Phthalate exposure in utero causes epigenetic changes and impairs insulin signalling

Mono-2-ethylhexyl phthalate-induced downregulation of MMP11 in foreskin fibroblasts contributes to the pathogenesis of hypospadias

Hypospadias is one of the most common congenital anomalies of the male urogenital system, and di(2-ethylhexyl) phthalate (DEHP), a widely used endocrine-disrupting chemical (EDC), is considered a significant risk factor for this condition. Mono-2-ethylhexyl phthalate (MEHP), the toxic active metabolite of DEHP, has been proven to affect penile development and ultimately result in the hypospadias phenotype. However, while it is acknowledged that hypospadias arises from the aberrant development of multiple penile tissues, the specific impact of MEHP on human foreskin tissue development and its underlying molecular mechanisms of action remain unclear. In this study, we constructed an in vitro toxicity assay for MEHP using human foreskin fibroblasts and employed high-throughput RNA sequencing to investigate the molecular mechanisms subserving the defects in cellular function. We subsequently conducted multi-omics data analysis using public databases to analyze key target genes, and identified MMP11 as a chief downstream gene responsible for the effects of MEHP on HFF-1 cell migration. Through molecular docking analysis and molecular biology experiments, we further demonstrated that the nuclear receptor PPAR-gamma was activated upon binding with MEHP, leading to the suppression of MMP11 expression. Additionally, we found that epigenetic modifications induced by MEHP were also involved in its pathogenic effects on hypospadias. Our research highlights the crucial role of impaired cellular proliferation and migration in MEHP-induced hypospadias. We identified the MEHP/PPAR-gamma/MMP11 pathway as a novel pathogenic mechanism, providing important potential targets for future preventive strategies with respect to hypospadias.

Effects of Developmental Lead and Phthalate Exposures on DNA Methylation in Adult Mouse Blood, Brain, and Liver: A Focus on Genomic Imprinting by Tissue and Sex

BACKGROUND

Maternal exposure to environmental chemicals can cause adverse health effects in offspring. Mounting evidence supports that these effects are influenced, at least in part, by epigenetic modifications. It is unknown whether epigenetic changes in surrogate tissues such as the blood are reflective of similar changes in target tissues such as cortex or liver.

OBJECTIVE

We examined tissue- and sex-specific changes in DNA methylation (DNAm) associated with human-relevant lead (Pb) and di(2-ethylhexyl) phthalate (DEHP) exposure during perinatal development in cerebral cortex, blood, and liver.

METHODS

Female mice were exposed to human relevant doses of either Pb (32  ppm ) via drinking water or DEHP (5 mg / kg-day ) via chow for 2 weeks prior to mating through offspring weaning. Whole genome bisulfite sequencing (WGBS) was utilized to examine DNAm changes in offspring cortex, blood, and liver at 5 months of age. Metilene and methylSig were used to identify differentially methylated regions (DMRs). Annotatr and ChIP-enrich were used for genomic annotations and gene set enrichment tests of DMRs, respectively.

RESULTS

The cortex contained the majority of DMRs associated with Pb (66%) and DEHP (57%) exposure. The cortex also contained the greatest degree of overlap in DMR signatures between sexes (n = 13 and 8 DMRs with Pb and DEHP exposure, respectively) and exposure types (n = 55 and 39 DMRs in males and females, respectively). In all tissues, detected DMRs were preferentially found at genomic regions associated with gene expression regulation (e.g., CpG islands and shores, 5' UTRs, promoters, and exons). An analysis of GO terms associated with DMR-containing genes identified imprinted genes to be impacted by both Pb and DEHP exposure. Of these, Gnas and Grb10 contained DMRs across tissues, sexes, and exposures, with some signatures replicated between target and surrogate tissues. DMRs were enriched in the imprinting control regions (ICRs) of Gnas and Grb10, and we again observed a replication of DMR signatures between blood and target tissues. Specifically, we observed hypermethylation of the Grb10 ICR in both blood and liver of Pb-exposed male animals.

CONCLUSIONS

These data provide preliminary evidence that imprinted genes may be viable candidates in the search for epigenetic biomarkers of toxicant exposure in target tissues. Additional research is needed on allele- and developmental stage-specific effects, as well as whether other imprinted genes provide additional examples of this relationship. https://doi.org/10.1289/EHP14074.

Endocrine disrupting chemicals: gestational diabetes and beyond

Gestational Diabetes Mellitus (GDM) has been on the rise for the last two decades along with the growing incidence of obesity. The ubiquitous use of Endocrine-Disrupting Chemicals (EDCs) worldwide has been associated with this increase in GDM incidence. Epigenetic modifications such as DNA methylation, histone acetylation, and methylation have been associated with prenatal exposure to EDCs. EDC exposure can also drive a sustained disruption of the hypothalamus-pituitary-thyroid axis and various other signaling pathways such as thyroid signaling, PPARγ signaling, PI3K-AKT signaling. This disruption leads to impaired glucose metabolism, insulin resistance as well as β-cell dysfunction, which culminate into GDM. Persistent EDC exposure in pregnant women also increases adipogenesis, which results in gestational weight gain. Importantly, pregnant mothers transfer these EDCs to the fetus via the placenta, thus leading to other pregnancy-associated complications such as intrauterine growth restriction (IUGR), and large for gestational age neonates. Furthermore, this early EDC exposure of the fetus increases the susceptibility of the infant to metabolic diseases in early life. The transgenerational impact of EDCs is also associated with higher vascular tone, cognitive aberrations, and enhanced susceptibility to lifestyle disorders including reproductive health anomalies. The review focuses on the impact of environmental toxins in inducing epigenetic alterations and increasing the susceptibility to metabolic diseases during pregnancy needs to be extensively studied such that interventions can be developed to break this vicious cycle. Furthermore, the use of EDC-associated ExomiRs from the serum of patients can help in the early diagnosis of GDM, thereby leading to triaging of patients based on increasing risk factor of the clinicopathological condition.

Non-monotonic dose-response of di-(2-ethylhexyl) phthalate isolated from Penicillium citrinum XT6 on adipogenesis and expression of PPARγ and GLUT4 in 3T3-L1 adipocytes

OBJECTIVES

Adipogenesis is the fat cell formation process regulated by peroxisome proliferator-activated receptors (PPARγ). The insulin-responsive glucose transporter 4 (GLUT4) has a major role in glucose uptake and metabolism in insulin target tissues (i.e., adipose and muscle cells). The interplay between PPARγ and GLUT4 is essential for proper glucose homeostasis. This study aimed to isolate, elucidate, and investigate the effect of an isolated compound from Penicillium citrinum XT6 on adipogenesis, PPARγ, and GLUT4 expression in 3T3-L1 adipocytes.

METHODS

The isolated compound was determined by analyzing spectroscopic data (LC-MS, FT-IR, Spectrophotometry UV-Vis, and NMR). The adipogenesis activity of the isolated compound in 3T3-L1 cells was determined by the Oil Red O staining method. RT-PCR was used to analyze the gene expression of PPARγ and GLUT4.

RESULTS

Di-(2-ethylhexyl)-phthalate (DEHP) was the isolated compound from P.citrinum XT6. The results revealed adipogenesis stimulation and inhibition, as well as PPARγ and GLUT4 expressions.

CONCLUSIONS

DEHP showed a non-monotonic dose-response (NMDR) effect on adipogenesis and PPARγ and GLUT4 expression. It is the first study that reveals DEHP's NMDR effects on lipid and glucose metabolism in adipocytes.

Worldwide risk assessment of phthalates and bisphenol A in humans: The need for updating guidelines

Phthalates and bisphenol A (BPA) are compounds widely used as raw materials in the production of plastics, making them ubiquitous in our daily lives. This results in widespread human exposure and human health hazards. Although efforts have been conducted to evaluate the risk of these compounds in diverse regions around the world, data scattering may mask important trends that could be useful for updating current guidelines and regulations. This study offers a comprehensive global assessment of human exposure levels to these chemicals, considering dietary and nondietary ingestion, and evaluates the associated risk. Overall, the exposure daily intake (EDI) values of phthalates and BPA reported worldwide ranged from 1.11 × 10-7 to 3 700 µg kg bw-1 d-1 and from 3.00 × 10-5 to 6.56 µg kg bw-1 d-1, respectively. Nevertheless, the dose-additive effect of phthalates has been shown to increase the EDI up to 5 100 µg kg bw-1 d-1, representing a high risk in terms of noncarcinogenic (HQ) and carcinogenic (CR) effects. The worldwide HQ values of phthalates and BPA ranged from 2.25 × 10-7 to 3.66 and from 2.74 × 10-7 to 9.72 × 10-2, respectively. Meanwhile, a significant number of studies exhibit high CR values for benzyl butyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP). Moreover, DEHP has shown the highest maximum mean CR values for humans in numerous studies, up to 179-fold higher than BBP. Despite mounting evidence of the harmful effects of these chemicals at low-dose exposure on animals and humans, most regulations have not been updated. Thus, this article emphasizes the need for updating guidelines and public policies considering compelling evidence for the adverse effects of low-dose exposure, and it cautions against the use of alternative plasticizers as substitutes for phthalates and BPA because of the significant gaps in their safety.

Effects of Developmental Lead and Phthalate Exposures on DNA Methylation in Adult Mouse Blood, Brain, and Liver Identifies Tissue- and Sex-Specific Changes with Implications for Genomic Imprinting

Background

Maternal exposure to environmental chemicals can cause adverse health effects in offspring. Mounting evidence supports that these effects are influenced, at least in part, by epigenetic modifications.

Objective

We examined tissue- and sex-specific changes in DNA methylation (DNAm) associated with human-relevant lead (Pb) and di(2-ethylhexyl) phthalate (DEHP) exposure during perinatal development in cerebral cortex, blood, and liver.

