancies. Importantly, the responses to high-fat diet and maternal diabetes were distinct, suggesting that perturbed embryonic development under these conditions is mediated by different molecular pathways. This conclusion is supported by morphometric analyses that reveal a trend for maternal diabetes to delay embryonic development in the C57BL/6 strain, while high-fat diet appears to be associated with accelerated development. Taken together, our results link changes in histone acetylation to metabolic conditions during pregnancy, and implicate distinct epigenetic mechanisms in susceptibility to neural tube defects under conditions of maternal diabetes and obesity.

Diabetic embryopathy: a role for the epigenome?

Embryonic development under adverse conditions, such as maternal diabetes or obesity during pregnancy, constitutes a major risk factor for birth defects, as well as for long-term health consequences and disease susceptibility in the offspring. While contributions from epigenetic changes have been invoked previously to explain the long-term changes in terms of developmental programming, we here review how maternal metabolism may directly affect the embryonic epigenome in relationship to teratogenic processes. We consider four epigenetic modalities--DNA methylation, non-coding RNA, transcription factors, and histone modifications--and their contribution to epigenetic memory, and discuss how epigenomic changes may mediate the altered control of embryonic gene expression brought about by maternal diabetes. In combination, the epigenomic modalities serve to define transcription-permissive domains of the genome, resulting in distinct epigenomic landscapes in different developmental cell types. We evaluate experimental approaches to characterize the epigenome in adverse pregnancy conditions, highlighting the role of next-generation sequencing on the technological side, while emphasizing the necessity to study defined cell populations in terms of biologic impact. Finally, we outline the challenges in moving from findings that correlate epigenomics to developmental phenotypes to scenarios that establish teratogenic causality.

Male gender significantly increases risk of oxidative stress related congenital anomalies in the non-diabetic population

OBJECTIVE

Oxidative stress (OS) is an important mechanism of teratogenesis. Recent work suggests increased OS in males. We evaluated whether male gender increased the risk of cyanotic congenital heart defects (CCHD) whose development is linked to OS and other common congenital anomalies (CA) in non-diabetic pregnancies.

METHODS

CDC-National Center for Health Statistics data for 19 states in 2006 were reviewed. CCHD, anencephaly, spina bifida, congenial diaphragmatic hernia (CDH), omphalocele, gastroschisis, limb defects, cleft lip with or without cleft palate (CL/P) and isolated cleft palate were evaluated. Adjusted odds ratio (OR) (95% CI) were calculated for CA in males with females as the reference group.

RESULTS

Of 1,194, 581, cases analyzed after exclusions, 3037 (0.25%) had major CA. Males had elevated adjusted OR (95% CI) for CCHD: 1.198 (1.027, 1.397), CDH: 1.487 (1.078, 2.051), and CL/P: 1.431 (1.24, 1.651). There was a significant interaction between cigarette use and (male) fetal gender and also with maternal age in the CL/P group.

CONCLUSIONS

In non-diabetic pregnancies, male gender appears to be an independent risk factor for some types of CA believed to be associated with OS. Cigarette smoking, a well recognized source of OS only increased the risk of CL/P in males.

Pictorial Essay: Infants of diabetic mothers

About 3 to 10% of pregnancies are complicated by glycemic control abnormalities. Maternal diabetes results in significantly greater risk for antenatal, perinatal, and neonatal morbidity and mortality, as well as congenital malformations. The number of diabetic mothers is expected to rise, as more and more of the obese pediatric female population in developed and some developing countries progresses to childbearing age. Radiologists, being part of the teams managing such pregnancies, should be well aware of the findings that may be encountered in infants of diabetic mothers. Timely, accurate, and proper radiological evaluation can reduce morbidity and mortality in these infants. The purpose of this essay is to illustrate the imaging findings in the various pathological conditions involving the major body systems in the offspring of women with diabetes.

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.

Late-gestation ventricular myocardial reduction in fetuses of hyperglycemic CD1 mice is associated with increased apoptosis

BACKGROUND

Previous work in our laboratory showed reduced myocardium and dilated ventricular chambers in gestation day (GD) 17 hearts that were collected from hyperglycemic CD1 mouse dams. Pre-breeding maternal immune stimulation, using Freund's complete adjuvant (FCA), diminished the severity of these fetal heart lesions. The following experiments were performed to detect possible changes in fetal heart apoptotic cell death, under hyperglycemic conditions and with or without maternal immune stimulation.

METHODS

Female CD1 mice were injected with 200 mg/kg of streptozocin (STZ) to induce insulin-dependent diabetes mellitus. Half of these mice received prior FCA injection. Fetal hearts were collected on GD 17 and myocardial apoptotic cells were quantified using flow cytometry. A panel of apoptosis regulatory genes (Bcl2, p53, Casp3, Casp9, PkCe) was then examined in the fetal myocardium using RT-PCR.

