Low-Dose Bisphenol-A Impairs Adipogenesis and Generates Dysfunctional 3T3-L1 Adipocytes

Bisphenol A exposure and type 2 diabetes mellitus risk: a meta-analysis

BACKGROUND

This meta-analytic study explored the relationship between the risk of type 2 diabetes mellitus (T2DM) and bisphenol A concentrations.

METHODS

The Embase and Medline (PubMed) databases were searched, using relevant keywords, for studies published between 1980 and 2018. A total of 16 studies, twelve cross-sectional, two case-control and one prospective, were included in the meta-analysis. The odds ratio (OR) and its 95% confidence interval (CI) were determined across the sixteen studies. The OR and its 95% CI of diabetes associated with bisphenol A were estimated using both fixed-effects and random-effects models.

RESULTS

A total of 41,320 subjects were included. Fourteen of the sixteen studies included in the analysis provided measurements of urine bisphenol A levels and two study provided serum bisphenol A levels. Bisphenol A concentrations in human bio-specimens showed positive associations with T2DM risk (OR 1.28, 95% CI 1.14, 1.44). A sensitivity analysis indicated that urine bisphenol A concentrations were positively associated with T2DM risk (OR 1.20, 95% CI 1.09, 1.31).

CONCLUSIONS

This meta-analysis indicated that Bisphenol A exposure is positively associated with T2DM risk in humans.

Effects of bisphenol A on metabolism and evidences of a mode of action mediated through endocrine disruption

Based on rodent studies after prenatal and/or perinatal or adult exposure, there is now evidence that BPA may increase metabolic disturbances eventually leading to type-2 diabetes development via an ED MoA. In particular, BPA has been shown to alter insulin synthesis and/or release by pancreatic β-cells, and insulin signaling within insulin-sensitive organs (i.e., liver, muscle, adipose tissues). This resulted in variations in the expression of specific hepatic or adipose tissue markers, which are indicative of a state of insulin resistance. These effects are considered by experts to be hallmarks of adverse hormonal effects, each leading to insulin resistance within the different insulin-sensitive tissues. Although epidemiological studies are inconclusive, these effects are considered relevant for humans, because similarities exist in homeostatic regulation of insulin production and sensitivity between rodents and humans and because evidence was also shown through in vitro experimental data using human cells or tissues.

Obesogenic Endocrine Disrupting Chemicals: Identifying Knowledge Gaps

Endocrine disrupting chemicals (EDCs) are compounds that are part of everyday consumer products and industrial manufacturing processes. EDCs can interfere with the endocrine system, including the adipose tissue. Accumulating evidence from epidemiological, animal, and in vitro studies demonstrates that EDCs can alter body weight, adipose tissue expansion, circulating lipid profile, and adipogenesis, with some resulting in transgenerational effects. These outcomes appear to be mediated through multiple mechanisms, from nuclear receptor binding to epigenetic modifications. A better understanding of the signaling pathways via which these EDCs contribute to an obesogenic phenotype, the interaction amongst complex mixtures of obesogenic EDCs, and the risks they pose relative to the obesity epidemic are still needed for risk assessment and development of prevention strategies.

Exposure of adipocytes to bisphenol-A in vitro interferes with insulin action without enhancing adipogenesis

Bisphenol-A (BPA) is a lipophilic compound widely used in the manufacture of plastic items and thought to play a role in the growing obesity epidemic. Recent publications suggest that BPA may have a pro-adipogenic effect. Here we explore the effect of low, but environmentally relevant, concentrations of BPA on adipogenesis using a variety of cellular models. Mouse 3T3-L1, C3H10T1/2 and human adipose-derived stromal cells (hADSCs) were cultured with BPA concentrations ranging from 0.1nM to 100μM. We failed to observe positive effects on differentiation at any dose or in any model. 3T3-L1 adipocytes differentiated with high concentrations of BPA showed decreased mRNA expression of several adipocyte markers. Mature adipocytes differentiated in the presence of BPA were insulin resistant, with an approximate 25% reduction in insulin-stimulated glucose uptake. This was accompanied by a significant decrease in insulin-stimulated Akt phosphorylation, and an increase in mRNA levels of inflammatory markers (i.e. IL-6, TNFα). In conclusion, low, but environmentally relevant, doses of BPA may contribute to the development of a chronic, low-grade inflammatory state in exposed adipocytes, which in turn may affect adipose tissue insulin sensitivity, independent of adipogenesis. These studies suggest an alternative mechanism by which BPA may contribute to the development of obesity.

Glyphosate affects swine ovarian and adipose stromal cell functions

Although Glyphosate (GLY) is a widely used pesticide, its effects on ovarian function and stem cell differentiation are still largely unknown. Therefore, as a contribution on this subject, the present work reports an investigation of the in vitro effects of GLY on swine granulosa cells and adipose stromal cells (ASCs). The effect of GLY at different doses (0.2, 4 and 16 μg/mL) was evaluated on granulosa cells growth (BrDU incorporation and ATP production), steroidogenesis (17-β estradiol and progesterone secretion) and redox status (superoxide and nitric oxide production and non-enzymatic scavenging activity). GLY has been shown to inhibit cell growth, 17-β estradiol and non-enzymatic scavenging activity and to increase progesterone and nitric oxide secretion (P < 0.05). In addition, GLY significantly decreased the viability of ASCs (P < 0.001), and inhibited their adipogenic differentiation. These data indicate that GLY alters the main features of granulosa cells and ASCS thus suggesting that GLY could affect both reproductive function and adipose tissues homeostasis.

