Mono-2-ethylhexylphthalate (MEHP) induces TNF-α release and macrophage differentiation through different signalling pathways in RAW264.7 cells

Metabolic Reprogramming in Primary Microglial Cell and Extracellular Vesicle Triggered by Aβ Exposure

Microglia, key immune cells in the brain, play a pivotal role in brain homeostasis and immune responses. Emerging evidence suggests their critical involvement in Alzheimer's disease (AD) pathogenesis and propagation. The propagation of AD pathology is related to the extracellular matrix of microglia, including extracellular vesicles (EV). Recently, microglia-derived EVs are implicated in inflammatory processes and neuronal death. This study aimed to extensively profile and propose the metabolic role of microglial EVs in AD. Accordingly, we determined the significant alterations of the EV metabolome associated with the metabolites in primary microglial cells. Aβ exposure induced significant metabolic alteration of 39, 18, and 28 metabolites in microglial cells, cultured media, and EVs, respectively. Aβ exposure triggered common alteration of key metabolic pathways between microglial cells and EVs, including purine, amino acid, and fatty acid metabolisms. While most of the common metabolites showed the same directional changes among the microglial system, N-acetyl aspartic acid displayed the opposite directional change in EVs. N-acetyl aspartic acid decreased 2.3-fold and twofold in microglial cells and media, respectively, but increased 3.5-fold in EVs under Aβ exposure. Moreover, mediation analysis proposed key EV metabolites that were directly affected by the metabolic dysregulation of Aβ-exposed microglial cells. The up-regulation of cysteic acid in EVs was mediated by up-regulated IMP in microglial cells. The down-regulation of 1-16:0-lysoPE in EVs was mediated by stearoyl-L-carnitine in microglial cells. Our study sheds new light on the role of microglia and EVs in neurodegenerative diseases, offering promising avenues for future therapeutic interventions.

Advances in immunology of male reproductive toxicity induced by common environmental pollutants

Humans are exposed to an ever-increasing number of environmental toxicants, some of which have gradually been identified as major risk factors for male reproductive health, even associated with male infertility. Male infertility is usually due to the reproductive system damage, which may be influenced by the exposure to contaminants such as heavy metals, plasticizers, along with genetics and lifestyle. Testicular immune microenvironment (TIM) is important in maintaining normal physiological functions of the testis, whether disturbed TIM after exposure to environmental toxicants could induce reproductive toxicity remains to be explored. Therefore, the current review aims to contribute to the further understanding of exposure and male infertility by characterizing environmental exposures and the effect on TIM. We first summarized the male reproductive toxicity phenotypes induced by common environmental pollutants. Contaminants including heavy metals and plastic additives and fine particulate matter (PM2.5), have been repetitively associated with male infertility, whereas emerging contaminants such as perfluoroalkyl substances and micro(nano)plastics have also been found to disrupt TIM and lead to male reproductive toxicity. We further reviewed the importance of TIM and its homeostasis in maintaining the normal physiological functions of the testis. Most importantly, we discussed the advances in immunology of male reproductive toxicity induced by metals and metalloids, plastic additives, persistent organic pollutants (POPs), micro(nano)plastic and PM2.5 to suggest the importance of reproductive immunotoxicology in the future study of environmental toxicants, but also contribute to the development of effective prevention and treatment strategies for mitigating adverse effects of environmental pollutants on human health.

Surface property and in vitro toxicity effect of insoluble particles given by protein corona: Implication for PM cytotoxicity assessment

In vitro toxicological assessment helps explore key fractions of particulate matter (PM) in association with the toxic mechanism. Previous studies mainly discussed the toxicity effects of the water-soluble and organic-soluble fractions of PM. However, the toxicity of insoluble fractions is relatively poorly understood, and the adsorption of proteins is rarely considered. In this work, the formation of protein corona on the surface of insoluble particles during incubation in a culture medium was investigated. It was found that highly abundant proteins in fetal bovine serum were the main components of the protein corona. The adsorbed proteins increased the dispersion stability of insoluble particles. Meanwhile, the leaching concentrations of some metal elements (e.g., Cu, Zn, and Pb) from PM increased in the presence of proteins. The toxicity effects and potential mechanisms of the PM insoluble particle-protein corona complex on macrophage cells RAW264.7 were discussed. The results revealed that the PM insoluble particle-protein corona complex could influence the phagosome pathway in RAW264.7 cells. Thus, it promoted the intracellular reactive oxygen species generation and induced a greater degree of cell differentiation, significantly altering cell morphology. Consequently, this work sheds new light on the combination of insoluble particles and protein corona in terms of PM cytotoxicity assessment.

Phthalate exposure and lung disease: the epidemiological evidences, plausible mechanism and advocacy of interventions

Phthalates are a kind of synthetic plasticizers, which extensively used as plastic productions to improve their plasticity and flexibility. However, exposure to phthalates has been proved an increased risk of respiratory disease, because by they affect the development and functions of the lung and immune system. Here, we attempt to review respiratory health of phthalate exposure. Firstly, we describe the relationship between phthalates and lung function and airway inflammation. Then, the role of phthalates in asthma, lung cancer, rhinitis, and respiratory tract infections and the possible mechanisms of action are discussed. Finally, possible effective measures to reduce exposure to phthalates are proposed, and health care workers are called upon to provide educational resources and advocate for informed public health policies. Overall, the evidence for association between phthalate exposure and respiratory disease is weak and inconsistent. Therefore, thorough implementation in large populations is needed to produce more consistent and robust results and to enhance the overall understanding of the potential respiratory health risks of phthalate in long-term exposure.

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

Background

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). For example, increased biomonitoring and epidemiological studies suggest that daily phthalate chemical exposure contributes to neurological and behavioral abnormalities; however, these mechanisms remain poorly understood. Therefore, the current study was aimed at examining the effects of chronic phthalate exposure on rodent anxiety behaviors and cognition and the impact on hypothalamic-pituitary-adrenal axis function.

Methods

Adult male mice (C57BL6/J) were administered MEHP via drinking water (1 mg/mL), and anxiety-like behavior and cognition combined with hypothalamic-pituitary-adrenal axis and inflammatory assays were assessed after 3 weeks of MEHP exposure.

Results

MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze and center exploration in the open field. Tests of spatial memory and cognition were unchanged. Following MEHP administration, circulating levels of corticosterone and proinflammatory cytokines were significantly increased, while at the tissue level, there were MEHP-dependent reductions in glucocorticoid metabolism genes Hsd11b1 and Hsd11b2.

Conclusions

These data suggest that chronic MEHP exposure leads to enhanced generalized anxiety behaviors independent of rodent measures of cognition and memory, which may be driven by MEHP-dependent effects on hypothalamic-pituitary-adrenal axis and peripheral glucocorticoid metabolism function.

The effects of industrial chemicals bonded to plastic materials in newborns: A systematic review

BACKGROUND

Phthalates are a family of industrial chemicals noncovalently bonded to plastic materials to enhance flexibility and durability. These compounds are extensively used in a variety of consumer products and even in many medical devices. Newborns present a higher susceptibility to phthalates.

OBJECTIVE

To assess the short- and long-term health consequences of exposure to phthalates during the neonatal period.

METHODS

Systematic review in accordance with the PRISMA statements. Eligible articles in English language were searched in MEDLINE, Scopus, ISI Web of Science, and Ovid databases using the following terms: "phthalate", "newborn", and "neonate". Unpublished data were searched in ClinicalTrials.gov website. All in vivo studies of any design published before May 16th, 2023 and fulfilling the following criteria were included: 1) investigations in which preterm and/or term newborns underwent one or more measurement of concentrations of phthalates on biological samples taken during the neonatal period; 2) studies in which quantitative measurement of phthalates was related to any kind of health outcome. Subgroup analysis was conducted by type of outcome. The quality assessment was performed according to the criteria from the "NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies".

