Gestational di-(2-ethylhexyl) phthalate exposure causes fetal intrauterine growth restriction through disturbing placental thyroid hormone receptor signaling

Prenatal phthalate exposure and birth size: a systematic review and meta-analysis

Phthalates are common endocrine disruptors. The placental barrier can be crossed by phthalates and may have a negative impact on the health of the fetus. However, the association between prenatal exposure to phthalates and birth size is still debatable. Here, we performed this meta-analysis to assess the relationship between prenatal phthalates exposure and birth size. Eighteen studies were finally included by searching PubMed, Embase, Scopus, Ovid, and Web of Science databases and standardized regression coefficients and standard errors were used to pool effect size. Our results showed that prenatal exposure to MMP (=-0.04, 95%CI: -0.08, -0.01) and MEP (=-0.01, 95%CI: -0.01, -0.002) was significantly associated with birth weight. However, no significant associations were identified for phthalate exposure with birth length, head circumference and chest circumference. Because the limiting of studies, more high-quality case-control studies or cohort studies are urgently needed to draw the best conclusions.

Association of phthalate exposure with reproductive outcomes among infertile couples undergoing in vitro fertilization: A systematic review

Human fertility is impacted by changes in lifestyle and environmental deterioration. To increase human fertility, assisted reproductive technology (ART) has been extensively used around the globe. As early as 2009, the Endocrine Society released its first scientific statement on the potential adverse effects of environmental endocrine-disrupting chemicals (EDCs) on human health and disease development. Chemicals known as phthalates, frequently employed as plasticizers and additives, are common EDCs. Numerous studies have shown that phthalate metabolites in vivo exert estrogen-like or anti-androgenic effects in both humans and animals. They are associated with the progression of a range of diseases, most notably interference with the reproductive process, damage to the placenta, and the initiation of chronic diseases in adulthood. Phthalates are ingested by infertile couples in a variety of ways, including household products, diet, medical treatment, etc. Exposure to phthalates may exacerbate their infertility or poor ART outcomes, however, the available data on phthalate exposure and ART pregnancy outcomes are sparse and contradictory. Therefore, this review conducted a systematic evaluation of 16 papers related to phthalate exposure and ART pregnancy outcomes, to provide more aggregated results, and deepen our understanding of reproductive outcomes in infertile populations with phthalate exposure.

Gender associations between phthalate exposure and biomarkers of oxidative stress: A prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to adverse birth outcomes in a sex-specific manner. However, the biological mechanism of phthalate exposure that causes these birth outcomes remains poorly defined. In this research, we investigated the association between phthalate exposure and placental oxidative stress in a large population-based cohort study, aiming to initially explore the relationship between phthalate exposure and gene expression in placental oxidative stress in a sex-specific manner. Quantitative PCR was performed to measure the expression of placental inflammatory mRNAs (HO-1, HIF1α, and GRP78) in 2469 placentae. The multiple linear regression models were used to investigate the associations between mRNA and urinary phthalate monoesters. Phthalate metabolites monomethyl phthalate (MMP) and mono-n-butyl phthalate (MBP) were positively correlated with higher HIF1α expression in placentae of male fetuses (p < .05). Mono-benzyl phthalate (MBzP) increased the expression of HO-1, HIF1α, and GRP78 in placentae of male fetuses, and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) up-regulated the expression of HIF1α and GRP78. Additionally, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with HO-1, HIF1α, and GRP78 in placentae of female fetuses. Maternal phthalate exposure was associated with oxidative stress variations in placental tissues. The associations were closer in the placentas of male fetuses than in that of female ones. The placenta oxidative stress is worth further investigation as a potential mediator of maternal exposure-induced disease risk in children.

Phthalate ester levels in agricultural soils of greenhouses, their potential sources, the role of plastic cover material, and dietary exposure calculated from modeled concentrations in tomato

Soil samples collected from 50 greenhouses (GHs) cultivated with tomatoes (plastic-covered:24, glass-covered:26), 5 open-area tomato growing farmlands, and 5 non-agricultural areas were analyzed in summer and winter seasons for 13 PAEs. The total concentrations (Σ13PAEs) in the GHs ranged from 212 to 2484 ng/g, wheeas the concentrations in open-area farm soils were between 240 and 1248 ng/g. Σ13PAE in non-agricultural areas was lower (35.0 - 585 ng/g). PAE exposure through the ingestion of tomatoes cultivated in GH soils and associated risks were estimated with Monte Carlo simulations after calculating the PAE concentrations in tomatoes using a partition-limited model. DEHP was estimated to have the highest concentrations in the tomatoes grown in both types of GHs. The mean carcinogenic risk caused by DEHP for tomato grown in plastic-covered GHs, glass-covered GHs, and open-area soils were 2.4 × 10-5, 1.7 × 10-5 and 1.1 × 10-5, respectively. Based on Positive Matrix Factorization results, plastic material usage in GHs (including plastic cover material source for plastic-GHs) was found to be the highest contributing source in both types of GHs. Microplastic analysis indicated that the ropes and irrigation pipes inside the GHs are important sources of PAE pollution. Pesticide application is the second highest contributing source.

Thyroid hormone transport and metabolism are disturbed in the placental villi of miscarriage

BACKGROUND

It has been long known that thyroid hormone regulates placental villi development, which is associated with the occurrence of miscarriage. However, whether abnormal thyroid hormone metabolism and transport in placental villi are involved in miscarriage is still to be verified.

METHODS

Placental villi of elective terminations of pregnancies (ETPs) and miscarriage were collected. Proliferative activity and apoptosis of villi trophoblasts and angiogenesis were detected by TUNEL and immunochemistry. The expressions of thyroid hormone receptors (THRs), transthyretin (TTR), monocarboxylate transporter 8 (MCT8), organic anion transporting polypeptides 1A1 (OATP1A1), deiodinase 2 (Dio2) and Dio3 were examined by RT-PCR, Western blot, immunohistochemistry and immunofluorescence. JEG3 cell was treated with iopanoic acid (IOP), an inhibitor of Dio2 activity, the expressions of Dio2, placenta growth factor (PLGF) and sFlt1 were detected by RT-PCR and Western blot.

RESULTS

Cell proliferation was suppressed and apoptosis was increased in placental villi cytotrophoblasts of miscarriage. CD34+ vessel number and vascular endothelial growth factor (VEGF) protein abundance were decreased in miscarriage. In miscarriage group, the gene expression of Dio2, Dio3, TTR and THRα, but not THRβ, MCT8 and OATP1A1, were downregulated. The protein abundances of TTR and THRα were downregulated in miscarriage group, but not THRβ. The protein abundance of Dio2 in miscarriage villi was decreased compared with that in ETP. In JEG3 cells, the gene expression of PLGF was decreased and the expression of sFlt1 was increased in IOP treatment; The protein abundance of Dio2 was downregulated but the gene expression of Dio2 was unaffected in IOP treatment.

CONCLUSION

Thyroid hormone transport and metabolism in miscarriage were disturbed and may impaired angiogenesis of placental villi, which was associated with the occurrence of miscarriage.

The Role of Endocrine Disrupting Chemicals in Gestation and Pregnancy Outcomes

Endocrine disrupting chemicals (EDCs) are exogenous substances widely disseminated both in the environment and in daily-life products which can interfere with the regulation and function of the endocrine system. These substances have gradually entered the food chain, being frequently found in human blood and urine samples. This becomes a particularly serious issue when they reach vulnerable populations such as pregnant women, whose hormones are more unstable and vulnerable to EDCs. The proper formation and activity of the placenta, and therefore embryonic development, may get seriously affected by the presence of these chemicals, augmenting the risk of several pregnancy complications, including intrauterine growth restriction, preterm birth, preeclampsia, and gestational diabetes mellitus, among others. Additionally, some of them also exert a detrimental impact on fertility, thus hindering the reproductive process from the beginning. In several cases, EDCs even induce cross-generational effects, inherited by future generations through epigenetic mechanisms. These are the reasons why a proper understanding of the reproductive and gestational alterations derived from these substances is needed, along with efforts to establish regulations and preventive measures in order to avoid exposition (especially during this particular stage of life).