Cytotoxicity of seven bisphenol analogues compared to bisphenol A and relationships with membrane affinity data

Bisphenol A (BPA) is a chemical used in numerous industrial applications. Due to its well ascertained toxicity as endocrine disruptor, industries have started to replace it with other bisphenols whose alleged greater safety is scarcely supported by literature studies. In this study, the toxicity of seven BPA analogues was evaluated using both in silico and in vitro techniques, as compared to BPA toxicity. Furthermore, their affinity indexes for phospholipids (i.e. phospholipophilicity) were determined by immobilized artificial membrane liquid chromatography (IAM-LC) and possible relationships with in vitro toxic activity were also investigated. The results on four different cell cultures yielded similar ranking of toxicity for the bisphenols considered, with IC₅₀ values confirming their poor acute toxicity. As compared to BPA, bisphenol AF, bisphenol B, bisphenol M, and bisphenol A diglycidyl ether resulted more toxic, while bisphenol S, bisphenol F and bisphenol E were found as the less toxic congeners. These results are partly consistent with the scale of phospholipid affinity showing that toxicity increases at increasing membrane affinity. Therefore, phospholipophilicity determination can be assumed as a useful preliminary tool to select less toxic congeners to surrogate BPA in industrial applications.

Urinary bisphenol A concentration and the risk of central obesity in Chinese adults: A prospective study

BACKGROUND

Bisphenol A (BPA) exposure has been associated with diabetes and related metabolic disorders, such as obesity, but studies of the association of urinary BPA concentrations with central obesity risk are limited. The aim of this study was to prospectively investigate the association between urinary BPA and incident central obesity in a Chinese population aged ≥40 years.

METHODS

The study followed 888 participants from Shanghai, China, who did not have central obesity at baseline (in 2009) for 4 years. Concentrations of BPA were measured in baseline morning spot urine samples. Central obesity was defined as waist circumference ≥90 cm in men and ≥80 cm in women.

RESULTS

During a mean follow-up of 4 years, 124 (14.0%) participants developed central obesity. Each 1-unit increase in log [BPA] was positively associated with a 2.30-fold risk of incident central obesity (95% confidence interval [CI] 1.39-3.78; P  < 0.001) after adjustment for confounders. Compared with the lowest tertile of urinary BPA concentration, Tertiles 2 and 3 were associated with a higher risk of incident central obesity (odds ratios 1.73 [95% CI 1.04-2.88] and 1.81 [95% CI 1.08-3.05], respectively). Stratified analysis showed significant associations of BPA with incident central obesity in women and individuals <60 years of age, with normal weight, non-smokers, non-drinkers, or non-hypertensives.

CONCLUSIONS

The results indicate that higher urinary BPA concentrations may be associated with a greater risk of incident central obesity in Chinese adults. The study emphasizes the effects of BPA exposure on metabolic risk from a public health perspective.

Possible Obesogenic Effects of Bisphenols Accumulation in the Human Brain

Evidence of bisphenols’ obesogenic effects on humans is mixed and inconsistent. We aimed to explore the presence of bisphenol A (BPA), bisphenol F (BPF) and chlorinated BPA (ClBPA), collectively called the bisphenols, in different brain regions and their association with obesity using post-mortem hypothalamic and white matter brain material from twelve pairs of obese (body mass index (BMI) >30 kg/m²) and normal-weight individuals (BMI <25 kg/m²). Mean ratios of hypothalamus:white matter for BPA, BPF and ClBPA were 1.5, 0.92, 0.95, respectively, suggesting no preferential accumulation of the bisphenols in the grey matter (hypothalamic) or white matter-enriched brain areas. We observed differences in hypothalamic concentrations among the bisphenols, with highest median level detected for ClBPA (median: 2.4 ng/g), followed by BPF (2.2 ng/g) and BPA (1.2 ng/g); similar ranking was observed for the white matter samples (median for: ClBPA-2.5 ng/g, BPF-2.3 ng/g, and BPA-1.0 ng/g). Furthermore, all bisphenol concentrations, except for white-matter BPF were associated with obesity (p < 0.05). This is the first study reporting the presence of bisphenols in two distinct regions of the human brain. Bisphenols accumulation in the white matter-enriched brain tissue could signify that they are able to cross the blood-brain barrier.