RESULTS

11,895 records were identified; finally, 5 articles were included for review. A mixture of phthalates was associated with improved performance on the NNNS summary scales of Attention, Handling, and Non-optimal reflexes before NICU discharge. At 2 months' corrected age, some phthalates were positively associated with problem-solving and gross motor abilities; increased levels of mono (2-ethylhexyl) phthalate, mono (2-ethyl-5-carboxypentyl) phthalate, and sum of di (2-ethylhexyl) phthalate (DEHP) metabolites (∑3DEHP and ∑4DEHP) were associated with worse fine motor performance. Furthermore, DEHP was associated with transient alteration of gut microbiota and increased IgM production after vaccine. A linear positive association between a mixture of phthalates and slope of the first growth spurt was even reported in preterm newborns. No relationship emerged between phthalates and bronchopulmonary dysplasia. Three studies out of 5 had fair quality.

CONCLUSION

Given some methodological issues and the paucity of related studies, further investigations of flawless quality aimed at clarifying the relationship between early exposure to phthalates and health outcomes are needed.

Association of mono-2-ethylhexyl phthalate with adverse outcomes in chronic hemodialysis patients

Phthalate exposure is widespread and has a global impact. Growing evidence shows that mono-2-ethylhexyl phthalate (MEHP) exposure has a negative impact on human health. However, whether MEHP exposure is associated with mortality and other adverse outcomes in hemodialysis patients remains unknown. This study prospectively enrolled 217 patients on maintenance hemodialysis from June 30, 2021, to August 16, 2022. Baseline serum MEHP, di-2-ethylhexyl phthalate (DEHP), and indoxyl sulfate (IS) concentrations were measured. Primary endpoints were all-cause mortality or composite adverse outcomes, including all-cause death plus hospitalization due to cardiovascular disease, heart failure, stroke, infection, or cancer. Serum MEHP concentrations were positively associated with DEHP but not indoxyl sulfate concentrations in hemodialysis patients. Additionally, serum MEHP concentrations were significantly and independently associated with all-cause mortality and composite adverse outcomes (adjusted hazard ratios [HRs], 1.04 and 1.03 per ng/mL, 95% confidence intervals [CIs], 1.01-1.07 and 1.00-1.05; p = 0.016 and 0.015, respectively). We found a cutoff value of MEHP for predicting both endpoints. Patients with serum MEHP concentrations of ≥ 41.8 ng/mL had much higher risks for all-cause mortality and composite adverse outcomes (adjusted HRs, 39.2 and 13; 95% CIs, 2.44-65.7 and 2.74-61.4; p = 0.011 and 0.001, respectively). MEHP exposure is significantly associated with higher risks for all-cause mortality and composite adverse outcomes. Hemodialysis patients with serum MEHP concentrations above 41.8 ng/mL had much poorer prognoses regarding both outcomes.

Exposure to phthalates and their alternatives in relation to biomarkers of inflammation and oxidative stress in adults: evidence from NHANES 2017-2018

Phthalates and their alternatives are considered significant environmental risk factors that potentially influence inflammation and oxidative stress. However, their impact on biomarkers of inflammation and oxidative stress was inconsistent. This study aimed to explore the associations between phthalates and high-sensitivity C-reactive protein (hsCRP), gamma-glutamyl transferase (GGT), and white blood cell (WBC) counts, employing both univariate exposure and multivariate co-exposure models. For this analysis, a total of 1619 individuals aged 18 years and above, sourced from the National Health and Nutrition Examination Survey (NHANES) conducted between 2017 and 2018, were selected as subjects. We explored the associations between hsCRP, GGT, and WBC counts and eighteen different phthalate metabolites. Multiple linear regression analysis revealed significant associations between both MCNP and MEHP and hsCRP. We observed negative correlations of MCOP, MCPP, MHBP, and MONP with GGT. Conversely, MEHHP and MEHHTP exhibited positive correlations with GGT. Furthermore, MECPTP and MEHHTP showed positive correlations with WBC. Notably, we identified a non-linear relationship between phthalates and inflammation and oxidative stress markers. The Bayesian kernel machine regression (BKMR) analysis demonstrated a negative joint effect of the phthalates mixture on GGT, particularly at lower concentrations. The BKMR model also found that MEOHP and MHiBP were negatively associated with GGT. In contrast, MEHHP showed a significant positive association with GGT. Moderating effect analysis suggested that dietary inflammatory index (DII), income-to-poverty ratio (PIR), age, BMI, and physical activity influenced the association between phthalates and inflammation and oxidative stress. These findings contribute to a deeper understanding of the relationships between phthalates and inflammation and oxidative stress.

Exposure to the non-phthalate plasticizer di-heptyl succinate is less disruptive to C57bl/6N mouse recovery from a myocardial infarction than DEHP, TOTM or related di-octyl succinate

Phthalate plasticizers are incorporated into plastics to make them soft and malleable, but are known to leach out of the final product into their surroundings with potential detrimental effects to human and ecological health. The replacement of widely-used phthalate plasticizers, such as di-ethylhexyl phthalate (DEHP), that are of known toxicity, by the commercially-available alternative Tris(2-ethylhexyl) tri-mellitate (TOTM) is increasing. Additionally, several newly designed "green" plasticizers, including di-heptyl succinate (DHPS) and di-octyl succinate (DOS) have been identified as potential replacements. However, the impact of plasticizer exposure from medical devices on patient recovery is unknown and, moreover, the safety of TOTM, DHPS, and DOS is not well established in the context of patient recovery. To study the direct effect of clinically based chemical exposures, we exposed C57bl/6 N male and female mice to DEHP, TOTM, DOS, and DHPS during recovery from cardiac surgery and assessed survival, cardiac structure and function, immune cell infiltration into the cardiac wound and activation of the NLRP3 inflammasome. Male, but not female, mice treated in vivo with DEHP and TOTM had greater cardiac dilation, reduced cardiac function, increased infiltration of neutrophils, monocytes, and macrophages and increased expression of inflammasome receptors and effectors, thereby suggesting impaired recovery in exposed mice. In contrast, no impact was detected in female mice and male mice exposed to DOS and DHPS. To examine the direct effects in cells involved in wound healing, we treated human THP-1 macrophages with the plasticizers in vitro and found DEHP induced greater NLRP3 expression and activation. These results suggest that replacing current plasticizers with non-phthalate-based plasticizers may improve patient recovery, especially in the male population. In our assessment, DHPS is a promising possibility for a non-toxic biocompatible plasticizer.

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). Increased biomonitoring and epidemiological studies, for example, suggest that daily phthalate chemical exposure contribute to neurological and behavioral abnormalities, however these mechanisms remain poorly understood. The current study therefore aimed to examine the effects of chronic phthalate exposure on rodent anxiety behaviors, cognition, and the impact on hypothalamic-pituitary- adrenal (HPA)-axis function. Adult male mice (C57BL6/J) were administered mono-2-ethylhexyl phthalate (MEHP) via drinking water (1 mg/ml), and anxiety-like behavior, cognition combined with HPA- axis and inflammatory assays were assessed after 3 weeks of MEHP exposure. MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze (EPM) and center exploration in the open field (OF). Tests of spatial, cognition and memory function were unchanged. Following MEHP administration, circulating levels of corticosterone and pro- inflammatory cytokines were significantly increased, while at the tissue level, MEHP-dependent reductions in glucocorticoid metabolism genes 11β-hydroxysteroid dehydrogenase (11β-HSD) 1 and 2. These data suggest that chronic MEHP exposure leads to enhanced generalized-anxiety behaviors independent of rodent measures of cognition and memory, which maybe driven by MEHP-dependent effects on HPA-axis and peripheral glucocorticoid metabolism function.

The emerging role of PPAR-alpha in breast cancer

Breast cancer has been confirmed to have lipid disorders in the tumour microenvironment. Peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcriptional factor that belongs to the family of nuclear receptors. PPARα regulates the expression of genes involved in fatty acid homeostasis and is a major regulator of lipid metabolism. Because of its effects on lipid metabolism, an increasing number of studies have investigated the relationship of PPARα with breast cancer. PPARα has been shown to impact the cell cycle and apoptosis in normal cells and tumoral cells through regulating genes of the lipogenic pathway, fatty acid oxidation, fatty acid activation, and uptake of exogenous fatty acids. Besides, PPARα is involved in the regulation of the tumour microenvironment (anti-inflammation and inhibition of angiogenesis) by modulating different signal pathways such as NF-κB and PI3K/AKT/mTOR. Some synthetic PPARα ligands are used in adjuvant therapy for breast cancer. PPARα agonists are reported to reduce the side effects of chemotherapy and endocrine therapy. In addition, PPARα agonists enhance the curative effects of targeted therapy and radiation therapy. Interestingly, with the emerging role of immunotherapy, attention has been focused on the tumour microenvironment. The dual functions of PPARα agonists in immunotherapy need further research. This review aims to consolidate the operations of PPARα in lipid-related and other ways, as well as discuss the current and potential applications of PPARα agonists in tackling breast cancer.

