Gestational and lactational exposure to low-dose bisphenol A increases Th17 cells in mice offspring

Integrated analysis reveals the immunotoxicity mechanism of BPs on human lymphocytes

Bisphenol A (BPA) is a well-documented endocrine-disrupting chemical widely used in plastic products. In addition to its endocrine-disrupting effects, BPA exhibits immunotoxicity. Many countries have banned BPA because of its adverse effects on human health. In recent years, many chemicals such as bisphenol B (BPB), bisphenol E (BPE), bisphenol S (BPS), and bisphenol fluorene (BHPF) have been used to replace BPA. Because these replacement chemicals have chemical structures similar to that of BPA, they may also harm human health. However, their immunotoxicity and the molecular mechanisms underlying their toxicity remain largely unknown. The aim of this study was to investigate the immunotoxicity of BPA and its replacement chemicals, as well as the underlying mechanisms by exposing primary human lymphocytes to BPA and its replacement chemicals. Our results showed that exposure to BPA and its replacement chemicals altered the interleukin (IL) and cytokine production, such as IL-1b, IL-5, IL-6, IL-8, interferon alfa-2b (IFN-a2B), and tumor necrosis factor alpha (TNF-α), in the lymphocytes. Among these, BPA and BHPF caused a greater inhibition. Using comparative transcriptomic analysis, we further investigated the biological processes and signaling pathways altered by BHPF exposure. Our data highlighted alterations in the immune response, T cell function, and cytokine-cytokine receptor interactions in human lymphocytes through the deregulation of gene clusters. In addition, the results of ingenuity pathway analysis demonstrated the inhibition of T lymphocyte function, including differentiation, movement, and infiltration. Our results, for the first time, delineate the mechanisms underlying the immunotoxicity of BHPF in human lymphocytes.

Controversy on health-based guidance values for bisphenol A-the need of criteria for studies that serve as a basis for risk assessment

Since 2006, the responsible regulatory bodies have proposed five health-based guidance values (HBGV) for bisphenol A (BPA) that differ by a factor of 250,000. This range of HBGVs covers a considerable part of the range from highly toxic to relatively non-toxic substances. As such heterogeneity of regulatory opinions is a challenge not only for scientific risk assessment but also for all stakeholders, the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) analyzed the reasons for the current discrepancy and used this example to suggest improvements for the process of HBGV recommendations. A key aspect for deriving a HBGV is the selection of appropriate studies that allow the identification of a point of departure (PoD) for risk assessment. In the case of BPA, the HBGV derived in the 2023 EFSA assessment was based on a study that reported an increase of Th17 cells in mice with a benchmark dose lower bound (BMDL40) of 0.53 µg/kg bw/day. However, this study does not comply with several criteria that are important for scientific risk assessment: (1) the selected end-point, Th17 cell frequency in the spleen of mice, is insufficiently understood with respect to health outcomes. (2) It is unclear, by which mechanism BPA may cause an increase in Th17 cell frequency. (3) It is unknown, if an increase of Th17 cell frequency in rodents is comparably observed in humans. (4) Toxicokinetics were not addressed. (5) Neither the raw data nor the experimental protocols are available. A further particularly important criterion (6) is independent data confirmation which is not available in the present case. Previous studies using other readouts did not observe immune-related adverse effects such as inflammation, even at doses orders of magnitude higher than in the Th17 cell-based study. The SKLM not only provides here key criteria for the use of such studies, but also suggests that the use of such a "checklist" requires a careful and comprehensive scientific judgement of each item. It is concluded that the Th17 cell-based study data do not represent an adequate basis for risk assessment of BPA.

Decreased Treg cells induced by bisphenol A is associated with up-regulation of PI3K/Akt/mTOR signaling pathway and Foxp3 DNA methylation in spleen of adolescent mice

The current study aimed to explore whether bisphenol A (BPA) exposure aggravated the decrease in Tregs induced by ovalbumin (OVA) in adolescent female mouse models of asthma, and whether the process was associated with mTOR-mediated signaling pathways and DNA methylation levels. A total of 40 female C57BL/6 mice at the age of four weeks were used and divided into five groups after 1 week of domestication. Each group consisted of eight mice: the control group, OVA group, OVA + BPA (0.1 μg mL-1) group, OVA + BPA (0.2 μg mL-1) group, and OVA + BPA (0.4 μg mL-1) group. Results revealed that Foxp3 protein levels decreased in the spleens of mice exposed to BPA compared to those in the OVA group. After an elevation in BPA dose, the mRNAs of methyltransferases (Dnmt1, Dnmt3a, and Dnmt3b) were gradually upregulated. The mechanism was related to the activity of TLR4/NF-κB and PI3K/Akt/mTOR signaling pathways and the enhancement of Foxp3 DNA methylation. Our results, collectively, provided a new view for studying the mechanisms underlying BPA exposure-induced immune dysfunction. Investigation of the regulatory mechanisms of DNA methylation in the abnormal Th immune response caused by BPA exposure could help reveal the causes and molecular mechanisms underlying the high incidence of allergic diseases in children in recent years.