Methods

Female mice were exposed to human relevant doses of either Pb (32ppm) via drinking water or DEHP (5 mg/kg-day) via chow for two weeks prior to mating through offspring weaning. Whole genome bisulfite sequencing (WGBS) was utilized to examine DNAm changes in offspring cortex, blood, and liver at 5 months of age. Metilene and methylSig were used to identify differentially methylated regions (DMRs). Annotatr and Chipenrich were used for genomic annotations and geneset enrichment tests of DMRs, respectively.

Results

The cortex contained the majority of DMRs associated with Pb (69%) and DEHP (58%) exposure. The cortex also contained the greatest degree of overlap in DMR signatures between sexes (n = 17 and 14 DMRs with Pb and DEHP exposure, respectively) and exposure types (n = 79 and 47 DMRs in males and females, respectively). In all tissues, detected DMRs were preferentially found at genomic regions associated with gene expression regulation (e.g., CpG islands and shores, 5' UTRs, promoters, and exons). An analysis of GO terms associated with DMR-containing genes identified imprinted genes to be impacted by both Pb and DEHP exposure. Of these, Gnas and Grb10 contained DMRs across tissues, sexes, and exposures. DMRs were enriched in the imprinting control regions (ICRs) of Gnas and Grb10, with 15 and 17 ICR-located DMRs across cortex, blood, and liver in each gene, respectively. The ICRs were also the location of DMRs replicated across target and surrogate tissues, suggesting epigenetic changes these regions may be potentially viable biomarkers.

Conclusions

We observed Pb- and DEHP-specific DNAm changes in cortex, blood, and liver, and the greatest degree of overlap in DMR signatures was seen between exposures followed by sex and tissue type. DNAm at imprinted control regions was altered by both Pb and DEHP, highlighting the susceptibility of genomic imprinting to these exposures during the perinatal window of development.

Modulation of fetoplacental growth, development and reproductive function by endocrine disrupters

Maternal endocrine homeostasis is vital to a successful pregnancy, regulated by several hormones such as human chorionic gonadotropin, estrogen, leptin, glucocorticoid, insulin, prostaglandin, and others. Endocrine stress during pregnancy can modulate nutrient availability from mother to fetus, alter fetoplacental growth and reproductive functions. Endocrine disrupters such as bisphenols (BPs) and phthalates are exposed in our daily life's highest volume. Therefore, they are extensively scrutinized for their effects on metabolism, steroidogenesis, insulin signaling, and inflammation involving obesity, diabetes, and the reproductive system. BPs have their structural similarity to 17-β estradiol and their ability to bind as an agonist or antagonist to estrogen receptors to elicit an adverse response to the function of the endocrine and reproductive system. While adults can negate the adverse effects of these endocrine-disrupting chemicals (EDCs), fetuses do not equip themselves with enzymatic machinery to catabolize their conjugates. Therefore, EDC exposure makes the fetoplacental developmental window vulnerable to programming in utero. On the one hand prenatal BPs and phthalates exposure can impair the structure and function of the ovary and uterus, resulting in placental vascular defects, inappropriate placental expression of angiogenic growth factors due to altered hypothalamic response, expression of nutrient transporters, and epigenetic changes associated with maternal endocrine stress. On the other, their exposure during pregnancy can affect the offspring's metabolic, endocrine and reproductive functions by altering fetoplacental programming. This review highlights the latest development in maternal metabolic and endocrine modulations from exposure to estrogenic mimic chemicals on subcellular and transgenerational changes in placental development and its effects on fetal growth, size, and metabolic & reproductive functions.

Mono-(2-ethylhexyl)-phthalate potentiates methylglyoxal-induced blood-brain barrier damage via mitochondria-derived oxidative stress and bioenergetic perturbation

Phthalates in contaminated foods and personal care products are one of the most frequently exposed chemicals with a public health concern. Phthalate exposure is related to cardiovascular diseases, including diabetic vascular complications and cerebrovascular diseases, yet the mechanism is still unclear. The blood-brain barrier (BBB) integrity disruption is strongly associated with cardiovascular and neurological disease exacerbation. We investigated BBB damage by di-(2-ethylhexyl) phthalate (DEHP) or its metabolite mono-(2-ethylhexyl) phthalate (MEHP) using brain endothelial cells and rat models. BBB damage by the subthreshold level of MEHP, but not a DEHP, significantly increased by the presence of methylglyoxal (MG), a reactive dicarbonyl compound whose levels increase in the blood in hyperglycemic conditions in diabetic patients. Significant potentiation in apoptosis and autophagy activation, mitochondria-derived reactive oxygen species (ROS) production, and mitochondrial metabolic disturbance were observed in brain ECs by co-exposure to MG and MEHP. N-acetyl cysteine (NAC) restored autophagy activation as well as tight junction protein impairment induced by co-exposure to MG and MEHP. Intraperitoneal administration of MG and MEHP significantly altered mitochondrial membrane potential and tight junction integrity in rat brain endothelium. This study may provide novel insights into enhancing phthalate toxicity in susceptible populations, such as diabetic patients.

Glucose transporter 4: Insulin response mastermind, glycolysis catalyst and treatment direction for cancer progression

The glucose transporter family (GLUT) consists of fourteen members. It is responsible for glucose homeostasis and glucose transport from the extracellular space to the cell cytoplasm to further cascade catalysis. GLUT proteins are encoded by the solute carrier family 2 (SLC2) genes and are members of the major facilitator superfamily of membrane transporters. Moreover, different GLUTs also have their transporter kinetics and distribution, so each GLUT member has its uniqueness and importance to play essential roles in human physiology. Evidence from many studies in the field of diabetes showed that GLUT4 travels between the plasma membrane and intracellular vesicles (GLUT4-storage vesicles, GSVs) and that the PI3K/Akt pathway regulates this activity in an insulin-dependent manner or by the AMPK pathway in response to muscle contraction. Moreover, some published results also pointed out that GLUT4 mediates insulin-dependent glucose uptake. Thus, dysfunction of GLUT4 can induce insulin resistance, metabolic reprogramming in diverse chronic diseases, inflammation, and cancer. In addition to the relationship between GLUT4 and insulin response, recent studies also referred to the potential upstream transcription factors that can bind to the promoter region of GLUT4 to regulating downstream signals. Combined all of the evidence, we conclude that GLUT4 has shown valuable unknown functions and is of clinical significance in cancers, which deserves our in-depth discussion and design compounds by structure basis to achieve therapeutic effects. Thus, we intend to write up a most updated review manuscript to include the most recent and critical research findings elucidating how and why GLUT4 plays an essential role in carcinogenesis, which may have broad interests and impacts on this field.

Consequences of in vitro benzyl butyl phthalate exposure for blubber gene expression and insulin-induced Akt activation in juvenile grey seals

Plastic and plasticiser pollution of marine environments is a growing concern. Although phthalates, one group of plasticisers, are rapidly metabolised by mammals, they are found ubiquitously in humans and have been linked with metabolic disorders and altered adipose function. Phthalates may also present a threat to marine mammals, which need to rapidly accumulate and mobilise their large fat depots. High molecular weight (HMW) phthalates may be most problematic because they can accumulate in adipose. We used blubber explants from juvenile grey seals to examine the effects of overnight exposure to the HMW, adipogenic phthalate, benzyl butyl phthalate (BBzP) on expression of key adipose-specific genes and on phosphorylation of Akt in response to insulin. We found substantial differences in transcript abundance of Pparγ, Insig2, Fasn, Scd, Adipoq and Lep between moult stages, when animals were also experiencing differing mass changes, and between tissue depths, which likely reflect differences in blubber function. Akt abundance was higher in inner compared to outer blubber, consistent with greater metabolic activity in adipose closer to muscle than skin, and its phosphorylation was stimulated by insulin. Transcript abundance of Pparγ and Fasn (and Adipoq in some animals) were increased by short term (30 min) insulin exposure. In addition, overnight in vitro BBzP exposure altered insulin-induced changes in Pparγ (and Adipoq in some animals) transcript abundance, in a tissue depth and moult stage-specific manner. Basal or insulin-induced Akt phosphorylation was not changed. BBzP thus acted rapidly on the transcript abundance of key adipose genes in an Akt-independent manner. Our data suggest phthalate exposure could alter seal blubber development or function, although the whole animal consequences of these changes are not yet understood. Knowledge of typical phthalate exposures and toxicokinetics would help to contextualise these findings in terms of phthalate-induced metabolic disruption risk and consequences for marine mammal health.

Adverse cardiovascular effects and potential molecular mechanisms of DEHP and its metabolites-A review

Currently, cardiovascular disease (CVD) is a health hazard that is associated with progressive deterioration upon exposure to environmental pollutants. Di(2-ethylhexyl) phthalate (DEHP) has been one of the focuses of emerging concern due to its ubiquitous nature and its toxicity to the cardiovascular (CV) system. DEHP has been noted as a causative risk factor or a risk indicator for the initiation and augment of CVDs. DEHP represents a precursor that contributes to the pathogenesis of CVDs through its active metabolites, which mainly include mono (2-ethylhexyl) phthalate (MEHP). Herein, we systematically presented the association between DEHP and its metabolites and adverse CV outcomes and discussed the corresponding effects, underlying mechanisms and possibly interventions. Epidemiological and experimental evidence has suggested that DEHP and its metabolites have significant impacts on processes and factors involved in CVD, such as cardiac developmental toxicity, cardiac injury and apoptosis, cardiac arrhythmogenesis, cardiac metabolic disorders, vascular structural damage, atherogenesis, coronary heart disease and hypertension. DNA methylation, PPAR-related pathways, oxidative stress and inflammation, Ca²⁺ homeostasis disturbance may pinpoint the relevant mechanisms. The preventive and therapeutic measures are potentially related with P-glycoprotein, heat-shock proteins, some antioxidants, curcumin, apigenin, β-thujaplicin, glucagon-like peptide-1 receptor agonists and Ang-converting enzyme inhibitors and so on. Promisingly, future investigations should aid in thoroughly assessing the causal relationship and molecular interactions between CVD and DEHP and its metabolites and explore feasible prevention and treatment measures accordingly.