Obeticholic acid alleviates intrauterine growth restriction induced by di-ethyl-hexyl phthalate in pregnant female mice by improving bile acid disorder

Di-(2-ethylhexyl)-phthalate (DEHP) is a ubiquitous environmental pollutant and is widely used in industrial plastics. Intrahepatic cholestasis of pregnancy (ICP), distinguished by maternal pruritus and elevated serum bile acid levels, is linked to unfavorable pregnancy consequences. Few studies have investigated the potential effect of gestational DEHP exposure on the cholestasis in pregnant female mice, and the underlying mechanisms remain unclear. In the present study, a mouse model of cholestasis during pregnancy was established by DEHP exposure. We found that DEHP induces elevated bile acid levels by affecting bile acid synthesis and transporter receptor expression in the maternal liver and placenta of pregnant female mice, ultimately leading to intrauterine growth restriction (IUGR). In addition, DEHP changed the bile acid composition of maternal serum and liver as well as placenta and amniotic fluid in pregnant female mice; Importantly, we found that DEHP down-regulates the expression of farnesoid X receptor (FXR), which is considered to be a bile acid receptor. FXR agonist obeticholic acid (OCA) effectively alleviated the adverse effects of DEHP on pregnant female mice. While, OCA itself had no adverse effects on normal pregnant female mice. In summary, DEHP could induces bile acid disorder and IUGR in pregnant female mice by affect FXR, which was reversed by OCA.

Prenatal exposure to common plasticizers: a longitudinal study on phthalates, brain volumetric measures, and IQ in youth

Exposure to phthalates, used as plasticizers and solvents in consumer products, is ubiquitous. Despite growing concerns regarding their neurotoxicity, brain differences associated with gestational exposure to phthalates are understudied. We included 775 mother-child pairs from Generation R, a population-based pediatric neuroimaging study with prenatal recruitment, who had data on maternal gestational phthalate levels and T1-weighted magnetic resonance imaging in children at age 10 years. Maternal urinary concentrations of phthalate metabolites were measured at early, mid-, and late pregnancy. Child IQ was assessed at age 14 years. We investigated the extent to which prenatal exposure to phthalates is associated with brain volumetric measures and whether brain structural measures mediate the association of prenatal phthalate exposure with IQ. We found that higher maternal concentrations of monoethyl phthalate (mEP, averaged across pregnancy) were associated with smaller total gray matter volumes in offspring at age 10 years (β per log10 increase in creatinine adjusted mEP = -10.7, 95%CI: -18.12, -3.28). Total gray matter volumes partially mediated the association between higher maternal mEP and lower child IQ (β for mediated path =-0.31, 95%CI: -0.62, 0.01, p = 0.05, proportion mediated = 18%). An association of higher monoisobutyl phthalate (mIBP) and smaller cerebral white matter volumes was present only in girls, with cerebral white matter volumes mediating the association between higher maternal mIBP and lower IQ in girls. Our findings suggest the global impact of prenatal phthalate exposure on brain volumetric measures that extends into adolescence and underlies less optimal cognitive 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.

Exposure to di-isononyl phthalate during early pregnancy disrupts decidual angiogenesis and placental development in mice

Di-isononyl phthalate (DiNP), an endocrine-disrupting chemical, is found in numerous consumer products and human exposure to this phthalate is becoming inevitable. The impact of DiNP exposure on the establishment and maintenance of pregnancy remains largely unknown. Thus, we conducted studies in which pregnant mice were exposed to an environmentally relevant dose (20 µg/kg BW/day) of DiNP on days 1-7 of gestation, then analyzed the effects of this exposure on pregnancy outcome. Our studies revealed that exposure to DiNP during this window led to fetal loss towards the end of gestation. Further studies showed that, although embryos were able to attach to the uterus, implantation sites in DiNP-exposed uteri exhibited impaired differentiation of stromal cells to decidual cells and an underdeveloped angiogenic network in the decidual bed. We also found that exposure to this phthalate has a significant effect on trophoblast differentiation and causes disorganization of the placental layers. The labyrinth was significantly reduced, resulting in compromised expression of nutrient transporters in the placentas of mice exposed to DiNP. These placental defects in DiNP-exposed females were the cause of fetal loss during the later stages of gestation.

Prenatal and Neonatal Bone Health: Updated Review on Early Identification of Newborns at High Risk for Osteopenia

Bone health starts with maternal health and nutrition, which influences bone mass and density already in utero. The mechanisms underlying the effect of the intrauterine environment on bone health are partly unknown but certainly include the 'foetal programming' of oxidative stress and endocrine systems, which influence later skeletal growth and development. With this narrative review, we describe the current evidence for identifying patients with risk factors for developing osteopenia, today's management of these populations, and screening and prevention programs based on gestational age, weight, and morbidity. Challenges for bone health prevention include the need for new technologies that are specific and applicable to pregnant women, the foetus, and, later, the newborn. Radiofrequency ultrasound spectrometry (REMS) has proven to be a useful tool in the assessment of bone mineral density (BMD) in pregnant women. Few studies have reported that transmission ultrasound can also be used to assess BMD in newborns. The advantages of this technology in the foetus and newborn are the absence of ionising radiation, ease of use, and, above all, the possibility of performing longitudinal studies from intrauterine to extrauterine life. The use of these technologies already in the intrauterine period could help prevent associated diseases, such as osteoporosis and osteopenia, which are characterised by a reduction in bone mass and degeneration of bone structure and lead to an increased risk of fractures in adulthood with considerable social repercussions for the related direct and indirect costs.

Cumulative Exposure to Phthalates and Their Alternatives and Associated Female Reproductive Health: Body Burdens, Adverse Outcomes, and Underlying Mechanisms

The global birth rate has recently shown a decreasing trend, and exposure to environmental pollutants has been identified as a potential factor affecting female reproductive health. Phthalates have been widely used as plasticizers in plastic containers, children's toys, and medical devices, and their ubiquitous presence and endocrine-disrupting potential have already raised particular concerns. Phthalate exposure has been linked to various adverse health outcomes, including reproductive diseases. Given that many phthalates are gradually being banned, a growing number of phthalate alternatives are becoming popular, such as di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) adipate (DEHA), and di(2-ethylhexyl) terephthalate (DEHTP), and they are beginning to have a wide range of environmental effects. Studies have shown that many phthalate alternatives may disrupt female reproductive function by altering the estrous cycle, causing ovarian follicular atresia, and prolonging the gestational cycle, which raises growing concerns about their potential health risks. Herein, we summarize the effects of phthalates and their common alternatives in different female models, the exposure levels that influence the reproductive system, and the effects on female reproductive impairment, adverse pregnancy outcomes, and offspring development. Additionally, we scrutinize the effects of phthalates and their alternatives on hormone signaling, oxidative stress, and intracellular signaling to explore the underlying mechanisms of action on female reproductive health, because these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption. Given the declining global trends of female reproductive capacity and the potential ability of phthalates and their alternatives to negatively impact female reproductive health, a more comprehensive study is needed to understand their effects on the human body and their underlying mechanisms. These findings may have an important role in improving female reproductive health and in turn decreasing the number of complications during pregnancy.

Maternal urinary bisphenols and phthalates in relation to estimated fetal weight across mid to late pregnancy

BACKGROUND

Bisphenols and phthalates are high production volume chemicals used as additives in a variety of plastic consumer products leading to near ubiquitous human exposure. These chemicals have established endocrine disrupting properties and have been linked to a range of adverse reproductive and developmental outcomes. Here, we investigated exposure in relation to fetal growth.

