Genomic expression profiles of blood and placenta reveal significant immune-related pathways and categories in Chinese women with gestational diabetes mellitus

Association of serum folic acid levels in response to fasting blood glucose in early pregnancy with the risk of gestational diabetes mellitus: A retrospective cohort study

OBJECTIVE

With increasingly prevalent folic acid consumption in early pregnancy, concerns about its potentially negative effect on maternal metabolism have been raised. Recent findings regarding folic acid levels in the first trimester and the risk of gestational diabetes mellitus have been inconclusive. The aim of this study was to investigate the association of folic acid status in early pregnancy with gestational diabetes mellitus as well as examine whether glucose levels can be modulated by folic acid status during the same first trimester.

METHODS

This was a retrospective cohort study based on 27 128 Chinese pregnant women who registered during their first prenatal visit from January 2015 to December 2019. Serum folic acid and fasting blood glucose concentrations were measured during the 9th to 13th gestational weeks. Binary logistic regression was applied to estimate the odds ratios of gestational diabetes mellitus by using the serum folic acid levels quartiles with adjustment for major confounders. To investigate the potential effect of modifying key risk factors for gestational diabetes mellitus, we established subgroups, in which analyses were stratified by age (<25, 25-29, 30-34, and ≥35 y), parity (nulliparous and parous), prepregnancy body mass index (< 18.5, 18.5-23.9, and ≥ 24 kg/m2), and family history of diabetes (yes and no).

RESULTS

The positive association between maternal folate concentrations and fasting blood glucose was observed: the risk for hyperglycemia was higher in those in the middle (Q3) and higher (Q4) quartiles compared with those in Q1 and Q2. A higher risk for gestational diabetes mellitus was found in hyperglycemia of early pregnant women with high folate concentrations (Q3: odds ratio = 5.63; 95% CI, 4.56-6.95, and Q4: odds ratio = 5.57; 95% CI, 4.68-6.64) compared with normal fasting glucose mothers with folate concentrations in Q1 and Q2 after accounting for multiple covariables. Similar patterns were observed for different subgroups. Restricted cubic spline plots had a positive correlation of serum folic acid level with fasting blood glucose concentration as well as risk of gestational diabetes mellitus in a nonlinear pattern, with 32.5 nmol/L as the cutoff point for folic acid level.

CONCLUSIONS

Our findings underscore the importance of maintaining an appropriate folic acid concentration for preserving a lower risk of gestational diabetes mellitus, especially in women with relatively higher blood glucose in early pregnancy. Additionally, folic acid concentration > 32.5 nmol/L may be considered a risk factor for gestational diabetes mellitus. This research suggested that folic acid levels should be monitored during the first trimester from the first prenatal checkup to prevent adverse effects of excessive folic acid intake.

Discrete placental gene expression signatures accompany diabetic disease classifications during pregnancy

BACKGROUND

Gestational diabetes mellitus affects up to 10% of pregnancies and is classified into subtypes gestational diabetes subtype A1 (GDMA1) (managed by lifestyle modifications) and gestational diabetes subtype A2 (GDMA2) (requiring medication). However, whether these subtypes are distinct clinical entities or more reflective of an extended spectrum of normal pregnancy endocrine physiology remains unclear.

OBJECTIVE

Integrated bulk RNA-sequencing (RNA-seq), single-cell RNA-sequencing (scRNA-seq), and spatial transcriptomics harbors the potential to reveal disease gene signatures in subsets of cells and tissue microenvironments. We aimed to combine these high-resolution technologies with rigorous classification of diabetes subtypes in pregnancy. We hypothesized that differences between preexisting type 2 and gestational diabetes subtypes would be associated with altered gene expression profiles in specific placental cell populations.

STUDY DESIGN

In a large case-cohort design, we compared validated cases of GDMA1, GDMA2, and type 2 diabetes mellitus (T2DM) to healthy controls by bulk RNA-seq (n=54). Quantitative analyses with reverse transcription and quantitative PCR of presumptive genes of significant interest were undertaken in an independent and nonoverlapping validation cohort of similarly well-characterized cases and controls (n=122). Additional integrated analyses of term placental single-cell, single-nuclei, and spatial transcriptomics data enabled us to determine the cellular subpopulations and niches that aligned with the GDMA1, GDMA2, and T2DM gene expression signatures at higher resolution and with greater confidence.

RESULTS

Dimensional reduction of the bulk RNA-seq data revealed that the most common source of placental gene expression variation was the diabetic disease subtype. Relative to controls, we found 2052 unique and significantly differentially expressed genes (-22 thresholds; q<0.05 Wald Test) among GDMA1 placental specimens, 267 among GDMA2, and 1520 among T2DM. Several candidate marker genes (chorionic somatomammotropin hormone 1 [CSH1], period circadian regulator 1 [PER1], phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta [PIK3CB], forkhead box O1 [FOXO1], epidermal growth factor receptor [EGFR], interleukin 2 receptor subunit beta [IL2RB], superoxide dismutase 3 [SOD3], dedicator of cytokinesis 5 [DOCK5], suppressor of glucose, and autophagy associated 1 [SOGA1]) were validated in an independent and nonoverlapping validation cohort (q<0.05 Tukey). Functional enrichment revealed the pathways and genes most impacted for each diabetes subtype, and the degree of proximal similarity to other subclassifications. Surprisingly, GDMA1 and T2DM placental signatures were more alike by virtue of increased expression of chromatin remodeling and epigenetic regulation genes, while albumin was the top marker for GDMA2 with increased expression of placental genes in the wound healing pathway. Assessment of these gene signatures in single-cell, single-nuclei, and spatial transcriptomics data revealed high specificity and variability by placental cell and microarchitecture types. For example, at the cellular and spatial (eg, microarchitectural) levels, distinguishing features were observed in extravillous trophoblasts (GDMA1) and macrophages (GDMA2). Lastly, we utilized these data to train and evaluate 4 machine learning models to estimate our confidence in predicting the control or diabetes status of placental transcriptome specimens with no available clinical metadata.

CONCLUSION

Consistent with the distinct association of perinatal outcome risk, placentae from GDMA1, GDMA2, and T2DM-affected pregnancies harbor unique gene signatures that can be further distinguished by altered placental cellular subtypes and microarchitectural niches.

The Influence of Maternal Folate Status on Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

Maternal folate has been shown to relate to the risk of gestational diabetes mellitus (GDM). However, the existing studies have yielded inconsistent conclusions. The purpose of this study was to systematically review the association between maternal folate status and the risk of GDM. Observational studies up to 31 October 2022 were included. Study characteristics, the means and standard deviations (SDs) of folate levels (serum/red blood cell (RBC)), the odds ratios (ORs) with 95% confidence intervals (CIs) and the time for folate measurement were extracted. Compared with the non-GDM group, serum and RBC folate levels in women with GDM were significantly higher. Our subgroup analysis demonstrated that serum folate levels in the GDM group were significantly higher than in the non-GDM group only in the second trimester. RBC folate levels in the GDM group were significantly higher than in the non-GDM group in the first and second trimesters. Taking serum/RBC folate levels as continuous variables, the adjusted odds ratios of GDM risk showed that increased serum folate concentration rather than RBC folate elevated the risk of GDM. In the descriptive analysis, five studies reported high serum folate levels increased GDM risk, whereas the other five showed no association between serum folate levels and GDM risk. Moreover, the rest three studies pointed out high RBC folate levels increased GDM risk. Altogether we found that the risk of GDM is associated with high serum/plasma and RBC folate levels. Future studies should determine the recommended folic acid cutoff balancing the risk for GDM and fetal malformations.