Nonylphenol aggravates non-alcoholic fatty liver disease in high sucrose-high fat diet-treated rats

Exposure to environmental endocrine disruptors (EEDs) contributes to the pathogenesis of many metabolic disorders. Here, we have analyzed the effect of the EED-nonylphenol (NP) on the promotion of non-alcoholic fatty liver disease (NAFLD) in rats fed high sucrose-high fat diet (HSHFD). Fifty Sprague-Dawley rats were divided into five groups: controls fed a normal diet (C-ND); HSHFD-fed controls (C-HSHFD); and rats fed a HSHFD combined with NP at doses of 0.02 μg/kg/day (NP-L-HSHFD), 0.2 μg/kg/day (NP-M-HSHFD), and 2 μg/kg/day (NP-H-HSHFD). Subchronic exposure to NP coupled with HSHFD increased daily water and food intake (p < 0.05), hepatic echogenicity and oblique liver diameter (p < 0.05), and plasma levels of alanine aminotransferase, aspartate aminotransferase, total cholesterol, triglycerides, and low density lipoprotein cholesterol (p < 0.05). Combined exposure to NP and HSHFD induced macrovesicular steatosis with dilation and congestion of the central vein, liver inflammatory cell infiltration, and expression of genes regulating lipid metabolism, SREBP-1C, FAS, and Ucp2. These results demonstrate that NP aggravates NAFLD in HSHFD-treated rats by up-regulating lipogenic genes, and that HSHFD increases the toxic effects of NP. Thus subchronic NP exposure may lead to NAFLD, especially when combined with a high-sucrose/high-fat diet.

Lipid Metabolism Alteration by Endocrine Disruptors in Animal Models: An Overview

Exposure to potential Endocrine Disrupting Chemicals (EDCs) pose a documented risk to both wildlife and human health. Many studies so far described declining sperm counts, genital malformations, early puberty onset, highlighting the negative impact on reproduction caused by the exposure to many anthropogenic chemicals. In the last years, increasing evidence suggested that these compounds, other than altering reproduction, affect metabolism and induce the onset of obesity and metabolic disorders. According to the "environmental obesogens" hypothesis, evidence exists that exposure to potential EDCs during critical periods when adipocytes are differentiating, and organs are developing, can induce diseases that manifest later in the life. This review summarizes the effects occurring at the hepatic level in different animal models, describing morphological alterations and changes of molecular pathways elicited by the toxicant exposure. Results currently available demonstrated that these chemicals impair normal metabolic processes via interaction with members of the nuclear receptor superfamily, including steroid hormone receptors, thyroid hormone receptors, retinoid X receptors, peroxisome proliferator-activated receptors, liver X receptors, and farnesoid X receptors. In addition, novel results revealed that EDC exposure can either affect circadian rhythms as well as up-regulate the expression of signals belonging to the endocannabinoid system, in both cases leading to a remarkable increase of lipid accumulation. These results warrant further research and increase the interest toward the identification of new mechanisms for EDC metabolic alterations. The last part of this review article condenses recent evidences on the ability of potential EDCs to cause "transgenerational effects" by a single prenatal or early life exposure. On this regard, there is compelling evidence that epigenetic modifications link developmental environmental insults to adult disease susceptibility. This review will contribute to summarize the mechanisms underlying the insurgence of EDC-induced metabolic alterations as well as to build integrated strategies for their better management. In fact, despite the large number of results obtained so far, there is still a great demand for the development of frameworks that can integrate mechanistic and toxicological/epidemiological observations. This would increase legal and governmental institution awareness on this critical environmental issue responsible for negative consequences in both wild species and human health.

Immune System: An Emerging Player in Mediating Effects of Endocrine Disruptors on Metabolic Health

The incidence of metabolic disorders like type 2 diabetes and obesity continues to increase. In addition to the well-known contributors to these disorders, such as food intake and sedentary lifestyle, recent research in the exposure science discipline provides evidence that exposure to endocrine-disrupting chemicals like bisphenol A and phthalates via multiple routes (e.g., food, drink, skin contact) also contribute to the increased risk of metabolic disorders. Endocrine-disrupting chemicals (EDCs) can disrupt any aspect of hormone action. It is becoming increasingly clear that EDCs not only affect endocrine function but also adversely affect immune system function. In this review, we focus on human, animal, and in vitro studies that demonstrate EDC exposure induces dysfunction of the immune system, which, in turn, has detrimental effects on metabolic health. These findings highlight how the immune system is emerging as a novel player by which EDCs may mediate their effects on metabolic health. We also discuss studies highlighting mechanisms by which EDCs affect the immune system. Finally, we consider that a better understanding of the immunomodulatory roles of EDCs will provide clues to enhance metabolic function and contribute toward the long-term goal of reducing the burden of environmentally induced diabetes and obesity.

Timing of Exposure and Bisphenol-A: Implications for Diabetes Development

Bisphenol-A (BPA) is one of the most widespread endocrine disrupting chemicals (EDCs). It is used as the base compound in the production of polycarbonate and other plastics present in many consumer products. It is also used as a building block in epoxy can coating and the thermal paper of cash register receipts. Humans are consistently exposed to BPA and, in consequence, this compound has been detected in the majority of individuals examined. Over the last decade, an enlarging body of evidence has provided a strong support for the role of BPA in the etiology of diabetes and other metabolic disorders. Timing of exposure to EDCs results crucial since it has important implications on the resulting adverse effects. It is now well established that the developing organisms are particularly sensitive to environmental influences. Exposure to EDCs during early life may result in permanent adverse consequences, which increases the risk of developing chronic diseases like diabetes in adult life. In addition to that, developmental abnormalities can be transmitted from one generation to the next, thus affecting future generations. More recently, it has been proposed that gestational environment may also program long-term susceptibility to metabolic disorders in the mother. In the present review, we will comment and discuss the contributing role of BPA in the etiology of diabetes. We will address the metabolic consequences of BPA exposure at different stages of life and comment on the final phenotype observed in different whole-animal models of study.