Trimester-specific phthalate exposures in pregnancy are associated with circulating metabolites in children

Background

Prenatal phthalates exposures have been related to adiposity in peripuberty in a sex-specific fashion. Untargeted metabolomics analysis to assess circulating metabolites offers the potential to characterize biochemical pathways by which early life exposures influence the development of cardiometabolic risk during childhood and adolescence, prior to becoming evident in clinical markers.

Methods

Among mother-child dyads from the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) birth cohort, we measured 9 phthalate metabolites and bisphenol A in maternal spot urine samples obtained during each trimester of pregnancy, corrected for urinary specific gravity and natural log-transformed. In 110 boys and 124 girls aged 8–14 years, we used a mass-spectrometry based untargeted metabolomics platform to measure fasting serum metabolites, yielding 572 annotated metabolites. We estimated the associations between trimester-specific urinary toxicants and each serum metabolite, among all children or stratified by sex and adjusting for child age, BMI z-score, and pubertal onset. We accounted for multiple comparisons using a 10% false discovery rate (q<0.1).

Results

Associations between exposures and metabolites were observed among all children and in sex-stratified analyses (q<0.1). First trimester MEP, MiBP, and MCPP were associated with decreased 2-deoxy-D-glucose among all children. Among girls, third trimester concentrations of MECPP, MEHHP, MEHP, and MCPP were associated with 15, 13, 1, and 10 metabolites, respectively, including decreased choline and increased acylcarnitines and saturated FAs (FA). Among boys, third trimester MIBP was positively associated with 9 features including long chain saturated FAs, and second trimester MBzP was inversely associated with thyroxine.

Conclusions

Metabolomics biomarkers may reflect sex- and exposure timing-specific responses to prenatal phthalate exposures manifesting in childhood that may not be detected using standard clinical markers of cardiometabolic risk.

Hydrogen Sulfide Regulates Irisin and Glucose Metabolism in Myotubes and Muscle of HFD-Fed Diabetic Mice

Irisin, a novel myokine, is secreted by the muscle following proteolytic cleavage of fibronectin type III domain containing 5 (FNDC5) and is considered a novel regulator of glucose homeostasis. Cystathionine γ-lyase (CSE) produces hydrogen sulfide (H₂S) and is involved in glucose homeostasis. We examined the hypothesis that H₂S deficiency leads to decreased FNDC5 and irisin secretion, and thereby alters glucose metabolism. High-fat diet-fed mice exhibited elevated blood glucose and significantly reduced levels of CSE, H₂S, and PGC-1α, with decreased FNDC5/irisin levels and increased oxidative stress in the muscle compared with those of normal diet-fed mice (control). High glucose or palmitate decreases CSE/PGC-1α/FNDC5 levels and glucose uptake in myotubes. Inhibitors (propargylglycine and aminooxyacetate) of H₂S producing enzymes or CSE siRNA significantly decreased levels of H₂S and FNDC5 along with PGC-1α; similar H₂S-deficient conditions also resulted in decreased GLUT4 and glucose uptake. The levels of H₂S, PGC-1α, and FNDC5 and glucose uptake were significantly upregulated after treatment with l-cysteine or an H₂S donor. Myoblast differentiation showed upregulation of PGC-1α and FNDC5, which was consistent with the increased expression of CSE/H₂S. These findings suggest that the upregulation of H₂S levels can have beneficial effects on glucose homeostasis via activation of the PGC-1α/FNDC5/irisin signaling pathway.

Killing two birds with one stone: Pregnancy is a sensitive window for endocrine effects on both the mother and the fetus

Pregnancy is a complex process requiring tremendous physiological changes in the mother in order to fulfill the needs of the growing fetus, and to give birth, expel the placenta and nurse the newborn. These physiological modifications are accompanied with psychological changes, as well as with variations in habits and behaviors. As a result, this period of life is considered as a sensitive window as impaired functional and physiological changes in the mother can have short- and long-term impacts on her health. In addition, dysregulation of the placenta and of mechanisms governing placentation have been linked to chronic diseases later-on in life for the fetus, in a concept known as the Developmental Origin of Health and Diseases (DOHaD). This concept stipulates that any change in the environment during the pre-conception and perinatal (in utero life and neonatal) period to puberty, can be "imprinted" in the organism, thereby impacting the health and risk of chronic diseases later in life. Pregnancy is a succession of events that is regulated, in large part, by hormones and growth factors. Therefore, small changes in hormonal balance can have important effects on both the mother and the developing fetus. An increasing number of studies demonstrate that exposure to endocrine disrupting compounds (EDCs) affect both the mother and the fetus giving rise to growing concerns surrounding these exposures. This review will give an overview of changes that happen during pregnancy with respect to the mother, the placenta, and the fetus, and of the current literature regarding the effects of EDCs during this specific sensitive window of exposure.

Di-(2-ethylhexyl) phthalate triggers DNA methyltransferase 1 expression resulting in elevated CpG-methylation and enrichment of MECP2 in the p21 promoter in vitro

Leaching of the plastic constituents leading to their chronic exposure to humans is a major concern for our environmental and occupational health. Our previous and other numerous studies have demonstrated that environmental chemicals like di (2-Ethylhexyl)-phthalate (DEHP) could pose a risk towards the epigenetic mechanisms. Yet, the mechanisms underlying its possible epigenotoxicity are poorly understood. We aimed to assess the impact of DEHP exposure to the human breast cancer cells (MCF-7) and resultant changes in DNA methylation regulators ultimately altering the expression of the cell cycle regulator p21 as a model gene. The MCF-7 cells were exposed to environmentally relevant concentrations (50-500 nM) for 24 h. The results showed that DEHP was proliferative towards the MCF-7 cells while it induced global DNA hypermethylation with selective upregulation of DNMT1 and MECP2. In addition, DEHP significantly reduced p53 protein and its enrichment to the DNMT1 promoter binding site, while elevating SP1 and E2F1 transcription factor levels, stimulating their binding to the promoter DNA. Coincidently, increased DNMT1 level was highly associated with loss of p21 expression and increased cyclin D1 levels. Importantly, the p21, but not cyclin D1 promoter CpG-dinucleotides were hypermethylated after exposure to 500 nM DEHP for 24 h. Furthermore, it was observed that DEHP significantly enriched DNMT1 and MECP2 to the p21 promoter to induce DNA methylation-based epigenetic silencing of p21, resulting in increased cell proliferation. Our results suggest DEHP could potentially induce the epigenetic alterations that might increase the risk of breast cancer, given that the underlying mechanisms should be fully elucidated.

Association Between Phthalate Exposure in Pregnancy and Gestational Diabetes: A Chinese Cross-Sectional Study

Objective

The present study aims to explore the association between phthalate exposure and the risk of gestational diabetes mellitus (GDM).

Materials and Methods

A total of 11 plasticizer metabolites were measured in patient morning urine using high-performance liquid chromatography. Furthermore, fasting blood glucose and fasting insulin were detected in first-trimester blood samples. The chemical concentration was described using the median, the metabolite concentration difference between the GDM and control groups was compared using the bootstrap method, and the correlations of the fasting blood glucose, fasting insulin, insulin resistance index, and phthalic acid ester (PAE) metabolites were analyzed using Spearman correlation analysis. The multivariate logistic regression model and predictive probability map were performed to help assess the linearity and nature of any dose–response relationship.

Results

Of the 224 women recruited for the present study, 200 met the inclusion criteria. Their measured outcomes and biomonitoring data were examined for the presence of chemicals. The results showed that the patients in the GDM group had higher mono-(2-ethylhexyl) phthalate (MEHP) and methylerythritol cyclophosphane concentrations in their bodies than the patients in the control group. Statistically significant MEHP–GDM associations were also observed (P < 0.001). The GDM and MEHP dose–response relationships were different among pregnant women aged <35 years and those aged >35 years (P < 0.001). Furthermore, gestational age >28 weeks exhibited similar changes to those aged ≤28 weeks (P = 0.059).

Conclusion

The findings of the present study add to the growing body of evidence supporting phthalate exposure as a GDM risk factor.

Developmental toxicant exposures and sex-specific effects on epigenetic programming and cardiovascular health across generations

Despite substantial strides in diagnosis and treatment, cardiovascular diseases (CVDs) continue to represent the leading cause of death in the USA and around the world, resulting in significant morbidity and loss of productive years of life. It is increasingly evident that environmental exposures during early development can influence CVD risk across the life course. CVDs exhibit marked sexual dimorphism, but how sex interacts with environmental exposures to affect cardiovascular health is a critical and understudied area of environmental health. Emerging evidence suggests that developmental exposures may have multi- and transgenerational effects on cardiovascular health, with potential sex differences; however, further research in this important area is urgently needed. Lead (Pb), phthalate plasticizers, and perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with numerous adverse human health effects. Notably, recent evidence suggests that developmental exposure to each of these toxicants has sex-specific effects on cardiovascular outcomes, but the underlying mechanisms, and their effects on future generations, require further investigation. This review article will highlight the role for the developmental environment in influencing cardiovascular health across generations, with a particular emphasis on sex differences and epigenetic mechanisms. In particular, we will focus on the current evidence for adverse multi and transgenerational effects of developmental exposures to Pb, phthalates, and PFAS and highlight areas where further research is needed.