Association of maternal folate and B12 vitamin status with gestational diabetes mellitus: still an open issue

OBJECTIVES

There is conflicting evidence about the role of folate and B₁₂in gestational diabetes mellitus (GDM) onset. The association of vitamin status with GDM was therefore revalued, also measuring the B₁₂active form holotranscobalamin.

METHODS

677 women were evaluated at 24-28 weeks of gestation when OGTT was carried out. The 'one-step' strategy was employed for GDM diagnosis. Odds ratio (OR) of having GDM was estimated to quantify the association with vitamin levels.

RESULTS

180 women (26.6%) had GDM. They were older (median, 34.6 vs. 33.3 years, p=0.019) and had higher body mass index (BMI) (25.8 vs. 24.1 kg/m², p<0.001). Multiparous women had lower levels of all evaluated micronutrients, while overweight lowered both folate and total B₁₂, but not holotranscobalamin. Lower total B₁₂(270 vs. 290 ng/L, p=0.005), but not holotranscobalamin, was observed in GDM, being weakly negatively correlated with fasting glycemia (r=-0.11, p=0.005) and 1-h OGTT serum insulin (r=-0.09, p=0.014). At multivariate analysis, age, BMI and multiparity remained the strongest GDM predictors, while total B₁₂(but not holotranscobalamin and folate) showed a slight protective effect (OR=0.996, p=0.038).

CONCLUSIONS

A weak association between total B₁₂ levels and GDM risk was shown, but it was not confirmed when holotranscobalamin was measured.

Genetics and Epigenetics: Implications for the Life Course of Gestational Diabetes

Gestational diabetes (GDM) is one of the most common complications of pregnancy, affecting as many as one in six pregnancies. It is associated with both short- and long-term adverse outcomes for the mother and fetus and has important implications for the life course of affected women. Advances in genetics and epigenetics have not only provided new insight into the pathophysiology of GDM but have also provided new approaches to identify women at high risk for progression to postpartum cardiometabolic disease. GDM and type 2 diabetes share similarities in their pathophysiology, suggesting that they also share similarities in their genetic architecture. Candidate gene and genome-wide association studies have identified susceptibility genes that are shared between GDM and type 2 diabetes. Despite these similarities, a much greater effect size for MTNR1B in GDM compared to type 2 diabetes and association of HKDC1, which encodes a hexokinase, with GDM but not type 2 diabetes suggest some differences in the genetic architecture of GDM. Genetic risk scores have shown some efficacy in identifying women with a history of GDM who will progress to type 2 diabetes. The association of epigenetic changes, including DNA methylation and circulating microRNAs, with GDM has also been examined. Targeted and epigenome-wide approaches have been used to identify DNA methylation in circulating blood cells collected during early, mid-, and late pregnancy that is associated with GDM. DNA methylation in early pregnancy had some ability to identify women who progressed to GDM, while DNA methylation in blood collected at 26-30 weeks gestation improved upon the ability of clinical factors alone to identify women at risk for progression to abnormal glucose tolerance post-partum. Finally, circulating microRNAs and long non-coding RNAs that are present in early or mid-pregnancy and associated with GDM have been identified. MicroRNAs have also proven efficacious in predicting both the development of GDM as well as its long-term cardiometabolic complications. Studies performed to date have demonstrated the potential for genetic and epigenetic technologies to impact clinical care, although much remains to be done.

Current Status and Prospects of the Single-Cell Sequencing Technologies for Revealing the Pathogenesis of Pregnancy-Associated Disorders

Single-cell RNA sequencing (scRNA-seq) is a method that focuses on the analysis of gene expression profile in individual cells. This method has been successfully applied to answer the challenging questions of the pathogenesis of multifactorial diseases and open up new possibilities in the prognosis and prevention of reproductive diseases. In this article, we have reviewed the application of scRNA-seq to the analysis of the various cell types and their gene expression changes in normal pregnancy and pregnancy complications. The main principle, advantages, and limitations of single-cell technologies and data analysis methods are described. We discuss the possibilities of using the scRNA-seq method for solving the fundamental and applied tasks related to various pregnancy-associated disorders. Finally, we provide an overview of the scRNA-seq findings for the common pregnancy-associated conditions, such as hyperglycemia in pregnancy, recurrent pregnancy loss, preterm labor, polycystic ovary syndrome, and pre-eclampsia.

U-shaped Association Between Folic Acid Supplementation and the Risk of Gestational Diabetes Mellitus in Chinese Women

OBJECTIVE

Our aim in this study was to assess the association between folic acid (FA) supplementation before and during pregnancy and risk of gestational diabetes mellitus (GDM) in Chinese women.

METHODS

This case-control study was conducted at 2 hospitals in central China. A total of 1,300 pregnant women, including 396 GDM patients and 904 controls, participated in the study. Information on the dose and duration of FA supplementation was collected using a self-report questionnaire at enrolment (24 to 28 weeks of gestation).

RESULTS

We observed a U-shaped association between FA supplementation and GDM risk that demonstrated a 228% increased risk of GDM among women who never took FA supplements, a 28% increased risk among women who took supplements containing <400 μg/day FA or took FA supplements for <1 month and a 188% increased risk among women who took supplements containing ≥800 μg/day FA for an adequate duration (>1 month before pregnancy and >3 months during pregnancy) compared with women who took supplements containing 400 to 799 μg/day FA for an adequate duration (all p<0.05). For women who took supplements containing ≥800 μg/day FA for an adequate duration, the association between FA supplementation and GDM risk appeared to be stronger among those women with a prepregnancy body mass index (BMI) of ≥25 kg/m² than among those with a prepregnancy BMI of <25 kg/m² (p=0.006 for interaction).

CONCLUSIONS

There was a U-shaped association of FA supplementation with GDM risk; that is, FA supplementation both below and above the recommended levels may increase the risk of GDM.

O-GlcNAc transferase contributes to sex-specific placental deregulation in gestational diabetes

INTRODUCTION

Gestational diabetes (GDM) is traditionally thought to emerge from placental endocrine dysregulations, but recent evidence suggests that fetal sex can also impact GDM development. Understanding the molecular mechanisms through which sex modulates placenta physiology can help identify novel molecular targets for future clinical care. Thus, we investigated the nutrient-sensing O-GlcNAc pathway as a potential mediator of sex-specific placenta dysfunction in GDM.

METHODS

Expression levels of O-GlcNAc enzymes were measured in male and female (n = 9+/gender) human placentas based on the maternal diagnosis of GDM. We then simulated the observed differences in both BeWo cells and human syncytiotrophoblasts primary cells (SCT) from male and female origins (n = 6/gender). RNA sequencing and targeted qPCR were performed to characterize the subsequent changes in the placenta transcriptome related to gestational diabetes.

RESULTS

O-GlcNAc transferase (OGT) expression was significantly reduced only in male placenta collected from mothers with GDM compared to healthy controls. Similar downregulation of OGT in trophoblast-like BeWo male cells demonstrated significant gene expression deregulations that overlapped with known GDM-related genes. Notably, placental growth hormone (GH) production was significantly elevated, while compensatory factors against GH-related insulin resistance were diminished. Inflammatory and immunologic factors with toxic effects on pancreatic β cell mass were also increased, altogether leaning toward a decompensatory diabetic profile. Similar changes in hormone expression were confirmed in male human primary SCTs transfected with siOGT. However, down-regulating OGT in female primary SCTs did not impact hormone production.

CONCLUSION

Our study demonstrated the significant deregulation of placental OGT levels in mothers with GDM carrying a male fetus. When simulated in vitro, such deregulation impacted hormonal production in BeWo trophoblast cells and primary SCTs purified from male placentas. Interestingly, female placentas were only modestly impacted by OGT downregulation, suggesting that the sex-specific presentation observed in gestational diabetes could be related to O-GlcNAc-mediated regulation of placental hormone production.