RESULTS

Early apoptotic cells and late apoptotic/necrotic cells were significantly increased in fetal hearts from STZ or STZ+FCA dams. Pre-treatment with FCA reduced late apoptotic/necrotic cells to control level, suggesting some cell death protection was rendered by FCA. Paradoxically in the face of such increased cell death, the expression of pro-apoptotic genes Casp3 and Casp9 was decreased by diabetes, while the anti-apoptotic gene Bcl2 was increased.

CONCLUSIONS

Maternal hyperglycemia causes dys-regulated apoptosis of fetal myocardial cells. Such effect may be prevented by maternal immune stimulation.

Regulation of folate receptor 1 gene expression in the visceral endoderm

BACKGROUND

Nutrient supply to the developing mammalian embryo is a fundamental requirement. Before completion of the chorioallantoic placenta, the visceral endoderm plays a crucial role in nurturing the embryo. We have found that visceral endoderm cells express folate receptor 1, a high-affinity receptor for the essential micronutrient folic acid, suggesting that the visceral endoderm has an important function for folate transport to the embryo. The mechanisms that direct expression of FOLR1 in the visceral endoderm are unknown.

METHODS

Sequences were tested for transcriptional activation capabilities in the visceral endoderm utilizing reporter gene assays in a cell model for extraembryonic endoderm in vitro, and in transgenic mice in vivo.

RESULTS

With F9 embryo carcinoma cells as a model for extraembryonic endoderm, we demonstrate that the P4 promoter of the human FOLR1 gene is active during differentiation of the cells towards visceral endoderm. However, transgenic mouse experiments show that promoter sequences alone are insufficient to elicit reporter gene transcription in vivo. Using sequence conservation as guide to choose genomic sequences from the human FOLR1 gene locus, we demonstrate that the sequence termed F1CE2 exhibits specific enhancer activity in F9 cells in vitro, in the visceral endoderm, and later the yolk sac in transgenic mouse embryos in vivo. We further show that the transcription factor HNF4-alpha can activate this enhancer sequence.

CONCLUSIONS

We have identified a transcriptional enhancer sequence from the FOLR1 locus with specific activity in vitro and in vivo, and suggest that FOLR1 is a target for regulation by HNF4-alpha.

Caspase-8: a key role in the pathogenesis of diabetic embryopathy

Maternal diabetes causes neural tube defects in embryos, which are associated with increased apoptosis in the neuroepithelium. Many factors, including effector caspases, have been shown to be involved in the events. However, the key regulators have not been identified and the underlying mechanisms remain to be addressed. Caspase-8, an initiator caspase, has been shown to be altered in diabetic embryopathy, suggesting a role as an upstream apoptotic regulator. Using mouse embryos as a model system, this study demonstrates that caspase-8 is required for the production of hyperglycemia-associated embryonic malformations. Caspase-8 was shown to be expressed in the developing neural tube. Its activity, as evidenced by enhanced cleavage, was increased by hyperglycemia. These changes were associated with increased formation of the active cleavage of Bid. Inhibition of caspase-8 activity in high glucose-challenged embryos reduced the rate of embryonic malformation and this was associated with decreased apoptosis in the neuroepithelium of the neural tube. Inhibition of caspase-8 activity also reduced hyperglycemia-induced Bid activation and caspase-9 cleavage. These data suggest that caspase-8 may control diabetic embryopathy-associated apoptosis via regulation of the Bid-stimulated mitochondrion/caspase-9 pathway.

Heart changes in 17-day-old fetuses of diabetic ICR (Institute of Cancer Research) mothers: improvement with maternal immune stimulation

Maternal diabetes mellitus is associated with increased fetal teratogenesis, including cardiovascular defects. Non-specific maternal immune stimulation with Freund's complete adjuvant (FCA) or interferon gamma (IFNgamma) has been associated with protection against birth malformations. Using a diabetic mouse model, late-gestation fetal heart and great vessel morphology were analyzed. Four groups of mice were used: non-diabetic females as a control group, hyperglycemic females induced by streptozotocin as a diabetic group, and diabetic females injected either with FCA or IFNgamma. At day 17 of gestation, females were euthanized and one fetus was arbitrarily selected per litter for fixation and sectioning. Treatment-induced changes in cardiac development were assessed from digital images of serial sections taken at standardized levels in the thorax. One-way parametric and non-parametric ANOVA and ordinal logistic regression were performed to compare the difference among groups (P<0.05). Maternal hyperglycemia altered morphology of the late-gestation fetal mouse heart by causing ventricular chamber dilation, sectional myocardial reduction, and an increase in transversal aortic area. FCA protected the fetal heart from cavitary dilation in diabetic mothers. FCA and IFNgamma protected the fetal heart against reduction of myocardial area, and ascending thoracic aorta dilation. Consequences of late gestation heart chamber dilation and myocardial reduction are not yet known. Maternal immune stimulation partially protected against these developmental defects by mechanisms that remain unclear.