The Conflict between Regulatory Agencies over the 20,000-Fold Lowering of the Tolerable Daily Intake (TDI) for Bisphenol A (BPA) by the European Food Safety Authority (EFSA)

BACKGROUND

The European Food Safety Authority (EFSA) recommended lowering their estimated tolerable daily intake (TDI) for bisphenol A (BPA) 20,000-fold to 0.2  ng / kg  body weight  ( BW ) / day . BPA is an extensively studied high production volume endocrine disrupting chemical (EDC) associated with a vast array of diseases. Prior risk assessments of BPA by EFSA as well as the US Food and Drug Administration (FDA) have relied on industry-funded studies conducted under good laboratory practice protocols (GLP) requiring guideline end points and detailed record keeping, while also claiming to examine (but rejecting) thousands of published findings by academic scientists. Guideline protocols initially formalized in the mid-twentieth century are still used by many regulatory agencies. EFSA used a 21st century approach in its reassessment of BPA and conducted a transparent, but time-limited, systematic review that included both guideline and academic research. The German Federal Institute for Risk Assessment (BfR) opposed EFSA's revision of the TDI for BPA.

OBJECTIVES

We identify the flaws in the assumptions that the German BfR, as well as the FDA, have used to justify maintaining the TDI for BPA at levels above what a vast amount of academic research shows to cause harm. We argue that regulatory agencies need to incorporate 21st century science into chemical hazard identifications using the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) nonguideline academic studies in a collaborative government-academic program model.

DISCUSSION

We strongly endorse EFSA's revised TDI for BPA and support the European Commission's (EC) apparent acceptance of this updated BPA risk assessment. We discuss challenges to current chemical risk assessment assumptions about EDCs that need to be addressed by regulatory agencies to, in our opinion, become truly protective of public health. Addressing these challenges will hopefully result in BPA, and eventually other structurally similar bisphenols (called regrettable substitutions) for which there are known adverse effects, being eliminated from all food-related and many other uses in the EU and elsewhere. https://doi.org/10.1289/EHP13812.

Evidence evaluated by European Food Safety Authority does not support lowering the temporary tolerable daily intake for bisphenol A

The European Food Safety Authority (EFSA) recently derived a tolerable daily intake (TDI) for bisphenol A (BPA) of 0.2 ng/kg bw/day. There are several issues with EFSA's hazard assessment review process, including that it was based on a limited subset of relevant studies. Multiple public commenters on EFSA's draft evaluation of BPA, including several European regulatory agencies, noted these issues, yet they were not adequately addressed by EFSA in the final evaluation. The TDI for BPA was based on an intermediate immunotoxicity endpoint in mice that has not been observed in other species; there is no evidence that it is a precursor event to any downstream pathological outcome. The TDI is several orders of magnitude lower than estimates of safe doses of BPA established by agencies worldwide, including EFSA's temporary TDI (t-TDI) for BPA established in 2015. Overall, the EFSA hazard assessment review process has led to a conclusion that there are low-dose effects of BPA based on very few, lower quality experimental animal studies. This conclusion is not supported by the totality of the available evidence, which includes multiple high-quality studies not considered by EFSA and indicates that the t-TDI established in 2015 is protective of human health.

IVIVE-PBPK based new approach methodology for addressing early life toxicity induced by Bisphenol A

Bisphenol A (BPA) is a known endocrine disruptor mimicking natural estrogens with the potential to affect human health, especially during prenatal and postnatal exposure at or below current acceptable daily intake levels. Different adverse effects of BPA are still under investigation, and multiple mechanisms of action remain unexplored. This may be one of the reasons for the continuously changing tolerable daily intake (TDI) of BPA with the emergence of new adverse health effects over time. In addition, translational modelling through in vitro-in vivo extrapolation (IVIVE) can act as prerequisite bridge for translating in-vitro finding into human risk assessment. The objective of this study was to conduct in-vitro experiments and utilize an IVIVE-pregnancy physiologically based pharmacokinetic (P-PBPK) modeling to investigate developmental neurotoxicity and embryotoxicity in humans. The data obtained from human embryonic stem cells-based assays (study conducted between October 2020-2021) were used for the IVIVE-P-PBPK models to obtain the human equivalent doses (HEDs) which were further extrapolated to reference doses (RfDs). The results showed that simulated mean RfDs (μg/kg/day) derived from the HSD3B1 and NFATC2 gene of embryotoxicity and neurodevelopmental toxicity tests, respectively, were 4.94 and 5.18. The simulated RfDs were close to the temporary-tolerable daily intake (t-TDI) recommended by European Food Safety Authority (EFSA) in 2015 (t-TDI: 4 μg/kg·bw) and higher than the TDI of 2023 (0.2 ng/kg·bw). In conclusion, in-vitro toxicogenomics dose-response data combined with PBPK modeling can become a promising alternative new approach methodology (NAM) to support decision-making in chemical risk assessment. Based on the simulated RfDs derived from this NAM, the t-TDI set by EFSA in 2015 may be considered a safe exposure limit for mothers and fetuses at the current BPA intake levels in Chinese mothers. This study provided an animal-free new strategy for NAMs based risk assessment by combining toxicogenomics and computational toxicology.

Modulatory effects of bisphenol A on the hepatic immune response

The liver is a primary line of defense for protection from external substances next to the intestinal barrier. As a result, the hepatic immune system plays a central role in liver pathophysiology. Bisphenol A (BPA) is one of the most common endocrine disrupting chemicals and is primarily metabolized in the liver. Due to its ability to bind to estrogen receptors, BPA is well known to possess estrogenic activity and disrupt reproductive functions. The phase I and Phase II metabolism reactions of BPA mainly occur in the liver with the help of enzymes including cytochrome P450 (CYP), uridine 5'-diphospho-glucuronosyltransferase-glucuronosyltransferases, sulfotransferases, and glutathione-S-transferases. Although the majority of BPA is excreted after conjugation by these enzymes, untransformed BPA induces the production of reactive oxygen species through disruption of the enzymatic complex CYP, lipid accumulation, mitochondrial dysfunction, endoplasmic reticulum stress and inflammatory injury in the liver. Moreover, it has been proposed to possess a potential immunomodulatory effect. Indeed, several in vivo and in vitro studies have reported that low doses of BPA increase the population of T cells with type 1 T helper (Th1), Th2, and Th17 cells. Although the current literature lacks clear evidence on the mechanisms by which BPA is involved in T cell mediated immune responses, recent multi-omics studies suggest that it may directly interact with the antigen processing and presentation pathways. In this review, we first discuss the metabolism of BPA in the liver, before exploring currently available data on its effects on liver injury. Finally, we review its modulatory effects on the hepatic immune response, as well as potential mechanisms. By conducting this review, we aim to improve understanding on the relationship between BPA exposure and immune-related liver injury, with a focus on the antigen processing and presentation pathway and T cell-mediated response in the liver.