Transcriptomic Dysregulation of Inflammation-Related Genes in Leukocytes of Patients with Gestational Diabetes Mellitus (GDM) during and after Pregnancy: Identifying Potential Biomarkers Relevant to Glycemic Abnormality

Although the immune system has been implicated in the pathophysiology of gestational diabetes mellitus (GDM) and postpartum abnormal glucose tolerance (AGT), little is known about the transcriptional response of inflammation-related genes linked to metabolic phenotypes of GDM women during and after pregnancy, which may be potential diagnostic classifiers for GDM and biomarkers for predicting AGT. To address these questions, gene expression of IL6, IL8, IL10, IL13, IL18, TNFA, and the nuclear factor κB (NFκB)/RELA transcription factor were quantified in leukocytes of 28 diabetic women at GDM diagnosis (GDM group) and 1-year postpartum (pGDM group: 10 women with AGT and 18 normoglycemic women), using a nested RT-PCR method. Control pregnancies with normal glucose tolerance (NGT group; n = 31) were closely matched for maternal age, gestational age, pre-pregnancy BMI, pregnancy weight, and gestational weight gain. Compared with the NGT group, IL8 was downregulated in the GDM group, and IL13 and RELA were upregulated in the pGDM group, whereas IL6, IL10, and IL18 were upregulated in the GDM and pGDM groups. The TNFA level did not change from pregnancy to postpartum. Associations of some cytokines with glycemic measures were detected in pregnancy (IL6 and RELA) and postpartum (IL10) (p < 0.05). Receiver operating characteristic (ROC) curves showed that IL6, IL8, and IL18, if employed alone, can discriminate GDM patients from NGT individuals at GDM diagnosis, with the area under the ROC curves (AUCs) of 0.844, (95% CI 0.736−0.953), 0.771 (95% CI 0.651−0.890), and 0.714 (95% CI 0.582−0.846), respectively. By the logistic regression method, we also identified a three-gene panel (IL8, IL13, and TNFA) for postpartum AGT prediction. This study demonstrates a different transcriptional response of the studied genes in clinically well-characterized women with GDM at GDM diagnosis and 1-year postpartum, and provides novel transcriptomic biomarkers for future efforts aimed at diagnosing GDM and identifying the high risk of postpartum AGT groups.

Systematic review of transcriptome and microRNAome associations with gestational diabetes mellitus

PURPOSE

Gestational diabetes (GDM) is associated with increased risk for preterm birth and related complications for both the pregnant person and newborn. Changes in gene expression have the potential to characterize complex interactions between genetic and behavioral/environmental risk factors for GDM. Our goal was to summarize the state of the science about changes in gene expression and GDM.

DESIGN

The systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

METHODS

PubMed articles about humans, in English, from any date were included if they described mRNA transcriptome or microRNA findings from blood samples in adults with GDM compared with adults without GDM.

RESULTS

Sixteen articles were found representing 1355 adults (n=674 with GDM, n=681 controls) from 12 countries. Three studies reported transcriptome results and thirteen reported microRNA findings. Identified pathways described various aspects of diabetes pathogenesis, including glucose and insulin signaling, regulation, and transport; natural killer cell mediated cytotoxicity; and fatty acid biosynthesis and metabolism. Studies described 135 unique miRNAs that were associated with GDM, of which eight (miR-16-5p, miR-17-5p, miR-20a-5p, miR-29a-3p, miR-195-5p, miR-222-3p, miR-210-3p, and miR-342-3p) were described in 2 or more studies. Findings suggest that miRNA levels vary based on the time in pregnancy when GDM develops, the time point at which they were measured, sex assigned at birth of the offspring, and both the pre-pregnancy and gestational body mass index of the pregnant person.

CONCLUSIONS

The mRNA, miRNA, gene targets, and pathways identified in this review contribute to our understanding of GDM pathogenesis; however, further research is warranted to validate previous findings. In particular, longitudinal repeated-measures designs are needed that control for participant characteristics (e.g., weight), use standardized data collection methods and analysis tools, and are sufficiently powered to detect differences between subgroups. Findings may be used to improve early diagnosis, prevention, medication choice and/or clinical treatment of patients with GDM.

The Relationship Between Folate, Vitamin B12 and Gestational Diabetes Mellitus With Proposed Mechanisms and Foetal Implications

The incidence of gestational diabetes mellitus (GDM) is rising, which warrants attention due to the associated complications during pregnancy and in the long term for both mother and offspring. Studies have suggested a relationship between maternal folate (vitamin B9) and vitamin B12 status and GDM risk. Seemingly the most problematic scenario occurs when there is B-vitamin imbalance, with high folate and low vitamin B12. This nutritional state can occur in vitamin B12 deficient women who exceed the recommended folic acid supplementation. However, the pathological mechanisms behind this relationship are currently unclear and are explored in this review article. A high folate/low B12 can lead to a functional folate deficiency through the methyl-trap phenomenon, impairing re-methylation of homocysteine and regeneration of folates for DNA synthesis and repair. Consequently elevated homocysteine concentration leads to endothelial dysfunction and oxidative stress. Vitamin B12 deficiency also leads to an impairment of the conversion of methylmalonyl-CoA to succinyl-CoA, which has been associated with insulin resistance. Insulin resistance is thought to contribute to the etiology of GDM. More studies are needed to confirm the impact of these and other mechanisms on disease development. However, it highlights a potential avenue for GDM risk modification through a vitamin B12 supplement and improvement of maternal metabolic health.

Differential gene expression and network-based analyses of the placental transcriptome reveal distinct potential biomarkers for gestationaldiabetes mellitus

AIMS

Gestational diabetes mellitus (GDM) is a common complication during pregnancy affecting the mother and fetus. With the problems encountered with the oral glucose tolerance test (OGTT), we aim to identify potential early biomarkers of GDM.

METHODS

A cross-sectional study was conducted among 80 pregnant women. Blood samples were collected every trimester, and total RNA was isolated. After quality control and library preparation, next-generation sequencing was performed. Differential expression analysis was done. Enriched Gene Ontology: Biological Processes (GO: BP) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified. Gene co-expression networks were constructed. Protein-protein Interaction (PPI) networks were then built from modules significantly correlated with Hemoglobin A1c. Genes with the highest degree of interaction were identified as hub genes.

RESULTS

IGKV2D-28 and PTPRG were consistently differentially expressed among the three comparisons. Top enriched GO: BP terms and KEGG pathways are linked to immune responses. Orange (r = 0.59, p = 0.02) and purple modules (r = 0.41, p = 0.02) of the GDM cohorts in the first and second trimesters, respectively, significantly correlated with Hemoglobin A1c. HDAC8 of the orange module and MPO and CRISP3 of the purple module were identified as hub genes.

CONCLUSIONS

In this study, potential biomarkers of GDM were identified, namely, IGKV2D-28, PTPRG, HDAC8, MPO, and CRISP3.

Formyl peptide receptor-2 is upregulated in the blood and placenta of patients with gestational diabetes mellitus

Aim

To investigate the expression of formyl peptide receptor 2 (FPR2) in maternal blood, umbilical blood, and placenta of patients with gestational diabetes mellitus (GDM), and to analyze the changes of other pro‐inflammatory cytokines in blood, including interleukin 33 (IL‐33), IL‐1β, tumor necrosis factor alpha (TNF‐α), and C‐reactive protein (CRP), so as to reveal the pathogenesis of GDM.