METHODS

Participants included 855 mother-fetal pairs enrolled in the population-based New York University Children's Health and Environment Study (NYU CHES). Bisphenols and phthalates were measured in maternal urine collected repeatedly during pregnancy. Analyses included 15 phthalate metabolites and 2 bisphenols that were detected in 50 % of participants or more. Fetal biometry data were extracted from electronic ultrasonography records and estimated fetal weight (EFW) was predicted for all fetuses at 20, 30, and 36 weeks gestation. We used quantile regression adjusted for covariates to model exposure-outcome relations across percentiles of fetal weight at each gestational timepoint. We examined sex differences using stratified models.

RESULTS

Few statistically significant associations were observed across chemicals, gestational time periods, percentiles, and sexes. However, within gestational timepoints, we found that among females, the molar sums of the phthalates DiNP and DnOP were generally associated with decreases in EFW among smaller babies and increases in EFW among larger babies. Among males, the opposite trend was observed. However, confidence intervals were generally wide at the tails of the distribution.

CONCLUSION

In this sample, exposure to bisphenols and phthalates was associated with small sex-specific shifts in fetal growth; however, few associations were observed at the median of fetal weight and confidence intervals in the tails were wide. Findings were strongest for DiNP and DnOP, which are increasingly used as replacements for DEHP, supporting the need for future research on these contaminants.

Early-life exposure to di (2-ethyl-hexyl) phthalate: Role in children with endocrine disorders

Di (2-ethyl-hexyl) phthalate (DEHP), one of endocrine-disrupting chemicals (EDCs), has widespread concern due to its serious health hazards. Exposure to DEHP in the early stage of life affects fetal metabolic and endocrine function, which even would cause genetic lesions. To date, it is widely believed that the increasing incidence of childhood obesity and diabetes in adolescents is related to the impact of DEHP on glucose and lipid homeostasis in children. However, there remains a knowledge gap to recognize these adverse effects. Thus, in this review, besides the exposure routes and levels of DEHP, we further outline the effects of early-life exposure to DEHP on children and potential mechanisms, focusing on the aspect of metabolic and endocrine homeostasis.

Association of phthalate exposure with low birth weight in couples conceiving naturally or via assisted reproductive technology in a prospective birth cohort

BACKGROUND

Few studies have investigated the adverse effects of preconception phthalate (PAE) exposure on birth weight in couples receiving assisted reproductive technology (ART) compared to naturally conceived newborns.

OBJECTIVES

We examined the association between parental preconception/prenatal urinary phthalate exposure and low birth weight (LBW) risk in couples who conceived using ART or naturally.

METHODS

From the Jiangsu Birth Cohort Study (China), we recruited 544 couples who conceived after infertility treatment and 940 couples who conceived naturally and gave birth to a singleton infant between November 2014 and December 2019. Seventeen metabolites of phthalate and three metabolites of phthalate alternatives were analyzed in parental spot urine samples. Clinical data were collected from medical records. We used generalized linear models, elastic net regression, Bayesian kernel machine regression, and quantile-based g-computation to examine the individual and joint effects of parental phthalate exposure on birth weight and LBW risk ratios (RR).

RESULTS

The relationship between parental phthalate exposure and birth weight was consistent between ART and natural conception. Maternal exposure to mono-ethyl phthalate and mono-carboxyisooctyl phthalate was associated with an increased risk of LBW in ART-conceived infants (RR = 1.27; 95 % confidence interval (CI): 1.03, 1.56; and RR = 1.31; 95 % CI: 1.03, 1.67, respectively). In contrast, in the spontaneously conceived infants, higher paternal prenatal concentrations of mono-benzyl phthalate and mono-carboxyisononyl phthalate were associated with a 40 % and 53 % increase in LBW risk, respectively. Exposure to PAE mixtures was associated with LBW in ART-conceived infants, with the effects primarily driven by di-ethyl phthalate, benzylbutyl phthalate, and di-isononyl phthalate metabolites. Sex-specific LBW was observed, with females appearing to be more susceptible than males.

CONCLUSIONS

Maternal preconception and paternal prenatal exposure to phthalates were associated with increased risk of LBW in infants. Compared with natural conception, ART-conceived fetuses were more sensitive to PAE mixtures, which requires further attention.

Endocrine disruptor chemicals, adipokines and reproductive functions

The prevalence of adult obesity has risen markedly in recent decades. The endocrine system precisely regulates energy balance, fat abundance and fat deposition. Interestingly, white adipose tissue is an endocrine gland producing adipokines, which regulate whole-body physiology, including energy balance and reproduction. Endocrine disruptor chemicals (EDCs) include natural substances or chemicals that affect the endocrine system by multiple mechanisms and increase the risk of adverse health outcomes. Numerous studies have associated exposure to EDCs with obesity, classifying them as obesogens by their ability to activate different mechanisms, including the differentiation of adipocytes, increasing the storage of triglycerides, or elevating the number of adipocytes. Moreover, in recent years, not only industrial deception and obesity have intensified but also the problem of human infertility. Reproductive functions depend on hormone interactions, the balance of which may be disrupted by various EDCs or obesity. This review gives a brief summary of common EDCs linked with obesity, the mechanisms of their action, and the effect on adipokine levels, reproduction and connected disorders, such as polycystic ovarian syndrome, decrease in sperm motility, preeclampsia, intrauterine growth restriction in females and decrease of sperm motility in males.

Epigenetics Beyond Fetal Growth Restriction: A Comprehensive Overview

Fetal growth restriction is a pathological condition occurring when the fetus does not reach the genetically determined growth potential. The etiology of fetal growth restriction is expected to be multifactorial and include fetal, maternal, and placental factors, the latter being the most frequent cause of isolated fetal growth restriction. Severe fetal growth restriction has been related to both an increased risk of perinatal morbidity and mortality, and also a greater susceptibility to developing diseases (especially cardio-metabolic and neurological disorders) later in life. In the last decade, emerging evidence has supported the hypothesis of the Developmental Origin of Health and Disease, which states that individual developmental 'programming' takes place via a delicate fine tuning of fetal genetic and epigenetic marks in response to a large variety of 'stressor' exposures during pregnancy. As the placenta is the maternal-fetal interface, it has a crucial role in fetal programming, such that any perturbation altering placental function interferes with both in-utero fetal growth and also with the adult life phenotype. Several epigenetic mechanisms have been highlighted in modulating the dynamic placental epigenome, including alterations in DNA methylation status, post-translational modification of histones, and non-coding RNAs. This review aims to provide a comprehensive and critical overview of the available literature on the epigenetic background of fetal growth restriction. A targeted research strategy was performed using PubMed, MEDLINE, Embase, and The Cochrane Library up to January 2022. A detailed and fully referenced synthesis of available literature following the Scale for the Assessment of Narrative Review Articles guidelines is provided. A variety of epigenetic marks predominantly interfering with placental development, function, and metabolism were found to be potentially associated with fetal growth restriction. Available evidence on the role of environmental exposures in shaping the placental epigenome and the fetal phenotype were also critically discussed. Because of the highly dynamic crosstalk between epigenetic mechanisms and the extra level of complexity in interpreting the final placental transcriptome, a full comprehension of these phenomenon is still lacking and advances in multi-omics approaches are urgently needed. Elucidating the role of epigenetics in the developmental origins of health and disease represents a new challenge for the coming years, with the goal of providing early interventions and prevention strategies and, hopefully, new treatment opportunities.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

Maternal cadmium exposure impairs placental angiogenesis in preeclampsia through disturbing thyroid hormone receptor signaling

Cadmium is a ubiquitous environmental pollutant, which can increase the risk of preeclampsia. This study was designed to determine the mechanism of cadmium exposure during pregnancy impaired placental angiogenesis that was associated with the occurrence of preeclampsia. The effects of cadmium exposure on placental thyroid hormone receptor signaling were explored. JEG3 cells were treated with CdCl₂ (20 μM) and the Dio2 inhibitor, IOP (100 μM). Cadmium levels in maternal blood and placentae were increased in preeclampsia group. Placental angiogenesis of preeclampsia was decreased with decreased expression of PLGF and VEGF and increased expression of sFlt1. Meanwhile, the expression and nuclear translocation of thyroid hormone receptor α were decreased in preeclampsia placenta, as well as the expression of Dio2, but not the expression and nuclear translocation of thyroid hormone receptor β. Furthermore, we found that cadmium exposure downregulated the expression of thyroid hormone receptor α and Dio2, but not the expression of thyroid hormone receptor β in JEG3 cells. Also, we found that cadmium exposure decreased the expression of PLGF and VEGF and increased the expression of sFlt1 in JEG3 cells. IOP pretreatment decreased the expression of PLGF and increased the expression of sFlt1. In conclusion, our results elucidated that cadmium exposure would impair placental angiogenesis in preeclampsia through disturbing thyroid hormone receptor signaling.