Large-scale biomonitoring of bisphenol analogues and their metabolites in human urine from Guangzhou, China: Implications for health risk assessment

Bisphenol analogues (BPs) are ubiquitous in the environment and have gained significant attention regarding their associated health risks. However, there is a lack of comprehensive biomonitoring data on BPs and their metabolites in human urine. To address this, we conducted a study evaluate the exposure to BPs in the general population of Guangzhou, China. A total of 1440 urine samples were collected from volunteers and analyzed for the presence of BPs and their metabolites after being pooled into 36 groups based on age and gender. The findings revealed the common detection of ten free-form BPs, as well as the urinary metabolites of BPA and BPS, in the pooled urine samples. BPA was the predominant free-form compound, constituting 50% of the total BPs. The primary urinary metabolites of BPA and BPS are BPA-G and BPS-G, respectively, indicating glucuronidation as their primary metabolic pathway. The composition of urinary metabolites of BPA and BPS varied by age and sex, while the concentration of total BPs in urine was not significantly associated with age and sex. Enzymatic hydrolysis yielded a mean amplification of individual BPs concentrations in urine samples ranging from 1.8 times (BPA) to 4.6 times (BPS). Based on the outcomes, it was estimated that conjugated forms accounted for 96.9%, 96.2%, 94.7%, 94.1%, 92.6%, 89.1%, 87.3%, 87.2%, 87.1% and 85.8% of BPP, BPAF, BPZ, BPE, BPAP, BPF, BPA, BPC, BPS and BPF, respectively, in the pooled urine samples. Preliminary risk assessments indicated that the estimated daily intake of BPA was much higher than the latest proposed tolerable daily intake. Due to the unavailability of health-based guideline values for alternative BPs, some of them exhibit daily intakes comparable to BPA, implying that greater attention should be paid to health risks associated with exposure to BPs.

WITHDRAWN: Letter to editor: Evidence evaluated by EFSA does not support lowering the temporary tolerable daily intake for bisphenol A

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Evaluating endocrine disrupting chemicals: A perspective on the novel assessments in CLARITY-BPA

BACKGROUND

The Consortium Linking Academic and Regulatory Insights on Bisphenol A Toxicity (CLARITY-BPA) was a collaborative research effort to better link academic research with governmental guideline studies. This review explores the secondary goal of CLARITY-BPA: to identify endpoints or technologies from CLARITY-BPA and prior/concurrent literature from these laboratories that may enhance the capacity of rodent toxicity studies to detect endocrine disrupting chemicals (EDCs).

METHODS

A systematic literature search was conducted with search terms for BPA and the CLARITY-BPA participants. Relevant studies employed a laboratory rodent model and reported results on 1 of the 10 organs/organ systems evaluated in CLARITY-BPA (brain and behavior, cardiac, immune, mammary gland, ovary, penile function, prostate gland and urethra, testis and epididymis, thyroid hormone and metabolism, and uterus). Study design and findings were summarized, and a risk-of-bias assessment was conducted.

RESULTS

Several endpoints and methods were identified as potentially helpful to detect effects of EDCs. For example, molecular and quantitative morphological approaches were sensitive in detecting alterations in early postnatal development of the brain, ovary, and mammary glands. Hormone challenge studies mimicking human aging reported increased susceptibility of the prostate to disease following developmental BPA exposure. Statistical analyses for nonmonotonic dose responses, and computational approaches assessing multiple treatment-related outcomes concurrently in linked hormone-sensitive organ systems, reported effects at low BPA doses.

CONCLUSIONS

This review provided an opportunity to evaluate the unique insights provided by nontraditional assessments in CLARITY-BPA to identify technologies and endpoints to enhance detection of EDCs in future studies.

An integrated human health risk assessment framework for alkylphenols due to drinking water and crops' food consumption

The increasing overexploitation and pollution of freshater resources are potential threats for public health, causing cross-contamination among the interconnected environmental compartments (freshwater, soil, crops). In particular, contaminants of emerging concern (CECs) originating from anthropic activities are not completely removed by wastewater treatments plants. This leads to their presence in drinking water (DW) sources, soil and crops intended for human consumption due to discharges of treated wastewater in surface waters and direct wastewater reuse practices. Currently, health risk assessments are limited to single exposure sources without considering the multiple exposure routes to which humans are subjected. For instance, among CECs, bisphenol A (BPA) and nonylphenol (NP), respectively, adversely affect immune and renal systems and have been frequently detected in DW and food, their major exposure sources for humans. Here, an integrated procedure is proposed to quantitatively assess health risk from CECs due to multiple exposure from the consumption of both DW and food, considering the relevant inter-connected environmental compartments. This procedure was applied to BPA and NP to calculate their probabilistic Benchmark Quotient (BQ), showing its potential in quantitatively apportioning the risk between contaminants and exposure sources, and its use as a decision support tool for prioritizing mitigation measures. Our results indicate that, even though the human health risk due to NP is not negligible, the estimated risk due to BPA is significantly higher, and the consumption of food from edible crops determines a higher risk compared to tap water. Hence, BPA is undoubtedly a contaminant to be prioritized, especially through mitigation actions aimed at its prevention and removal from food.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Environmental endocrine disruptor Bisphenol A induces metabolic derailment and obesity via upregulating IL-17A in adipocytes

BACKGROUND

Bisphenol A (BPA), a ubiquitous environmental endocrine disruptor, has been extensively demonstrated to be associated with metabolic disorders, including obesity and type 2 diabetes mellitus. However, the underlying mechanism underpinning the environmental etiology of chronic metabolic disorders has not been sufficiently elucidated.