Demonstration of the essential role of protein kinase C isoforms in hyperglycemia-induced embryonic malformations

To address the role of PKC isoforms in hyperglycemia-induced apoptosis and malformations in the embryos of diabetic pregnancies, expression of PKCalpha, beta1, beta 2, gamma, delta, epsilon, and zeta was examined in the neural tube of rat embryos and showed to overlap with the regions of increased apoptosis. Levels of activated (phosphorylated) PKCalpha , beta2, and delta were increased in the embryos of diabetic dams whereas those of PKCepsilon and zeta were decreased when compared with those in control groups. Cytosolic phospholipase A(2) (cPLA(2)) was also activated. Blocking the activity of PKCalpha , beta2, and delta using isoform-specific inhibitors in embryos cultured in hyperglycemia (40 mM) reduced malformation rates when compared with those in untreated hyperglycemic and euglycemic (8.3 mM) groups. These observations demonstrate that PKCalpha, beta2, and delta play an essential role in diabetic embryopathy. Activation of cPLA(2) was also decreased, suggesting that PKCs mediate the hyperglycemic effects through the cPLA(2)-phospholipid peroxidation pathway.

Activation of oxidative stress signaling that is implicated in apoptosis with a mouse model of diabetic embryopathy

OBJECTIVE

A mouse model of diabetic embryopathy in C57BL/6J background was established to use the resources of genetically engineered mice in which a specific gene is deleted or overexpressed. To test whether our previous fundamental findings in the rat model of diabetic embryopathy are transferable to this mouse model of diabetic embryopathy, levels of phosphorylated-JNK1/2 (c-Jun N-terminal kinase 1 and 2) and apoptotic markers (cleaved caspase 3) were determined. To establish a link between oxidative stress signaling and diabetic embryopathy, levels of phosphorylated-p66Shc (which is a key signaling molecule that mediates oxidative stress-induced apoptosis) were evaluated.

STUDY DESIGN

Diabetes mellitus was induced in female C57BL/6J mice by an intravenous injection of streptozotocin (75 mg/kg). Glucose levels were controlled by the subcutaneous implantation of insulin pellets. The female mice were mated with normal male mice. At gestation day 5 or embryonic day 5 (E5), the insulin pellets were removed from a group of animals, which made them hyperglycemic (> 250 mg/dL glucose). The animals with retained insulin pellets served as controls. On embryonic day 11, mice were killed, and embryos were dissected from the uteri for examination. Embryos and yolk sacs from individual conceptus were collected. Levels of phosphorylated-JNK1/2, phosphorylated-p66Shc, and cleaved caspase 3 were determined in the embryos and yolk sacs.

RESULTS

Malformation rates in embryos from diabetic mice were 3-fold higher than those in embryos from nondiabetic or diabetic/euglycemic control groups. JNK1/2, especially p54 JNK isoform, which is predominantly expressed by jnk2 gene, was activated in malformed embryos and their respective yolk sacs from diabetic mice and was significantly higher than those in normally developed embryos and their respective yolk sacs from nondiabetic and diabetic mice. Correlating to JNK1/2 activation, phosphorylated-p66Shc was also significantly increased in malformed embryos and their respective yolk sacs from diabetic mice than in normally developed embryos and their respective yolk sacs from nondiabetic and diabetic mice. Cleaved caspase 3 was observed in malformed embryos from diabetic mice.

CONCLUSION

The present study shows that maternal hyperglycemia is able to induce embryonic dysmorphogenesis in C57BL/6J mice that is comparable with that seen in the rat model of diabetic embryopathy. Like the well-studied rat model of diabetic embryopathy, activation of JNK1/2 and p66Shc and the increase of apoptotic markers are manifested in this mouse model of diabetic embryopathy. These findings suggest that the activation of oxidative stress signaling in diabetic embryopathy leads to excessive embryonic cell apoptosis and ultimately embryonic dysmorphogenesis. To apply the powerful genetic approach to the research of diabetic embryopathy, a mouse is a better animal model than a rat because all gene knockout (deletion) and gene transgenic (gene overexpression) animals are made in the mouse. The mouse model of diabetic embryopathy that was established in the present study may serve as a suitable substitute for the rat model of diabetic embryopathy, thus enabling us and other investigators to use genetically engineered technologies in the study of diabetic embryopathy.

Glucose metabolism in pregnancy and embryogenesis

PURPOSE OF REVIEW

It has been known for decades that diabetic women have somewhat decreased fertility and that their offspring have an increased risk of being born with developmental abnormalities. We review results from studies examining the impact of maternal hyperglycemia and diabetes on oocyte and early embryo development. We focus on the effects of the maternal milieu on metabolism, cell signaling and the regulation of glucose-transporter expression in the developing oocyte and embryo.

RECENT FINDINGS

Offspring of diabetic mothers have metabolic disease at higher rates than can be explained by genetic inheritance alone. Oocytes from hyperglycemic animals display several abnormalities and are of lower quality than oocytes from control animals. There appears to be a decrease in glucose transport in embryos exposed to a hyperglycemic environment, which may lead to programmed cell death.