Association of preconception mixtures of phenol and phthalate metabolites with birthweight among subfertile couples

Although parental preconception exposure to some phenols and phthalates have been associated with reduced birthweight, few studies have examined these chemicals as complex mixtures.

Phthalate Exposures and Placental Health in Animal Models and Humans: A Systematic Review

Phthalates are ubiquitous compounds known to leach from the plastic products that contain them. Due to their endocrine-disrupting properties, a wide range of studies have elucidated their effects on reproduction, metabolism, neurodevelopment, and growth. Additionally, their impacts during pregnancy and on the developing fetus have been extensively studied. Most recently, there has been interest in the impacts of phthalates on the placenta, a transient major endocrine organ critical to maintenance of the uterine environment and fetal development. Phthalate-induced changes in placental structure and function may have significant impacts on the course of pregnancy and ultimately, child health. Prior reviews have described the literature on phthalates and placental health; however to date, there has been no comprehensive, systematic review on this topic. Here, we review 35 papers (24 human and 11 animal studies) and summarize phthalate exposures in relation to an extensive set of placental measures. Phthalate-related alterations were reported for placental morphology, hormone production, vascularization, histopathology, and gene/protein expression. The most consistent changes were observed in vascular and morphologic endpoints, including cell composition. These changes have implications for pregnancy complications such as preterm birth and intrauterine growth restriction as well as potential ramifications for children's health. This comprehensive review of the literature, including common sources of bias, will inform the future work in this rapidly expanding field.

MiR-550a-3p restores damaged vascular smooth muscle cells by inhibiting thrombomodulin in an <em>in vitro</em> atherosclerosis model

Thrombomodulin (TM) is involved in the pathological process of atherosclerosis; however, the underlying mechanism remains unclear. Oxidised low-density lipoprotein (Ox-LDL; 100 μg/mL) was used to induce human vascular smooth muscle cells (HVSMCs) into a stable atherosclerotic cell model. The expression levels of miR-550a-3p and TM were detected by real-time reverse transcription-polymerase chain reaction. Cell proliferation was estimated using CCK8 and EDU assays. Wound scratch and transwell assays were used to measure the ability of cells to invade and migrate. Propidium iodide fluorescence-activated cell sorting was used to detect apoptosis and cell cycle changes. A dual-luciferase reporter assay was performed to determine the binding of miR-550a-3p to TM. Our results suggested the successful development of a cellular atherosclerosis model. Our data revealed that TM overexpression significantly promoted the proliferation, invasion, migration, and apoptosis of HVSMCs as well as cell cycle changes. Upregulation of miR-550a-3p inhibited the growth and metastasis of HVSMCs. Furthermore, miR-550a-3p was confirmed to be a direct target of TM. Restoration of miR-550a-3p expression rescued the effects of TM overexpression. Thus, miR-550a-3p might play a role in atherosclerosis and, for the first time, normalised the function of injured vascular endothelial cells by simultaneous transfection of TM and miR-550a-3p. These results suggest that the miR-550a-3p/TM axis is a potential therapeutic target for atherosclerosis.

Microplastics and di (2-ethylhexyl) phthalate synergistically induce apoptosis in mouse pancreas through the GRP78/CHOP/Bcl-2 pathway activated by oxidative stress

With the widespread use of plastics, microplastics (MPs) and di(2-ethylhexyl) phthalate (DEHP) have become emerging environmental pollutants. The combined toxicity of MPs and DEHP on the mouse pancreas and the specific mechanism of toxicity remain unclear. To establish in vitro and in vivo models to address these questions, mice were continuously exposed to 200 mg/kg/d DEHP and 10 mg/L MPs for 4 weeks. In vitro, MIN-6 cells were treated with 200 μg/mL MPs and 200 μM DEHP for 24 h. Based on toxicity assessed using CCK8 of the equivalent TU binary mixture, the IC50 of the TU-mix of DEHP and MPs 0.692 < 0.8, indicating a synergistic effect of the two toxicants. Meanwhile, our data revealed that compared to the control group, MPs and DEHP combined treatment increased ROS levels, inhibited the activity, and enhanced the expression of GRP78, and CHOP. Simultaneously, activated CHOP decreased the expression of Bcl-2, and increased the expression of Bax. In conclusion, DEHP and MPs synergistically induce oxidative stress, and activate the GRP78/CHOP/Bcl-2 pathway to induce pancreatic apoptosis in mice. Our finding provides a new direction for the research on the specific mechanism of MPs and DEHP combined toxicity.

Identification of Phthalates from Artificial Products in Chinese Kindergarten Classrooms and the Implications for Preschool Children's Exposure Assessments

Phthalates are typical chemical pollutants in kindergarten classrooms since numerous artificial products (e.g., polyvinyl chloride (PVC) floorings, soft polymers and plastic toys) that might contain phthalates are widely distributed in kindergarten classrooms. Although Chinese preschool children spend a considerable amount of their waking hours (>8 h/day) in kindergartens, phthalate exposure in such indoor environment has not been given much attention. In this study, the mass fractions of six phthalates in twenty-six artificial products (fifteen flat decoration materials and eleven plastic toys) commonly found in Chinese kindergarten classrooms were measured. Di-2-ethylhexyl phthalate (DEHP) was the most predominant compound in all materials. The emission characteristics of the DEHP from these materials were further investigated. The measured emission characteristics were used for predicting multi-phase DEHP concentrations in kindergarten classrooms by applying a mass transfer model. The modeled concentrations were comparable with those measured in the real environment, indicating that these products might be the major sources of DEHP in Chinese kindergarten classrooms. Preschool children’s exposure to DEHP was found to be 0.42 μg/kg/day in kindergartens under baseline conditions, accounting for 18% of the total exposure to DEHP in Chinese indoor environments.

Bisphenol A Analogs Induce Cellular Dysfunction in Human Trophoblast Cells in a Thyroid Hormone Receptor-Dependent Manner: In Silico and In Vitro Analyses

Bisphenol A (BPA) and its analogs are frequently detected in human daily necessities and environmental media. Placental thyroid hormone plays an important role in fetal development. Herein, we followed the adverse outcome pathway (AOP) to explore the toxic mechanisms of BPA and its analogs toward placental thyroid hormone receptor (TR). First, the TOX21 database was used, and the interactions between BPA analogs and the ligand-binding domains (LBDs) of two subtypes of TR (TRα and TRβ) were subjected to in silico screening using molecular docking (MD) and molecular dynamics simulation (MDS). Fluorescence spectra and circular dichroism (CD) showed that BPA and its analogs interfere with TRs as a molecular initiation event (MIE), including static fluorescence quenching and secondary structural content changes in TR-LBDs. Key events (KEs) of the AOP, including the toxicity induced in placental chorionic trophoblast cells (HTR-8/SVneo) by an inverted U-shaped dose effect and changes in ROS levels, were tested in vitro. BPA, BPB, and BPAF significantly changed the expression level of TRβ, and only BPAF significantly downregulated the expression level of TRα. In conclusion, our study contributes to the health risk assessment of BPA and its analogs regarding placental adverse outcomes (AOs).