In utero exposure to endocrine-disrupting chemicals, maternal factors and alterations in the epigenetic landscape underlying later-life health effects

Widespread persistence of endocrine-disrupting chemicals (EDCs) in the environment has mandated the need to study their potential effects on an individual's long-term health after both acute and chronic exposure periods. In this review article a particular focus is given on in utero exposure to EDCs in rodent models which resulted in altered epigenetic programming and transgenerational effects in the offspring causing disrupted reproductive and metabolic phenotypes. The literature to date establishes the impact of transgenerational effects of EDCs potentially associated with epigenetic mediated mechanisms. Therefore, this review aims to provide a comprehensive overview of epigenetic programming and it's regulation in mammals, primarily focusing on the epigenetic plasticity and susceptibility to exogenous hormone active chemicals during the early developmental period. Further, we have also in depth discussed the epigenetic alterations associated with the exposure to selected EDCs such as Bisphenol A (BPA), di-2-ethylhexyl phthalate (DEHP) and vinclozlin upon in utero exposure especially in rodent models.

MEHP induces pyroptosis and autophagy alternation by cathepsin B activation in INS-1 cells

Mono-(2-ethylhexyl) phthalate (MEHP) is a primary metabolite of di-(2-ethyl hexyl) phthalate (DEHP) in the organism, which is a major component of plasticizers used worldwide. Exposure to DEHP causes pancreatic beta-cell (INS-1 cells) dysfunction, which is associated with insulin resistance and type 2 diabetes. The present study shows that MEHP decreases the cell viability of INS-1 cells in a concentration-dependent manner and induces pyroptosis at 400 μM. Furthermore, the 400 μM MEHP causes increased lysosomal membrane permeability and cathepsin B (CTSB) release, resulting in NLRP3 activation and pyroptosis. Additionally, low concentration of MEHP (50-200 μM) induces upregulation of autophagy, while 400 μM MEHP reduces autophagy level in INS-1 cells via altering mTORC1 phosphorylation. Surprisingly, CTSB contributes to mTORC1 activation in INS-1 cells treated with 400 μM MEHP. Furthermore, autophagy can alleviate inflammatory response by reducing CTSB activation in MEHP-treated INS-1 cells. These results indicate that exposure to MEHP induces pyroptosis and upregulates autophagy levels in a CTSB-dependent manner, and autophagy plays an essential role in pyroptosis onset in INS-1 cells. Our findings provide a new perspective of the connection between CTSB and autophagy.

Effect of maternal apical periodontitis on the final step of insulin signalling and inflammatory pathway in the adult male offspring of rats

AIM

To evaluate the final step of insulin signalling, inflammatory pathway (related to the inhibition of insulin signalling), peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) protein content and DNA methylation in the Slc2a4 gene promoter region in the skeletal muscle of adult male offspring of rats with apical periodontitis (AP) in a single tooth or in four teeth.

METHODOLOGY

Female Wistar rats were distributed into three groups: a control group, a group with one tooth with AP and a group with four teeth with AP. Thirty days after induction of AP, female rats from all groups were mated with healthy male rats. When male offspring reached 75 days of age, the following analyses were performed in the gastrocnemius muscle (GM): insulin-stimulated Akt serine and threonine phosphorylation status; NF-κB p50 and p65 subunits phosphorylation status; GLUT4, TNF-α and PGC-1α protein content by Western blotting; GLUT4 and TNF-α gene expression by real-time polymerase chain reaction (PCR); and DNA methylation in the Slc2a4 gene promoter region by restriction digestion and real-time PCR. Analysis of variance was performed, followed by Tukey's post hoc test. p values <.05 were considered to be statistically significant.

RESULTS

Maternal AP in four teeth decreased insulin-stimulated Akt serine and threonine phosphorylation status, reduced GLUT4 gene expression and its protein content, and increased NF-κB p50 and p65 subunits phosphorylation status in the GM of adult offspring. There were no alterations in the parameters analysed in the GM of adult offspring of rats with AP in a single tooth. In addition, maternal AP did not affect TNF-α gene expression and its protein content, PGC-1α protein content and DNA methylation in the Slc2a4 gene promoter region in the GM of adult offspring.

CONCLUSIONS

Maternal AP in four teeth was associated with impairment in the final step of insulin signalling in the GM of adult male offspring in rats. An increase in NF-κB activity may be involved in this decrease in insulin signalling. This study demonstrates the impact of maternal AP on the health of offspring, demonstrating the importance of maintaining adequate maternal oral health to prevent diseases in adult offspring in rats.

Environmental Exposure to Endocrine Disrupting Chemicals Influences Genomic Imprinting, Growth, and Metabolism

Genomic imprinting is an epigenetic mechanism that results in monoallelic, parent-of-origin-specific expression of a small number of genes. Imprinted genes play a crucial role in mammalian development as their dysregulation result in an increased risk of human diseases. DNA methylation, which undergoes dynamic changes early in development, is one of the epigenetic marks regulating imprinted gene expression patterns during early development. Thus, environmental insults, including endocrine disrupting chemicals during critical periods of fetal development, can alter DNA methylation patterns, leading to inappropriate developmental gene expression and disease risk. Here, we summarize the current literature on the impacts of in utero exposure to endocrine disrupting chemicals on genomic imprinting and metabolism in humans and rodents. We evaluate how early-life environmental exposures are a potential risk factor for adult metabolic diseases. We also introduce our mouse model of phthalate exposure. Finally, we describe the potential of genomic imprinting to serve as an environmental sensor during early development and as a novel biomarker for postnatal health outcomes.

Lactational polychlorinated biphenyls exposure induces epigenetic alterations in the Leydig cells of progeny rats

The present study was designed to establish the epigenetic mechanisms by which lactational exposure to PCBs affects the Leydig cell function in progeny rats. The lactating dams were oral gavaged with different doses of PCBs [1, 2 and 5 mg/kg or corn oil ] and Leydig cells were isolated from the testes of progeny rats at postnatal day (PND) 60. We assessed the expression of transcription factors regulating steroidogenic machinery and the promoter methylation of LHR and AR in the Leydig cells. Our results confirmed hypermethylation of SF-1, Sp1/3, LHR and AR genes. There was a significant reduction in the gene expression of SF-1 and Sp1. The mRNA expression of Sp3 was decreased. Interestingly, there was an increased gene expression levels of DNA methyltransferases (Dnmts) (Dnmt1, Dnmt3a/b and Dnmt3l) and unaltered histone deacetylase-1 (Hdac-1). Furthermore, increased percentage of 5-methylcytosine was observed in PCBs exposed Leydig cells. Taken together, our findings suggest that promoter hypermethylation of SF-1, Sp1/3, LHR and AR could have led to transcriptional repression of these genes in Leydig cells. In conclusion, our study demonstrates that lactational exposure to PCBs caused epigenetic changes in the Leydig cells which could have impaired the Leydig cell function in progeny (PND60) rats.

Exercise prevents the impairment of learning and memory in prenatally phthalate-exposed male rats by improving the expression of plasticity-related proteins

Regular exercise has been identified to facilitate neuroplasticity that maximize functional outcome after brain injuries. Brain-derived neurotrophic factor (BDNF) has emerged as a key facilitator of neuroplasticity after exercise. The activity-regulated cytoskeleton associated protein (Arc) is induced by BDNF and N-methyl-d-aspartic acid receptor (NMDAR), contributing to functional modification of neuroplasticity in the hippocampus. Meanwhile, early-life exposure to neuroendocrine disruptor di-(2-ethylhexyl)-phthalate (DEHP) is a risk factor for behavioral deficits, but the mechanisms responsible for DEHP-induced neurotoxicity are not well understood. The purpose of this study is to investigate whether hippocampal Arc expression is impaired by DEHP exposure and to examine the protective role of exercise in the prenatally DEHP-exposed male rats. Sprague Dawley dams were fed with vehicle or DEHP during gestation. The male offspring were trained to treadmill running for 5 weeks followed by examination of behavioral and biochemical outcomes. The results showed that DEHP-exposed rats exhibited impairment of spatial learning and memory as well as down-regulations of BDNF, NMDAR, Arc, and synaptophysin. Importantly, aerobic exercise during childhood-adolescence prevented the impairment of learning and memory by recovering the expressions of BDNF, NMDAR, Arc, and synaptophysin. These findings suggest that exercise may provide beneficial effects on ameliorating the impairment of neuroplasticity in the prenatally DEHP-exposed male rats at late adolescence.

Developmental origins of metabolic diseases

Almost 2 billion adults in the world are overweight, and more than half of them are classified as obese, while nearly one-third of children globally experience poor growth and development. Given the vast amount of knowledge that has been gleaned from decades of research on growth and development, a number of questions remain as to why the world is now in the midst of a global epidemic of obesity accompanied by the "double burden of malnutrition," where overweight coexists with underweight and micronutrient deficiencies. This challenge to the human condition can be attributed to nutritional and environmental exposures during pregnancy that may program a fetus to have a higher risk of chronic diseases in adulthood. To explore this concept, frequently called the developmental origins of health and disease (DOHaD), this review considers a host of factors and physiological mechanisms that drive a fetus or child toward a higher risk of obesity, fatty liver disease, hypertension, and/or type 2 diabetes (T2D). To that end, this review explores the epidemiology of DOHaD with discussions focused on adaptations to human energetics, placental development, dysmetabolism, and key environmental exposures that act to promote chronic diseases in adulthood. These areas are complementary and additive in understanding how providing the best conditions for optimal growth can create the best possible conditions for lifelong health. Moreover, understanding both physiological as well as epigenetic and molecular mechanisms for DOHaD is vital to most fully address the global issues of obesity and other chronic diseases.

Perinatal Exposure to Phthalates: From Endocrine to Neurodevelopment Effects

Phthalates, as other endocrine disrupting chemicals (EDCs), may alter the homeostasis and the action of hormones and signaling molecules, causing adverse health outcomes. This is true especially for infants, who are both more exposed and sensitive to their effects. Phthalates are particularly harmful when the exposure occurs during certain critical temporal windows of the development, such as the prenatal and the early postnatal phases. Phthalates may also interfere with the neuroendocrine systems (e.g., thyroid hormone signaling or metabolism), causing disruption of neuronal differentiation and maturation, increasing the risk of behavioral and cognitive disorders (ADHD and autistic behaviors, reduced mental, psychomotor, and IQ development, and emotional problems). Despite more studies being needed to better understand the role of these substances, plenty of evidence suggests the impact of phthalates on the neuroendocrine system development and function. This review aims to update the knowledge on the neuroendocrine consequences of neonatal and perinatal exposure to phthalates.