Associations between gastrointestinal infection and urinary phthalate metabolite concentrations in US children and adolescents from NHANES 2005-2016

The purpose of this study was to evaluate at the link between gastrointestinal illness and urine phthalate metabolite concentrations in children and adolescents in the United States between 2005 and 2016. A total of 4008 National Health and Nutrition Examination Survey (NHANES) participants had urine samples obtained during the survey and self-reported their gastrointestinal functional status over the previous week. High performance liquid chromatography/tandem mass spectrometry (HPLC/MS-MS) was used to identify twelve phthalate metabolites in urine samples. The link between PAE concentrations and gastrointestinal illnesses was investigated using logistic regression, which was controlled for possible confounders. The combined and independent effects of PAEs on gastrointestinal illnesses were investigated using Bayesian Kernel Machine Regression (BKMR) and quantile-based g-computation (qgcomp). In children and adolescents, the prevalence of gastrointestinal infection was 9.0%. One log-unit increase in urinary concentrations was associated with an increased risk of gastrointestinal infection for monocarboxyoctyl phthalate (MCOP) (adjusted odd ratio (aOR) = 1.36, 95 percent confidence interval (95%ci): 1.08, 1.62), mono(2-ethylhexyl) phthalate (MEHP) (aOR = 1.18, 95 percent CI: 1.05, 1.32) and mono(2-eth The mixed exposure model findings revealed that the combined effect of PAEs was substantially linked with gastrointestinal infection; exposure to the combination of PAEs was positively associated with the risk of gastrointestinal infection. In the BKMR model, the exposure to the mixture of PAEs was positively associated with the risk of gastrointestinal infection. In qgcomp, a substantial positive correlation between PAEs and gastrointestinal illnesses was identified (OR = 1.16, 95 percent CI: 1.05, 1.28). MCOP and MEHP may be the major contributors after controlling for other PAE homologs. These associations were more pronounced in overweight and obese children and adolescents. Mixed exposure to phthalates (PAEs) in children and adolescents was significantly associated with gastrointestinal infections, with MCOP and MEHP accounting for the major proportions. These associations were more pronounced in overweight and obese children and adolescents.

Estimated daily intake of phthalates, parabens, and bisphenol A in hospitalised very low birth weight infants

Very low birth weight infants (VLBW, birth weight (BW) < 1500 g) are exposed to phthalates, parabens and bisphenol A (BPA) early in life. We estimated daily intake (EDI) of these excipients in 40 VLBW infants the first and fifth week of life while hospitalised. Based on urinary samples collected in 2010, EDI was calculated and compared to the tolerable daily intake (TDI) with hazard quotients (HQs) evaluated. A HQ > 1 indicates that EDI exceeded TDI with increased risk of adverse health effects. EDI was higher in VLBW infants compared to term-born infants and older children. VLBW infants born at earlier gestational age (GA), or with lower BW, had higher EDI than infants born at later GA or with higher BW. First week median EDI for BPA was higher than TDI in 100% of infants, in 75% for di(2-ethylhexyl) phthalate (DEHP), 90% for the sum of butyl benzyl phthalate (BBzP), di-n-butyl phthalate (DnBP), DEHP and di-iso-nonyl phthalate (DiNP) = ∑BBzP+DnBP+DEHP+DiNP, and in 50% of infants for propylparaben (PrPa), indicating increased risk of adverse effects. Fifth week EDI remained higher than TDI in all infants for BPA, in 75% for DEHP and ∑BBzP+DnBP+DEHP+DiNP, and 25% of infants for PrPa, indicating prolonged risk. Maximum EDI for di-iso-butyl phthalate was higher than TDI suggesting risk of adverse effects at maximum exposure. VLBW infants born earlier than 28 weeks GA had higher EDI, above TDI, for PrPa compared to infants born later than 28 weeks GA. Infants with late-onset septicaemia (LOS) had higher EDI for DEHP, ∑BBzP+DnBP+DEHP+DiNP and BPA, above TDI, compared to infants without LOS. More 75% of the infants' EDI for DEHP and ∑BBzP+DnBP+DEHP+DiNP, 25% for PrPa, and 100% of infants' EDI for BPA, were above TDI resulting in HQs > 1, indicating increased risk of adverse health effects.

Medical devices as a source of phthalate exposure: a review of current knowledge and alternative solutions

Phthalates are a group of phthalic acid esters used as plasticisers in a large number of products to improve their flexibility, softness, and extensibility. Their wide use in medical devices, however, raises a lot of concern, as they can enter the organism and have toxic effects on human liver, thyroid, kidneys, lungs, reproductive, endocrine, nervous, and respiratory system and are associated with asthma, obesity, autism, and diabetes. The aim of this review is to summarise current knowledge about phthalate migration from medical devices during different medical procedures and possible impact on patient health. It also looks at alternative plasticisers with supposedly lower migration rates and safer profile. Not enough is known about which and how many phthalates make part of medical devices or about the health impacts of alternative plasticisers or their migration rates.

High-Temperature Soup Foods in Plastic Packaging Are Associated with Phthalate Body Burden and Expression of Inflammatory mRNAs: A Dietary Intervention Study

Plastic packaging material is widely used to package high-temperature soup food in China, but this combination might lead to increased exposure to phthalates. The health effects and potential biological mechanisms have not been well studied. This study aimed to examine urinary phthalate metabolites and the expression of inflammatory cytokines in the blood before, during, and after a "plastic-packaged high-temperature soup food" dietary intervention in healthy adults. The results showed that compared with those in the preintervention period, urinary creatinine-adjusted levels of monomethyl phthalate (MMP), mono-n-butyl phthalate (MBP), mono-isobutyl phthalate (MIBP), and total phthalate metabolites in the intervention period were significantly higher, with increases of 71.6, 41.8, 38.8, and 29.8% for MMP, MBP, MIBP, and the total phthalate metabolites, respectively. After intervention, the mean levels of IL-1β, IL-4, and TNF-α mRNA increased by 19.0, 21.5, and 25.0%, respectively, while IL-6 and IFN-γ mRNA decreased by 24.2 and 32.9%, respectively, when compared with the preintervention period. We also observed that several phthalates were associated with the mRNA or protein expression of IL-8, TNF-α, and IL-10. Therefore, consumption of plastic-packaged high-temperature soup food was linked to increased phthalate exposure and might result in significant changes in mRNA expression of several inflammatory cytokines.

A Novel Ex Vivo Approach Based on Proteomics and Biomarkers to Evaluate the Effects of Chrysene, MEHP, and PBDE-47 on Loggerhead Sea Turtles (Caretta caretta)

The principal aim of the present study was to develop and apply novel ex vivo tests as an alternative to cell cultures able to evaluate the possible effects of emerging and legacy contaminants in Caretta caretta. To this end, we performed ex vivo experiments on non-invasively collected whole-blood and skin-biopsy slices treated with chrysene, MEHP, or PBDE-47. Blood samples were tested by oxidative stress (TAS), immune system (respiratory burst, lysozyme, and complement system), and genotoxicity (ENA assay) biomarkers, and genotoxic and immune system effects were observed. Skin slices were analyzed by applying a 2D-PAGE/MS proteomic approach, and specific contaminant signatures were delineated on the skin proteomic profile. These reflect biochemical effects induced by each treatment and allowed to identify glutathione S-transferase P, peptidyl-prolyl cis-trans isomerase A, mimecan, and protein S100-A6 as potential biomarkers of the health-threatening impact the texted toxicants have on C. caretta. Obtained results confirm the suitability of the ex vivo system and indicate the potential risk the loggerhead sea turtle is undergoing in the natural environment. In conclusion, this work proved the relevance that the applied ex vivo models may have in testing the toxicity of other compounds and mixtures and in biomarker discovery.