Endocrine disruptors and the tumor microenvironment: A new paradigm in breast cancer biology

Breast cancer is one of the most frequently diagnosed malignancies in women and is characterized by predominantly estrogen dependent growth. Endocrine disruptors (EDCs) have estrogenic properties which have been shown to increase breast cancer risk. While the direct effects of EDCs on breast cancer cell biology and tumor progression have been well studied, the roles for EDCs on tumor microenvironment composition, signaling and structure are incompletely defined. Estrogen targeting of tumor stromal cells can drive paracrine signaling to breast cancer cells regulating tumorigenesis and progression. Additionally, estrogen and estrogen receptor signaling has been shown to alter breast architecture and extracellular matrix component synthesis. Unsurprisingly, EDCs have been shown to induce structural changes in the mammary gland as well as increased collagen fibers in the tissue stroma. Previous work demonstrates that human mesenchymal stem cells (hMSC) are essential components of the tumor microenvironment and are direct targets of both estrogens and EDCs. Furthermore, estrogen-stem cell cross talk has been implicated in breast cancer progression and results in increased tumor cell proliferation, angiogenesis and invasion. This review aims to dissect the possible relationship and mechanisms between EDCs, the tumor microenvironment, and breast cancer progression.

Exposure assessment to bisphenol A (BPA) in Portuguese children by human biomonitoring

Exposure to bisphenol A (BPA) is known to be widespread and available data suggests that BPA can act as an endocrine disruptor. Diet is generally regarded as the dominant BPA exposure source, namely through leaching to food from packaging materials. The aim of this study was to evaluate the exposure of 110 Portuguese children (4-18 years old), divided in two groups: the regular diet group (n = 43) comprised healthy normal weight/underweight children with no dietary control; the healthy diet group (n = 67) comprised children diagnosed for obesity/overweight (without other known associated diseases) that were set on a healthy diet for weight control. First morning urine samples were collected and total urinary BPA was analyzed after enzymatic hydrolysis via on-line HPLC-MS/MS with isotope dilution quantification. Virtually, all the children were exposed to BPA, with 91% of the samples above the LOQ (limit of quantification) of 0.1 μg/L. The median (95th percentile) urinary BPA levels for non-normalized and creatinine-corrected values were 1.89 μg/L (16.0) and 1.92 μg/g creatinine (14.4), respectively. BPA levels in the regular diet group were higher than in the healthy diet group, but differences were not significant. Calculated daily BPA intakes, however, were significantly higher in children of the regular diet group than in children of healthy diet group. Median (95th percentile) daily intakes amounted to 41.6 (467) ng/kg body weight/day in the regular diet group, and 23.2 (197) ng/kg body weight/day in the healthy diet group. Multiple logistic regression analysis revealed that children in the healthy diet group had 33% lower intakes than children in the regular diet group (OR 0.67; 95% CI 0.51-0.89). For both groups, however, urinary BPA levels and daily BPA intakes were within the range reported for other children's populations and were well below health guidance values such as the European Food Safety Authority (EFSA) temporary tolerable daily intake (t-TDI) of 4 μg/kg body weight/day. In addition, lower daily BPA intakes were more likely linked with the inherent dietary approach rather than with high BMI or obesity.

Polluted Pathways: Mechanisms of Metabolic Disruption by Endocrine Disrupting Chemicals

PURPOSE OF REVIEW

Environmental toxicants are increasingly implicated in the global decline in metabolic health. Focusing on diabetes, herein, the molecular and cellular mechanisms by which metabolism disrupting chemicals (MDCs) impair energy homeostasis are discussed.

RECENT FINDINGS

Emerging data implicate MDC perturbations in a variety of pathways as contributors to metabolic disease pathogenesis, with effects in diverse tissues regulating fuel utilization. Potentiation of traditional metabolic risk factors, such as caloric excess, and emerging threats to metabolism, such as disruptions in circadian rhythms, are important areas of current and future MDC research. Increasing evidence also implicates deleterious effects of MDCs on metabolic programming that occur during vulnerable developmental windows, such as in utero and early post-natal life as well as pregnancy. Recent insights into the mechanisms by which MDCs alter energy homeostasis will advance the field's ability to predict interactions with classical metabolic disease risk factors and empower studies utilizing targeted therapeutics to treat MDC-mediated diabetes.