Sex-Specific Programming of Cardiac DNA Methylation by Developmental Phthalate Exposure

Phthalate plasticizers are ubiquitous chemicals linked to several cardiovascular diseases in animal models and humans. Despite this, the mechanisms by which phthalate exposures cause adverse cardiac health outcomes are unclear. In particular, whether phthalate exposures during pregnancy interfere with normal developmental programming of the cardiovascular system, and the resulting implications this may have for long-term disease risk, are unknown. Recent studies suggest that the effects of phthalates on metabolic and neurobehavioral outcomes are sex-specific. However, the influence of sex on cardiac susceptibility to phthalate exposures has not been investigated. One mechanism by which developmental exposures may influence long-term health is through altered programming of DNA methylation. In this work, we utilized an established mouse model of human-relevant perinatal exposure and enhanced reduced representation bisulfite sequencing to investigate the long-term effects of diethylhexyl phthalate (DEHP) exposure on DNA methylation in the hearts of adult male and female offspring at 5 months of age (n = 5-7 mice per sex and exposure). Perinatal DEHP exposure led to hundreds of sex-specific, differentially methylated cytosines (DMCs) and differentially methylated regions (DMRs) in the heart. Pathway analysis of DMCs revealed enrichment for several pathways in females, including insulin signaling, regulation of histone methylation, and tyrosine phosphatase activity. In males, DMCs were enriched for glucose transport, energy generation, and developmental programs. Notably, many sex-specific genes differentially methylated with DEHP exposure in our mouse model were also differentially methylated in published data of heart tissues collected from human heart failure patients. Together, these data highlight the potential role for DNA methylation in DEHP-induced cardiac effects and emphasize the importance of sex as a biological variable in environmental health studies.

DNA methylation of JAK3/STAT5/PPARγ regulated the changes of lipid levels induced by di (2-ethylhexyl) phthalate and high-fat diet in adolescent rats

Di (2-ethylhexyl) phthalate (DEHP) and high-fat diet (HFD) could induce lipid metabolic disorder. This study was undertaken to identify the effect of DNA methylation of JAK3/STAT5/PPARγ on lipid metabolic disorder induced by DEHP and HFD. Wistar rats were divided into a normal diet (ND) group and HFD group. Each diet group treated with DEHP (0, 5, 50, 500 mg/kg/d) for 8 weeks' gavage. The DNA-methylated levels of PPARγ, JAK3, STAT5a, and STAT5b in rats' livers and adipose were analyzed with MethylTarget. The lipid levels of rats' livers and adipose were detected with ELISA. Results showed in ND group that the DNA methylation levels of PPARγ, JAK3 in livers, and STAT5b in adipose were lower in 500 mg/kg/d group than the control. And the level of total cholesterol (TC) in adipose was higher in 500 mg/kg/d group than the control. In HFD group, the DNA methylation level of JAK3 was the lowest in livers and the highest in adipose in 50 mg/kg/d group. And the level of TC in livers was the lowest in 50 mg/kg/d group. In the 500 mg/kg/d group, the DNA methylation level of STAT5b was lower in livers and higher in adipose in HFD group than that in ND group. And the levels of TC in livers were lower in HFD group than those in ND group. Therefore, DNA methylation of JAK3/STAT5/PPARγ regulated the changes in lipid levels induced by DEHP and HFD in adolescent rats.

Epigenetic repression of miR-17 contributed to di(2-ethylhexyl) phthalate-triggered insulin resistance by targeting Keap1-Nrf2/miR-200a axis in skeletal muscle

Rationale: Skeletal muscle insulin resistance is detectable before type 2 diabetes is diagnosed. Exposure to di(2-ethylhexyl) phthalate (DEHP), a typical environmental endocrine-disrupting chemical, is a novel risk factor for insulin resistance and type 2 diabetes. This study aimed to explore insulin signaling regulatory pathway in skeletal muscle of the DEHP-induced insulin-resistant mice and to investigate potential therapeutic strategies for treating insulin resistance. Methods: C57BL/6J male mice were exposed to 2 mg/kg/day DEHP for 15 weeks. Whole-body glucose homeostasis, oxidative stress and deregulated miRNA-mediated molecular transduction in skeletal muscle were examined. microRNA (miRNA) interventions based on lentiviruses and adeno-associated viruses 9 (AAV9) were performed. Results: Dnmt3a-dependent promoter methylation and lncRNA Malat1-related sponge functions cooperatively downregulated miR-17 in DEHP-exposed skeletal muscle cells. DEHP suppressed miR-17 to disrupt the Keap1-Nrf2 redox system and to activate oxidative stress-responsive Txnip in skeletal muscle. Oxidative stress upregulated miR-200a, which directly targets the 3'UTR of Insr and Irs1, leading to hindered insulin signaling and impaired insulin-dependent glucose uptake in skeletal muscle, ultimately promoting the development of insulin resistance. AAV9-induced overexpression of miR-17 and lentivirus-mediated silencing of miR-200a in skeletal muscle ameliorated whole-body insulin resistance in DEHP-exposed mice. Conclusions: The miR-17/Keap1-Nrf2/miR-200a axis contributed to DEHP-induced insulin resistance. miR-17 is a positive regulator, whereas miR-200a is a negative regulator of insulin signaling in skeletal muscle, and both miRNAs have the potential to become therapeutic targets for preventing and treating insulin resistance or type 2 diabetes.

Developmental programming of insulin resistance: are androgens the culprits?

Insulin resistance is a common feature of many metabolic disorders. The dramatic rise in the incidence of insulin resistance over the past decade has enhanced focus on its developmental origins. Since various developmental insults ranging from maternal disease, stress, over/undernutrition, and exposure to environmental chemicals can all program the development of insulin resistance, common mechanisms may be involved. This review discusses the possibility that increases in maternal androgens associated with these various insults are key mediators in programming insulin resistance. Additionally, the intermediaries through which androgens misprogram tissue insulin sensitivity, such as changes in inflammatory, oxidative, and lipotoxic states, epigenetic, gut microbiome and insulin, as well as data gaps to be filled are also discussed.

Phthalate Exposure and Long-Term Epigenomic Consequences: A Review

Phthalates are esters of phthalic acid which are used in cosmetics and other daily personal care products. They are also used in polyvinyl chloride (PVC) plastics to increase durability and plasticity. Phthalates are not present in plastics by covalent bonds and thus can easily leach into the environment and enter the human body by dermal absorption, ingestion, or inhalation. Several in vitro and in vivo studies suggest that phthalates can act as endocrine disruptors and cause moderate reproductive and developmental toxicities. Furthermore, phthalates can pass through the placental barrier and affect the developing fetus. Thus, phthalates have ubiquitous presence in food and environment with potential adverse health effects in humans. This review focusses on studies conducted in the field of toxicogenomics of phthalates and discusses possible transgenerational and multigenerational effects caused by phthalate exposure during any point of the life-cycle.

Transgenerational Effects of Periconception Heavy Metal Administration on Adipose Weight and Glucose Homeostasis in Mice at Maturity

We previously demonstrated that periconception maternal administration (2 mg/kg body weight each) of cadmium chloride (CdCl2) plus methylmercury (II) chloride (CH3HgCl) impaired glucose homeostasis and increased body weights and abdominal adipose tissue weight of male offspring in the F1 generation. However, transgenerational effects of this exposure have not been studied. Therefore, the effects of periconception Cd+Hg administration on indices of chronic diseases at adulthood in F2-F4 generations were examined. Male and female progeny of Cd+Hg periconceptionally treated females, and offspring of vehicle control females were bred with naïve CD1 mice to obtain F2 offspring, with additional crosses as above to the F4 generation (F1-F4 animals were not administered Cd+Hg). Birth weights and litter size were similar in all generations. Indices of impaired glucose homeostasis were observed in matrilineally descended F2 male offspring, including reduced glucose tolerance, along with increased basal phosphorylation of insulin receptor substrate 1 (IRS1) at serine 307 suggesting altered insulin signaling. Reduced glucose tolerance was also seen in F4 males. Increased body weight and/or abdominal adiposity were observed through the F4 generation in males descended matrilineally from the treated female progenitors. Patrilineally derived F2 females displayed reduced glucose tolerance. Females (F2) patrilineally and matrilineally derived displayed significant kidney enlargement. Periconception administration of cadmium and mercury caused persistent transgenerational effects in offspring through the F4 generation in the absence of continued toxicant exposure, with persistent transgenerational effects inherited specifically through the matrilineal germline.

Prenatal low-dose DEHP exposure induces metabolic adaptation and obesity: Role of hepatic thiamine metabolism

Di-(2-ethylhexyl)-phthalate (DEHP) is a ubiquitous environmental pollutant and is widely used in industrial plastics. However, the long-term health implications of prenatal exposure to DEHP remains unclear. We set out to determine whether prenatal DEHP exposure can induce metabolic syndrome in offspring and investigate the underlying mechanisms. A mouse model of prenatal DEHP exposure (0.2, 2, and 20 mg/kg/day) was established to evaluate the long-term metabolic disturbance in offspring. The mice were profiled for the hepatic metabolome, transcriptome and gut microbiota to determine the underlying mechanisms. Thiamine supplementation (50 mg/kg/day) was administered to offspring to investigate the role of thiamine in ameliorating metabolic syndrome. Prenatal exposure to low-dose DEHP (0.2 mg/kg/day) resulted in metabolic syndrome, including abnormal adipogenesis, energy expenditure and glucose metabolism, along with dysbiosis of the gut microbiome, in male offspring. Notably, hepatic thiamine metabolism was disrupted in these offspring due to the dysregulation of thiamine transport enzymes, which caused abnormal glucose metabolism. Prenatal low-dose DEHP exposure caused life-long metabolic consequences in a sex-dependent manner, and these consequences were be attenuated by thiamine supplementation in offspring. Our findings suggest low-dose DEHP exposure during early life stages is a potential risk factor for later obesity and metabolic syndrome.