Endocrine Disruptors and Obesity: an Overview

Obesity is a growing pandemic. Endocrine-disrupting chemicals are widespread in the environment. In this perspective, the authors examine the issue related to the exposure to several chemicals with endocrine-disrupting properties as promoting factors to obesity. Data show that Phthalates, Bisphenol compounds, Persistent Organic Pollutants (POPs), solvents, and personal care products can modify metabolic properties in a dose-response and sex-specific manner. Phthalates and bisphenol compounds increase body mass index, waist circumference, waist to height ratio, and the sum of skinfold thicknesses in women and not in men. Low-dose exposure to Persistent Organic Pollutants is strongly associated with increased body mass index in men and decreased this parameter in women. The mechanism through which these compounds act on anthropometric parameters is not entirely understood. Several studies suggest a possible interference in gonadotropin secretion and the thyroid axis. These inspire a decrease of both total and free testosterone levels in men and FT3 and FT4 levels in women, particularly after a pregnancy. The impact of endocrine disruptor chemicals on adipose tissue inflammation and future cardio-metabolic disorders remains to be elucidated. Therefore, studies involving both healthy and obese individuals are needed to unambiguously confirm results from in vitro and animal models.

Acute exposure to phthalates during recovery from a myocardial infarction induces greater inflammasome activation in male C57bl/6N mice

Plasticizers escape from medical devices used in cardiac surgery into patient blood and tissues. Increased di-ethylhexyl phthalate (DEHP) exposure is correlated with chronic inflammation in vivo and increased cytokine release in exposed monocytes in vitro. To determine if acute phthalate exposure enhanced inflammation in a model of cardiac damage, we measured immune cell infiltration, inflammasome expression and cardiac function in male C57bl/6 N mice exposed to phthalates during recovery from a surgically-induced myocardial infarction (MI). Phthalate exposed mice had greater neutrophil and pro-inflammatory macrophage infiltration, greater cardiac dilation and reduced cardiac function when compared with control mice. The greater expression of NLRP3 and NLRP6, but not AIM2 or P2xR7, in the infarcts of phthalate exposed versus control mice suggests a selectivity in pattern recognition receptor activation. Treatment of human THP-1 macrophages with phthalates revealed increased NLRP3 and NLRP6 expression and induction of a pro-inflammatory macrophage population. Pre-treatment with the PPARγ antagonist GW9662 reduced these increases. An increase in expression of IL-1R, MyD88 and IRAK4 in infarcts of phthalate exposed mice and THP-1 cells argues for greater priming downstream of IL-1R signaling and increased susceptibility for inflammasome activation. Importantly, these effects were moderated in vivo when phthalate exposure was reduced by 90% and when the NLRP3 antagonist MCC950 was co-administered. Our study suggests that reductions in phthalate exposure, which might be realized using plasticizers with a reduced ability to leach out from plastic, or short-term treatment with an anti-inflammasome may improve healing post-surgery.

Organic UV Filters Induce Toll-like-Receptors and Related Signaling Pathways in Peripheral Blood Mononuclear Cells of Juvenile Loggerhead Sea Turtles (Caretta caretta)

Simple Summary

Emerging environmental contaminants, such as sunscreen agents, have been broadly identified in marine ecosystems. Thus, the present work aims to investigate whether organic UV filters cause immunotoxic effects in juvenile loggerhead sea turtles (Caretta caretta). We found that loggerhead sea turtles showing high circulating levels of organic UV filters manifested increased expression of genes involved in inflammatory responses, probably due to contaminant-induced oxidative damage.

Abstract

Recent evidence suggests that exposure to organic ultraviolet filters (UV filters) is associated with dysregulated neuroendocrine-immune homeostasis. Marine species are likely to be among the most vulnerable to UV filters due to widespread diffusion of these chemicals in the aquatic environment. In the present study, the effects of UV filter bioaccumulation on toll-like-receptors (TLRs) and related signaling pathways were investigated in peripheral blood mononuclear cells (PBMCs) of juvenile loggerhead sea turtles (Caretta caretta). We found that the expression of both TLR1 and TLR2 was significantly increased in UV-filter exposed turtles compared to control animals. Similarly, the signaling pathway downstream of activated TLRs (i.e., Ras-related C3 botulinum toxin substrate 1 (RAC1), Phosphoinositide 3-kinase (PI3K), serine/threonine-protein kinase (AKT3), and nuclear factor κB (NF-κB)) was significantly up-regulated, leading to an enhanced transcription of pro-inflammatory cytokines. In addition, we demonstrated that high levels of plasma UV filters increased lipid peroxidation in sea turtles’ PBMCs. Our results indicated that UV filters affected the inflammatory responses of PBMCs via modulation of the TLR/NF-κB signaling pathway and provided a new insight into the link between exposure to sunscreen agents and sea turtle health.

Association of urinary phthalate metabolites with sarcopenia in US adults: NHANES 1999-2006

Phthalates have been extensively detected in environmental and biological matrices. Exposure to phthalates is implicated in various human diseases. In this study, we conducted a cross-sectional study to determine whether urinary phthalate metabolite concentrations were correlated with prevalence of sarcopenia in US adult population. We included 3562 participants with detailed information on skeletal muscle mass and urinary phthalate metabolites based on National Health and Nutrition Examination Survey (NHANES) 1999-2006 data. A total of 7 main phthalate metabolites were analyzed in the urine sample of each participant. Appendicular skeletal muscle mass (ASM) was measured using dual-energy X-ray absorptiometry. Multivariable linear regression models were conducted following adjustment for multiple covariates. ASM adjusted by body mass index (ASM/BMI) was calculated, and sarcopenia was defined as the lowest quintile for ASM/BMI value. Compared with participants in quartile 1, those in quartile 2 of urinary mono-n-butyl phthalate (MnBP) and quartile 4 of urinary monobenzyl phthalate (MBzP) had decreased ASM/BMI. Urinary MnBP in quartile 4, as well as urinary MBzP in quartile 2, was shown to be significantly correlated with higher sarcopenia prevalence. In subgroup analysis, negative association of MBzP with ASM/BMI was observed in both males and females, while this negative association was only observed in males for MnBP. Females with higher urinary monoethyl phthalate (MEP) concentrations had higher sarcopenia risk. Taken together, the present study found several urinary phthalate metabolites were positively associated with sarcopenia prevalence in US adult population. These findings indicated phthalate exposure might be an important environmental risk factor contributing to sarcopenia development.

Di(2-ethylhexyl)phthalate exposure exacerbates metabolic disorders in diet-induced obese mice

Both phthalate exposure and obesity are positively associated with metabolic disorders. The study aimed to investigate whether DEHP exposure caused metabolic disorders in an obesity-dependent manner. Both lean and diet-induced obese mice were subjected to environmentally relevant DEHP exposure. DEHP-treated obese mice exhibited higher glucose intolerance and insulin resistance than obese mice; the metabolic disorders were accompanied by increased blood levels of leptin, LDL cholesterol, and alanine transaminase. In obese mice, DEHP enhanced macrophage infiltration into epididymal white adipose tissue (eWAT) and hepatic tissue, and promoted hepatic steatosis/steatohepatitis. The DEHP effects were not observed in lean mice. Transcriptomic changes in eWAT and hepatic tissue were determined with microarray analysis. Results indicated that obesity and DEHP synergistically regulated carbohydrate uptake, lipolysis, and abnormality of adipose tissue, via the upstream regulators Pparg, Lipe, Cd44, and Irs1. Meanwhile, obesity and DEHP differentially modulated transcriptomic changes in hepatic tissue. Obesity was associated with lipid/cholesterol synthesis, lipid accumulation, and inflammation in hepatic tissue via the upstream regulators Zbtb20 and Nr1i2. In obese mice, DEHP exposure caused hepatic injury, cell migration, and changes in glycogen quantity mainly via Cd44. Microarray analysis suggested the potential mechanism underlying the early onset of metabolic disorders in DEHP-treated obese mice.