OBJECTIVES

This study is designed to explore the toxicological pathogenesis of chronic inflammation in BPA exposure during obesity.

METHODS

We investigated the role of IL-17A in the association of BPA exposure and obesity from human cross-sectional study to animal models, including genetically modified IL-17A^-/- mice.

RESULTS

Here, our work started from case-control observation that BPA exposure was significantly associated with risk of obesity (odds ratio = 4.72, 95%CI: 3.18 - 11.18, P < 0.01), metabolic disorder and levels of interleukin-17A (IL-17A) in human adipose (estimated changes β = 0.46, 95%CI: 0.15 - 1.01, P < 0.01) with bariatric surgery. Animal model fed with high-fat diet (HFD) confirmed that BPA exposure aggravated body weight gain and insulin resistance, concurrent with much heightened inflammatory responses in the adipose tissue including increase in IL-17A and macrophage polarization towards M1 stage. Genetically modified IL-17A ablated mice (IL-17A^-/-) showed reversed adipose tissue inflammation response, improved macrophage polarization homeostasis, along with insulin sensitivity in both HFD group alone or much more significantly the HFD + BPA group. Moreover, mediation analysis in human epidemiological investigation demonstrated that plasma IL-17A attributed up to 30.01% mediating role in the associations between BPA exposure and obesity risk.

DISCUSSION

This research paradigm from human to animal provides strong evidence for the elucidation of IL-17A moderating inflammation and insulin resistance in obesity. Such findings reiterate the obesogenic role of environmental endocrine disruptor BPA in metabolic disorders and unveils the potential toxicological mechanisms underpinning such effect.

Characterization and regulation of microplastic pollution for protecting planetary and human health

Microplastics are plastic particles <5 mm in diameter. Since the 1950s, there has been an exponential increase in the production of plastics. As of 2015, it is estimated that approximately 6300 million metric tons of plastic waste had been generated of which 79% has accumulated in landfills or the natural environment. Further, it is estimated that if current trends continue, roughly 12,000 million metric tons of plastic waste will accumulate by 2050. Plastics and microplastics are now found ubiquitously-in the air, water, and soil. Microplastics are small enough to enter the tissues of plants and animals and have been detected in human lungs, stools, placentas, and blood. Their presence in human tissues and the food chain is a cause for concern. While direct clinical evidence or epidemiological studies on the adverse effects of microplastic on human health are lacking, in vitro cellular and tissue studies and in vivo animal studies suggest potential adverse effects. With the ever-increasing presence of plastic waste in our environment, it is critical to understand their effects on our environment and on human health. The use of plastic additives, many of which have known toxic effects are also of concern. This review provides a brief overview of microplastics and the extent of the microplastic problem. There have been a few inroads in regulating plastics but currently these are insufficient to adequately mitigate plastic pollution. We also review recent advances in microplastic testing methodologies, which should support management and regulation of plastic wastes. Significant efforts to reduce, reuse, and recycle plastics are needed at the individual, community, national, and international levels to meet the challenge. In particular, significant reductions in plastic production must occur to curb the impacts of plastic on human and worldwide health, given the fact that plastic is not truly recyclable.

Bisphenol A, TH17 cells, and allergy: a commentary

There is a continuing interest in whether Bisphenol A (BPA) is able to cause adverse health effects through interaction with elements of the immune system. That interest has been fuelled further by the recent publication of a draft opinion on BPA prepared by the European Food Safety Authority (EFSA) Panel on Food Contact Materials, Enzymes and Processing Aids (CEP). This draft opinion judged effects on the immune system to be the most sensitive health outcome, and identified BPA-induced changes in the frequency of T-helper (T_H)-17 cells in the spleens of mice as being the critical effect based on an association of these cells with inflammation. Based on these evaluations the CEP Panel recommended that a revised Tolerable Daily Intake (TDI) for BPA of 0.04 ng/kg bw/day should be adopted; representing a very substantial reduction (100,000-fold) compared with the existing TDI. The purpose of this commentary is to summarize briefly the role of T_H17 cells in immune responses, and to review relevant literature regarding the influence of BPA on these cells, and on inflammatory responses in the lung and respiratory allergy. The conclusion drawn is that based on uncertainties about the effects of BPA on T_H17 cells and lung inflammation in mice, the absence of consistent or persuasive evidence from human studies that exposure of BPA is associated with inflammation or allergy, and unresolved questions regarding the species selectivity of immune effects induced by BPA, it is inappropriate to adopt the revised TDI. Additional research is required to explore further the influence of BPA on the immune system and immune responses.