Association of Phthalate Exposure with Endometriosis and Idiopathic Infertility in Egyptian Women

BACKGROUND: Phthalates are compounds found in medical supplies, cellophane wraps, beverage containers, metal can linings, and other products. They have the potential to be significant endocrine disruptors. In experimental animals, thereby affecting their reproductive capacity. Endometriosis is a gynecological condition defined by ectopic endometrial glands and stromal development. Exposure to phthalates has been linked to the development of endometriosis in numerous studies. The dangers of phthalates to women’s reproductive health and fertility have been widely reported. AIM: So far, the relationship between phthalates and infertility is not proven so we decided to see if there was a link between the urine phthalate metabolite levels and endometriosis or idiopathic infertility in Egyptian women. METHODS: Our research was carried out at the infertility outpatient clinic of the Faculty of Medicine of Cairo University. It included 100 female subjects aged 18−40-years-old. Group A (idiopathic infertility; n = 40), Group B (endometriosis; n = 40), and Group C (control; n = 20) were the three age-matched groups that were studied. Using high-performance liquid chromatography (HPLC), the urine levels of mono-2-ethylhexyl phthalate (MEHP) were quantified. RESULTS: The comparison between the study groups has revealed statistically significant differences regarding the urine MEHP levels between Groups A and B. An analysis of the urine MEHP levels in the study Groups A and B has also revealed that the significantly higher urinary MEHP levels are correlated with the use of dietary plastic containers, the use of cosmetics, and the patients’ estrogen levels. Moreover, the urinary MEHP levels of Group A were associated with a history of abortions. CONCLUSIONS: Higher levels of urinary MEHP are positively associated with female reproductive disorders, specifically endometriosis, idiopathic infertility, and abortion.

Synaptic loss in a mouse model of euthyroid Hashimoto's thyroiditis: possible involvement of the microglia

Background

Hashimoto’s thyroiditis (HT) is an autoimmune illness that renders individuals vulnerable to neuropsychopathology even in the euthyroid state, the mechanisms involved remain unclear. We hypothesized that activated microglia might disrupt synapses, resulting in cognitive disturbance in the context of euthyroid HT, and designed the present study to test this hypothesis.

Methods

Experimental HT model was induced by immunizing NOD mice with thyroglobulin and adjuvant twice. Morris Water Maze was measured to determine mice spatial learning and memory. The synaptic parameters such as the synaptic density, synaptic ultrastructure and synaptic-markers (SYN and PSD95) as well as the interactions of microglia with synapses were also determined.

Results

HT mice had poorer performance in Morris Water Maze than controls. Concurrently, HT resulted in a significant reduction in synapse density and ultrastructure damage, along with decreased synaptic puncta visualized by immunostaining with synaptophysin and PSD-95. In parallel, frontal activated microglia in euthyroid HT mice showed increased engulfment of PSD95 and EM revealed that the synaptic structures were visible within the microglia. These functional alterations in microglia corresponded to structural increases in their attachment to neuronal perikarya and a reduction in presynaptic terminals covering the neurons.

Conclusion

Our results provide initial evidence that HT can induce synaptic loss in the euthyroid state with deficits might be attributable to activated microglia, which may underlie the deleterious effects of HT on spatial learning and memory.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00710-2.

Maternal exposure to bis(2-ethylhexyl) phthalate during the thyroid hormone-dependent stage induces persistent emotional and cognitive impairment in middle-aged offspring mice

Prenatal DEHP exposure can cause offspring neurodevelopmental toxicity, but the persistent effects of such exposure window are unclear. This study aimed to investigate the lasting neurobehavioral impact of DEHP on offspring following early exposure from GD9.5 (fetal neural tube closure) to GD16.5 (fetal thyroxin, TH, synthesis). Data showed maternal exposure to DEHP during the thyroid hormone-dependent stage induced a range of neurobehavioral phenotypic changes in adult and middle-aged mice, including anxiety, depression and cognitive impairment. Significant reductions in free TH, TH transporters, and TH metabolic enzyme deiodinase II (D2) were observed in the fetal brain, whereas D3 was elevated, indicating that TH signaling disruption was caused by in utero exposure. Gene expression analyses suggested the expression levels of the TH receptors Trα1, Trβ1 and their downstream target, brain-derived neurotrophic factor, were significantly attenuated, which may partially explain the mechanisms of neurodevelopmental impairment. This study provides new evidence of the persistent effects of sex-specific neurodevelopmental impairment due to in utero DEHP exposure, possibly through damage to the fetal brain TH signaling systems that causes lifelong brain damage. These results further suggest a profound neurobehavioral toxicity of DEHP that may be programmed during early developmental stage exposure and manifested later in life.

Prenatal phthalate exposure associated with age-specific alterations in markers of adiposity in offspring: A systematic review

Childhood obesity and metabolic disorders are of concern and are public health problems globally. Environmental endocrine disruptors, including phthalates, are well known as "obesogens" and "metabolic disruptors". Several studies have investigated the relationships between prenatal phthalate exposure and childhood obesity with inconsistent conclusions. Given the child growth trajectory/pattern as a possible early marker of metabolic disorders, we aimed to assess the effect of prenatal phthalate exposure on offspring growth trajectory. A systematic literature search was conducted using MEDLINE (accessed through PubMed), Web of Science, and CNKI (Chinese National Knowledge Infrastructure) until July 2021. We evaluated the risk of bias for adherence to the prespecified criteria. Fourteen eligible articles were finally included in this systematic review according to the defined PECOS statement. The risk of bias of the included studies was "low" or "probably low", and few were "probably high" and "high". These studies were mostly carried out in the United States (N = 6); others were conducted in China (N = 2), Mexico (N = 2), France (N = 1), Spain (N = 1), Greece (N = 1), and Australia (N = 1) and published from 2015 to 2021. The combined subjects of the 14 studies were 10,396 mother-child pairs. Except for 3 studies not reporting the sex ratio, at least 4001 boys and 3366 girls were included. For the association of prenatal phthalate exposure with an absolute adiposity marker (at a specific visit timepoint), only a few studies were using the same obesity marker as the outcome endpoint and using the same statistical method to explore their associations. However, MEP appeared to be positively associated with several obesity markers, such as the absolute BMI z score, weight-for-age z score, waist circumference, and overweight status. For the association of prenatal phthalate exposure with a repeated measurement of the adiposity marker over the age range, neither associations of adiposity markers with a specific phthalate metabolite nor relationships of a specific adiposity marker with prenatal phthalate exposure were of a consistent result. All four articles reported that phthalate metabolite exposure during pregnancy was associated with children's growth trajectory. Three suggested a sex-specific association between prenatal phthalate exposure and obesity trajectory. In conclusion, the current articles did not show any relationship between prenatal phthalate exposure and children's age-specific outcomes, except for positive associations of prenatal MEP exposure with absolute adiposity markers. However, epidemiological data supported a weak relationship between prenatal phthalate exposure and children's obesity trajectory in a sex-specific manner.

Gaps in the knowledge of thyroid hormones and placental biology

Thyroid hormones (THs) are required for the growth and development of the foetus, stimulating anabolism and oxygen consumption from the early stages of pregnancy to the period of foetal differentiation close to delivery. Maternal changes in the hypothalamic–pituitary thyroid axis are also well known. In contrast, several open questions remain regarding the relationships between the placenta and the maternal and foetal TH systems. The exact mechanism by which the placenta participates in regulating the TH concentration in the foetus and mother and the role of TH in the placenta are still poorly studied. In this review, we aim to summarize the available data in the area and highlight significant gaps in our understanding of the ontogeny and cell-specific localization of TH transporters, TH receptors and TH metabolic enzymes in the placenta in both human and rodent models. Significant deficiencies also exist in knowledge of the contribution of genomic and nongenomic effects of TH on the placenta and finally how the placenta reacts during pregnancy when the mother has thyroid disease. By addressing these key knowledge gaps, improved pregnancy outcomes and management of women with thyroid alterations may be possible.