SUMMARY

Maternal hyperglycemia and diabetes have detrimental effects on the developing embryo at several stages of development. Although the exact pathophysiology of the developmental defects seen in infants born to diabetic mothers remains unclear, the role of glucose transport and regulation seems to play a critical role in early growth and development.

Aortic and ventricular dilation and myocardial reduction in gestation day 17 ICR mouse fetuses of diabetic mothers

BACKGROUND

Maternal diabetes mellitus is associated with increased fetal teratogenesis, including cardiovascular defects. Information regarding cardiovascular changes in late-gestation fetal mice, related to maternal hyperglycemia, is not present in the literature.

METHODS

Late-gestation fetal heart and great vessel morphology were analyzed in fetuses from control and diabetic mice. Female ICR mice were injected with streptozocin (200 mg/kg IP) prior to mating to induce diabetes (n = 8). Nonhyperglycemic females were used as controls (n = 8). At day 17 of gestation, females were euthanized and one fetus was arbitrarily selected per litter to analyze the heart and great vessels. Six additional fetuses from different litters, showing external malformations (spina bifida and/or exencephaly), were also evaluated from the diabetic group. Fetal thoraxes were processed using routine histopathologic techniques, and 7-mum transversal sections were stained with hematoxylin-eosin. Digital images of sections were made and analyzed using NIH Image J software to compare regional cardiac development. Student's t tests for means were performed to determine differences between groups (p < .05).

RESULTS

Maternal hyperglycemia caused a dilation of late-gestation fetal ventricular chambers, a reduction of total ventricular myocardial area, and an increase in transversal ascending thoracic aortic area. Three of six fetuses that displayed external malformations showed an overt cardiac defect, beyond the ventricular and myocardial changes.

CONCLUSIONS

Maternal hyperglycemia altered morphology of the late-gestation fetal mouse heart. Postnatal persistence or consequences of late-gestation heart chamber dilation and myocardial reduction are not yet known.

Characterization of differential gene expression profiles in diabetic embryopathy using DNA microarray analysis

OBJECTIVE

The molecular mechanisms by which maternal diabetes impairs embryogenesis are not established. This study aimed to determine the developmental genes and molecular pathways that are involved in diabetic embryopathy, by comparing gene expression profiles in the yolk sacs between the embryos of diabetic and control rats by using DNA microarray analysis.

STUDY DESIGN

Diabetes was induced in female rats by injecting streptozotocin (65 mg/kg) intravenously. Glucose levels were controlled by subcutaneously implanting insulin pellets. The female rats were mated with normal male rats. At gestation day 4, the insulin pellets were removed from a group of animals, making them hyperglycemic. The animals with insulin pellets served as controls. At gestational day 12, embryos were explanted, and yolk sacs were collected. Total RNA, free of DNA contamination, was extracted from the yolk sacs. Complementary DNA probes were synthesized, labeled with Cy3 and Cy5 fluorescent dyes, and used to hybridize rat oligo-array containing 10,000 genes. Data were analyzed by using 1-sample t test on log2 ratios, with P < .05 representing a significant difference. The changes in expression levels of important genes were verified with the use of a real-time polymerase chain reaction (PCR).

RESULTS

Five microarray experiments produced consistent results. A total of 101 genes were found to be differentially expressed between the embryos of diabetic and control rats. Analyses that used PathwayAssist (Ariadne Genomics, Rockville, MD) revealed a number of potential signaling pathways and genes involved in insulin signaling and stress response (insulin 2, insulin-binding protein 1, GST pi1), cell growth (GAP43, CSF1R, HGF), calcium signaling (calbindin 3, CBP A6), and PKC signaling (PKCBP beta15, FABP5), in concert with prior biochemical and molecular findings.

CONCLUSION

These observations show significant alterations in expression of developmental and stress response genes in diabetic embryopathy, and demonstrate, for the first time, that the yolk sac cells express insulin during early development. In addition, these data also demonstrate that hyperglycemia induces altered gene expression, resulting in aberrant cell signaling, morphogenesis, and embryopathy.

Experimental mechanisms of diabetic embryopathy and strategies for developing therapeutic interventions

A high frequency of birth defects is seen in infants born to diabetic mothers. The mechanisms by which maternal hyperglycemia, the major teratogenic factor, induces embryonic malformations remain to be addressed. It has been shown that increases in programmed cell death are one of the factors causing embryonic malformations. Hyperglycemia-induced apoptosis is associated with oxidative stress, lipid peroxidation, and decreased antioxidant defense capacity in the embryos. Recent studies have revealed that mitogen-activated protein kinases as intracellular signaling factors are involved in hyperglycemia-induced embryopathy. Based on the findings, interventions to prevent embryonic malformations have been explored. Strategies include supplementation of molecules that are deficient in the embryos under hyperglycemic conditions and antioxidants to alleviate the adverse effects of oxidative stress. The ultimate goal is to develop multi-nutrient dietary supplements to eliminate embryonic abnormalities induced by maternal diabetes.