Maternal bisphenol A and triclosan exposure and allergic diseases in childhood: a meta-analysis of cohort studies

Bisphenol A (BPA) and triclosan (TCS) are both endocrine-disrupting chemicals (EDCs), and pregnant women are usually exposed to them through daily consumption. This study aimed to explore the relationship between prenatal BPA and TCS exposure and allergic diseases in childhood by systematic review and meta-analysis. We searched the topic of prenatal BPA and TCS exposure and allergic diseases in childhood published before March 22, 2021, in four databases, including PubMed, Web of Science, Embase, and Cochrane. Statistical analysis was completed using Stata software (version 16.0). Seven papers on BPA and four papers on TCS were included in this meta-analysis. The association between prenatal exposure to BPA and total allergic diseases in childhood showed a pooled effect estimate of 1.13 (95% CI, 1.04, 1.23), with I² = 0.0% (P = 0.615). The effect estimates between BPA exposure and each allergic disease were 1.18 (95% CI, 1.02, 1.36) for wheezing, 1.23 (95% CI, 1.01, 1.50) for asthma, 1.03 (95% CI, 0.89, 1.18) for eczema/rashes or hives, and 1.19 (95% CI, 0.91, 1.56) for aeroallergies. Prenatal exposure to TCS had no association with the four types of allergic disease in childhood. BPA exposure during the prenatal period was positively associated with allergic disease in childhood. Strengthening prenatal EDC exposure control is necessary for child health.

In utero exposure to bisphenols and asthma, wheeze, and lung function in school-age children: a prospective meta-analysis of 8 European birth cohorts

BACKGROUND

In utero exposure to bisphenols, widely used in consumer products, may alter lung development and increase the risk of respiratory morbidity in the offspring. However, evidence is scarce and mostly focused on bisphenol A (BPA) only.

OBJECTIVE

To examine the associations of in utero exposure to BPA, bisphenol F (BPF), and bisphenol S (BPS) with asthma, wheeze, and lung function in school-age children, and whether these associations differ by sex.

METHODS

We included 3,007 mother-child pairs from eight European birth cohorts. Bisphenol concentrations were determined in maternal urine samples collected during pregnancy (1999-2010). Between 7 and 11 years of age, current asthma and wheeze were assessed from questionnaires and lung function by spirometry. Wheezing patterns were constructed from questionnaires from early to mid-childhood. We performed adjusted random-effects meta-analysis on individual participant data.

RESULTS

Exposure to BPA was prevalent with 90% of maternal samples containing concentrations above detection limits. BPF and BPS were found in 27% and 49% of samples. In utero exposure to BPA was associated with higher odds of current asthma (OR = 1.13, 95% CI = 1.01, 1.27) and wheeze (OR = 1.14, 95% CI = 1.01, 1.30) (p-interaction sex = 0.01) among girls, but not with wheezing patterns nor lung function neither in overall nor among boys. We observed inconsistent associations of BPF and BPS with the respiratory outcomes assessed in overall and sex-stratified analyses.

CONCLUSION

This study suggests that in utero BPA exposure may be associated with higher odds of asthma and wheeze among school-age girls.

Environmental exposure during pregnancy and the risk of childhood allergic diseases

BACKGROUND

Allergic diseases are one of the most common and important diseases that can exert hazardous effects on children's health. The prevalence of allergic diseases in childhood is gradually increasing all over the world in recent decades. Known causes of these diseases include anomalous immune responses and allergic inflammatory reactions, but the causes of allergic diseases in childhood are complex.

DATA SOURCES

PubMed, Cochrane Library, Embase and Web of Science were searched for articles focusing on environmental exposure during pregnancy and the risk of childhood allergic diseases, including asthma and atopic dermatitis, and the possible underlying mechanism.

RESULTS

In terms of environmental factors, allergic diseases in childhood are closely related to environmental chemical exposure during pregnancy, including bisphenols, phthalates acid esters, perfluorochemicals, polybrominated diphenyl ethers, and polychlorinated biphenyls. However, allergic diseases in childhood are also closely associated with maternal dietary nutrition, maternal intake of drugs, such as acetylsalicylic acid (aspirin), paracetamol and antibiotics, and maternal lifestyle.

CONCLUSIONS

Several harmful environmental factors during pregnancy can result in the interruption of the function of helper T cells (Th1/Th2), cytokines and immunoglobulins and may activate allergic reactions, which can lead to allergic diseases during childhood.

Bisphenol A as a Factor in the Mosaic of Autoimmunity

The population worldwide is largely exposed to bisphenol A (BPA), a commonly used plasticizer, that has a similar molecular structure to endogenous estrogens. Therefore, it is able to influence physiological processes in human body, taking part in the pathophysiology of various endocrinopathies, as well as, cardiovascular, neurological and oncological diseases. BPA has been found to affect the immune system, leading to the development of autoimmunity and allergies, too. In the last few decades, the prevalence of autoimmune diseases has significantly increased, that could be explained by a rising exposure of the population to environmental factors, such as BPA. BPA has been found to play a role in the pathogenesis of systemic autoimmune diseases and also organ-specific autoimmunity (thyroid autoimmunity, diabetes mellitus type 1, myocarditis, inflammatory bowel disease, multiple sclerosis, encephalomyelitis etc), but the results of some studies remain still controversial, so further research is needed.

Early Life Exposure to Food Contaminants and Social Stress as Risk Factor for Metabolic Disorders Occurrence?-An Overview

The global prevalence of obesity has been increasing in recent years and is now the major public health challenge worldwide. While the risks of developing metabolic disorders (MD) including obesity and type 2 diabetes (T2D) have been historically thought to be essentially driven by increased caloric intake and lack of exercise, this is insufficient to account for the observed changes in disease trends. Based on human epidemiological and pre-clinical experimental studies, this overview questioned the role of non-nutritional components as contributors to the epidemic of MD with a special emphasis on food contaminants and social stress. This overview examines the impact of early life adverse events (ELAE) focusing on exposures to food contaminants or social stress on weight gain and T2D occurrence in the offspring and explores potential mechanisms leading to MD in adulthood. Indeed, summing up data on both ELAE models in parallel allowed us to identify common patterns that appear worthwhile to study in MD etiology. This overview provides some evidence of a link between ELAE-induced intestinal barrier disruption, inflammation, epigenetic modifications, and the occurrence of MD. This overview sums up evidence that MD could have developmental origins and that ELAE are risk factors for MD at adulthood independently of nutritional status.