Di (2-ethyl-hexyl) phthalate disrupts placental growth in a dual blocking mode

Di (2-ethyl-hexyl) phthalate (DEHP) is a widely used plasticizer. Maternal DEHP exposure inhibits cell proliferation and reduces placentas size, which associates with fetal growth restriction and adulthood diseases. However, the mechanism of placental cell proliferation inhibition by DEHP remains elusive. This study investigated the effect of DEHP on placental cell proliferation from cell cycle arrest. Utilizing in vitro and in vivo experiments, we investigated cell cycle arrest, DNA double-strand break (DSB) repair, genotoxic stress response, and micronuclei formation. Most DEHP metabolizes to mono (2-Ethylhexyl) phthalate (MEHP) and distributes to organs quickly, so MEHP and DEHP were used in cultured cell and animal experiments, respectively. Here, a double blocking mode for the proliferation inhibition of the placental cell was revealed. One is that the classical DSB repair pathways were suppressed, which arrested the cell cycle at the G2/M phase. The other is that DEHP stimulated an elevated level of progesterone, which blocked the cell cycle at metaphase by disrupting chromosome arrangement. These two sets of events facilitated micronuclei formation and resulted in cell proliferation inhibition. This findings provide a novel mechanistic understanding for DEHP to inhibit placental cell proliferation.

Contribution of prenatal endocrine-disrupting chemical exposure to genital anomalies in males: The pooled results from current evidence

The etiology of hypospadias and cryptorchidism, which are the two most common genital anomalies in males, has not been elucidated. Although prenatal exposure to endocrine-disrupting chemicals (EDCs) may increase the risks of hypospadias and cryptorchidism, the associations have not been confirmed. Therefore, we performed a meta-analysis to establish the relationships between prenatal exposure to EDCs and male genital anomalies. A systematic search of PubMed, EMbase, and Cochrane Library CENTRAL for relevant published studies providing quantitative data on the associations between prenatal EDCs exposure and hypospadias/cryptorchidism in humans was conducted. In total, sixteen case-controlled studies were included. Prenatal exposure to overall EDCs was associated with an increased risk of hypospadias in males (OR, 1.34, 95 % CI 1.12 to 1.60). Although there was no statistically significant association between overall EDCs exposure and cryptorchidism (OR, 1.11, 95 % CI 0.99 to 1.24), exposure to phenol substances was associated with an increased risk of cryptorchidism (OR, 1.81, 95 % CI, 1.12 to 2.93). Using the GRADE tool, we found the overall evidence to be of moderate certainty. In conclusion, the current evidence suggests prenatal EDCs exposure may increase the risk of hypospadias in males.

Di(2-ethylhexyl) phthalate (DEHP) and thyroid: biological mechanisms of interference and possible clinical implications

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental endocrine disruptor. DEHP can be absorbed into the human body through the air, food, water, and skin. After entering the human body, DEHP is rapidly converted to mono(2-ethylhexyl) phthalate (MEHP) with greater toxicity than DEHP. An increasing number of studies indicates that DEHP or MEHP can damage the thyroid tissue and disrupt the function, but the mechanisms remain unclear. This article reviews the toxicity of DEHP on thyroid structures and functions and summarizes the potential mechanisms to provide evidence for preventing the thyroid-related diseases.

Association of phthalate exposure with thyroid function during pregnancy

BACKGROUND

The extent of thyroid disruptive effects of phthalates during pregnancy remains unclear.

AIM

To investigate the association of maternal urinary phthalates with markers of the thyroid system during early pregnancy.

METHODS

Urinary concentrations of phthalate metabolites and serum concentrations of thyroid stimulating hormone (TSH), free and total thyroxine (FT4 and TT4) and free and total triiodothyronine (FT3 and TT3) were measured in pregnant women in early pregnancy in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (2007-ongoing), a population-based prospective cohort.

RESULTS

In the 1,996 included women, higher di-ethyl-hexyl phthalate (DEHP) metabolites were associated with a lower FT4 (β [SE] for the molar sum: -0.13 [0.06], P = 0.03) and a higher TSH/FT4 ratio (0.003 [0.001], P = 0.03). Higher concentrations of di-iso-nonyl phthalate (DINP) metabolites were associated with a lower TT4 (β [SE] for the molar sum: 0.93 [0.44], P = 0.03) as well as with lower TT4/FT4 and TT4/TT3 ratios. Higher metabolites of both dibutyl and butyl-benzyl phthalate (DBP and BBzP) were associated with lower T4/T3 ratio (free and total) and higher FT4/TT4 and FT3/TT3 ratios. A higher diisononyl cyclohexane dicarboxylate (DINCH) metabolite concentration was associated with a higher TT3.

CONCLUSIONS

These results translate results from experimental studies suggesting that exposure to phthalates may interfere with the thyroid system during pregnancy. This is also true for compounds that have been introduced to replace known disruptive phthalates. Further experimental studies should take into account the human evidence to better investigate the potential underlying mechanisms of thyroid disruption by phthalates.

Phthalates in Chinese vehicular environments: Source emissions, concentrations, and human exposure

Phthalates are typical air pollutants in vehicular environment since numerous synthetic materials that might contain phthalates are widely used to fabricate vehicle interiors (e.g., seat cushions, floor mats and dashboards). Hitherto, the importance of phthalate pollution in vehicular environment is not well-recognized because people spend only a small portion (around 8%) of their time in vehicles. In this study, the mass fractions of six phthalates in nine materials commonly used in Chinese vehicles (floor mats and seat cushions) were measured. Two phthalates, di-n-butyl phthalate (DnBP) and di-2-ethylhexyl phthalate (DEHP), were identified in most materials (the other phthalates were not detected). The emission characteristics of DnBP and DEHP from these materials were further investigated. The measured emission parameters were used as input for a mass-transfer model to estimate DnBP and DEHP concentrations in cabin air. Finally, the ratios between human exposures (via inhalation and dermal absorption from the gas phase) in vehicular environment and the total exposures in typical indoor environments (e.g., residences and offices) were estimated to be up to 110% and 20% for DnBP and DEHP, respectively. Based on these results, the vehicular environment might be a considerable site for human exposure to airborne phthalates.

A Comprehensive Assessment of Associations between Prenatal Phthalate Exposure and the Placental Transcriptomic Landscape

BACKGROUND

Phthalates are commonly used endocrine-disrupting chemicals that are ubiquitous in the general population. Prenatal phthalate exposure may alter placental physiology and fetal development, leading to adverse perinatal and childhood health outcomes.

OBJECTIVE

We examined associations between prenatal phthalate exposure in the second and third trimesters and the placental transcriptome at birth, including genes and long noncoding RNAs (lncRNAs), to gain insight into potential mechanisms of action during fetal development.

METHODS

The ECHO PATHWAYs consortium quantified 21 urinary phthalate metabolites from 760 women enrolled in the CANDLE study (Shelby County, TN) using high-performance liquid chromatography-tandem mass spectrometry. Placental transcriptomic data were obtained using paired-end RNA sequencing. Linear models were fitted to estimate separate associations between maternal urinary phthalate metabolite concentration during the second and third trimester and placental gene expression at birth, adjusted for confounding variables. Genes were considered differentially expressed at a Benjamini-Hochberg false discovery rate (FDR) p<0.05. Associations between phthalate metabolites and biological pathways were identified using self-contained gene set testing and considered significantly altered with an FDR-adjusted p<0.2.

RESULTS

We observed significant associations between second-trimester phthalate metabolites mono (carboxyisooctyl) phthalate (MCIOP), mono-2-ethyl-5-carboxypentyl phthalate, and mono-2-ethyl-5-oxohexyl phthalate and 18 genes in total, including four lncRNAs. Specifically, placental expression of NEAT1 was associated with multiple phthalate metabolites. Third-trimester MCIOP and mono-isobutyl phthalate concentrations were significantly associated with placental expression of 18 genes and two genes, respectively. Expression of genes within 27 biological pathways was associated with mono-methyl phthalate, MCIOP, and monoethyl phthalate concentrations.