Methods

FPR2, IL‐33, IL‐1β, T TNF‐α, and CRP in maternal blood and umbilical cord blood of 50 pregnant women with GDM and 30 normal pregnant women were analyzed by ELISA method to explore the correlation between inflammatory factors and blood glucose. The expression of FPR2 in placental tissues was analyzed by PCR and immunohistochemistry.

Results

The expression of FPR2 in maternal blood of gestational diabetes patients was significantly higher than that of normal pregnant women, and other inflammatory factors IL‐33 and IL‐1β in maternal blood were also significantly increased. The expression of FPR2 in umbilical cord blood of gestational diabetes was higher than that of normal pregnant women, but the difference was not significant. Other inflammatory factors IL‐33, IL‐1β, and CRP in umbilical cord blood were also significantly increased. The expression of FPR2mRNA and protein in placental tissues of gestational diabetes was significantly higher than that of normal pregnant women.

Conclusions

The level of FPR2, IL‐33, and IL‐1β in maternal blood was related to the pathogenesis of GDM and these inflammatory factors could be used as special candidate direction of marks for the prevention, clinical treatment and drug design of GDM, laying a new theoretical foundation for the treatment of GDM.

Vitamin B12 and Folate Levels During Pregnancy and Risk of Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

Background: The role of vitamin B12 and folate levels with risk of gestational diabetes mellitus (GDM) is unclear. The purpose of the current study was to conduct a systematic review and meta-analysis for assessing the relationship between vitamin B12 and folate concentrations during pregnancy and the risk of GDM.

Methods: PubMed, Embase, CENTRAL, and Ovid databases were searched up to 10th December, 2020 for all types of studies assessing the relationship. Qualitative and quantitative analysis of data was carried out.

Results: Twelve studies were included. Pooled serum vitamin B12 concentrations were found to be significantly lower in the GDM group as compared to the non-GDM group. No such difference was noted in serum folate levels. On pooled analysis of adjusted odds ratio's for risk of GDM with red blood cell (RBC) folate, serum folate, and vitamin B12 as continuous variables, no significant relationship was seen. On qualitative analysis, studies reported higher RBC folate levels with a significantly increased risk of GDM. Majority studies reported no relationship between serum folate and risk of GDM. Four of six studies reported a lowered risk of GDM with higher or normal vitamin B12 levels.

Conclusion: The association between vitamin B12 and folate levels during pregnancy and the risk of GDM is unclear. Limited number of studies indicate increased risk of GDM with higher RBC folate levels, but majority studies found no association between serum folate and risk of GDM. Based on available studies, the association between the risk of GDM with vitamin B12 deficiency is conflicting. There is a need for further large-scale studies from different regions worldwide to strengthen current evidence.

Current approaches and developments in transcript profiling of the human placenta

BACKGROUND

The placenta is the active interface between mother and foetus, bearing the molecular marks of rapid development and exposures in utero. The placenta is routinely discarded at delivery, providing a valuable resource to explore maternal-offspring health and disease in pregnancy. Genome-wide profiling of the human placental transcriptome provides an unbiased approach to study normal maternal–placental–foetal physiology and pathologies.

OBJECTIVE AND RATIONALE

To date, many studies have examined the human placental transcriptome, but often within a narrow focus. This review aims to provide a comprehensive overview of human placental transcriptome studies, encompassing those from the cellular to tissue levels and contextualize current findings from a broader perspective. We have consolidated studies into overarching themes, summarized key research findings and addressed important considerations in study design, as a means to promote wider data sharing and support larger meta-analysis of already available data and greater collaboration between researchers in order to fully capitalize on the potential of transcript profiling in future studies.

SEARCH METHODS

The PubMed database, National Center for Biotechnology Information and European Bioinformatics Institute dataset repositories were searched, to identify all relevant human studies using ‘placenta’, ‘decidua’, ‘trophoblast’, ‘transcriptome’, ‘microarray’ and ‘RNA sequencing’ as search terms until May 2019. Additional studies were found from bibliographies of identified studies.

OUTCOMES

The 179 identified studies were classifiable into four broad themes: healthy placental development, pregnancy complications, exposures during pregnancy and in vitro placental cultures. The median sample size was 13 (interquartile range 8–29). Transcriptome studies prior to 2015 were predominantly performed using microarrays, while RNA sequencing became the preferred choice in more recent studies. Development of fluidics technology, combined with RNA sequencing, has enabled transcript profiles to be generated of single cells throughout pregnancy, in contrast to previous studies relying on isolated cells. There are several key study aspects, such as sample selection criteria, sample processing and data analysis methods that may represent pitfalls and limitations, which need to be carefully considered as they influence interpretation of findings and conclusions. Furthermore, several areas of growing importance, such as maternal mental health and maternal obesity are understudied and the profiling of placentas from these conditions should be prioritized.

WIDER IMPLICATIONS

Integrative analysis of placental transcriptomics with other ‘omics’ (methylome, proteome and metabolome) and linkage with future outcomes from longitudinal studies is crucial in enhancing knowledge of healthy placental development and function, and in enabling the underlying causal mechanisms of pregnancy complications to be identified. Such understanding could help in predicting risk of future adversity and in designing interventions that can improve the health outcomes of both mothers and their offspring. Wider collaboration and sharing of placental transcriptome data, overcoming the challenges in obtaining sufficient numbers of quality samples with well-defined clinical characteristics, and dedication of resources to understudied areas of pregnancy will undoubtedly help drive the field forward.

Gestational Diabetes Mellitus and Maternal Immune Dysregulation: What We Know So Far

Gestational diabetes mellitus (GDM) is an obstetric complication that affects approximately 5-10% of all pregnancies worldwide. GDM is defined as any degree of glucose intolerance with onset or first recognition during pregnancy, and is characterized by exaggerated insulin resistance, a condition which is already pronounced in healthy pregnancies. Maternal hyperglycaemia ensues, instigating a 'glucose stress' response and concurrent systemic inflammation. Previous findings have proposed that both placental and visceral adipose tissue play a part in instigating and mediating this low-grade inflammatory response which involves altered infiltration, differentiation and activation of maternal innate and adaptive immune cells. The resulting maternal immune dysregulation is responsible for exacerbation of the condition and a further reduction in maternal insulin sensitivity. GDM pathology results in maternal and foetal adverse outcomes such as increased susceptibility to diabetes mellitus development and foetal neurological conditions. A clearer understanding of how these pathways originate and evolve will improve therapeutic targeting. In this review, we will explore the existing findings describing maternal immunological adaption in GDM in an attempt to highlight our current understanding of GDM-mediated immune dysregulation and identify areas where further research is required.

Identification of a novel association for the WWOX/HIF1A axis with gestational diabetes mellitus (GDM)

Background

Although the WW-domain-containing oxidoreductase (WWOX)/Hypoxia-inducible factor 1 (HIF1) pathway is a well-known regulator of cellular glucose and energy metabolism in pathophysiological processes, its role in gestational diabetes mellitus (GDM), remains elusive. We undertook this study to determine the effect of WWOX/HIF1A signaling on the expression of glucose metabolism genes in GDM patients.

Methods

Leukocytes were obtained from 135 pregnant women with (n = 98) or without (n = 37) GDM and, in turn, 3 months (n = 8) and 1 year (n = 12) postpartum. Quantitative RT-PCR was performed to determine gene expression profiles of the WWOX/HIF1A-related genes, including those involved in glucose transport (SLC2A1, SLC2A4), glycolytic pathway (HK2, PKM2, PFK, LDHA), Wnt pathway (DVL2, CTNNB1), and inflammatory response (NFKB1).