Interplay Between Endocrine Disruptors and Immunity: Implications for Diseases of Autoreactive Etiology

The sex-bias of disease susceptibility has remained a puzzling aspect of several autoimmune conditions, including post-infection viral autoimmunity. In the last half of the twentieth century, the incidence rate of female-biased autoimmunity has steadily increased independent of medical advances. This has suggested a role for environmental factors, such as endocrine disrupting chemicals, which have been described to interfere with endocrine signaling. Endocrine involvement in the proper function of innate and adaptive immunity has also been defined, however, these two areas have rarely been reviewed in correlation. In addition, studies addressing the effects of endocrine disruptors have reported findings resulting from a broad range of exposure doses, schedules and models. This experimental heterogeneity adds confusion and may mislead the translation of findings to human health. Our work will normalize results across experiments and provide a necessary summary relevant to human exposure. Through a novel approach, we describe how different categories of ubiquitously used environmental endocrine disruptors interfere with immune relevant endocrine signaling and contribute to autoimmunity. We hope this review will guide identification of mechanisms and concentration-dependent EDC effects important not only for the sex-bias of autoimmunity, but also for other conditions of immune dysfunction, including post-infection autoreactivity such as may arise following severe acute respiratory syndrome coronavirus 2, Epstein-Barr virus, Herpes Simplex virus.

Bisphenol A, S or F mother's dermal impregnation impairs offspring immune responses in a dose and sex-specific manner in mice

Bisphenol (BP)A is an endocrine disruptor (ED) widely used in thermal papers. Regulatory restrictions have been established to prevent risks for human health, leading to BPA substitution by structural analogues, like BPS and BPF. We previously demonstrated that oral perinatal exposure to BPA had long-term consequences on immune responses later in life. It appears now essential to enhance our understanding on immune impact of different routes of BP exposure. In this study, we aimed at comparing the impact of mother dermal exposure to BPs on offspring immune system at adulthood. Gravid mice were dermally exposed to BPA, BPS or BPF at 5 or 50 μg/kg of body weight (BW)/day (d) from gestation day 15 to weaning of pups at post-natal day (PND)21. In offspring, BPs dermal impregnation of mothers led to adverse effects on immune response at intestinal and systemic levels that was dependent on the BP, the dose and offspring sex. These findings provide, for the first time, results on long-term consequences of dermal perinatal BPs exposure on immune responses in offspring. This work warns that it is mandatory to consider immune markers, dose exposure as well as sex in risk assessment associated with new BPA’s alternatives.

Differential influences of the BPA, BPS and BPF on in vitro IL-17 secretion by mouse and human T cells

The endocrine disruptor and food contaminant bisphenol A (BPA) is frequently present in consumer plastics and can produce several adverse health effects participating in the development of inflammatory and autoimmune diseases. Regulatory restrictions have been established to prevent risks for human health, leading to the substitution of BPA by structural analogues, such as bisphenol S (BPS) and F (BPF). In this study, we aimed at comparing the in vitro impact of these bisphenols from 0.05 to 50,000 nM on Th17 differentiation, frequency and function in mouse systemic and intestinal immune T cells and in human blood T cells. This study reports the ability of these bisphenols, at low and environmentally relevant concentration, i.e, 0.05 nM, to increase significantly IL-17 production in mouse T cells but not in human T lymphocytes. The use of an aryl hydrocarbon receptor (AhR) specific inhibitor demonstrated its involvement in this bisphenol-induced IL-17 production. We also observed an increased IL-17 secretion by BPS and BPF, and not by BPA, in mouse naive T cells undergoing in vitro Th17 differentiation. In total, this study emphasizes the link between bisphenol exposures and the susceptibility to develop immune diseases, questioning thus the rational of their use to replace BPA.

Oral exposure to bisphenols induced food intolerance and colitis in vivo by modulating immune response in adult mice

Bisphenol (BP) A, a known food contaminant, is a possible risk factor in the epidemic of non-communicable diseases (NCD) including food intolerance and inflammatory bowel diseases (IBD). Regulatory restrictions regarding BPA usage led to BPA removal and replacement by poorly described substitutes, like BPS or BPF (few data on occurrence in food and human samples and biological effect). Oral tolerance protocol to ovalbumin (OVA) in WT mice and Il10^-/- mice prone to IBD were used respectively to address immune responses towards food and microbial luminal antigens following BP oral exposure. Both mice models were orally exposed for five weeks to BPA, BPS or BPF at 0.5, 5 and 50 μg/kg of body weight (bw)/day (d). Oral exposure to BPs at low doses (0.5 and 5 μg/kg bw/d) impaired oral tolerance as indicated by higher humoral and pro-inflammatory cellular responses in OVA-tolerized mice. However, only BPF exacerbate colitis in Il10^-/- prone mice associated with a defect of fecal IgA and increased secretion of TNF-α in colon. These findings provide a unique comparative study on effects of adult oral exposure to BPs on immune responses and its consequences on NCD related to intestinal luminal antigen development.