Bisphenol A and Phthalates Exhibit Similar Toxicogenomics and Health Effects

Bisphenol A and phthalates are most frequently detected organic pollutants found in our surroundings because of their regular use as plasticizers in daily use polymeric products. BPA is used in manufacturing baby feeding bottles, water pipes, canned food linings, and food packaging materials. Phthalates are used in polyvinyl chloride products including clothing, toys, medical devices, and food packaging. These chemicals are not bound to the matrix and leach out into the surroundings on slight change in the environment, like alteration in pH, temperature, and pressure. Humans are continuously exposed to these chemicals through skin contact, inhalation, or ingestion when the leachates enter food, drinks, air, water, or soil. The Comparative Toxicogenomics Database (CTD) revealed that Bisphenol A has 1932 interactions with genes/proteins and few frequently used phthalates (DEHP, MEHP, DBP, BBP, and MBP) showed 484 gene/protein interactions. Similar toxicogenomics and adverse effects of Bisphenol A and phthalates on human health are attributed to their 89 common interacting genes/proteins.

Antidiabetic Activity of Gold Nanoparticles Synthesized Using Wedelolactone in RIN-5F Cell Line

We synthesized the gold nanoparticles (AuNPs) using wedelolactone (WDL) and characterized them using UV-visible spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopic (TEM), energy dispersive X-ray diffraction, and atomic force microscopic (AFM) studies. The electronic spectrum exhibited an absorption peak at 535 nm. The FT-IR results proved that WDL was stabilized on the surface of AuNPs by acting as a capping or reducing agent. The crystalline structure was affirmed by XRD pattern and the spherical shape of WDL-AuNPs was evidenced by SEM, TEM, and AFM. The synthesized WDL-AuNPS were evaluated for anti-diabetic activity in pancreatic RIN-5F cell lines. In vitro results showed that WDL-AuNPs did not only improve the insulin secretion affected by di-(2-ethylhexyl) phthalate (DEHP), but also the cell viability in RIN5F cells. WDL-AuNPs treatment modulates the pro-apoptotic proteins and anti-apoptotic proteins expression to prevent the cells undergoing apoptosis in DEHP-exposed RIN-5F cells. The exposure of DEHP causes an increase in ROS production and lipid peroxidation levels. The free radical scavenging and antioxidant properties of WDL-AuNPs increase the deleterious effect caused by DEHP. On the other side, WDL-AuNPs increase mRNA expressions of insulin-signaling proteins in RIN-5F cells. This study concludes that WDL-AuNPs can be successfully used to regulate the expression of Bcl-2 family proteins, reduce lipid peroxidation, and to improve the secretion of antioxidants and insulin through the GLUT2 pathway in RIN-5F cell lines.

Epigenetic Programming and Fetal Metabolic Programming

Fetal metabolic programming caused by the adverse intrauterine environment can induce metabolic syndrome in adult offspring. Adverse intrauterine environment introduces fetal long-term relatively irreversible changes in organs and metabolism, and thus causes fetal metabolic programming leading metabolic syndrome in adult offspring. Fetal metabolic programming of obesity and insulin resistance plays a key role in this process. The mechanism of fetal metabolic programming is still not very clear. It is suggested that epigenetic programming, also induced by the adverse intrauterine environment, is a critical underlying mechanism of fetal metabolic programming. Fetal epigenetic programming affects gene expression changes and cellular function through epigenetic modifications without DNA nucleotide sequence changes. Epigenetic modifications can be relatively stably retained and transmitted through mitosis and generations, and thereby induce the development of metabolic syndrome in adult offspring. This manuscript provides an overview of the critical role of epigenetic programming in fetal metabolic programming.

Developmental origins of type 2 diabetes: Focus on epigenetics

Traditionally, genetics and lifestyle are considered as main determinants of aging-associated pathological conditions. Accumulating evidence, however, suggests that risk of many age-related diseases is not only determined by genetic and adult lifestyle factors but also by factors acting during early development. Type 2 diabetes (T2D), an age-related disease generally manifested after the age of 40, is among such disorders. Since several age-related conditions, such as pro-inflammatory states, are characteristic of both T2D and aging, this disease is conceptualized by many authors as a kind of premature or accelerated aging. There is substantial evidence that intrauterine growth restriction (IUGR), induced by poor or unbalanced nutrient intake, exposure to xenobiotics, maternal substance abuse etc., may impair fetal development, thereby causing the fetal adipose tissue and pancreatic beta cell dysfunction. Consequently, persisting adaptive changes may occur in the glucose-insulin metabolism, including reduced capacity for insulin secretion and insulin resistance. These changes can lead to an improved ability to store fat, thus predisposing to T2D development in later life. The modulation of epigenetic regulation of gene expression likely plays a central role in linking the adverse environmental conditions early in life to the risk of T2D in adulthood. In animal models of IUGR, long-term persistent changes in both DNA methylation and expression of genes implicated in metabolic processes have been repeatedly reported. Findings from human studies confirming the role of epigenetic mechanisms in linking early-life adverse experiences to the risk for T2D in adult life are scarce compared to data from animal studies, mainly because of limited access to suitable biological samples. It is, however, convincing evidence that these mechanisms may also operate in human beings. In this review, theoretical models and research findings evidencing the role of developmental epigenetic variation in the pathogenesis of T2D are summarized and discussed.

First trimester maternal exposures to endocrine disrupting chemicals and metals and fetal size in the Michigan Mother-Infant Pairs study

Exposures to endocrine disrupting chemicals and metals are near ubiquitous worldwide, and their potential impact on children is a major public health concern. This pilot study was designed to characterize exposures to phthalates, phenols and metals among pregnant women in the first trimester, and to examine associations with fetal biometrics and birth weight. A total of 41 chemicals and elements were analyzed in urine from 56 mothers with full-term newborns from the Michigan Mother-Infant Pairs study. Bivariate analyses identified predictors of exposure biomarkers. Associations between birth weight, Fenton z-scores and second trimester fetal biometrics with toxicants were examined via multivariable linear regression. An average of 30 toxicants were detected in maternal urine. Fast food consumption was associated with several phthalate metabolites, phenols and metals, and canned food consumption with bisphenol F (P <0.05). Mono (3-carboxypropyl) phthalate was significantly associated with higher birth weight and Fenton z-score while the opposite was observed for bisphenol S. Estimated femur length from ultrasonography was significantly inversely associated with arsenic, barium and lead. While limited by sample size, this study is one of the first to evaluate birth outcomes with respect to emerging endocrine disrupting chemicals and to examine associations between toxicants and fetal biometrics. Exposure assessment was provided by the National Institute of Environmental Health Sciences' Children's Health Exposure Analysis Resource (NIEHS CHEAR), a resource available to children's studies with the goal of combining data across cohorts in an effort to characterize the impact of toxicants on child health from birth and beyond.

Hydrogen sulfide regulates circadian-clock genes in C2C12 myotubes and the muscle of high-fat-diet-fed mice

Hydrogen sulfide (H₂S) is an endogenous novel gasotransmitter which is implicated in the pathophysiology of the metabolic syndrome. Core clock genes (CCG) and its controlled genes disruption is implicated in the progression of metabolic syndrome. We examined whether H₂S has any effect on CCG in the skeletal muscle of mice fed a high-fat diet (HFD) and in myotubes. In the muscle of HFD-mice, the expression of H₂S biosynthesis enzyme genes (CSE, CBS, and 3-Mpst) along with antioxidant genes (GCLC, GCLM, GSS, and GSR) involved in GSH biosynthesis and recycling were reduced significantly, but the oxidative stress (OS) increased. Expression of the CCG (Bmal1, Clock, RORα, Cry2, Per2) and clock-controlled genes (PPARγ, PGC-1α, RXRα) was downregulated, whereas the levels of PPARα mRNA were upregulated. Similar to that in the muscle of HFD-mice, in vitro myotubes exposed to high glucose or palmitate to mimic metabolic syndrome, showed an increased OS and decreased in CSE mRNA, H₂S production and CCG mRNA levels were also downregulated. TNF and MCP-1 treatment on the myotubes was similar to that observed in HFD-muscle, with that the Rev-erbα mRNA was upregulated. Inhibition (siRNA/pharmacological inhibitors) of both CSE and GCLC (the rate-limiting enzyme in GSH biosynthesis) decreased H₂S, and increased OS; Bmal1 and Clock mRNA levels were downregulated, while Rev-erbα increased significantly in these conditions. CSE KD myotubes were post-treated with an H₂S donor partially restored the mRNA levels of core clock genes. These findings report that the deficiencies of H₂S/GSH impair expression of CCG and treatment with H₂S donor or GSH precursor exert a positive effect over CCG. Thus, suggest that H₂S as a new endogenous factor for regulating circadian clock, and its donors could provide a novel chrono-pharmacological therapy to manage metabolic disorders.