Results

GDM patients displayed a significant downregulation of WWOX with simultaneous upregulation of HIF1A which resulted in approximately six times reduction in WWOX/HIF1A ratio. As a consequence, HIF1A induced genes (SLC2A1, HK2, PFK, PKM) were found to be overexpressed in GDM compared to normal pregnancy and negative correlate with WWOX/HIF1A ratio. The postpartum WWOX expression was higher than during GDM, but its level was comparable to that observed in normal pregnancy.

Conclusions

The obtained results suggest a significant contribution of the WWOX gene to glucose metabolism in patients with gestational diabetes. Decreased WWOX expression in GDM compared to normal pregnancy, and in particular reduction of WWOX/HIF1A ratio, indicate that WWOX modulates HIF1α activity in normal tissues as described in the tumor. The effect of HIF1α excessive activation is to increase the expression of genes encoding proteins directly involved in the glycolysis which may lead to pathological changes in glucose metabolism observed in gestational diabetes.

Upregulation of T Cell Receptor Signaling Pathway Components in Gestational Diabetes Mellitus Patients: Joint Analysis of mRNA and circRNA Expression Profiles

OBJECTIVE

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy, and its pathogenesis is still unclear. Studies have shown that circular RNAs (circRNAs) can regulate blood glucose levels by targeting mRNAs, but the role of circRNAs in GDM is still unknown. Therefore, a joint microarray analysis of circRNAs and their target mRNAs in GDM patients and healthy pregnant women was carried out.

METHODS

In this study, microarray analyses of mRNA and circRNA in 6 GDM patients and 6 healthy controls were conducted to identify the differentially expressed mRNA and circRNA in GDM patients, and some of the discovered mRNAs and circRNAs were further validated in additional 56 samples by quantitative realtime PCR (qRT-PCR) and droplet digital PCR (ddPCR).

RESULTS

Gene ontology and pathway analyses showed that the differentially expressed genes were significantly enriched in T cell immune-related pathways. Cross matching of the differentially expressed mRNAs and circRNAs in the top 10 KEGG pathways identified 4 genes (CBLB, ITPR3, NFKBIA, and ICAM1) and 4 corresponding circRNAs (circ-CBLB, circ-ITPR3, circ-NFKBIA, and circ-ICAM1), and these candidates were subsequently verified in larger samples. These differentially expressed circRNAs and their linear transcript mRNAs were all related to the T cell receptor signaling pathway, and PCR results confirmed the initial microarray results. Moreover, circRNA/miRNA/mRNA interactions and circRNA-binding proteins were predicted, and circ-CBLB, circ-ITPR3, and circ-ICAM1 may serve as GDM-related miRNA sponges and regulate the expression of CBLB, ITPR3, NFKBIA, and ICAM1 in cellular immune pathways.

CONCLUSION

Upregulation of T cell receptor signaling pathway components may represent the major pathological mechanism underlying GDM, thus providing a potential approach for the prevention and treatment of GDM.

Associations Between Gestational Diabetes Mellitus Risk and Folate Status in Early Pregnancy and MTHFR C677T Polymorphisms in Chinese Women

PURPOSE

Red blood cell (RBC) folate indicates long-term folate intake, and methylenetetrahydrofolate reductase (MTHFR) gene is the main gene affecting folate status. Increasing evidence suggests an association between gestational diabetes mellitus (GDM) and increased folate levels. Whether RBC folate concentrations in the first trimester of pregnancy or polymorphisms of MTHFR C677T (rs1801133) affect GDM risk in Chinese pregnant women remains unknown. Therefore, we analyzed the associations of RBC folate concentrations and rs1801133 polymorphisms with GDM risk among pregnant women in China.

METHODS

A total of 366 women with a singleton pregnancy were followed prospectively from their first prenatal visit to delivery. RBC folate concentrations and rs1801133 polymorphisms were assessed during the first trimester of pregnancy. Binary logistic regression analyses were performed to determine the odds ratios (ORs) of GDM and 95% confidence intervals (CIs) by using the RBC folate concentration quartiles and rs1801133 polymorphisms.

RESULTS

Participants with the TT genotype had the highest RBC folate concentrations. Those with heterozygous or homozygous variants did not have a significantly higher risk of GDM than did women with C alleles. After adjustments for covariates, women in the highest quartile for RBC folate concentration had a higher risk of GDM (adjusted OR = 2.473, 95% CI = 1.013-6.037, P = 0.047) than did those in the lowest quartile, but this association was nonsignificant after adjustment for rs1801133 polymorphisms.

CONCLUSION

Higher RBC folate, partly caused by MTHFR 677C→T, may be associated with increased GDM risk, even in early pregnancy. Assessing RBC folate status and appropriately supplementing folate during early pregnancy, particularly for patients with MTHFR 677C→T, may prevent GDM. Further studies with larger populations are warranted.

Identification of hub-methylated differentially expressed genes in patients with gestational diabetes mellitus by multi-omic WGCNA basing epigenome-wide and transcriptome-wide profiling

Gestational diabetes mellitus (GDM), defined as dysglycaemia that is detected during pregnancy for the first time, has become a global health burden. GDM was found to be correlated to epigenetic changes, which would cause abnormal expression of placental genes. In the present study, we performed multi-omic weighted gene coexpression network analysis (WGCNA) to systematically identify the hub genes for GDM using both epigenome- and transcriptome-wide microarray data. Two microarray datasets (GSE70493 and GSE70494) were downloaded from the Gene Expression Omnibus (GEO) database. GEO2R was used to screen differentially expressed genes (DEGs) and differentially methylated genes (DMGs) between normal and GDM samples, separately. The results of WGCNA found that 15 modules were identified and the MEblack module had a significantly negative correlation with GDM (r = -.28, P = .03). GO enrichment analysis by BinGO of the MEblack module showed that genes were primarily enriched for the presentation of antigen processing, regulation of interferon-α production and interferon-γ-mediated signaling pathway. By comparing the DEGs, DMGs and hub genes in the coexpression network, we identified five hypermethylated, lowly expressed genes (ABLIM1, GRHL1, HLA-F, NDRG1, and SASH1) and one hypomethylated, highly expressed gene (EIF3F) as GDM-related hub DMGs. Moreover, the expression levels of ABLIM1, GRHL1, HLA-F, NDRG1, and SASH11 in the GDM patients and healthy controls were validated by a real-time quantitative polymerase chain reaction. Finally, gene set enrichment analysis showed that the biological function of cardiac muscle contraction was enriched for four GDM-related hub DMGs (ABLIM1, GRHL1, NDRG1, and SASH1). Analysis of this study revealed that dysmethylated hub genes in GDM placentas might affect the placental function and thus, take part in GDM pathogenesis and fetal cardiac development.

Association of maternal folate status in the second trimester of pregnancy with the risk of gestational diabetes mellitus

Interest in the high folate status of pregnant women has increased due to its role in the prevention of neural tube defects (NTDs). The effect of increased red blood cell (RBC) folate status during the second trimester of pregnancy on gestational diabetes mellitus (GDM) remains unclear. We measured RBC folate concentrations by competitive protein-binding assay and obtained clinical information from electronic medical records. Logistic regression analysis was used to explore the associations of RBC folate concentrations with risks of gestational diabetes mellitus (GDM). We further assessed the potential nonlinear relations between continuous log-transformed RBC folate concentrations and GDM risk by using the restricted cubic splines. We observed high RBC folate concentrations in GDM patients compared to control group [median (interquartile range, IQR), GDM vs. controls: 1,554.03 (1,240.54-1,949.99) vs. 1,478.83 (1,124.60-1,865.71) nmol/L, p = .001]. Notably, high folate concentrations were significantly associated with an increased risk of GDM [RR per 1-SD increase: 1.16 (1.03, 1.30), p = .012] after adjustment for maternal age, parity, and body mass index (BMI) at enrollment. In the restricted cubic spline model, a test of the null hypothesis of the linear relationship was rejected (p = .001). Our study firstly showed that maternal RBC folate concentrations during the second trimester of pregnancy increase the risk of GDM in a Chinese population. Further randomized clinical trials (RCTs) are warranted to confirm the adverse effect.