DISCUSSION

To our knowledge, this is the first genome-wide assessment of the relationship between the placental transcriptome at birth and prenatal phthalate exposure in a large and diverse birth cohort. We identified numerous genes and lncRNAs associated with prenatal phthalate exposure. These associations mirror findings from other epidemiological and in vitro analyses and may provide insight into biological pathways affected in utero by phthalate exposure. https://doi.org/10.1289/EHP8973.

Placental outcomes of phthalate exposure

Proper placental development and function relies on hormone receptors and signaling pathways that make the placenta susceptible to disruption by endocrine disrupting chemicals, such as phthalates. Here, we review relevant research on the associations between phthalate exposures and dysfunctions of the development and function of the placenta, including morphology, physiology, and genetic and epigenetic effects. This review covers in vitro studies, in vivo studies in mammals, and studies in humans. We also discuss important gaps in the literature. Overall, the evidence indicates that toxicity to the placental and maternal-fetal interface is associated with exposure to phthalates. Further studies are needed to better elucidate the mechanisms through which phthalates act in the placenta as well as additional human studies that assess placental disruption through pregnancy with larger sample sizes.

Endocrine disrupting chemicals (EDCs) and placental function: Impact on fetal brain development

Pregnancy is a critical time of vulnerability for the development of the fetal brain. Exposure to environmental pollutants at any point in pregnancy can negatively impact many aspects of fetal development, especially the organization and differentiation of the brain. The placenta performs a variety of functions that can help protect the fetus and sustain brain development. However, disruption of any of these functions can have negative impacts on both the pregnancy outcome and fetal neurodevelopment. This review presents current understanding of how environmental exposures, specifically to endocrine disrupting chemicals (EDCs), interfere with placental function and, in turn, neurodevelopment. Some of the key differences in placental development between animal models are presented, as well as how placental functions such as serving as a xenobiotic barrier and exchange organ, immune interface, regulator of growth and fetal oxygenation, and a neuroendocrine organ, could be vulnerable to environmental exposure. This review illustrates the importance of the placenta as a modulator of fetal brain development and suggests critical unexplored areas and possible vulnerabilities to environmental exposure.

Trimester-specific and sex-specific effects of prenatal exposure to di(2-ethylhexyl) phthalate on fetal growth, birth size, and early-childhood growth: A longitudinal prospective cohort study

Prenatal exposure to di(2-ethylhexyl) phthalate (DEHP) may cause adverse health outcomes. However, trimester-specific impacts of DEHP exposure on offspring growth from fetal to early childhood stage have not been thoroughly evaluated. In this study, participants who provided a full series of urine specimens at three trimesters were selected from a birth cohort conducted at Wuhan, China from 2014 to 2015. 814 mother-offspring pairs were included in the study. Urinary concentrations of DEHP metabolites were determined using liquid chromatography-tandem mass spectrometry. Z-scores for ultrasound-measured fetal growth parameters at 14.0-18.9, 22.6-27.0, and 29.0-33.9 weeks of gestation, were calculated. Weight, height, and body mass index (BMI) at 6, 12, and 24 months were standardized to z-scores using sex-specific and age-specific WHO child growth standards. Linear regressions with generalized estimating equations were used to assess the relationships of DEHP levels per trimester to fetal growth, birth size, and growth at 6, 12, and 24 months to explore the trimester-specific impacts of DEHP exposure on offspring development. Among males, the1^st-trimester DEHP was negatively related to fetal growth (β < 0, p < 0.05), but positively related to 24-month BMI. The 2nd-trimester DEHP was negatively related to birth weight and birth length, but positively related to weight gain rates from birth to 24 months old. The 3rd-trimester DEHP was positively (β > 0, p < 0.05) associated with birth weight and BMI at 6 and 12 months. Among females, the 1st-trimester DEHP was associated with increased birth length, while the 2nd-trimester DEHP was negatively associated with BMI at 6 and 12 months. A negative association between DEHP and weight gain rates at 6 months was noted among females. This prospective cohort revealed the sex-specific and trimester-specific relationships of DEHP exposure to offspring growth from fetal to early-childhood stage.

Multiple bioanalytical methods reveal a thyroid-disrupting mechanism related to the membrane receptor integrin αvβ3

Di(2-ethylhexyl) phthalate (DEHP), a manufactured chemical, is suitable for large-scale production and has extensive applications. Although restricted for use, DEHP is still ubiquitous in the environment and shows potential to disrupt the structure or function of the thyroid system. However, its toxic mechanism is complex and not clearly understood. In this study, a battery of methods was employed to investigate DEHP-induced thyroid-disrupting effects and their mechanism of action, focusing on a newly discovered membrane receptor-mediated mechanism. The results showed that DEHP promoted rat pituitary tumor (GH3) cell proliferation and c-fos gene expression at environment level concentrations (2 and 5 μmol/L) in a manner similar to that of the natural thyroid hormone 3,3',5-triiodo-L-thyronine (T3). The macromolecule DEHP-BSA cannot pass through the cell membrane to interact with nuclear receptors but upregulated the c-fos gene expression when administered at concentrations comparable to DEHP concentrations; molecular docking demonstrated that DEHP has affinity for the membrane receptor integrin α_vβ₃; DEHP at 2 μmol/L upregulated the β₃ gene expression in GH3 cells; after the addition of integrin α_vβ₃-inhibiting RGD peptide, DEHP-induced c-fos gene upregulation decreased. All of these findings support the supposition that DEHP-induced thyroid-disrupting effects might be mediated by the membrane receptor integrin α_vβ₃. Moreover, DEHP activated the downstream extracellular regulated protein kinase (ERK1/2) pathway, upregulating the gene expression of raf-1, MEK-1 and MAPK1 and increasing the protein levels of p-ERK; interestingly, ERK1/2 activation and c-fos upregulation induced by DEHP were attenuated by PD98059 (an ERK1/2 inhibitor). Taken together, the data suggest that the membrane receptor integrin α_vβ₃ and the downstream ERK1/2 pathway might be involved in DEHP-induced thyroid-disrupting effects. This study provides new insight into the thyroid-disrupting effect and the underlying mechanism and will advance the effort to construct adverse outcome pathways of DEHP and other thyroid hormone disrupting chemicals.

The interplay between thyroid hormones and the placenta: a comprehensive review†

Thyroid hormones (THs) regulate a number of metabolic processes during pregnancy. After implantation, the placenta forms and enhances embryonic growth and development. Dysregulated maternal THs signaling has been observed in malplacentation-mediated pregnancy complications such as preeclampsia, miscarriage, and intrauterine growth restriction (IUGR), but the molecular mechanisms involved in this association have not been fully characterized. In this review, we have discussed THs signaling and its roles in trophoblast proliferation, trophoblast differentiation, trophoblast invasion of the decidua, and decidual angiogenesis. We have also explored the relationship between specific pregnancy complications and placental THs transporters, deiodinases, and THs receptors. In addition, we have examined the effects of specific endocrine disruptors on placental THs signaling. The available evidence indicates that THs signaling is involved in the formation and functioning of the placenta and serves as the basis for understanding the pathogenesis and pathophysiology of dysthyroidism-associated pregnancy complications such as preeclampsia, miscarriage, and IUGR.

Review of endocrine disruptors on male and female reproductive systems

Endocrine disruptors (EDs) interfere with different hormonal and metabolic processes and disrupt the development of organs and tissues, as well as the reproductive system. In toxicology research, various animal models have been utilized to compare and characterize the effects of EDs. We reviewed studies assessing the effect of ED exposure in humans, zebrafish, and mouse models and the adverse effects of EDs on male and female reproductive systems. This review outlines the distinctive morphological characteristics, as well as gene expression, factors, and mechanisms that are known to occur in response to EDs. In each animal model, disturbances in the reproductive system were associated with certain factors of apoptosis, the hypothalamic-pituitary-gonadal axis, estrogen receptor pathway-induced meiotic disruption, and steroidogenesis. The effects of bisphenol A, phthalate, and 17α-ethinylestradiol have been investigated in animal models, each providing supporting outcomes and elaborating the key regulators of male and female reproductive systems.