Mechanistic insight into toxicity of phthalates, the involved receptors, and the role of Nrf2, NF-κB, and PI3K/AKT signaling pathways

The wide use of phthalates, as phthalates are used in the manufacturing of not only plastics but also many others goods, has become a main concern in the current century because of their potency to induce deleterious effects on organism health. The toxic effects of phthalates such as reproductive toxicity, cardiotoxicity, hepatotoxicity, nephrotoxicity, teratogenicity, and tumor development have been widely indicated by previous experimental studies. Some of the important mechanisms of toxicity by phthalates are the induction and promotion of inflammation, oxidative stress, and apoptosis. Awareness of the involved molecular pathways of these mechanisms will permit the detection of exact molecular targets of phthalates to protect or treat their toxicity. Up to now, various transcription factors and signaling pathways have been associated with phthalate-induced toxicity which by influencing on nuclear surface and the expression of different genes can alter cell hemostasis. In different studies, the role of nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor-κB (NF-κB), and phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathways in processes of oxidative stress, inflammation, apoptosis, and cancer has been shown following exposure to phthalates. In the present review, we aim to survey experimental studies (in vitro and in vivo) in order to show firstly the most involved receptors and also the importance and the role of the mentioned signaling pathways in phthalate-induced toxicity, and with considering this point, the future studies can focus on these molecular targets as a strategic method to reduce environmental chemicals-induced toxicity especially phthalates toxic effects.

First trimester mechanisms of gestational sac placental and foetal teratogenicity: a framework for birth cohort studies

BACKGROUND

The function of the gestational sac (GS) and the placenta in the closely related processes of embryogenesis and teratogenicity in the first trimester has been minimally described. The prevailing assumption is that direct teratogenic effects are mediated by the critical extraembryonic organ, the placenta, which either blocks or transfers exposures to the foetus. Placental transfer is a dominant mechanism, but there are other paradigms by which the placenta can mediate teratogenic effects. Knowledge of these paradigms and first trimester human developmental biology can be useful to the epidemiologist in the conduct of biomarker-based studies of both maternal and child health.

OBJECTIVE AND RATIONALE

Our aim is to provide a causal framework for modelling the teratogenic effects of first trimester exposures on child health outcomes mediated by the GS and placenta using biomarker data collected in the first trimester. We initially present first trimester human developmental biology for the sake of informing and strengthening epidemiologic approaches. We then propose analytic approaches of modelling placental mechanisms by way of causal diagrams using classical non-embryolethal teratogens (diethylstilboestrol [DES], folic acid deficiency and cytomegalovirus [CMV]) as illustrative examples. We extend this framework to two chronic exposures of particular current interest, phthalates and maternal adiposity.

SEARCH METHODS

Information on teratogens was identified by a non-systematic, narrative review. For each teratogen, we included papers that answered the five following questions: (i) why were these exposures declared teratogens? (ii) is there a consensus on biologic mechanism? (iii) is there reported evidence of a placental mechanism? (iv) can we construct a theoretical model of a placental mechanism? and (v) can this knowledge inform future work on measurement and modelling of placental-foetal teratogenesis? We prioritized literature specific to human development, the organogenesis window in the first trimester and non-embryolethal mechanisms.

OUTCOMES

As a result of our review of the literature on five exposures considered harmful in the first trimester, we developed four analytic strategies to address first trimester placental mechanisms in birth cohort studies: placental transfer and direct effects on the foetus (DES and maternal adiposity), indirect effects through targeted placental molecular pathways (DES and phthalates), pre-placental effects through disruptions in embryonic and extraembryonic tissue layer differentiation (folic acid deficiency), and multi-step mechanisms that involve maternal, placental and foetal immune function and inflammation (DES and CMV).

WIDER IMPLICATIONS

The significance of this review is to offer a causal approach to classify the large number of potentially harmful exposures in pregnancy when the exposure occurs in the first trimester. Our review will facilitate future research by advancing knowledge of the first trimester mechanisms necessary for researchers to effectively associate environmental exposures with child health outcomes.

Biomarkers of phthalates and inflammation: Findings from a subgroup of Women's Health Initiative participants

BACKGROUND

Recent experimental work has shown that phthalates may increase inflammation. Prior research has not examined the role of exposure to phthalates in relation to inflammatory status among postmenopausal women who are at higher risk of developing inflammation-related chronic disorders.

OBJECTIVES

We aimed to examine the associations of urinary phthalate biomarker concentrations with circulating levels of c-reactive protein [CRP] and interleukin-6 [IL-6] among 443 postmenopausal women selected into a breast cancer case-control study nested within the Women's Health Initiative (WHI).

METHODS

A total of 13 phthalate metabolites were measured in urine samples provided at WHI enrollment from 1993 to 1998. We also measured baseline levels of CRP and IL-6 in these women's serum or plasma samples. Multivariable linear models were used to investigate the role of each phthalate biomarker in relation to CRP and IL-6, adjusting for potential confounding factors and specifically evaluating the role of BMI.

RESULTS

In adjusted models we observed positive associations of monocarboxynonyl phthalate (MCNP) with CRP (β = 0.092; 95% CI 0.026, 0.158) and IL-6 (β = 0.108; 95% CI 0.013, 0.204). These positive associations were attenuated and non-significant, however, after further adjustment for body mass index (BMI). In contrast, we observed inverse associations of monoethyl phthalate (MEP) (β = -0.019; 95% CI -0.036, -0.001) and monobenzyl phthalate (MBzP) (β = -0.034; 95% CI -0.058, -0.010) with CRP levels only after adjustment for BMI. Other phthalate biomarkers examined were not significantly associated with either CRP or IL-6 levels.

CONCLUSIONS

Overall, these results do not suggest an important role for phthalates in promoting an inflammatory response. Future prospective studies are warranted to improve understanding of these associations, particularly in clarifying the role of BMI.

Mono-(2-ethylhexyl) phthalate Promotes Dengue Virus Infection by Decreasing IL-23-Mediated Antiviral Responses

Exposure to environmental hormones such as di(2-ethylhexyl) phthalate (DEHP) has become a critical human health issue globally. This study aimed to investigate the correlations between DEHP/mono-(2-ethylhexyl) phthalate (MEHP) levels and macrophage-associated immune responses and clinical manifestations in dengue virus (DV)-infected patients. Among 89 DV-infected patients, those with DV infection-related gastrointestinal (GI) bleeding (n = 13, 15% of patients) had significantly higher DEHP exposure than those without GI bleeding (n = 76, 85% of patients), which were 114.2 ng/ml versus 52.5 ng/ml ΣDEHP in urine; p = 0.023). In an in vitro study using cultured human monocyte-derived macrophages (MDMs) to investigate the effects of MEHP, treatment increased IL-1β and TNF-α release but decreased IL-23 release, with negative correlations observed between urine ΣDEHP and serum IL-23 levels in patients. MEHP-treated MDMs had lower antiviral Th17 response induction activity in mixed T-cell response tests. The in vitro data showed that MEHP increased DV viral load and decreased IL-23 release dose-dependently, and adding IL-23 to MEHP-exposed MDMs significantly reduced the DV viral load. MEHP also suppressed IL-23 expression via the peroxisome proliferator-activated receptor-gamma (PPAR-γ) pathway. Further, the PPAR-γ antagonist GW9662 significantly reversed MEHP-induced IL-23 suppression and reduced the DV viral load. These study findings help to explain the associations between high MEHP levels and the high global burden of dengue disease.

Seasonal exposure to phthalates and inflammatory parameters: A pilot study with repeated measures

Exposure to phthalates poses potential to damage multiple organs and system in the body. However, limited data are available regarding effects of seasonal exposure levels of phthalates and indicators reflecting inflammatory response. We designed a pilot study with repeated measures. We recruited 106 eligible habitants from Wuhan city, China. They completed questionnaires, physical examinations and provided urine specimens in winter and summer seasons. We found that urinary levels of low-molecular-weight phthalate metabolites were higher in summer than in winter (all P < 0.01). In winter, an interquartile range increase (1.264 μg/L) in 3-day moving average of high-molecular-weight phthalate metabolites corresponded to a 13.634% (95% CI: -22.331, -3.941) decrease in mean platelet volume, 25.879% (95% CI: -37.424, -12.204) for lymphocyte count or 10.862% (95% CI: -18.716, -2.125) for platelet count (P < 0.05 or P < 0.01). However, in summer, an interquartile range increase (1.215 μg/L) in urinary levels of high-molecular-weight phthalate metabolites corresponded to an 8.743% (95% CI: 4.217, 13.467) increase in platelet distribution width value or a 4.597% (95% CI: 2.335, 6.780) for mean platelet volume value at 3-day lag (both P < 0.01). In conclusion, phthalate exposure exhibited the potential for the activation of platelet function, particularly in winter. Seasonal variations of phthalate exposure should be considered when assessing health risk.