A genome-wide association study of gestational diabetes mellitus in Chinese women

BACKGROUND

Recently, gestational diabetes mellitus (GDM) exhibits an obvious trend of increase in pregnant mothers and usually causes several abnormities or diseases for the offspring. Although several studies have been reported for potential molecular mechanisms, relevant genes or mutated sites have not been intensively investigated in China.

MATERIALS AND METHODS

In the present study, 218 pregnant mothers (GDM group: 103 individuals and control group: 115 individuals) in China were enrolled to conduct genome-wide association study (GWAS) and pathway analyses for the purpose of related genes associated with GDM in China.

RESULTS

Our results identified 23 SNPs exhibiting closely association with GDM using multiple tests. Annotation of these 23 SNPs identified four genes (SYNPR, CDH18, CTIF, and PTGIS), which suggests that the four genes may associate with GDM. GO enrichment and KEGG pathway analysis showed that gene SYNPR, CDH18, and PTGIS were enriched or located into the pathways or process associated with glycometabolism (e.g. insulin resistance and glucose tolerance), which further indicates that the three genes may associate with the GDM.

CONCLUSION

The identification of these potential genes associating with GDM enriched the potential molecular mechanisms of GDM in Asia and will provide abundant stocks for subsequent clinical verifications for better understanding the molecular mechanisms, diagnosis, drug development and clinical treatment of GDM.

Expression Profile of Diabetes-Related Genes Associated with Leukocyte Sirtuin 1 Overexpression in Gestational Diabetes

Although compelling evidence indicates that Sirtuin 1 (SIRT1) plays a prominent role in type 2 diabetes, its relationship with gestational diabetes (GDM) remains elusive. This study was aimed at identifying diabetes-related genes and cellular pathways linked to changes of leukocyte SIRT1 expression at the time of GDM diagnosis. For this purpose, 122 GDM patients were screened for leukocyte SIRT1 expression, and two subgroups were distinguished, namely GDM/SIRT1(↑) (n = 30, p < 0.05) and GDM/SIRT1(↔) (n = 92, p > 0.05), with significant and insignificant changes in leukocyte SIRT1 expression compared to a normal glucose tolerant (NGT) group (n = 41), respectively. PCR array analysis identified 11 diabetes-related genes with at least a ± 2-fold difference in expression in GDM/SIRT1(↑) patients (n = 9) vs. NGT controls (n = 7); in addition, significant differences in the expression of four of the six investigated genes were confirmed between the entire GDM/SIRT1(↑) group and the whole NGT group (p < 0.05). Interestingly, of these four genes, only ACLY expression was found to significantly differ between GDM/SIRT1(↑) and GDM/SIRT1(↔). This study demonstrates that under hyperglycemic conditions, leukocyte SIRT1 overexpression is accompanied by an over-abundance of three transcripts and an under-abundance of another; these four govern related metabolism, inflammation, and transport functions, suggesting that such alterations might represent systemic biological adaptations with a unique ACLY under-expression in GDM/SIRT1(↑) women.

Diabetes in Pregnancy and MicroRNAs: Promises and Limitations in Their Clinical Application

Maternal diabetes is associated with an increased risk of complications for the mother and her offspring. The latter have an increased risk of foetal macrosomia, hypoglycaemia, respiratory distress syndrome, preterm delivery, malformations and mortality but also of life-long development of obesity and diabetes. Epigenetics have been proposed as an explanation for this long-term risk, and microRNAs (miRNAs) may play a role, both in short- and long-term outcomes. Gestation is associated with increasing maternal insulin resistance, as well as β-cell expansion, to account for the increased insulin needs and studies performed in pregnant rats support a role of miRNAs in this expansion. Furthermore, several miRNAs are involved in pancreatic embryonic development. On the other hand, maternal diabetes is associated with changes in miRNA both in maternal and in foetal tissues. This review aims to summarise the existing knowledge on miRNAs in gestational and pre-gestational diabetes, both as diagnostic biomarkers and as mechanistic players, in the development of gestational diabetes itself and also of short- and long-term complications for the mother and her offspring.

MicroRNA profiling of second trimester maternal plasma shows upregulation of miR-195-5p in patients with gestational diabetes

Gestational diabetes (GDM) is defined as glucose intolerance that presents during pregnancy. It increases the risk of developing diabetes later in life. Recent studies indicate the important role of microRNAs (miRNAs) in the pathogenesis of diabetes, including GDM. However, information on the plasma miRNA profile in GDM patients at the late second trimester, at which time the glucose metabolism disorder manifests, is scarce. This study aimed to determine the plasma miRNA expression profiles of the pregnant women with GDM and compare them to those of pregnant controls using the real-time PCR array method. The study involved 22 single-pregnancy women (mean age ± standard deviation of 29.9 ± 4.5 years old) who underwent a glucose tolerance test between 23 and 31 weeks of gestation. Of them, 13 were diagnosed with GDM. We identified 15 upregulated miRNAs in the GDM patients that were involved in 41 pathways. Among the top 10 associated pathways, fatty acid biosynthesis and fatty acid metabolism were targeted by the most, of the miRNAs investigated, with very low p values (p < 1e-325, false discovery rate corrected). MiR-195-5p, which targeted the highest number of genes important in metabolism, showed the highest fold upregulation. We conclude that increased miRNA expression, especially miR-195-5p, in plasma is characteristic of and causally related to the development of GDM.

Microarray analysis of differentially expressed genes and their functions in omental visceral adipose tissues of pregnant women with vs. without gestational diabetes mellitus

Increasing evidence has shown that insulin resistance in omental visceral adipose tissue (OVAT) is a characteristic of gestational diabetes mellitus (GDM). The present study aimed to identify differentially expressed genes (DEGs) and their associated functions and pathways involved in the pathogenesis of GDM by comparing the expression profiles of OVATs obtained from pregnant Chinese women with and without GDM during caesarian section. A total of 935 DEGs were identified, including 450 downregulated and 485 upregulated genes. In the gene ontology category cellular components, the DEGs were predominantly associated with functions of the extracellular region, while receptor binding was predominant in the molecular function category and biological process terms included antigen processing and presentation, extracellular matrix organization, positive regulation of cell-substrate adhesion, response to nutrients and response to dietary excess. Functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were performed and a functional interaction network was constructed. Functions of downregulated genes included antigen processing and presentation as well as cell adhesion molecules, while those of upregulated genes included transforming growth factor (TGF)-β-signaling, focal adhesion, phosphoinositide-3 kinase-Akt-signaling, P53 signaling, extracellular matrix-receptor interaction and regulation of actin cytoskeleton pathway. The five main pathways associated with GDM were antigen processing and presentation, cell adhesion molecules, Type 1 diabetes mellitus, natural killer cell-mediated cytotoxicity and TGF-β signaling. These pathways were included in the KEGG pathway categories of ‘signaling molecules and interaction’, ‘immune system’ and ‘inflammatory response’, suggesting that these processes are involved in GDM. The results of the present study enhanced the present understanding of the mechanisms associated with insulin resistance in OVATs of GDM.