Dietary vitamin and lipid therapy rescues aberrant signaling and apoptosis and prevents hyperglycemia-induced diabetic embryopathy in rats

OBJECTIVE

Maternal diabetes causes developmental malformations in the embryo. Dietary supplementation with antioxidants can reduce the malformation rates in animal models. To investigate the molecular mechanisms underlying diabetes-induced embryonic abnormalities and dietary interventions, activity of mitogen-activated protein kinases and factors associated with apoptotic pathways were examined in the maternal diabetic rat model.

STUDY DESIGN

Diabetes was induced in pregnant rats using streptozotocin. In the yolk sacs of the embryos, activity of the extracellular signal-regulated kinases, Raf-1, and Akt was dramatically reduced in diabetic rats, whereas that of c-jun N-terminal kinases/stress-activated protein kinases was increased.

RESULTS

When the diabetic dams were fed with arachidonic acid, vitamin E, or a combination of arachidonic acid, vitamin E, and myoinositol, the changes in the expression of these kinases were reversed and correlated with the decreases in the rates of apoptosis and embryonic malformations.

CONCLUSION

These results suggest that mitogen-activated protein kinases are involved in diabetic embryopathy, and dietary supplementations can rescue the aberrant signaling pathways and reduce embryonic malformation rate.

Effects of alpha-lipoic acid supplementation on maternal diabetes-induced growth retardation and congenital anomalies in rat fetuses

The mechanism of diabetic embryopathy is not known. Excessive reactive oxygen species (ROS) produced in diabetes may be causally related to foetal anomalies. The objective of this study was to determine whether supplementation with the antioxidant lipoic acid (LA) could prevent maternal diabetes-related foetal malformations and intrauterine growth retardation (IUGR) in rats. Pregnant rats were non-treated (Group I) or made diabetic on gestation day (GD) 2 by injecting streptozotocin (Group II). Group III was injected with 20 mg kg(-1) of LA daily starting on GD 6 and continued through GD 19. Group IV was administered only Tris buffer on the corresponding days. Group V was a set of STZ-treated animals, which were supplemented with a daily dose of 20 mg kg(-1) of LA from GD 6 through GD 19. All fetuses were collected on GD 20. Lipoic acid did not affect the blood sugar levels of diabetic animals significantly but improved their body weight gain and reduced food and water consumption. Diabetic group had a high incidence of embryonic resorption, IUGR, craniofacial malformations, supernumerary ribs and skeletal hypoplasia. Lipoic acid significantly reduced these abnormalities. These data support the hypothesis that ROS are causally related to fetal maldevelopment and IUGR associated with maternal diabetes in the rat. They also highlight the possible role of antioxidants in the normal processes of embryo survival, growth and development.

Role of reactive oxygen species in gynecologic diseases

Free radicals derived from molecular oxygen and nitrogen are highly reactive metabolites called reactive oxygen species (ROS). Cells continuously produce free radicals and ROS as part of the metabolic process. They are involved in the various functions of the reproductive system. Antioxidants are enzymes or compounds that scavenge and reduce the presence of free radicals. Normally, a balance exists between concentrations of reactive oxygen species and antioxidant scavenging systems. The disruption of the delicate balance between pro- and antioxidants results in oxidative stress. Oxidative stress has been implicated in embryo fragmentation, DNA damage, apoptosis and poor pregnancy outcome. It has also been implicated in a large number of gynecologic diseases, such as endometriosis, pre-eclampsia and maternal diabetes. The use of antioxidants may be beneficial in combating the harmful effects of oxidative stress in many of these diseases. The present review outlines the importance of these species in the pathology of various gynecologic diseases. (Reprod Med Biol 2004; 3: 177 - 199).

Teratogen update: azathioprine and 6-mercaptopurine

BACKGROUND

Cyclosporine (CsA) therapy must often be continued during pregnancy to maintain maternal health in such conditions as organ transplantation and autoimmune disease. This meta-analysis was performed to determine whether CsA exposure during pregnancy is associated with an increased risk of congenital malformations, preterm delivery, or low birthweight.

METHODS

Various health science databases were searched to identify relevant articles. Articles selected for inclusion in the study were required to be free of any apparent selection bias and report outcomes in at least 10 newborns exposed to CsA in utero, specifically commenting on the presence or absence of congenital malformations. Article selection and data extraction were performed by two independent reviewers, with adjudication in cases of disagreement. To assess risks of CsA exposure, a summary odds ratio was calculated. Prevalence of malformations was calculated as a rate for all cyclosporine-exposed live births and for the subgroups identified. Ninety-five percent confidence intervals were constructed for both the odds ratio and prevalence rates.