Longitudinal Metabolic Impacts of Perinatal Exposure to Phthalates and Phthalate Mixtures in Mice

Developmental exposures to phthalates are suspected to contribute to risk of metabolic syndrome. However, findings from human studies are inconsistent, and long-term metabolic impacts of early-life phthalate and phthalate mixture exposures are not fully understood. Furthermore, most animal studies investigating metabolic impacts of developmental phthalate exposures have focused on diethylhexyl phthalate (DEHP), whereas newer phthalates, such as diisononyl phthalate (DINP), are understudied. We used a longitudinal mouse model to evaluate long-term metabolic impacts of perinatal exposures to three individual phthalates, DEHP, DINP, and dibutyl phthalate (DBP), as well as two mixtures (DEHP+DINP and DEHP+DINP+DBP). Phthalates were administered to pregnant and lactating females through phytoestrogen-free chow at the following exposure levels: 25 mg of DEHP/kg of chow, 25 mg of DBP/kg of chow, and 75 mg of DINP/kg of chow. One male and female per litter (n = 9 to 13 per sex per group) were weaned onto control chow and followed until 10 months of age. They underwent metabolic phenotyping at 2 and 8 months, and adipokines were measured in plasma collected at 10 months. Longitudinally, females perinatally exposed to DEHP only had increased body fat percentage and decreased lean mass percentage, whereas females perinatally exposed to DINP only had impaired glucose tolerance. Perinatal phthalate exposures also modified the relationship between body fat percentage and plasma adipokine levels at 10 months in females. Phthalate-exposed males did not exhibit statistically significant differences in the measured longitudinal metabolic outcomes. Surprisingly, perinatal phthalate mixture exposures were statistically significantly associated with few metabolic effects and were not associated with larger effects than single exposures, revealing complexities in metabolic effects of developmental phthalate mixture exposures.

Effects of citrate ester plasticizers and bis (2-ethylhexyl) phthalate in the OECD 28-day repeated-dose toxicity test (OECD TG 407)

Citrate esters are considered functional alternatives to phthalate plasticizers, but their toxicity remains poorly understood. The toxicity of citrate esters, including triethyl 2-acetylcitrate (ATEC) and trihexyl O-acetylcitrate (ATHC), were examined together with that of bis (2-ethylhexyl) phthalate (DEHP) using the Organization for Economic Co-operation and Development Test Guideline 407 (OECD TG407). Following 28-day oral administration, no significant differences in body weight or the weight of the brain, pituitary, heart, epididymis, seminal vesicles, or coagulating gland were found between the vehicle control and DEHP, ATEC or ATHC groups. In the 400 mg/kg day DEHP group, liver, adrenal, thymus, spleen, kidney, testis, and prostate weights were significantly increased. In the 400 mg/kg day ATHC group, kidney, adrenal, thymus, testis and prostate weights were significantly increased. In the 400 mg/kg day ATEC group, kidney, adrenal and testis weights were significantly increased. Hepatocyte size was significantly increased in the 400 mg/kg day DEHP group, suggestive of hepatotoxicity, but was not increased in the ATEC or ATHC groups. There were no significant differences in white blood cell, red blood cell or platelet counts, hemoglobin concentrations, hematocrit, mean corpuscular volume, fasting glucose, insulin, or testosterone concentrations between the vehicle control and DEHP, ATEC and ATHC groups. In the ATHC 400 mg/kg day group, T3 was decreased while T4 was increased, suggestive of disruption of thyroid function. The results of the OECD TG407 subacute repeated dosing toxicity test indicate ATEC is less toxic compared to ATHC or DEHP and could be recommended as an alternative to phthalate plasticizers.

Diet and Contaminants: Driving the Rise to Obesity Epidemics?

The obesity epidemic is spreading worldwide without reversal trend and despite specific policies oriented to dietary habits and lifestyle, which seem to have modest effects. Genetic factors only partly explain the rise, whereas environmental factors seem to play a key role, mainly by gene-environment interactions through epigenetic mechanisms. A number of animal and human studies point to maternal diet, intestinal microbiota and chemicals introduced as contaminants with food, all factors able to increase the risk of obesity. Widely diffused toxics (mainly BPA, phthalates, pesticides) are able to promote obesity in children and adults, mainly by acting on the differentiation pathway linking multipotent stromal stem cell to mature adipocyte, modulating epigenetic factors and influencing a series of mechanisms finally leading to altered dietary habits, increased adipocyte formation and fat storage. Furthermore, the adipose tissue is an important target for several chemicals (mainly POPs) which represent a threat to metabolic health. In conclusion, besides excessive individual energy intake and inadequate lifestyle, other broadly diffused and modifiable factors (mainly ingestion of toxic chemicals with food) seem to have a critical role in the rapid epidemiological growing of obesity, also considering trans-generational transmission of risk and later development of obesity due to exposure during early life. Further studies are needed, to better assess interactions between cumulative effects of toxic food contaminants and modification of diet and lifestyle, and to verify the efficacy of primary prevention strategies acting on all these factors and potentially able to reverse the continuous rising of the obesity epidemic.

Developmental exposure to DEHP alters hepatic glucose uptake and transcriptional regulation of GLUT2 in rat male offspring

Type-2-diabetes (T2D) is a long term metabolic disorder characterized by high blood glucose and insulin resistance. It has become an alarming issue globally due to tremendous increase in number of new subjects every year. Apart from the classical factors, there are few non-classical factors such as environmental pollutants, endocrine disrupting chemicals (EDCs) which also play a major role in pathogenesis of T2D. Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer which is an endocrine disrupting chemical. It is used in the plastic industry to give flexibility and durability. Its widespread use resulted in constant presence in the environment and human are under high risk of exposure to this compound. There are literature available stating that DEHP has an impact on glucose homeostasis. Glucose transporter 2 (GLUT2) is a principal transporter of glucose in liver and it is a bi-directional transporter. We investigated whether DEHP exposure during gestation and lactation alters transcriptional regulation of GLUT2 and epigenetics changes in the rat F₁ male offspring at adulthood. Pregnant rats were divided into three groups and administered with DEHP (10 and 100 mg /kg /day) or olive oil from gestational day (GD) 9- to postnatal day (PND) 21 through oral gavage. DEHP treated rats showed decreased glucose uptake and oxidation, decreased mRNA levels of insulin receptor (IR), GLUT2 and reduced GLUT2 protein in cytosol but unaltered level in plasma membrane. There are three main transcription factors (SREBP1c, HNF3β and HNF1α) involved in the regulation of GLUT2 gene and all these proteins were reduced in DEHP exposed groups. A weak interaction of the transcription factors (SREBP1c & HNF1α) with GLUT2 gene promoter was observed in DEHP-treated groups. Hyper- methylation of IR and GLUT2 gene promoter was observed in both the DEHP-exposed groups compared to control. The present study reveals that DEHP exposure alters transcriptional regulation of GLUT2 and imposes epigenetic alteration in IR and GLUT2 gene promoters which plays a significant role in the development of metabolic abnormality in F₁ male offspring at adulthood.

Maternal di-(2-ethylhexyl) phthalate exposure alters hepatic insulin signal transduction and glucoregulatory events in rat F1 male offspring

Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer with endocrine disrupting properties. Its widespread use resulted in constant human exposure including fetal development and postnatal life. Epidemiological and experimental data have shown that DEHP has a negative influence on glucose homeostasis. However, the evidence regarding the effect of maternal DEHP exposure on hepatic glucose homeostasis is scarce. Hence, we investigated whether DEHP exposure during gestation and lactation disrupts glucose homeostasis in the rat F₁ male offspring at adulthood. Pregnant rats were divided into three groups and administered with DEHP (10 and 100 mg/kg/day) or olive oil from gestational day 9 to postnatal day 21 (lactation period) through oral gavage. DEHP-exposed offspring exhibited hyperglycemia, impaired glucose and insulin tolerances along with hyperinsulinemia at postnatal day 80. DEHP exposure significantly reduced the levels of insulin signaling molecules such as insulin receptors, IRS1, Akt and its phosphorylated forms. GSK3β and FoxO1 proteins increased in DEHP-exposed groups whereas its phosphorylated forms decreased. Treated groups showed decreased glycogen synthase activity and glycogen concentration. Glucose-6-phosphatase and phosphoenolpyruvate carboxykinase mRNA level and enzyme activity increased in DEHP-treated groups. The interaction between FoxO1-glucose-6-phosphatase and FoxO1-phosphoenolpyruvate carboxykinase was also increased. This study suggests that DEHP exposure impairs insulin signal transduction and alters glucoregulatory events leading to the development of type 2 diabetes in F₁ male offspring.

The role of endocrine disruptors in ocular surface diseases

Endocrine disruptors are a group of compounds that occur in increasing amounts in the environment. These compounds change the hormone homeostasis of the target organs regulated by those hormones, mostly by binding to their receptors and affecting their signaling pathways. Among the hormones altered by endocrine disruptors are sex hormones, thyroid hormones, and insulin. Studies have documented abnormalities in the reproductive and metabolic systems of various animal species exposed to endocrine disruptors. Endocrine disruptors can play a significant role in ocular diseases once hormone deficiency or excess are involved in the mechanism of that disease. Cataracts, dry eye disease and retinal diseases, such as macular hole and diabetic retinopathy, are some of the frequent problems where hormones have been implicated. We found that some compounds function as endocrine disruptors in the metabolism of body organs and systems. The increasing frequency of dry eye and other ocular diseases indicates the need to better investigate the potential relationships beyond the isolated associations mentioned by patients and documented as rare case reports. The evidence from case-control studies and experimental assays can provide the information necessary to confirm the endocrine effects of these chemicals in the pathophysiology of dry eye disease. We hypothesize that endocrine disruptors may contribute to the increase of ocular diseases, such as dry eye disease, in recent years.