The relationships between HLA class II alleles and antigens with gestational diabetes mellitus: A meta-analysis

Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset or first recognition during pregnancy. It is associated with an increased risk of pregnancy complications. Susceptibility to GDM is partly determined by genetics and linked with type 1 diabetes-associated high risk HLA class II genes. However, the evidence for this relationship is still highly controversial. In this study, we assessed the relationship between HLA class II variants and GDM. We performed meta-analysis on all of literatures available in PubMed, Embase, Web of Science and China National Knowledge Infrastructure databases. The odds ratio and 95% confidence interval of each variant were estimated. All statistical analyses were conducted using the Comprehensive Meta Analysis 2.2.064 software. At the allelic analysis, DQB1*02, DQB1*0203, DQB1*0402, DQB1*0602, DRB1*03, DRB1*0301 and DRB1*1302 reached a nominal level of significance, and only DQB1*02, DQB1*0602 and DRB1*1302 were statistically significant after Bonferroni correction. At the serological analysis, none of DQ2, DQ6, DR13 and DR17 was statistically significant following Bonferroni correction although they reached a nominal level of significance. In sum, our meta-analysis demonstrated that there were the associations between HLA class II variants and GDM but more studies are required to elucidate how these variants contribute to GDM susceptibility.

Gene expression in term placentas is regulated more by spinal or epidural anesthesia than by late-onset preeclampsia or gestational diabetes mellitus

Pre-eclampsia (PE) and gestational diabetes mellitus (GDM) are common complications of pregnancy, but the mechanisms underlying these disorders remain unclear. The aim was to identify the extent of altered gene expression in term placentas from pregnant women with late-onset PE and GDM compared to controls. RNAseq identified few significantly differentially regulated genes in placental biopsies between PE, GDM, or uncomplicated pregnancy (n = 10 each group). Five genes were altered in placentas from PE including 4 non-coding genes and Angiopoietin 2 (ANGPT2). No genes were significantly regulated by GDM. In contrast, many genes were significantly regulated by fetal, maternal and delivery-specific variables, particularly spinal and epidural anesthesia. We selected ANGPT2 and Chemokine (C-X-C motif) ligand 14 (CXCL14) to test with qPCR in a larger set of placentas (n = 475) and found no differences between the groups. However, regression analysis revealed a stronger association between placental ANGPT2 and CXCL14 mRNA expression and fetal, maternal and delivery-specific variables than diagnostic group. To conclude, the gene expression in term placentas are highly affected by fetal, maternal and delivery specific variables. Few regulated genes were found in late-onset PE and GDM placentas, which may suggest that these conditions could be more affected by maternal factors.

Differential expression network analysis for diabetes mellitus type 2 based on expressed level of islet cells

OBJECTIVE

Diabetes mellitus type 2 (T2DM) is a metabolic disease that has become a pressing issue, with potential adverse impact on mental health. We aimed to explore the potential molecular mechanism of T2DM.

MATERIAL AND METHODS

GSE38642 microarray data downloaded from gene expression omnibus was used to identify the differentially expressed genes (DEGs). Profiling of complex functionality (ProfCom) was used to analyze the complex function and mine T2DM signature genes. Finally, the differential expression network (DEN) was constructed.

RESULTS

We identified 147 DEGs including 59 up- and 88 down-regulated genes. With increasing of degree, the specificity of functional description of DEGs was higher. GO term of "integral to membrane and immune response (not receptor activity) not regulation of immune response" in degree 4 was enriched by 6 DEGs, while the GO term of "immune response" in degree 1 was enriched by 12 DEGs. Two complex functions of integral to membrane an immune response and response to glucose stimulus were enriched by 11 T2DM signature genes including ARG2, GLP1R, PFKFB2, PTPRN, ACSL5, CCR7, IL2RA, IL7R, IL1R2, IL1RL1 and CHST4. Finally, DEN including 11 signature genes and 491 edges was obtained.

CONCLUSION

The identified DEGs especially 11 signature genes such as PTPRN, GLP1R, CCR7 and IL2RA may play important roles in the pathogenesis of T2DM.

Increased expression of immune-related genes in leukocytes of patients with diagnosed gestational diabetes mellitus (GDM)

Compelling evidence indicates that the immune system is linked to metabolism in gestational diabetes mellitus (GDM), but factors participating in these processes still are awaiting identification. Inducible nitric oxide synthase, encoded by the NOS2 gene, and surfactant protein D, encoded by the SFTPD gene, have been implicated in diabetes. We investigated NOS2 and SFTPD mRNA levels in leukocytes obtained from 125 pregnant women with (n = 87) or without (control group; n = 38) GDM, and, in turn, correlated their expression with clinical parameters of subjects. Leukocytes were isolated from the blood of pregnant women and NOS2 and SFTPD expression in these cells was determined by quantitative real time PCR (qRT-PCR). Univariate correlation analyses were performed to assess an association between leukocyte NOS2 and SFTPD expression and clinical characteristics of patients. qRT-PCR experiments disclosed significantly increased leukocyte NOS2 and SFTPD mRNA levels in hyperglycemic GDM patients (P < 0.05). In the entire study group, there were significant positive associations of leukocyte NOS2 and SFTPD mRNAs with C-reactive protein. Additionally, transcript level of SFTPD also correlated positively with fasting glycemia and insulin resistance. This study demonstrates that an impaired glucose metabolism in GDM may be predominant predictor of leukocyte NOS2 and SFTPD overexpression in diabetic patients. Furthermore, alterations in the expression of these genes are associated with glucose metabolism dysfunction and/or inflammation during pregnancy. In addition, these findings support the utilization of leukocytes as good experimental model to study a relationship between immune-related genes and metabolic changes in women with GDM, as well as to assess the potential mechanisms underlying these alterations.

Epigenome-wide and transcriptome-wide analyses reveal gestational diabetes is associated with alterations in the human leukocyte antigen complex

Background

Gestational diabetes mellitus (GDM) affects approximately 10 % of pregnancies in the United States and increases the risk of adverse health outcomes in the offspring. These adult disease propensities may be set by anatomical and molecular alterations in the placenta associated with GDM.

Results

To assess the mechanistic aspects of fetal programming, we measured genome-wide methylation (Infinium HumanMethylation450 BeadChips) and expression (Affymetrix transcriptome microarrays) in placental tissue of 41 GDM cases and 41 matched pregnancies without maternal complications from the Harvard Epigenetic Birth Cohort. Specific transcriptional and epigenetic perturbations associated with GDM status included alterations in the major histocompatibility complex (MHC) region, which were validated in an independent cohort, the Rhode Island Child Health Study. Gene ontology enrichment among gene regulation influenced by GDM revealed an over-representation of immune response pathways among differential expression, reflecting these coordinated changes in the MHC region. This differential methylation and expression may be capturing shifts in cellular composition, reflecting physiological changes in the placenta associated with GDM.

Conclusions

Our study represents the largest investigation of transcriptomic and methylomic differences associated with GDM, providing comprehensive insight into how GDM shapes the intrauterine environment, which may have implications for fetal (re)programming.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0116-y) contains supplementary material, which is available to authorized users.

Gestational tissue transcriptomics in term and preterm human pregnancies: a systematic review and meta-analysis

BACKGROUND

Preterm birth (PTB), or birth before 37 weeks of gestation, is the leading cause of newborn death worldwide. PTB is a critical area of scientific study not only due to its worldwide toll on human lives and economies, but also due to our limited understanding of its pathogenesis and, therefore, its prevention. This systematic review and meta-analysis synthesizes the landscape of PTB transcriptomics research to further our understanding of the genes and pathways involved in PTB subtypes.

METHODS

We evaluated published genome-wide pregnancy studies across gestational tissues and pathologies, including those that focus on PTB, by performing a targeted PubMed MeSH search and systematically reviewing all relevant studies.