Maternal vitamin D supplementation inhibits bisphenol A-induced proliferation of Th17 cells in adult offspring

Bisphenol A (BPA) exposure can increase the risk of immune-related diseases in later life. Vitamin D3 (Vit D3) has been shown to have multiple immunomodulatory actions and has been used to treat immune diseases. However, the potential beneficial effects of Vit D3 on BPA-induced adverse effects in the immune system have not explored. We hypothesize that VitD3 may ameliorate BPA-induced side effects in the immune system, even in offspring of VitD3-supplemented mothers. Here, we established our experimental model by exposing pregnant dams with 1000 nM BPA with or without VitD3 (0.25 μg/kg, 1 μg/kg and 4 μg/kg) treatment. We show that mother's exposure to BPA increases proliferation of the spleen T helper 17 (Th17) cells and serum protein level of IL-17 in the offspring; however, VitD3 supplementation in mothers dose-dependently ameliorated these BPA-induced side effects on the immune system in the offspring as evidenced by attenuated upregulation of Th17 proliferation, and RORγt, IL-17, IL-6, and IL-23 expressions in the offspring. Our data provide the first evidence that maternal VitD3 supplementation offers benefits to the offspring by attenuating BPA-induced side effects on the immune system through vitamin D receptor (VDR)-dependent regulation of transcription factors and cytokines, suggesting its translational potential.

Perinatal oral exposure to low doses of bisphenol A, S or F impairs immune functions at intestinal and systemic levels in female offspring mice

BACKGROUND

Bisphenol A (BPA), one of the highest-volume chemicals produced worldwide, has been identified as an endocrine disruptor. Many peer-reviewing studies have reported adverse effects of low dose BPA exposure, particularly during perinatal period (gestation and/or lactation). We previously demonstrated that perinatal oral exposure to BPA (via gavage of mothers during gestation and lactation) has long-term consequences on immune response and intestinal barrier functions. Due to its adverse effects on several developmental and physiological processes, BPA was removed from consumer products and replaced by chemical substitutes such as BPS or BPF, that are structurally similar and not well studied compare to BPA. Here, we aimed to compare perinatal oral exposure to these bisphenols (BPs) at two doses (5 and 50 μg/kg of body weight (BW)/day (d)) on immune response at intestinal and systemic levels in female offspring mice at adulthood (Post Natal Day PND70).

METHODS

Pregnant female mice were orally exposed to BPA, BPS or BPF at 5 or 50 μg/kg BW/d from 15th day of gravidity to weaning of pups at Post-Natal Day (PND) 21. Humoral and cellular immune responses of adult offspring (PND70) were analysed at intestinal and systemic levels.

RESULTS

In female offspring, perinatal oral BP exposure led to adverse effects on intestinal and systemic immune response that were dependant of the BP nature (A, S or F) and dose of exposure. Stronger impacts were observed with BPS at the dose of 5 μg/kg BW/d on inflammatory markers in feces associated with an increase of anti-E. coli IgG in plasma. BPA and BPF exposure induced prominent changes at low dose in offspring mice, in term of intestinal and systemic immune responses, provoking an intestinal and systemic Th1/Th17 inflammation.

CONCLUSION

These findings provide, for the first time, results of long-time consequences of BPA, S and F perinatal exposure by oral route on immune response in offspring mice. This work warns that it is mandatory to consider immune markers and dose exposure in risk assessment associated to new BPA's alternatives.

Investigation of the effects of bisphenol-A exposure on lymphoid system in prenatal stage

Bisphenol-A (BPA) used in the production of plastic materials is a temperature-soluble agent. It also has a steroid hormone-like activity; therefore, it poses a danger to human health. In our study, we aimed to investigate the effects of BPA on lymph node and spleen in male rats exposed to this agent during prenatal stage. The pregnant female rats were divided into four groups: control, sham, low dose (300 µg/kg BPA), and high dose (900 µg/kg BPA). BPA was dissolved in 1 mL of corn oil and administered to the pregnant rats every day during pregnancy. On the 21st and 45th day after the birth, male rats' lymph node and spleen samples were taken and histopathological examination was performed. Samples were stained with hematoxylin and eosin to determine the general histological appearance, and with CD3 and CD20 immunohistochemically. The results of staining were evaluated by H-score, and statistical analysis was performed. In the samples, BPA applications were not found to cause significant tissue damage. But there was a significant decrease in the immunoreactivities of CD3 and CD20 after BPA applications in both 21st and 45th day samples. After high dose BPA administration, decreased CD3 immunoreactivity was statistically significant. It is thought that BPA does not cause histologically significant tissue damage, but it may impair organ function at cellular level. The investigation of molecules involved in organ function will be useful in revealing the mechanisms that will cause dysfunction.

In vitro impact of bisphenol A on maturation and function of monocyte-derived dendritic cells in patients with primary Sjögren's syndrome

Background: Epidemiological studies have shown that environmental factors accelerate the progress of primary Sjögren's syndrome (pSS). Bisphenol A (BPA), a classic endocrine disrupting chemical, affects the immune system. However, the impact of BPA on pSS has not yet been reported. The present study aimed to evaluate the potential relationship between BPA, estrogen receptor (ER), and pSS.Methods: We studied the impact of BPA on monocyte-derived dendritic cells (moDCs) from pSS patients and age-matched healthy controls (HCs). Morphological effects were observed under inverted microscope. Surface markers were analyzed by flow cytometry. ER and cytokine profiles were assessed using real-time polymerase chain reaction. The ability of moDCs to stimulate CD4⁺ T cells activation was assessed by mixed lymphocyte reaction (MLR).Results: moDCs from both pSS patients and HCs expressed ERα as well as ERβ. After BPA-exposure, expression of ERα increased significantly in pSS patients, while that of ERβ remained unchanged. moDCs from BPA-exposed pSS patients showed irregular morphology and reduction in cell aggregation. BPA increased HLA-DR on moDCs of pSS patients via ERα, and promoted the secretion of IL6 and IL12. When co-cultured with BPA-treated moDCs, cytokines (IFN-γ, IL4, IL17, IL10) and transcription factors (T-bet, Gata3, RoR-γt, Foxp3) of CD4⁺ T cells showed imbalance of Th1/Th2/Th17/Treg polarization, with Th1 and Th17 dominating.Conclusions: BPA altered the function of moDCs through ERα, including antigen capture, secretion of inflammatory factors, and ability to stimulate T cells, as well as accelerated the progression and further deterioration of pSS.