Analysis of Lipid Metabolism, Immune Function, and Neurobehavior in Adult C57BL/6JxFVB Mice After Developmental Exposure to di (2-ethylhexyl) Phthalate

Background: Developmental exposure to di (2-ethylhexyl) phthalate (DEHP) has been implicated in the onset of metabolic syndrome later in life. Alterations in neurobehavior and immune functions are also affected by phthalate exposure and may be linked to the metabolic changes caused by developmental exposure to DEHP. Objectives: Our goal was to study the effects of developmental exposure to DEHP in the context of metabolic syndrome by integrating different parameters to assess metabolic, neurobehavioral, and immune functions in one model. Methods: Female C57BL/6J mice were exposed to DEHP through the diet during gestation and lactation at doses ranging from 3.3 to 100,000 μg/kg body weight/day (μkd). During a 1-year follow-up period, a wide set of metabolic parameters was assessed in the F1 offspring, including weekly body weight measurements, food consumption, physical activity, glucose homeostasis, serum lipids, and endocrine profile. In addition, neurobehavioral and immune functions were assessed by sweet preference test, object recognition test, acute phase protein, and cytokines production. Animals were challenged with a high fat diet (HFD) in the last 9 weeks of the study. Results: Increased free fatty acids (FFA) and, high density lipoprotein (HDL-C) were observed in serum, together with a decrease in glycated hemoglobin levels in blood of 1-year old male DEHP-exposed offspring after HFD challenge. For the most sensitive endpoint measured (FFA), a lower bound of the 90%-confidence interval for benchmark dose (BMD) at a critical effect size of 5% (BMDL) of 2,160 μkd was calculated. No persistent changes in body weight or fat mass were observed. At 33,000 μkd altered performance was found in the object recognition test in males and changes in interferon (IFN)γ production were observed in females. Conclusions: Developmental exposure to DEHP combined with HFD in adulthood led to changes in lipid metabolism and neurobehavior in male offspring and cytokine production in female offspring. Our findings contribute to the evidence that DEHP is a developmental dyslipidemic chemical, however, more research is needed to further characterize adverse health outcomes and the mechanisms of action associated with the observed sex-specific effects.

Postnatal exposure to di-(2-ethylhexyl)phthalate alters cardiac insulin signaling molecules and GLUT4Ser488 phosphorylation in male rat offspring

Di-(2-ethylhexyl)phthalate (DEHP), a distinctive endocrine-disrupting chemical, is widely used as a plasticizer in a variety of consumer products. It can easily cross the placenta and enter breast milk and then it is rapidly absorbed by offspring. Since it is generally accepted that individuals are more sensitive to chemical exposure during vital developmental periods, we investigated whether DEHP exposure during lactation affects cardiac insulin signaling and glucose homeostasis in the F₁ male rat offspring at postnatal day 22 (PND22). Lactating Wistar rats were administered with DEHP (1, 10, and 100 mg/kg/d) or olive oil from lactation day 1 to 21 by oral gavage. All the male pups were perfused and killed on PND22. On the day before the killing, they were kept for fasting overnight and blood was collected. The cardiac muscle was dissected out, washed in ice-cold physiological saline repeatedly and used for the assay of various parameters. DEHP-exposed offspring had significantly lower body weight than the control. DEHP-exposed offspring showed elevated blood glucose, decreased ¹⁴ C-2-deoxyglucose uptake and ¹⁴ C-glucose oxidation in cardiac muscle at PND22. The concentration of upstream insulin signaling molecules such as insulin receptor subunit β (InsRβ) and insulin receptor substrate 1 (IRS1) were downregulated in DEHP-exposed offspring. However, no significant alterations were observed in protein kinase B (Akt) and Akt substrate of 160 kDa (AS160). Surprisingly, phosphorylation of IRS1 ^Tyr632 and Akt ^Ser473 were diminished. Low levels of glucose transporter type 4 (GLUT4) protein and increased GLUT4 ^Ser488 phosphorylation which decreases its intrinsic activity and translocation towards plasma membrane were also recorded. Lactational DEHP exposure predisposes F ₁ male offspring to cardiac glucometabolic disorders at PND22, which may impair cardiac function.

Prenatal phthalate exposure, birth outcomes and DNA methylation of Alu and LINE-1 repetitive elements: A pilot study in China

BACKGROUND

Epigenetic mechanisms, such as altered DNA methylation, may participate in the relationship between prenatal phthalate exposure and adverse birth outcomes.

OBJECTIVE

To explore the mediation effect of DNA methylation in the associations of phthalate exposure before delivery with birth outcomes in a Chinese cohort.

METHODS

Eight phthalate metabolites in maternal urine before delivery and DNA methylation of Alu and long interspersed nucleotide elements (LINE-1) in cord blood were determined among 106 mother-infant pairs. General additive models were used to assess the associations of maternal urinary phthalate metabolites with birth outcomes and DNA methylation; the mediating role of DNA methylation in cord blood was evaluated by mediation analysis.

RESULTS

We found sex-specific associations between prenatal phthalate exposure and birth outcomes and DNA methylation of cord blood. For example, the molar sum of di-2-(ethylhexyl) phthalate (∑DEHPm) metabolites in maternal urine was positively associated with gestational age among male newborns only (P < 0.05); maternal urinary monobenzyl phthalate (MBzP) was negatively associated with Alu methylation among female newborns only (P < 0.05). Mediation analysis did not find that methylation of Alu and LINE-1 to be a direct mediator in the relationships between maternal urinary phthalate metabolites before delivery and birth outcomes.

CONCLUSION

Prenatal exposure to certain phthalates was associated with altered birth outcomes and decreased repetitive element methylation of newborns. However, the altered birth outcomes exerted by prenatal phthalate exposure does not seem to be directly mediated through repetitive element methylation in cord blood.

Perinatal exposures to phthalates and phthalate mixtures result in sex-specific effects on body weight, organ weights and intracisternal A-particle (IAP) DNA methylation in weanling mice

Developmental exposure to phthalates has been implicated as a risk for obesity; however, epidemiological studies have yielded conflicting results and mechanisms are poorly understood. An additional layer of complexity in epidemiological studies is that humans are exposed to mixtures of many different phthalates. Here, we utilize an established mouse model of perinatal exposure to investigate the effects of three phthalates, diethylhexyl phthalate (DEHP), diisononyl phthalate (DINP) and dibutyl phthalate (DBP), on body weight and organ weights in weanling mice. In addition to individual phthalate exposures, we employed two mixture exposures: DEHP+DINP and DEHP+DINP+DBP. Phthalates were administered through phytoestrogen-free chow at the following exposure levels: 25 mg DEHP/kg chow, 25 mg DBP/kg chow and 75 mg DINP/kg chow. The viable yellow agouti (A vy ) mouse strain, along with measurement of tail DNA methylation, was used as a biosensor to examine effects of phthalates and phthalate mixtures on the DNA methylome. We found that female and male mice perinatally exposed to DINP alone had increased body weights at postnatal day 21 (PND21), and that exposure to mixtures did not exaggerate these effects. Females exposed to DINP and DEHP+DINP had increased relative liver weights at PND21, and females exposed to a mixture of DEHP+DINP+DBP had increased relative gonadal fat weight. Phthalate-exposed A vy /a offspring exhibited altered coat color distributions and altered DNA methylation at intracisternal A-particles (IAPs), repetitive elements in the mouse genome. These findings provide evidence that developmental exposures to phthalates influence body weight and organ weight changes in early life, and are associated with altered DNA methylation at IAPs.

Epigenetics and developmental origins of diabetes: correlation or causation?

The incidence of metabolic disorders like type 2 diabetes (T2D) and obesity continue to increase. Although it is evident that the increasing incidence of diabetes confers a global societal and economic burden, the mechanisms responsible for the increased incidence of T2D are not well understood. Extensive efforts to understand the association of early-life perturbations with later onset of metabolic diseases, the founding principle of developmental origins of health and disease, have been crucial in determining the mechanisms that may be driving the pathogenesis of T2D. As the programming of the epigenome occurs during critical periods of development, it has emerged as a potential molecular mechanism that could occur early in life and impact metabolic health decades later. In this review, we critically evaluate human and animal studies that illustrated an association of epigenetic processes with development of T2D as well as intervention strategies that have been employed to reverse the perturbed epigenetic modification or reprogram the naturally occurring epigenetic marks to favor improved metabolic outcome. We highlight that although our understanding of epigenetics and its contribution toward developmental origins of T2D continues to grow, whether epigenetics is a cause, consequence, or merely a correlation remains debatable due to the many limitations/challenges of the existing epigenetic studies. Finally, we discuss the potential of establishing collaborative research efforts between different disciplines, including physiology, epigenetics, and bioinformatics, to help advance the developmental origins field with great potential for understanding the pathogenesis of T2D and developing preventive strategies for T2D.

Association of phthalate exposures with urinary free cortisol and 8-hydroxy-2'-deoxyguanosine in early childhood

Several studies suggested potential links of phthalates to stress-related outcomes. However, limited evidence has been available for the relationships between phthalate metabolites and free cortisol and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in perinatal and postnatal environments. Therefore, we evaluated the relationships between phthalate metabolites and free cortisol and 8-OHdG in mother-child pairs. We repeatedly collected urine samples of 287 mother-child pairs from just before delivery to 15 months of age to measure the levels of four phthalate metabolites - mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP) - and free cortisol and 8-OHdG. We used linear mixed effect models and generalized additive mixed models to estimate the relationship between the phthalate metabolites and free cortisol and 8-OHdG after adjusting for the child's gender, urine collection time, and maternal smoking status. The four phthalate metabolite levels were strongly correlated each other (all, p < .0001), and intra-class correlation for each metabolite in children ranged from 0.18 to 0.96. All four phthalate metabolites were positively associated with both free cortisol (MEHHP, β = 0.18 and p < .0001; MEOHP, β = 0.17 and p < .0001; MiBP, β = 0.13 and p = .0001; MnBP, β = 0.21 and p < .0001; and molar sum of metabolites, β = 0.21 and p < .0001) and 8-OHdG (MEHHP, β = 0.20 and p < .0001; MEOHP, β = 0.18 and p < .0001; MiBP, β = 0.23 and p < .0001; MnBP, β = 0.28 and p < .0001; and molar sum of metabolites, β = 0.29 and p < .0001) in childhood. Our findings suggest that phthalate exposures increase free cortisol and 8-OHdG levels in early childhood.