Prenatal and childhood exposure to phthalic acid esters and vaccination antibodies in children: A 15-year follow-up birth cohort study

Phthalic acid esters (PAE) are widely used during chemical synthesis and do not form covalent linkages with products. It has been reported that exposure to PAE affects the immune response. However, their effect on antibody concentrations in children is still under investigation. We aimed to examine the association between early-life phthalate exposure and antibody concentrations in children in a longitudinal birth cohort established in 2000-2001. We recruited 398 neonates in central Taiwan and followed them up every 2-3 years, with various antibody-related studies at 11- and 14-year follow-ups. Seven urinary phthalate metabolites were quantified in mothers during pregnancy and children aged 11 years. Four antibody concentrations were analyzed in children aged 11 and 14 years. The percent change in antibody concentrations from ages 11 to 14 years was calculated and its association with phthalate exposure was evaluated via multivariate regression analysis. Eighty-one followed-up children were with sufficient data. After adjusting for prenatal exposure and other confounders, double concentrations of the urinary sum of di-2-ethylhexyl phthalate (ΣDEHPm) and mono-n-butyl phthalate (MnBP) were associated with a 18.06% (95% CI = 3.34%, 32.78%) and 22.53% decrease (95% CI = 3.39%, 41.66%) in antibody concentration against hepatitis B, respectively. Phthalate exposure was found to be related to decreased antibody concentrations against hepatitis B (DEHP, DBnP) in the early teens. This exposure is suggested to be considered for clinical re-booster vaccines among junior high school students. Further verification with additional cohorts and studies on the underlying mechanisms of phthalate exposure are warranted.

Sex-specific difference in placental inflammatory transcriptional biomarkers of maternal phthalate exposure: a prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to birth outcomes in a sex-specific manner. These outcomes may be mediated by placental inflammation, which is the proposed biological mechanism. This is the first study to address the relationship between phthalate exposure and gene expression in placental inflammation in a sex-specific manner. We performed quantitative PCR to measure placental inflammatory mRNAs (CRP, TNF-α, IL-1β, IL-6, IL-10, MCP-1, IL-8, CD68, and CD206) in 2469 placentae that were sampled at birth. We estimated the associations between mRNA and urinary phthalate monoesters using multiple linear regression models. Mono-n-butyl phthalate (MBP) was correlated with higher IL-1β, IL-6, and CRP expression in placentae of male fetuses and with higher IL-6, CRP, MCP-1, IL-8, IL-10, and CD68 expression in placentae of female fetuses. Mono benzyl phthalate (MBzP) increased the expression of TNF-α, MCP-1, and CD68 only in placentae of male fetuses. Mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with CRP, MCP-1, and CD68 in placentae of female fetuses. Maternal phthalate exposure was associated with inflammatory variations in placental tissues. The associations were stronger in placentae of male than of female fetuses. Compared with the other metabolites, MBP plays a strong role in these associations. The placenta is worth being further investigated as a potential mediator of maternal exposure-induced disease risk in children.

Phthalate exposure and allergic diseases: Review of epidemiological and experimental evidence

Phthalates are among the most ubiquitous environmental contaminants and endocrine-disrupting chemicals. Exposure to phthalates and related health effects have been extensively studied over the past four decades. An association between phthalate exposure and allergic diseases has been suggested, although the literature is far from conclusive. This article reviews and evaluates epidemiological (n = 43), animal (n = 49), and cell culture studies (n = 42), published until the end of 2019, on phthalates and allergic diseases, such as asthma, rhinoconjunctivitis, and eczema. In contrast to earlier reviews, emphasis is placed on experimental studies that use concentrations with relevance for human exposure. Epidemiological studies provide support for associations between phthalate exposures and airway, nasal, ocular, and dermal allergic disease outcomes, although the reported significant associations tend to be weak and demonstrate inconsistencies for any given phthalate. Rodent studies support that phthalates may act as adjuvants at levels likely to be relevant for environmental exposures, inducing respiratory and inflammatory effects in the presence of an allergen. Cell culture studies demonstrate that phthalates may alter the functionality of innate and adaptive immune cells. However, due to limitations of the applied exposure methods and models in experimental studies, including the diversity of phthalates, exposure routes, and allergic diseases considered, the support provided to the epidemiological findings is fragmented. Nevertheless, the current evidence points in the direction of concern. Further research is warranted to identify the most critical windows of exposure, the importance of exposure pathways, interactions with social factors, and the effects of co-exposure to phthalates and other environmental contaminants.

Recovery From a Myocardial Infarction Is Impaired in Male C57bl/6 N Mice Acutely Exposed to the Bisphenols and Phthalates That Escape From Medical Devices Used in Cardiac Surgery

Bisphenols and phthalates leach from medical devices, and this exposure is likely to increase in postcardiac surgery patients. Previous studies suggest that such chemical exposure may impact recovery and wound healing, yet the direct effects of bisphenols and phthalates are unknown in this context. To study the direct effect of clinically based chemical exposures, we measured the metabolites representative of 6 bisphenols and 10 phthalates in men before and after cardiac surgery and then replicated this exposure in a mouse model of cardiac surgery and assessed survival, cardiac function and inflammation. Bisphenol A (BPA), di-ethyl hexyl phthalate (DEHP), butylbenzyl phthalate, di-isodecyl phthalate, and di-n-butyl phthalate metabolites were increased after surgery. DEHP exposure predominated, was positively correlated with duration on the cardiopulmonary bypass machine and exceeded its tolerable daily intake limit by 37-fold. In vivo, C57bl/6 N male mice treated with BPA+phthalates during recovery from surgery-induced myocardial infarction had reduced survival, greater cardiac dilation, reduced cardiac function and increased infiltration of neutrophils, monocytes and macrophages suggesting impaired recovery. Of interest, genetic ablation or estrogen receptor beta (ERβ) antagonism did not improve recovery and replacement of DEHP with tri-octyl trimellitate or removal of BPA from the mixture did not ameliorate these effects. To examine the direct effects on inflammation, treatment of human THP-1 macrophages with BPA and phthalates induced a dysfunctional proinflammatory macrophage phenotype with increased expression of M1-type macrophage polarization markers and MMP9 secretion, yet reduced phagocytic activity. These results suggest that chemicals escape from medical devices and may impair patient recovery.

A Multi-Functional Silicon Nanoparticle Designed for Enhanced Osteoblast Calcification and Related Combination Therapy

Implant materials applied in bone defect commonly focus on the inducement of bone regeneration and neglect to cure complications including bacterial infection and inflammation, which may result in delayed unions or even amputation. In this study, a microporous silica nanoparticle-poly(N-isopropylacrylamide-b-(2-(dimethylamino)ethyl methacrylate) is synthesized for loading DXMS and the ECM-derived peptide (Sequence: Succinic acid-GTPGPQGIAGQRGVV) in order to enhance the osteoblast calcification and relieve related symptoms. Positively charged PDMA blocks endow the nanoparticle with the antimicrobial property. Moreover, the combination of DXMS makes it have the ability of anti-inflammation and promoting calcification formation. Furthermore, incorporation of the peptide leads to a significant improvement of mineralization and alkaline phosphatase expression in the preosteoblast. After intramuscular implantation in mice for four weeks, the results indicate the composite nanoparticle can promote ectopic bone formation. These combined properties make the composite silicon nanoparticle a promising osteogenic drug appropriate for further study in bone repair and related combination therapy.

Immunomodulatory Activity of Low Molecular-Weight Peptides from Nibea japonica in RAW264.7 Cells via NF-κB Pathway

In this study, a low molecular-weight (Mw) peptide named NJP (<1 kDa), was purified from a protein hydrolysate of Nibea japonica by ultrafiltration, and its immunomodulatory effect on RAW264.7 cells was evaluated. The lactate dehydrogenase (LDH) and MTT assays were performed to explore the cytotoxicity of NJP. The results showed that NJP promoted cell proliferation and had no significant toxic effects on RAW264.7 cells. Moreover, the cells formed multiple pseudopodia indicating that they were in activated state. Further tests showed that NJP significantly promoted phagocytic capacity, and the secretion of proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). It also increased the synthesis of nitric oxide (NO) by upregulating inducible nitric oxide synthase (iNOS) protein level. Flow cytometry revealed that NJP promoted cell cycle progression and increased the percentage of cells in G0/G1 phase. NJP promoted IκBα degradation, p65 and nuclear factor (NF)-κB activation and translocation by up-regulating IKKα/β protein expression. In conclusion, these results indicated that NJP exerts immunomodulatory effects on RAW264.7 cells through the NF-κB signaling pathway. Therefore, NJP can be incorporated in the production of functional foods or nutraceuticals.