RESULTS

Fifteen studies (6 with control groups of transplant without use of cyclosporine; total patients: 410) met the inclusion criteria for major malformations, 10 for preterm delivery (4 with control groups; total patients: 379) and 5 for low birth weight (1 with control groups; total number of patients: 314). The calculated odds ratio of 3.83 for malformations did not achieve statistical significance (CI 0.75-19.6). The overall prevalence of major malformations in the study population (4.1%) also did not vary substantially from that reported in the general population. OR for prematurity [1.52 (CI 1.00-2.32)] did not reach statistical significance although the overall prevalence rate was 56.3%. The OR for low birth weight [1.5 (CI 0.95-2.44 based on 1 study)].

CONCLUSIONS

CsA does not appear to be a major human teratogen. It may be associated with increased rates of prematurity. More research is needed to evaluate whether cyclosporine increases teratogenic risk.

Aberrant patterns of cellular communication in diabetes-induced embryopathy. I. Membrane signalling

OBJECTIVE

Our purpose was to investigate the role of membrane signalling in the mechanism of diabetes-induced embryopathy.

METHODS

Three groups of 70-90-day-old Sprague-Dawley rats were employed in our study: group 1 was normal control rats receiving a normal diet; group 2 represented experimentally induced diabetic rats with malformed offspring (intravenous injection of 65 mg/kg streptozotocin on pregnancy day 6) and group 3 included streptozotocin-induced diabetic rats with normal offspring. Embryos were examined on day 12 under light microscopy, categorized as morphologically normal or defective, and yolk sac cells were harvested from each group. Activities of ERK1 and 2, Raf-1, JNK1 and 2 in yolk sac cells were analyzed by Western blot with primary antibodies specific to the phosphorylated kinases, respectively.

RESULTS

A strong link between hyperglycemia and congenital malformations was confirmed. Key mitogen-activated protein kinases serve as syllabic intermediates: increased activities of Jun-amino-terminal kinase (JNK1 and 2) and decreased activities of extracellular signal-regulated kinase (ERK1 and 2) were observed during hyperglycemia-induced embryopathy.

CONCLUSIONS

Poorly controlled maternal diabetes results in embryopathy which is mediated via a pattern of aberrant cellular communication manifested by both macroscopic and microscopic membrane injury.

Maternal diabetes: an independent risk factor for major cardiovascular malformations with increased mortality of affected infants

BACKGROUND

Intensive medical care of women with diabetes has reduced their risks of bearing infants with congenital anomalies. To assess the preventive potential of preconceptional care, the data of a population-based study of cardiovascular malformations (CVM) were analyzed to determine the morphogenetic specificity of maternal diabetes risks, the morbidity and mortality of the infants, and maternal characteristics that might affect these risks.

METHODS

The Baltimore-Washington Infant Study was a case-control study (1981-1989) that included all live born infants with confirmed CVM; control infants were a representative sample of the birth cohort. A questionnaire administered in home visits recorded parental information on social, medical, occupational, and environmental factors. For these analyses of preconceptional diabetes risks, the case group excluded chromosomal and mendelian disorders and was divided into 3 developmental categories and 12 diagnostic groups.

RESULTS

Preconceptional maternal diabetes was strongly associated with CVM of early embryonic origin (odds ratio [OR] = 4.7, 95% confidence interval [CI] 2.8-7.9) and with cardiomyopathy (OR = 15.1, 95% CI 5.5-41.3), but not with obstructive and shunting defects (OR = 1.4, 95% CI 0.7-3.0). There was heterogeneity within these developmental categories: among laterality defects, diabetes was associated only with cardiovisceral and atrioventricular discordance (OR = 10.0, 95% CI 3.7-27.0); among outflow tract anomalies, the risk was strongly associated with normally related great arteries (OR = 6.6, 95% CI 3.2-13.3) but not with simple transpositions; and among atrioventricular septal defects, diabetes was associated with the complete but not with the partial forms (OR = 22.8, 95% CI 7.4-70.5). The association in early CVM was strongest among infants with multisystem, predominantly VACTERL, anomalies. All-cause mortality of infants with CVM was 39% among those with diabetic mothers and 17.8% in those with nondiabetic mothers. Deceased infants of diabetic mothers were also more likely to have extracardiac anomalies (P = 0.041), to be born prematurely (P = 0.007), and to have low birth weight (P = 0.011). Multivariate analyses of maternal factors revealed no significant confounders of the diabetes associations.

CONCLUSIONS

The evidence of diabetes-induced major cardiac defects is of urgent clinical significance. The effectiveness of early preconceptional care in the prevention of congenital anomalies has been demonstrated repeatedly.

Antiviral therapy: respiratory infections, chronic hepatitis

This review focuses on the activity, clinical pharmacology, and clinical indications of antiviral agents used in the management of influenza, respiratory syncytial virus infections, and chronic hepatitis B and C. Two neuraminidase inhibitors, a new class of antiviral agents, were recently approved for the treatment of influenza A and B in children.