Obesogenic endocrine disruptors and obesity: myths and truths

Obesogenic endocrine disruptors, also known as obesogens, are chemicals potentially involved in weight gain by altering lipid homeostasis and promoting adipogenesis and lipid accumulation. They included compounds to which human population is exposed over daily life such as pesticides/herbicides, industrial and household products, plastics, detergents and personal care products. The window of life during which the exposure happens could lead to different effects. A critical window is during utero and/or neonatal period in which the obesogens could cause subtle changes in gene expression and tissue organization or blunt other levels of biological organization leading to increased susceptibility to diseases in the adulthood. Some of the reasons for this increased sensitivity include the lack of the protective mechanisms that are available in adult such as DNA repair mechanisms, a competent immune system, detoxifying enzymes, liver metabolism and the blood/brain barrier still not fully functional in the fetus or newborn. The mechanisms of action of obesogens lay on their ability to increase the number and/or the size of the adipocytes and to alter appetite, satiety and food preferences. The ability of obesogens to increase fat deposition results in an increased capacity for their own retention due to their lipophilic properties; thus prolonging the exposure and increasing the detrimental metabolic consequences.

Adipose Tissue as a Site of Toxin Accumulation

We examine the role of adipose tissue, typically considered an energy storage site, as a potential site of toxicant accumulation. Although the production of most persistent organic pollutants (POPs) was banned years ago, these toxicants persist in the environment due to their resistance to biodegradation and widespread distribution in various environmental forms (e.g., vapor, sediment, and water). As a result, human exposure to these toxicants is inevitable. Largely due to their lipophilicity, POPs bioaccumulate in adipose tissue, resulting in greater body burdens of these environmental toxicants with obesity. POPs of major concern include polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), and polybrominated biphenyls and diphenyl ethers (PBBs/PBDEs), among other organic compounds. In this review, we (i) highlight the physical characteristics of toxicants that enable them to partition into and remain stored in adipose tissue, (ii) discuss the specific mechanisms of action by which these toxicants act to influence adipocyte function, and (iii) review associations between POP exposures and the development of obesity and diabetes. An area of controversy relates to the relative potential beneficial versus hazardous health effects of toxicant sequestration in adipose tissue. © 2017 American Physiological Society. Compr Physiol 7:1085-1135, 2017.

Bisphenol A and Metabolic Diseases: Challenges for Occupational Medicine

The prevalence of metabolic diseases has markedly increased worldwide during the last few decades. Lifestyle factors (physical activity, energy-dense diets), together with a genetic predisposition, are well known factors in the pathophysiology of health problems. Bisphenol A (BPA) is a chemical compound used for polycarbonate plastics, food containers, epoxy resins coating metallic cans for food and beverage conservation. The ability of BPA to act as an endocrine disruptor-xenoestrogen in particular-is largely documented in literature, with numerous publications of in vivo and in vitro studies as well as epidemiological data on humans. Recently, different researchers studied the involvement of BPA in the development of insulin resistance; evidences in this way showed a potential role in etiology of metabolic disease, both for children and for adults. We review the epidemiological literature in the relation between BPA exposure and the risk of metabolic diseases in adults, with a focus on occupational exposure. Considering published data and the role of occupational physicians in promoting Workers' Health, specific situations of exposure to BPA in workplace are described, and proposals for action to be taken are suggested. The comparison of the studies showed that exposure levels were higher in workers than in the general population, even if, sometimes, the measurement units used did not permit rapid comprehension. Nevertheless, occupational medicine focus on reproductive effects and not metabolic ones.

Contribution of Inhibitor of DNA Binding/Differentiation-3 and Endocrine Disrupting Chemicals to Pathophysiological Aspects of Chronic Disease

The overwhelming increase in the global incidence of obesity and its associated complications such as insulin resistance, atherosclerosis, pulmonary disease, and degenerative disorders including dementia constitutes a serious public health problem. The Inhibitor of DNA Binding/Differentiation-3 (ID3), a member of the ID family of transcriptional regulators, has been shown to play a role in adipogenesis and therefore ID3 may influence obesity and metabolic health in response to environmental factors. This review will highlight the current understanding of how ID3 may contribute to complex chronic diseases via metabolic perturbations. Based on the increasing number of reports that suggest chronic exposure to and accumulation of endocrine disrupting chemicals (EDCs) within the human body are associated with metabolic disorders, we will also consider the impact of these chemicals on ID3. Improved understanding of the ID3 pathways by which exposure to EDCs can potentiate complex chronic diseases in populations with metabolic disorders (obesity, metabolic syndrome, and glucose intolerance) will likely provide useful knowledge in the prevention and control of complex chronic diseases associated with exposure to environmental pollutants.

First-Trimester Urinary Bisphenol A Concentration in Relation to Anogenital Distance, an Androgen-Sensitive Measure of Reproductive Development, in Infant Girls

INTRODUCTION

Evidence from animal models suggests that prenatal exposure to bisphenol A (BPA), a ubiquitous endocrine-disrupting chemical, is associated with adverse reproductive outcomes in females. Exposure during early gestation, a critical period for reproductive development, is of particular concern. Anogenital distance (AGD) is a sensitive biomarker of the fetal hormonal milieu and a measure of reproductive toxicity in animal models. In some studies, the daughters of BPA-exposed dams have shorter AGD than controls. Here, we investigate this relationship in humans.