Bisphenol A promotes macrophage proinflammatory subtype polarization via upregulation of IRF5 expression in vitro

Exposure to environmental endocrine-disrupting chemical Bisphenol-A (BPA) is closely associated with an imbalance of immune homeostasis, but the underlying mechanisms are not fully understood. In the present study, the effects of BPA on the polarization of mouse peritoneal macrophages were investigated in vitro. Environmentally relevant low concentrations of BPA treatment under M1 type polarization conditions increased the number of M1 subtype macrophages, the gene expression of M1 phenotypic marker CD11c and the activity and gene expression of M1 functional marker iNOS, as well as the production of pro-inflammatory cytokines. However, The same dose BPA treatment under M2 type polarization conditions reduced the number of M2 subtype macrophages, the gene expression of M2 phenotypic marker CD206 and the activity and gene expression of M2 functional marker Arg-1, along with the production of anti-inflammatory cytokines. We also identified that the expression of transcription factor IRF5 was upregulated by BPA exposure in M1 macrophages under M1 type polarization conditions. Our results demonstrate that BPA promotes macrophage polarization toward proinflammatory M1 subtype and M1 activity, associated with upregulated expression of IRF5, while BPA inhibits macrophage toward anti-inflammatory M2 subtype polarization. These findings provide new insight into the link between exposure to BPA and impairment of immune functions.

Environmental exposures during pregnancy: Mechanistic effects on immunity

In human studies, it is well established that exposures during embryonic and fetal development periods can influence immune health. Coupled with genetic predisposition, these exposures can alter lifetime chronic and infectious disease trajectory, and, ultimately, life expectancy. Fortunately, as research advances, mechanisms governing long-term effects of prenatal exposures are coming to light and providing the opportunity for intervention and risk reduction. For instance, human association studies have provided a foundation for the association of prenatal exposure to particulate matter with early immunosuppression and later allergic disease in the offspring. Only recently, the mechanisms mediating this response have been revealed and there is much we have yet to discover. Although cellular immune response is understood for many exposure scenarios, molecular pathways are still unidentified. This review will provide commentary and synthesis of the current literature regarding environmental exposures during pregnancy and mechanisms determining immune outcomes. Shared mechanistic features and current gaps in the state of the science are identified and discussed. To such purpose, we address exposures by their immune effect type: immunosuppression, autoimmunity, inflammation and tissue damage, hypersensitivity, and general immunomodulation.

Gut dysbiosis and impairment of immune system homeostasis in perinatally-exposed mice to Bisphenol A precede obese phenotype development

Epidemiology evidenced the Bisphenol A (BPA), a chemical found in daily consumer products, as an environmental contributor to obesity and type II diabetes (T2D) in Humans. However, the BPA-mediated effects supporting these metabolic disorders are still unknown. Knowing that obesity and T2D are associated with low-grade inflammation and gut dysbiosis, we performed a longitudinal study in mice to determine the sequential adverse effects of BPA on immune system and intestinal microbiota that could contribute to the development of metabolic disorders. We observed that perinatal exposure to BPA (50 µg/kg body weight/day) induced intestinal and systemic immune imbalances at PND45, through a decrease of Th1/Th17 cell frequencies in the lamina propria concomitant to an increase of splenic Th1/Th17 immune responses. These early effects are associated with an altered glucose sensitivity, a defect of IgA secretion into faeces and a fall of faecal bifidobacteria relative to control mice. Such BPA-mediated events precede infiltration of pro-inflammatory M1 macrophages in gonadal white adipose tissue appearing with ageing, together with a decreased insulin sensitivity and an increased weight gain. Our findings provide a better understanding of the sequential events provoked by perinatal exposure to BPA that could support metabolic disorder development in later life.

Impacts of Bisphenol A and Ethinyl Estradiol on Male and Female CD-1 Mouse Spleen

The endocrine disruptor bisphenol A (BPA) and the pharmaceutical 17α-ethinyl estradiol (EE) are synthetic chemicals with estrogen-like activities. Despite ubiquitous human exposure to BPA, and the wide-spread clinical use of EE as oral contraceptive adjuvant, the impact of these estrogenic endocrine disrupting chemicals (EDCs) on the immune system is unclear. Here we report results of in vivo dose response studies that analyzed the histology and microstructural changes in the spleen of adult male and female CD-1 mice exposed to 4 to 40,000 μg/kg/day BPA or 0.02 to 2 μg/kg/day EE from conception until 12–14 weeks of age. Results of that analysis indicate that both BPA and EE have dose- and sex-specific impacts on the cellular and microanatomical structures of the spleens that reveal minor alterations in immunomodulatory and hematopoietic functions. These findings support previous studies demonstrating the murine immune system as a sensitive target for estrogens, and that oral exposures to BPA and EE can have estrogen-like immunomodulatory affects in both sexes.