High insulin-like growth factor 1 (IGF-1) and insulin concentrations trigger apoptosis in the mouse blastocyst via down-regulation of the IGF-1 receptor

Women with polycystic ovary syndrome have significantly higher rates of pregnancy loss, as well as elevated insulin and IGF-1 levels. In this study, preimplantation embryos exposed to high concentrations of IGF-1 or insulin undergo extensive apoptosis of the ICM nuclei. Lack of BAX expression, the caspase inhibitor, zVAD, or the ceramide synthase inhibitor, fumonisin B1, prevents this event, suggesting involvement of programmed cell death effector pathways. In other systems, the IGF-1 concentration regulates IGF-1R expression and thus high concentrations lead to down-regulation of the receptor. Here, data show a decrease in IGF-1 receptor protein expression, both by confocal immunofluorescent microscopy and by Western analysis upon exposure to 130 nM IGF-1. Insulin-stimulated glucose uptake, an event regulated via the IGF-1 receptor, is decreased upon exposure to excess IGF-1, suggesting decreased function of the receptor. The data also show that, by blocking receptor signal transduction or by decreasing receptor expression, the apoptotic event can be recreated, thus strongly suggesting that the mechanism of high IGF-1 induced apoptosis is decreased downstream IGF-1 receptor signaling. This embryotoxic insult by high IGF-1 levels may be responsible for the high incidence of pregnancy loss seen in women with polycystic ovary syndrome.

Detection of placental growth hormone variant and chorionic somatomammotropin-L RNA expression in normal and diabetic pregnancy by reverse transcriptase-polymerase chain reaction

Diabetes is a common complication encountered during pregnancy. Earlier studies indicated that diabetic placentas bear morphological alterations consistent with modified placental differentiation, including alterations in the villous cellular content, structure, and total surface. Limited data associating the diabetic status with the expression of terminal placental differentiation markers are available. The human growth hormone/chorionic somatomammotropin (hGH/CS) family consists of five genes, one of which (GH-N) is expressed efficiently in pituitary while the other four (CS-A, B, L, and hGH-V) are expressed in placenta and represent ultimate placental differentiation markers. We developed and applied a sensitive RT-PCR method coupled with diagnostic restriction digestion to determine the relative levels of the hGH/CS family in normal pregnancies and examine whether their mRNA expression pattern is altered in pregnancies complicated by diabetes. We show that relative hCS-L content changes during placental development. Specifically, normal term placentas express higher relative levels of hCS-L, lower relative hGH-V levels and a 70-fold lower hGH-V/CS-L mRNA ratio compared to early placentas. Also, many term placentas from diabetic pregnancies express lower relative levels of hCS-L mRNA and a much higher hGH-V/CS-L mRNA ratio compared to normal term placenta, resembling more an early placenta pattern of expression. Thus, our study suggests that the expression of terminal placental differentiation markers, such as the hGH/CS genes, is altered in term placentas from these diabetics reflecting either impaired placental differentiation or post-differentiation impairment of normal placental function.

Prevention by L-arginine and polyamines of delayed development and embryotoxicity caused by chemically-induced diabetes in rats

Diabetes mellitus induction with alloxan at a dose of 110 mg/kg i.p. in rats on Day 4 of pregnancy causes delayed development and resorptions as signs of embryotoxicity. In the present study, the administration of human NPH insulin at doses of 1 to 5 U/d to rats or 1.0 mL of 10 mM L-arginine for 8 d, starting the day following diabetes induction, prevented embryotoxicity and delayed development. Similar results were obtained when the polyamines putrescine, spermidine, or spermine were administered at doses of 1.0 mL of a 10 microM solution to each rat daily. However, even though L-arginine and polyamines prevented adverse effects of severe diabetes on the conceptus, and caused normalization of glucose, beta-hydroxybutyrate levels remained elevated. These results support the hypothesis that the mechanisms of normal and altered development could be mediated by the action of polyamines.

Hyperglycemia induces apoptosis in pre-implantation embryos through cell death effector pathways

Although perinatal mortality rates have improved for pregnant diabetic women because of insulin therapy and tight metabolic control, infants of diabetics still experience significantly higher rates of congenital malformations and spontaneous miscarriages compared with those of non-diabetic women. Our results here indicate that hyperglycemic conditions, either in vivo or in vitro, modulate the expression of an apoptosis regulatory gene as early as the pre-implantation blastocyst stage in the mouse. Apoptosis in the mammalian pre-implantation blastocyst is a normal process, thought to protect the early embryo by eliminating abnormal cells. Here we demonstrate that expression of Bax, a Bcl-2-like protein, is increased at the blastocyst stage in the presence of high concentrations of glucose, and that these changes correlate morphologically with increased DNA fragmentation. Expression of Bax and caspase are necessary for this in vitro glucose-induced apoptotic event, and ceramide is involved in mediating this embryotoxic effect of glucose. We also show that these apoptotic cellular changes can be prevented in vivo by treating hyperglycemic mice with insulin before and immediately after conception. These findings emphasize the importance of tight glycemic control in diabetic women at the earliest stages after conception.