Organic UV filters exposure induces the production of inflammatory cytokines in human macrophages

Organic ultraviolet (UV) filters, found in many personal care products, are considered emerging contaminants due to growing concerns about potential long-term deleterious effects. We investigated the immunomodulatory effects of four commonly used organic UV filters (2-hydroxy-4-methoxybenzophenone, BP-3; 4-methylbenzylidene camphor, 4-MBC; 2-ethylhexyl 4-methoxycinnamate, EHMC; and butyl-methoxydibenzoylmethane, BDM) on human macrophages. Our results indicated that exposure to these four UV filters significantly increased the production of various inflammatory cytokines in macrophages, particular tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). After exposure to the UV filters, a significant 1.1-1.5 fold increase were found in TNF-α and IL-6 mRNA expression. In addition, both the p38 MAPK and the NF-κB signaling pathways were enhanced 2 to 10 times in terms of phosphorylation after exposure to the UV filters, suggesting that these pathways are involved in the release of TNF-α and IL-6. Molecular docking analysis predicted that all four UV filter molecules would efficiently bind transforming growth factor beta-activated kinase 1 (TAK1), which is responsible for the activation of the p38 MAPK and NF-κB pathways. Our results therefore demonstrate that exposure to the four organic UV filters investigated may alter human immune system function. It provides new clue for the development of asthma or allergic diseases in terms of the environmental pollutants.

MEHP-induced rat testicular inflammation does not exacerbate germ cell apoptosis

The testis is an organ that maintains an immune suppressive environment. We previously revealed that exposure of pre-pubertal rats to an acute dose of a well-described Sertoli cell toxicant, mono-(2-ethylhexyl) phthalate (MEHP), leads to an accumulation of CD11b+ immune cells in the testicular interstitial space that closely correlates with a robust incidence of germ cell (GC) apoptosis. Here, we test the hypothesis that the infiltrating immune cells contribute to GC apoptosis. Postnatal day 28 Fischer rats that received an oral dose of 700 mg/kg MEHP showed a significant infiltration of both CD11bc+/CD68+/CD163- macrophages and neutrophils. The infiltration peaked at 12 h, but had reduced by 48 h. Testicular macrophages from MEHP-treated rats showed significantly upregulated expression of Tnfa and Il6, and the Arg1/Nos2 ratio was reduced compared to controls. However, small increases in anti-inflammatory genes Il10 and Tgfb1 were also observed. Depletion of circulating monocytes with clodronate liposomes prior to MEHP treatment reduced the macrophage influx into the testis, but did not lower GC apoptosis. Additionally, depletion of neutrophils using an anti-polymorphonuclear cell antibody prevented both macrophage and neutrophil infiltration into the testis, and also did not affect GC apoptosis. Together, these results show that exposure to MEHP leads to a rapid and temporary influx of pro-inflammatory monocytes and neutrophils in the interstitium of the testis. However, with this acute dosing paradigm, these infiltrating leukocytes do not appear to contribute to MEHP-induced testicular GC apoptosis leaving the functional significance of these infiltrating cells in the pathogenesis of MEHP-induced testicular injury unresolved.

Bisphenol A and Phthalates Modulate Peritoneal Macrophage Function in Female Mice Involving SYMD2-H3K36 Dimethylation

Ample evidence suggests that environmental and occupational exposure to bisphenol A (BPA) and phthalate, two chemicals widely used in the plastics industry, disturbs homeostasis of innate immunity and causes inflammatory diseases. However, the underlying molecular mechanisms of these toxicants in the regulation of macrophage inflammatory functions remain poorly understood. In this study, we addressed the effect of chronic exposure to BPA or phthalate at levels relevant to human exposure, either in vitro or in vivo, on the inflammatory reprograming of peritoneal macrophages. Our studies revealed that BPA and phthalates adversely affected expression levels of the proinflammatory cytokines and mediators in response to lipopolysaccharide stimulation. Exposure to these toxicants also affected gene expression of scavenger receptors and phagocytic capacity of peritoneal macrophages. Our studies revealed that the epigenetic inhibitors differentially modulated target gene expression in these cells. Further analysis revealed that certain histone modification enzymes were aberrantly expressed in response to BPA or phthalate exposure, leading to alteration in the levels of H3K36 acetylation and dimethylation, two chromatin modifications that are critical for transcriptional efficacy and accuracy. Our results further revealed that silencing of H3K36-specific methyltransferase Smyd2 expression or inhibition of SMYD2 enzymatic activity attenuated H3K36 dimethylation and enhanced interleukin-6 and tumor necrosis factor-α expression but dampened the phagocytic capacity of peritoneal macrophages. In summary, our results indicate that peritoneal macrophages are vulnerable to BPA or phthalate at levels relevant to human exposure. These environmental toxicants affect phenotypic programming of macrophages via epigenetic mechanisms involving SMYD2-mediated H3K36 modification.

Stromal fibroblasts present in breast carcinomas promote tumor growth and angiogenesis through adrenomedullin secretion

Tumor- or cancer-associated fibroblasts (TAFs or CAFs) are active players in tumorigenesis and exhibit distinct angiogenic and tumorigenic properties. Adrenomedullin (AM), a multifunctional peptide plays an important role in angiogenesis and tumor growth through its receptors calcitonin receptor-like receptor/receptor activity modifying protein-2 and -3 (CLR/RAMP2 and CLR/RAMP3). We show that AM and AM receptors mRNAs are highly expressed in CAFs prepared from invasive breast carcinoma when compared to normal fibroblasts. Immunostaining demonstrates the presence of immunoreactive AM and AM receptors in the CAFs (n = 9). The proliferation of CAFs is decreased by anti-AM antibody (αAM) and anti-AM receptors antibody (αAMR) treatment, suggesting that AM may function as a potent autocrine/paracrine growth factor. Systemic administration of αAMR reduced neovascularization of in vivo Matrigel plugs containing CAFs as demonstrated by reduced numbers of the vessel structures, suggesting that AM is one of the CAFs-derived factors responsible for endothelial cell-like and pericytes recruitment to built a neovascularization. We show that MCF-7 admixed with CAFs generated tumors of greater volume significantly different from the MCF-7 xenografts in nude mice due in part to the induced angiogenesis. αAMR and AM_22-52 therapies significantly suppressed the growth of CAFs/MCF-7 tumors. Histological examination of tumors treated with AM_22-52 and aAMR showed evidence of disruption of tumor vasculature with depletion of vascular endothelial cells, induced apoptosis and decrease of tumor cell proliferation. Our findings highlight the importance of CAFs-derived AM pathway in growth of breast carcinoma and in neovascularization by supplying and amplifying signals that are essential for pathologic angiogenesis.

Increased levels of phthalates in very low birth weight infants with septicemia and bronchopulmonary dysplasia

Very low birth weight infants (VLBW; birth weight<1500g) are exposed to potentially harmful phthalates from medical devices during their hospital stay. We measured urinary phthalate concentrations among hospitalized VLBW infants participating in a nutritional study. Possible associations between different phthalates and birth weight (BW), septicemia and bronchopulmonary dysplasia (BPD) were evaluated. Forty-six VLBW infants were enrolled in this randomized controlled nutritional study. The intervention group (n=24) received increased quantities of energy, protein, fat, essential fatty acids and vitamin A, as compared to the control group (n=22). The concentrations of 12 urinary phthalate metabolites were measured, using high-performance liquid chromatography coupled to tandem mass spectrometry, at 3 time points during the first 5weeks of life. During this study, the levels of di (2-ethylhexyl) phthalate (DEHP) metabolites decreased, whereas an increasing trend was seen regarding metabolites of di-iso-nonyl phthalate (DiNP). Significantly higher levels of phthalate metabolites were seen in infants with lower BW and those diagnosed with late onset septicemia or BPD. A significant positive correlation between the duration of respiratory support and DEHP metabolites was observed (p≤0.01) at 2.9weeks of age. Birth weight was negatively associated with urinary phthalate metabolite concentrations. Infants with lower BW and those diagnosed with septicemia or BPD experienced prolonged exposure from medical equipment containing phthalates, with subsequent higher levels of phthalate metabolites detected. Clinical Trial Registration no.: NCT01103219.