RESULTS

Our search yielded 2,361 studies on gestational tissues including placenta, decidua, myometrium, maternal blood, cervix, fetal membranes (chorion and amnion), umbilical cord, fetal blood, and basal plate. Selecting only those original research studies that measured transcription on a genome-wide scale and reported lists of expressed genetic elements identified 93 gene expression, 21 microRNA, and 20 methylation studies. Although 30 % of all PTB cases are due to medical indications, 76 % of the preterm studies focused on them. In contrast, only 18 % of the preterm studies focused on spontaneous onset of labor, which is responsible for 45 % of all PTB cases. Furthermore, only 23 of the 10,993 unique genetic elements reported to be transcriptionally active were recovered 10 or more times in these 134 studies. Meta-analysis of the 93 gene expression studies across 9 distinct gestational tissues and 29 clinical phenotypes showed limited overlap of genes identified as differentially expressed across studies.

CONCLUSIONS

Overall, profiles of differentially expressed genes were highly heterogeneous both between as well as within clinical subtypes and tissues as well as between studies of the same clinical subtype and tissue. These results suggest that large gaps still exist in the transcriptomic study of specific clinical subtypes as well in the generation of the transcriptional profile of well-studied clinical subtypes; understanding the complex landscape of prematurity will require large-scale, systematic genome-wide analyses of human gestational tissues on both understudied and well-studied subtypes alike.

Assessment of immune status using blood transcriptomics and potential implications for global health

The immune system plays a key role in health maintenance and pathogenesis of a wide range of diseases. Leukocytes that are present in the blood convey valuable information about the status of the immune system. Blood transcriptomics, which consists in profiling blood transcript abundance on genome-wide scales, has gained in popularity over the past several years. Indeed, practicality and simplicity largely makes up for what this approach may lack in terms of cell population-level resolution. An extensive survey of the literature reveals increasingly widespread use across virtually all fields of medicine as well as across a number of different animal species, including model organisms but also animals of economical importance. Dissemination across such a wide range of disciplines holds the promise of adding a new perspective, breadth or context, to the considerable depth afforded by whole genome profiling of blood transcript abundance. Indeed, it is only through such contextualization that a truly global perspective will be gained from the use of systems approaches. Also discussed are opportunities that may arise for the fields of immunology and medicine from using blood transcriptomics as a common denominator for developing interactions and cooperation across fields of research that have traditionally been and largely remain compartmentalized. Finally, an argument is made for building immunology research capacity using blood transcriptomics platforms in low-resource and high-disease burden settings.

Predicting of disease genes for gestational diabetes mellitus based on network and functional consistency

OBJECTIVE

Gestational diabetes mellitus (GDM) is a world-widely prevalent disease with adverse outcomes. This study aims to identify its disease genes through bioinformatics analysis.

STUDY DESIGN

The raw gene expression profiling (ID: GSE19649) was downloaded from Gene Expression Omnibus database, including 3 GDM and 2 healthy control specimens. Then limma package in R was utilized to identify differentially expressed genes (DEGs, criteria: p value <0.05 and |log2 FC|>1). Simultaneously, known disease genes of GDM were downloaded from Online Mendelian Inheritance in Man database. Then, DEGs and known disease genes were uploaded to STRING to investigate their protein-protein interactions (PPIs). Gene pairs with confidence score >0.8 were utilized to construct PPI network. Furthermore, pathway and functional enrichment analyses were performed through KOBAS (criterion: p value <0.05) and DAVID (The Database for Annotation, Visualization and Integrated Discovery) software (criterion: false discovery rate <0.05), respectively.

RESULTS

A total of 404 DEGs were identified, including 273 up-regulated and 131 down-regulated DEGs. Moreover, 68 known disease genes of GDM were obtained. Then, 190 gene pairs were identified to significantly interact with each other. After deleting PPIs between DEGs, PPI network was constructed, consisting of 115 gene pairs. Furthermore, genes in PPI network were significantly enriched in 10 functions and 8 pathways.

CONCLUSION

Based on PPI network and functional consistency, 6 candidate genes of GDM were considered to be candidate disease genes of GDM, including CYP1A1, LEPR, ESR1, GYS2, AGRP, and CACNA1G. However, further studies are required to validate these results.

Integrative analysis of the transcriptome profiles observed in type 1, type 2 and gestational diabetes mellitus reveals the role of inflammation

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease, while type 2 (T2D) and gestational diabetes (GDM) are considered metabolic disturbances. In a previous study evaluating the transcript profiling of peripheral mononuclear blood cells obtained from T1D, T2D and GDM patients we showed that the gene profile of T1D patients was closer to GDM than to T2D. To understand the influence of demographical, clinical, laboratory, pathogenetic and treatment features on the diabetes transcript profiling, we performed an analysis integrating these features with the gene expression profiles of the annotated genes included in databases containing information regarding GWAS and immune cell expression signatures.

METHODS

Samples from 56 (19 T1D, 20 T2D, and 17 GDM) patients were hybridized to whole genome one-color Agilent 4x44k microarrays. Non-informative genes were filtered by partitioning, and differentially expressed genes were obtained by rank product analysis. Functional analyses were carried out using the DAVID database, and module maps were constructed using the Genomica tool.

RESULTS

The functional analyses were able to discriminate between T1D and GDM patients based on genes involved in inflammation. Module maps of differentially expressed genes revealed that modulated genes: i) exhibited transcription profiles typical of macrophage and dendritic cells; ii) had been previously associated with diabetic complications by association and by meta-analysis studies, and iii) were influenced by disease duration, obesity, number of gestations, glucose serum levels and the use of medications, such as metformin.

CONCLUSION

This is the first module map study to show the influence of epidemiological, clinical, laboratory, immunopathogenic and treatment features on the transcription profiles of T1D, T2D and GDM patients.

The effect of pre-existing maternal obesity on the placental proteome: two-dimensional difference gel electrophoresis coupled with mass spectrometry

Our aim was to study the protein expression profiles of placenta obtained from lean and obese pregnant women with normal glucose tolerance at the time of term Caesarean section. We used two-dimensional difference gel electrophoresis (2D-DIGE), utilising narrow-range immobilised pH gradient strips that encompassed the broad pH range of 4-5 and 5-6, followed by MALDI-TOF mass spectrometry of selected protein spots. Western blot and quantitative RT-PCR (qRT-PCR) analyses were performed to validate representative findings from the 2D-DIGE analysis. Eight proteins were altered (six down-regulated and two up-regulated on obese placentas). Annexin A5 (ANXA5), ATP synthase subunit beta, mitochondria (ATPB), brain acid soluble protein 1 (BASP1), ferritin light chain (FTL), heterogeneous nuclear ribonucleoprotein C (HNRPC) and vimentin (VIME) were all lower in obese patients. Alpha-1-antitrypsin (A1AT) and stress-70 protein, mitochondrial (GRP75) were higher in obese patients. Western blot analysis of ANXA5, ATPB, FTL, VIME, A1AT and GRP75 confirmed the findings from the 2D-DIGE analysis. For brain acid soluble protein 1 and HNRPC, qRT-PCR analysis also confirmed the findings from the 2D-DIGE analysis. Immunohistochemical analysis was also used to determine the localisation of the proteins in human placenta. In conclusion, proteomic analysis of placenta reveals differential expression of several proteins in patients with pre-existing obesity. These proteins are implicated in a variety of cellular functions such as regulation of growth, cytoskeletal structure, oxidative stress, inflammation, coagulation and apoptosis. These disturbances may have significant implications for fetal growth and development.