METHODS

BPA was assayed in first-trimester urine samples from 385 participants who delivered infant girls in a multicenter pregnancy cohort study. After birth, daughters underwent exams that included two measures of AGD (AGD-AC: distance from center of anus to clitoris; AGD-AF: distance from center of anus to fourchette). We fit linear regression models to examine the association between specific gravity-adjusted (SPG-adj) maternal BPA concentrations and infant AGD, adjusting for covariates.

RESULTS

BPA was detectable in 94% of women. In covariate-adjusted models fit on 381 eligible subjects, the natural logarithm of SpG-adj maternal BPA concentration was inversely associated with infant AGD-AC [β=−0.56, 95% confidence interval (CI): −0.97, −0.15]. We observed no association between maternal BPA and infant AGD-AF.

CONCLUSION

BPA may have toxic effects on the female reproductive system in humans, as it does in animal models. Higher first-trimester BPA exposure was associated with significantly shorter AGD in daughters, suggesting that BPA may alter the hormonal environment of the female fetus. https://doi.org/10.1289/EHP875.

Is bisphenol A an environmental obesogen?

Bisphenol A (BPA) is an endocrine disruptor with an oestrogenic activity that is widely produced for the manufacture of polycarbonate plastic, epoxy resin, and thermal paper. Its ubiquitous presence in the environment contributes to broad and continuous human exposure, which has been associated with deleterious health effects. Despite numerous controversial discussions and a lack of consensus about BPA's safety, growing evidence indicates that BPA exposure positively correlates with an increased risk of developing obesity. An updated analysis of the epidemiological, in vivo, and in vitro studies indicates that BPA should be considered an obesogenic environmental compound. Precisely, BPA exposure during all life stages correlates with increased body weight and/or body mass index. Developmental periods that include prenatal, infancy, and childhood appear to be critical windows with increased sensitivity to BPA effects. Finally, blood analysis and in vitro data clearly demonstrate that BPA promotes adipogenesis, lipid and glucose dysregulation, and adipose tissue inflammation, thus contributing to the pathophysiology of obesity. Future prevention efforts should now be employed to avoid BPA exposure, and more research to determine in depth the critical time windows, doses, and impact of long-term exposure of BPA is warranted in order to clarify its risk assessment.

Effect of nonylphenol on the regulation of cell growth in colorectal cancer cells

Nonylphenol (NP) is a well-known endocrine-disrupting chemical (EDC), which can enhance the progression of cancer by functioning as an estrogen‑like factor. In the present study, the effects of different concentrations of NP on COLO205 colorectal cancer (CRC) cells were examined. The results of flow cytometric analysis revealed that NP significantly decreased the proportion of cells in the G0/G1 phase in a dose‑dependent manner, which was accompanied by a marginal increase in the proportions of cells in S and G2/M phases. NP did not induce apoptosis, whereas estradiol (E2) did induce apoptosis. To elucidate the mechanisms underlying the action of NP on COLO205 cells, the transcriptional levels of extracellular signal‑regulated kinase (ERK)1, ERK2 and phosphoinositide 3‑kinase (PI3K) were assessed using reverse transcription‑quantitative polymerase chain reaction analysis. The expressions levels of ERK1, ERK2 and PI3K were increased by treatment with NP in a dose‑dependent manner. On examining protein levels, the expression of PI3K p38 was increased by NP and E2, and the expression of ERK1/2 was increased by NP. The phosphorylation of the ERK protein was significantly increased by treatment with NP at a high concentration (10‑4 M; P<0.01), but significantly decreased by E2 (P<0.01). Two key proteins in the transforming growth factor (TGF)β pathway (c‑Fos and SnoN) were selected for analysis using western blot analysis in the COLO205 cells treated with NP and E2. The expression levels of c‑Fos and SnoN were significantly increased by treatment with E2 (10‑7 M; P<0.01) and NP (10‑7‑10‑4 M; P<0.01). Taken together, these results indicated that NP affected the development of CRC via the ERK signaling pathway and TGFβ pathway.

Low-dose exposure to bisphenols A, F and S of human primary adipocyte impacts coding and non-coding RNA profiles

Bisphenol A (BPA) exposure has been suspected to be associated with deleterious effects on health including obesity and metabolically-linked diseases. Although bisphenols F (BPF) and S (BPS) are BPA structural analogs commonly used in many marketed products as a replacement for BPA, only sparse toxicological data are available yet. Our objective was to comprehensively characterize bisphenols gene targets in a human primary adipocyte model, in order to determine whether they may induce cellular dysfunction, using chronic exposure at two concentrations: a “low-dose” similar to the dose usually encountered in human biological fluids and a higher dose. Therefore, BPA, BPF and BPS have been added at 10 nM or 10 μM during the differentiation of human primary adipocytes from subcutaneous fat of three non-diabetic Caucasian female patients. Gene expression (mRNA/lncRNA) arrays and microRNA arrays, have been used to assess coding and non-coding RNA changes. We detected significantly deregulated mRNA/lncRNA and miRNA at low and high doses. Enrichment in “cancer” and “organismal injury and abnormalities” related pathways was found in response to the three products. Some long intergenic non-coding RNAs and small nucleolar RNAs were differentially expressed suggesting that bisphenols may also activate multiple cellular processes and epigenetic modifications. The analysis of upstream regulators of deregulated genes highlighted hormones or hormone-like chemicals suggesting that BPS and BPF can be suspected to interfere, just like BPA, with hormonal regulation and have to be considered as endocrine disruptors. All these results suggest that as BPA, its substitutes BPS and BPF should be used with the same restrictions.