Maternal diabetes alters extracellular matrix protein levels in rat placentas

OBJECTIVES

The aim of this study was to determine whether maternal diabetes affects placental levels of the extracellular matrix components fibronectin, laminin, and collagen-IV.

STUDY DESIGN

Fibronectin, laminin, and collagen-IV deposition in term (day 20) rat placentas from normal and diabetic pregnancies was detected by use of Western blot, slot-blot, and immunohistochemical studies.

RESULTS

Increased placental and decreased fetal wet weight were found in offspring of manifestly diabetic rats compared with offspring of normal pregnancies. Laminin deposition was reduced whereas fibronectin levels were increased in placentas from diabetic rats. No diabetes-induced changes of collagen-IV expression and deposition were found.

CONCLUSION

The diabetes-induced alterations of laminin and fibronectin protein levels in the fetal-maternal interface may affect placental development and alter gas exchange and nutrient transfer to the offspring. This may in turn contribute to the abnormal fetal development in diabetic pregnancy.

Immunomodulating functions of recombinant ovine interferon tau: potential for therapy in multiple sclerosis and autoimmune disorders

The interferons (IFN) are a family of complex proteins possessing antiviral, antiproliferative, and immunomodulatory activities. Two type I recombinant human IFN have been recently approved for the treatment of multiple sclerosis (MS). However, use of high dose type I IFN treatment in MS patients has been limited by dose-related toxicity. Ovine IFN tau is a unique type I interferon discovered for its role in the animal reproductive cycle. It differs from other type I IFNs in that it is remarkably less toxic even at high concentrations, is able to cross species barriers, and is not inducible by viral infection. Ovine IFN tau has been shown to be very effective in the treatment of animal models of MS. In this study, we examined the toxicity of OvIFN tau on human T-cells at high doses and its immunregulatory properties at equivalent doses. Our experiments confirmed the remarkably non-toxic nature of OvIFN tau on human cells at high concentrations as well as immunomodulating properties consistent with other type I IFNs including an antilymphoproliferative effect and inhibition of IFN gamma-induced HLA class II expression. These results suggest that OvIFN tau could be developed into a potentially less toxic therapeutic option for immune-mediated disorders including MS.

Free radical scavenging enzymes in fetal dysmorphogenesis among offspring of diabetic rats

Recent studies have suggested that the fetal dysmorphogenesis in diabetic pregnancies is associated with an increase in embryonic oxygen-free radicals. This excess of oxygen-free radicals may result from either overproduction or decreased clearance by the enzymatic scavenging mechanism. However, there are no in vivo data on the activity of embryonic oxygen-free radical scavenging enzymes. The purpose of the current study is to investigate whether this increase in embryonic oxygen-free radicals is the result of a change in the activity of the fetal oxygen-free radical scavenging/antioxidant enzymes during pregnancy complicated by maternal diabetes in an in vivo rat model. Thirty-six Sprague-Dawley rats were randomly assigned to one of two study groups: nondiabetic control and an untreated diabetic group. On day 12, fetuses were examined for crown-rump lengths, somite numbers, and external anomalies. The activity of fetal oxygen-free radical scavenging enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT), were determined. The untreated diabetic group of rats had a significantly higher mean blood glucose level than that of the nondiabetic controls and also a significantly lower weight gain, higher resorption rate, smaller embryonic size with lower total protein content, and a approximately 6-fold increase in the rate of fetal neural tube defects compared to the nondiabetic controls. Superoxide dismutase activity was significantly reduced in the embryos with neural tube defects regardless of maternal diabetic status (2.25 +/- 0.83 vs. 1.17 +/- 0.04 u/mg protein; P < 0.05). Glutathione peroxidase and catalase activity were significantly reduced in malformed versus normal-formed embryos of nondiabetic mothers (GPX-2.68 +/- 1.15 vs. 4.46 +/- 1.12 mu/mg protein, CAT -1.67 +/- 0.53 vs 2.49 +/- 0.61 u/mg protein respectively; P < 0.01). However, overall catalase activity was increased in embryos of diabetic mothers as compared to controls. Two-way analysis of variance identified fetal malformations as the variance associated with reduced fetal SOD activity, whereas maternal diabetes was associated with the increase in fetal catalase activity. Neither neural tube defect nor maternal diabetes was found to be the variable affecting fetal GPX activity, Fetal oxygen-free radical scavenging enzymes respond differently to the adverse environment created by maternal diabetes during pregnancy. Defects in embryonic SOD and catalase activity, regardless of maternal diabetic status, may reduce the ability of the fetus to clear free oxygen radicals, thereby exposing it to an increased oxidative load that may cause fetal dysmorphogenesis. The diabetic state of the mothers did not decrease embryonic activity of any of the scavenging enzymes. Therefore, although excess oxidative load, as observed in diabetes, may cause tissue injury and embryopathy, the mechanism does not appear to be a diabetes-induced reduction in the action of the scavenging enzymes.