Maternal phthalate urine concentrations, fetal growth and adverse birth outcomes. A population-based prospective cohort study

IMPORTANCE

Exposure to phthalates may affect fetal growth, but previous studies are inconsistent and have not explored the trimester-specific effects of phthalates on repeated measures of fetal growth.

OBJECTIVE

To assess the associations of maternal phthalate metabolites urine concentrations with fetal growth measures and birth outcomes and identify potential windows of vulnerability to exposure.

DESIGN

Population-based prospective cohort study, the Generation R Study (2002-2006). Data analysis was performed from November 2019 to June 2020.

SETTING

Rotterdam, the Netherlands.

PARTICIPANTS

1379 pregnant women.

EXPOSURES

Maternal phthalate metabolites urine concentrations in first, second and third trimester.

MAIN OUTCOMES AND MEASURES

Fetal head circumference, length and weight measured in the second and third trimester by ultrasound and at birth and preterm birth and small size for gestational age at birth.

RESULTS

Higher pregnancy-averaged phthalic acid, low molecular weight phthalate (LMWP), high molecular weight phthalate (HMWP) and di-2-ethylhexylphthalate (DEHP) concentrations tended to be associated with lower fetal weight SDS across gestation. The associations of phthalic acid and LMWP with fetal weight became stronger as pregnancy progressed (differences -0.08 (95% CI -0.14 to -0.02) SDS and -0.09 (95% CI -0.16 to -0.02) SDS at 40 weeks per interquartile range increase in phthalic acid and LMWP, respectively). Higher concentrations of specific LMWP, HMWP and DEHP metabolites were also associated with smaller head circumference and lower length SDS at birth and an increased risk of preterm birth and small size for gestational age at birth (p-values < 0.05). We observed differences by timing of exposure in these associations.

CONCLUSIONS AND RELEVANCE

Higher maternal phthalate metabolites urine concentrations seem to be related with fetal growth restriction and preterm birth. Phthalates may have trimester specific effects on fetal growth and birth outcomes. Further studies are needed to explore the underlying mechanisms and long-term consequences.

Di-(2-ethylhexyl) phthalate induces testicular endoplasmic reticulum stress and germ cell apoptosis in adolescent mice

Di-(2-ethylhexyl) phthalate (DEHP) is a male reproductive toxicant. This research is aimed at investigating the effect of pubertal DEHP exposure on testicular endoplasmic reticulum (ER) stress and germ cell apoptosis. Five-week-old male mice were orally administered with DEHP (0, 0.5, 50, or 500 mg/kg/day) for 35 days. Testis weight and sperm count were reduced in mice exposed to 500 mg/kg/day DEHP. The number of seminiferous tubules in stages VII-VIII, mature seminiferous tubules, was reduced and the number of seminiferous tubules in stages IX-XII, immature seminiferous tubules, was elevated in mice treated with 500 mg/kg/day DEHP. Numerous apoptotic germ cells were observed in mouse seminiferous tubules exposed to 50 and 500 mg/kg/day DEHP. Moreover, cleaved caspase-3 was elevated in mouse testes exposed to 500 mg/kg/day DEHP. In addition, Bcl-2 was reduced and Bax/Bcl-2 was elevated in mouse testes exposed to 500 mg/kg/day DEHP. Additional experiment showed that GRP78, an ER molecular chaperone, was downregulated in mouse testes exposed to 500 mg/kg/day DEHP. Testicular p-IRE-1α, p-JNK, and CHOP, three markers of ER stress, were upregulated in mice exposed to 500 mg/kg/day DEHP. These results suggest that pubertal exposure to high doses of DEHP induces germ cell apoptosis partially through initiating ER stress in testes.

Gene expression in rat placenta after exposure to di(2-ethylhexyl) phthalate

The organic compound di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in many products. Exposure to DEHP has been reported to lead to adverse pregnancy outcomes by suppressing placenta growth and development. The aim of this study was to determine the gene expression profiles of rat placenta exposed to (DEHP) and identify genes crucial for the DEHP response. Three groups of Wistar rats were administered an intragastric dose of 1,000 mg/kg DEHP, 500 mg/kg DEHP, or corn oil, RNA was isolated from placenta tissue, and hybridization was performed. Gene expression profiles were analyzed by identifying functional enrichment, differentially expressed genes (DEGs), protein-protein interaction (PPI) networks and modules, and transcription factor (TF)-miRNA-target regulatory networks. We obtained 2,032 DEGs, including cytochrome P450, family 2, subfamily R, polypeptide 1 (CYP2R1), sterol O-acyltransferase 2 (SOAT2), and 24-dehydrocholesterol reductase (DHCR24) from the steroid biosynthesis pathway and somatostatin receptor 4 (SSTR4) and somatostatin receptor 2 (SSTR2) in the neuroactive ligand-receptor interaction pathway. The PPI network included 476 nodes, 2,682 interaction pairs, and three sub-network modules. Moreover, eight miRNAs, three TFs, and 176 regulatory pairs were obtained from the TF-miRNA-target regulatory network. CYP2R1, SOAT2, DHCR24, SSTR4, and SSTR2 may affect DEHP influence on rat placenta development.

An inadvertent issue of human retina exposure to endocrine disrupting chemicals: A safety assessment

Endocrine disrupting chemicals (EDCs) are a group of chemical compounds that present a considerable public health problem due to their pervasiveness and associations with chronic diseases. EDCs can interrupt the endocrine system and interfere with hormone homeostasis, leading to abnormalities in human physiology. Much attention has been focused on the adverse effects EDCs have on the reproductive system, neurogenesis, neuroendocrine system, and thyroid dysfunction. The eye is usually directly exposed to the surrounding environment; however, the influences of EDCs on the eye have received comparatively little attention. Ocular diseases, such as ocular surface diseases and retinal diseases, have been implicated in hormone deficiency or excess. Epidemiologic studies have shown that EDC exposure not only causes ocular surface disorders, such as dry eye, but also associates with visual deficits and retinopathy. EDCs can pass through the human blood-retinal barrier and enter the neural retina, and can then accumulate in the retina. The retina is an embryologic extension of the central nervous system, and is extremely sensitive and vulnerable to EDCs that could be passed across the placenta during critical periods of retinal development. Subtle alterations in the retinal development process usually result in profound immediate, long-term, and delayed effects late in life. This review, based on extensive literature survey, briefly summarizes the current knowledge about the impact of representative manufactured EDCs on retinal toxicity, including retinal structure alterations and dysfunction. We also highlight the potential mechanism of action of EDCs on the retina, and the predictive retinal models of EDC exposure.

Phthalates and fetal growth velocity: tracking down the suspected links

Fetuses that have not achieved their full growth potential are associated with adverse perinatal and long-term outcomes; thus, it is essential to identify environmental factors that can potentially impair normal intrauterine development. Endocrine disrupting compounds (EDCs), substances capable of altering the homeostasis of the endocrine system, are thought to play a role in restriction of growth velocity, with phthalates being among the most common EDCs to which pregnant women are exposed. Such exposure can potentially lead to changes to the epigenome, placental structure, and hormone function and trigger oxidative stress. Given that these pathways have been linked to fetal growth restriction, we reviewed the literature on the relationship between phthalates and fetal growth. The majority of the studies, which used birth weight as an indicator of intrauterine development, showed contradictory results, the main reason being the EDCs' rapid metabolism. However, we can draw more consistent conclusions when phthalates are quantified at more than one time point during pregnancy. In this narrative review, we present current data indicating the role of phthalates, and especially di-(2-ethylhexyl) phthalate (DEHP), in abnormal fetal growth velocity.