Endocrine Disruptors and Obesity

PURPOSE OF REVIEW

The purpose of this review was to summarise current evidence that some environmental chemicals may be able to interfere in the endocrine regulation of energy metabolism and adipose tissue structure.

RECENT FINDINGS

Recent findings demonstrate that such endocrine-disrupting chemicals, termed "obesogens", can promote adipogenesis and cause weight gain. This includes compounds to which the human population is exposed in daily life through their use in pesticides/herbicides, industrial and household products, plastics, detergents, flame retardants and as ingredients in personal care products. Animal models and epidemiological studies have shown that an especially sensitive time for exposure is in utero or the neonatal period. In summarising the actions of obesogens, it is noteworthy that as their structures are mainly lipophilic, their ability to increase fat deposition has the added consequence of increasing the capacity for their own retention. This has the potential for a vicious spiral not only of increasing obesity but also increasing the retention of other lipophilic pollutant chemicals with an even broader range of adverse actions. This might offer an explanation as to why obesity is an underlying risk factor for so many diseases including cancer.

Clastogenic effects of bisphenol A on human cultured lymphocytes

Bisphenol A is an endocrine disrupting compound widely used in the production of polycarbonate plastics and epoxy resins. It is ubiquitously present in the environment, mostly in aquatic environments, with consequent risks to the health of aquatic organisms and humans. In the present study, we analysed the cytogenetic effects of bisphenol A on human lymphocytes using in vitro chromosomal aberrations and micronuclei assays. Lymphocyte cultures were exposed to five different concentrations of BP-A (0.20, 0.10, 0.05, 0.02 and 0.01 μg/mL) for 24 h (for chromosomal aberrations test) and 48 h (for micronuclei test). The concentration of 0.05 µg/mL represents the reference dose established by United States Environmental Protection Agency (US EPA); 0.02 μg/mL represents the higher concentration of unconjugated BP-A found in human serum and 0.01 μg/mL represents the tolerable daily intake established by European Union. Data obtained from both assays showed significant genotoxic effects of the bisphenol A at concentrations of 0.20, 0.10 and 0.05 μg/mL, whereas at the concentration of 0.02 μg/mL, we observed only a significant increase in the micronuclei frequency. Finally, at the concentration of 0.01 μg/mL, no cytogenetic effects were observed, indicating this latter as a more tolerable concentration for human health with respect to 0.05 μg/mL, the reference dose established by US EPA.

Bisphenol A exposure triggers apoptosis via three signaling pathways in Caenorhabditis elegans

Bisphenol A can trigger germline apoptosis via three signaling pathways including DNA damage response (DDR) pathway, mitogen-activated protein kinase (MAPK) cascades and insulin-like growth factor-1 (IGF-1) network in Caenorhabditis elegans.

3T3-L1 cells and perivascular adipocytes are not equivalent in amine transporter expression

Rat perivascular adipose tissue (PVAT) stores, takes up, and releases norepinephrine (NE; Ayala-Lopez et al. (2014) Pharmacol Res Perspect 2, e00041). We hypothesized that 3T3-L1 adipocytes would exhibit similar behaviors and, thus, could serve as a model for PVAT adipocytes. However, basal levels of NE were not detected in 3T3-L1 adipocytes. While incubation of 3T3-L1 adipocytes with exogenous NE increased their cellular NE content, the mRNA expression of several NE transporters [e.g., norepinephrine transporter (NET)] were not detected in these cells. Similarly, we observed expression of the vesicular monoamine transporter 1 (VMAT1) in 3T3-L1 adipocytes by qRT-PCR and immunostaining, but stimulation of the cells with tyramine (100 μm) did not cause a significant release of NE. These studies support that 3T3-L1 adipocytes are not an adequate model of perivascular adipocytes for studying NE handling.

Human Peripheral Blood Mononuclear Cell Function and Dendritic Cell Differentiation Are Affected by Bisphenol-A Exposure

Environmental pollutants, including endocrine disruptor chemicals (EDCs), interfere on human health, leading to hormonal, immune and metabolic perturbations. Bisphenol-A (BPA), a main component of polycarbonate plastics, has been receiving increased attention due to its worldwide distribution with a large exposure. In humans, BPA, for its estrogenic activity, may have a role in autoimmunity, inflammatory and allergic diseases. To this aim, we assessed the effect of low BPA doses on functionality of human peripheral blood mononuclear cells (PBMCs), and on in vitro differentiation of dendritic cells from monocytes (mDCs). Fresh peripheral blood samples were obtained from 12 healthy adult volunteers. PBMCs were left unstimulated or were activated with the mitogen phytohemagglutinin (PHA) or the anti-CD3 and anti-CD28 antibodies and incubated in presence or absence of BPA at 0.1 and 1nM concentrations. The immune-modulatory effect of BPA was assessed by evaluating the cell proliferation and the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-10 (IL-10) and interleukin-13 (IL-13) secreted by PBMCs. mDCs were differentiated with IL-4 and GC-CSF with or without BPA and the expression of differentiation/maturation markers (CD11c, CD1a, CD86, HLA-DR) was evaluated by flow cytometry; furthermore, a panel of 27 different cytokines, growth factors and chemokines were assayed in the mDC culture supernatants. PBMCs proliferation significantly increased upon BPA exposure compared to BPA untreated cells. In addition, a significant decrease in IL-10 secretion was observed in PBMCs incubated with BPA, either in unstimulated or mitogen-stimulated cells, and at both 0.1 and 1nM BPA concentrations. Similarly, IL-13 was reduced, mainly in cells activated by antiCD3/CD28. By contrast, no significant changes in IFN-γ and IL-4 production were found in any condition assayed. Finally, BPA at 1nM increased the density of dendritic cells expressing CD1a and concomitantly decreased the expression of HLA-DR and CD86 activation markers. In conclusion, in humans the exposure to BPA causes on PBMCs a significant modulation of proliferative capacity and cytokine production, and on mDCs alteration in differentiation and phenotype. These immune cell alterations suggest that low dose chronic exposure to BPA could be involved in immune deregulation and possibly in the increased susceptibility to develop inflammatory and autoimmune diseases.

Bisphenol-A and metabolic diseases: epigenetic, developmental and transgenerational basis

Exposure to environmental toxicants is now accepted as a factor contributing to the increasing incidence of obesity and metabolic diseases around the world. Such environmental compounds are known as 'obesogens'. Among them, bisphenol-A (BPA) is the most widespread and ubiquitous compound affecting humans and animals. Laboratory animal work has provided conclusive evidence that early-life exposure to BPA is particularly effective in predisposing individuals to weight gain. Embryonic exposure to BPA is reported to generate metabolic disturbances later in life, such as obesity and diabetes. When BPA administration is combined with a high-fat diet, there is an exacerbation in the development of metabolic disorders. Remarkably, upon BPA exposure of gestating females, metabolic disturbances have been found both in the offspring and later in life in the mothers themselves. When considering the metabolic effects generated by an early developmental exposure to BPA, one of the questions that arises is the role of precursor cells in the etiology of metabolic disorders. Current evidence shows that BPA and other endocrine disruptors have the ability to alter fat tissue development and growth by affecting the capacity to generate functional adipocytes, as well as their rate of differentiation to specific cell types. Epigenetic mechanisms seem to be involved in the BPA-induced effects related to obesity, as they have been described in both in vitro and in vivo models. Moreover, recent reports also show that developmental exposure to BPA generates abnormalities that can be transmitted to future generations, in a process called as transgenerational epigenetic inheritance.

Endocrine Aspects of Environmental "Obesogen" Pollutants

Growing evidence suggests the causal link between the endocrine-disrupting chemicals (EDCs) and the global obesity epidemics, in the context in the so-called “obesogenic environment”. Dietary intake of contaminated foods and water, especially in association with unhealthy eating pattern, and inhalation of airborne pollutants represent the major sources of human exposure to EDCs. This is of particular concern in view of the potential impact of obesity on chronic non-transmissible diseases, such as type 2 diabetes, cardiovascular disease, and hormone-sensitive cancers. The key concept is the identification of adipose tissue not only as a preferential site of storage of EDCs, but also as an endocrine organ and, as such, susceptible to endocrine disruption. The timing of exposure to EDCs is critical to the outcome of that exposure, with early lifetime exposures (e.g., fetal or early postnatal) particularly detrimental because of their permanent effects on obesity later in life. Despite that the mechanisms operating in EDCs effects might vary enormously, this minireview is aimed to provide a general overview on the possible association between the pandemics of obesity and EDCs, briefly describing the endocrine mechanisms linking EDCs exposure and latent onset of obesity.

The Effects of Endocrine Disruptors on Adipogenesis and Osteogenesis in Mesenchymal Stem Cells: A Review

Endocrine-disrupting chemicals (EDCs) are prevalent in the environment, and epidemiologic studies have suggested that human exposure is linked to chronic diseases, such as obesity and diabetes. In vitro experiments have further demonstrated that EDCs promote changes in mesenchymal stem cells (MSCs), leading to increases in adipogenic differentiation, decreases in osteogenic differentiation, activation of pro-inflammatory cytokines, increases in oxidative stress, and epigenetic changes. Studies have also shown alteration in trophic factor production, differentiation ability, and immunomodulatory capacity of MSCs, which have significant implications to the current studies exploring MSCs for tissue engineering and regenerative medicine applications and the treatment of inflammatory conditions. Thus, the consideration of the effects of EDCs on MSCs is vital when determining potential therapeutic uses of MSCs, as increased exposure to EDCs may cause MSCs to be less effective therapeutically. This review focuses on the adipogenic and osteogenic differentiation effects of EDCs as these are most relevant to the therapeutic uses of MSCs in tissue engineering, regenerative medicine, and inflammatory conditions. This review will highlight the effects of EDCs, including organophosphates, plasticizers, industrial surfactants, coolants, and lubricants, on MSC biology.