Urinary Phthalates and Leukocyte Telomere Length: An Analysis of NHANES 1999-2002

The International Agency for Research on Cancer classified the di-2-ethylhexyl phthalate (DEHP) as “possibly carcinogenic to humans”. In vitro studies reported that phthalate exposure resulted in induction of several nuclear transcription factors that are activators of telomerase reverse transcriptase (TERT) and telomerase activity of the human telomerase complex. The objective of this study was to determine whether there is an association between urinary phthalate metabolites [mono-ethyl phthalate (MEP), mono-butyl phthalate (MBP), mono-(2-ethyl)-hexyl phthalate (MEHP), and mono-benzyl phthalate (MBzP) and leukocyte telomere length (LTL) in the adult population of the National Health and Nutrition Examination Survey (NHANES) 1999–2002 (n = 2472). After adjustment for potential confounders, participants in the 3rd and 4th quartiles of urinary MEHP had statistically significantly longer LTL (5.34%, 95% CI: 1.31, 9.53; and 7.14%, 95% CI: 2.94, 11.63; respectively) compared to the lowest quartile, with evidence of a dose–response relationship (p-trend = 0.01). The association remained when the analyses were stratified by age groups (20–39 years, 40–59 years, and 60 years and older), and sex. Furthermore, MBP and MBzP were associated with higher LTL in older participants. The age independent association between longer LTL and MEHP (a metabolite of DEHP) might suggest a possible role of MEHP as tumor promoter.

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NHANES 1999–2002 analysis of phthalate metabolites (MEHP, MEP. MBP, and MBzP) and leukocyte telomere length (LTL)

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MEHP was associated with longer LTLs evidence of a dose–response relationship.

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Analyses stratified by age groups, sex and smoking confirmed the association of the MEHP with longer LTL.

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An association between MBP and MBzP with higher LTL was found in the 60 years and older participants.

Mono-(2-ethyl)-hexyl phthalate (MEHP) is a metabolite of di-2-ethylhexyl phthalate (DEHP) and recently the International Agency for Research on Cancer (IARC) classified DEHP as “possibly carcinogenic to humans” (Group 2B). Also, the National Toxicology Program list DEHP as “reasonably anticipated to be a human carcinogen.” The associations between MEHP and longer leukocyte telomere length (LTL) found in all age groups may potentially suggest a role of this compound as tumor promoter. However, further studies, such as prospective studies, are needed to more fully understand the implications of the findings of this study.

Mono-ethylhexyl phthalate stimulates prostaglandin secretion in human placental macrophages and THP-1 cells

BACKGROUND

Diethylhexyl phthalate (DEHP) is widely used as a plasticizer in polyvinyl chloride products. DEHP exposure, which is widespread in the US, increases preterm birth risk; however, the mechanisms driving this relationship are unclear. Because cyclooxygenase-2 (COX-2) dependent prostaglandin synthesis is implicated in preterm birth, we evaluated effects of mono-2-ethylhexyl phthalate (MEHP), the active metabolite of DEHP, on prostaglandin E2 (PGE2) synthesis and COX expression in human placental macrophages (PM). In addition, responses in PM were compared to those in a human macrophage-like cell line, THP-1.

METHODS

PM and THP-1 cells were treated for 2, 4, 8, or 24 h with MEHP concentrations ranging from 10 to 180 micromolar. PGE2 concentrations were assessed in culture medium using ELISA, and COX expression was determined by western blot.

RESULTS

Treatment of PM and THP-1 cells with 180 micromolar MEHP for 24 h significantly increased PGE2 release. Co-treatment of PMs or THP-1 cells with 180 micromolar MEHP and the non-selective COX inhibitor indomethacin reduced MEHP-stimulated PGE2 production. Similarly, co-treatment of PM and THP-1 cells with the COX-2 selective inhibitor NS-398 resulted in a significant decrease in PGE2, suggesting that MEHP-stimulated PGE2 is dependent specifically on increased COX-2 expression. Western blot analysis revealed a significant increase in COX-2 expression in PM and THP-1 cells treated with 180 micromolar MEHP, and no changes in COX-1 expression, supporting the role of COX-2 in MEHP-stimulated PGE2 synthesis.

CONCLUSIONS

The findings from this study are the first to demonstrate phthalate-stimulated PGE2 synthesis in PM and warrant future studies into COX-2-dependent prostaglandin synthesis as a mechanism of toxicant-associated preterm birth.

Prenatal and postnatal exposure to phthalate esters and asthma: a 9-year follow-up study of a taiwanese birth cohort

Previous studies have shown that phthalate exposure in childhood is associated with the development of respiratory problems. However, few studies have assessed the relative impact of prenatal and postnatal exposure to phthalates on the development of asthma later in childhood. Therefore, we assessed the impact of prenatal and postnatal phthalate exposure on the development of asthma and wheezing using a Taiwanese birth cohort. A total of 430 pregnant women were recruited, and 171 (39.8%) of them had their children followed when they were aged 2, 5, and 8 years. The International Study of Asthma and Allergies in Childhood questionnaire was used to assess asthma and wheezing symptoms and serum total immunoglobulin E levels were measured at 8 years of age. Urine samples were obtained from 136 women during their third trimester of pregnancy, 99 children at 2 years of age, and 110 children at 5 years. Four common phthalate monoester metabolites in maternal and children’s urine were measured using liquid chromatography-electrospray ionization-tandem mass spectrometry. Maternal urinary mono-benzyl phthalate [MBzP] concentrations were associated with an increased occurrence of wheezing in boys at 8 years of age (odds ratio [OR] = 4.95 (95% CI 1.08–22.63)), for upper quintile compared to the others) after controlling for parental allergies and family members' smoking status. Urinary mono-2-ethylhexyl phthalate [MEHP] levels over the quintile at 2-year-old were associated with increased asthma occurrence (adjusted OR = 6.14 (1.17–32.13)) in boys. Similarly, the sum of di-2-ethyl-hexyl phthalate [DEHP] metabolites at 5 years was associated with asthma in boys (adjusted OR = 4.36 (1.01–18.86)). Urinary MEHP in maternal and 5-year-old children urine were significantly associated with increased IgE in allergic children at 8 years. Prenatal and postnatal exposure to phthalate was associated with the occurrence of asthma in children, particularly for boys.

Influence of phthalates on cytokine production in monocytes and macrophages: a systematic review of experimental trials

Background

Phthalates are a group of endocrine disrupting chemicals suspected to influence the immune system. The aim of this systematic review is to summarise the present knowledge on the influence of phthalates on monocyte and macrophage production and secretion of cytokines, an influence which could affect both pro- and anti-inflammatory abilities of these cells.

Strategy and Results

A systematic search was performed in Medline, Embase and Toxline in June 2013, last updated 3rd of August 2014. Criteria used to select studies were described and published beforehand online on Prospero (http://www.crd.york.ac.uk/NIHR_PROSPERO, registration number CRD42013004236). In vivo, ex vivo and in vitro studies investigating the influence of phthalates on cytokine mRNA expression and cytokine secretion in animals and humans were included. A total of 11 reports, containing 12 studies, were found eligible for inclusion. In these, a total of four different phthalate diesters, six primary metabolites (phthalate monoesters) and seven different cytokines were investigated. Though all studies varied greatly in study design and species sources, four out of five studies that investigated di-2-ethylhexyl phthalate found an increased tumour necrosis factor-α secretion/production from monocytes or macrophages. A summary of cytokine measurements was not possible since few studies were comparable in study design and due to insufficient reporting of raw data for most of the included studies.

Conclusion

Results from this review have suggested that at least one phthalate (di-2-ethylhexyl phthalate) has the ability to enhance tumour necrosis factor-α production/secretion from monocytes/macrophages in vitro, but also observed ex vivo. Influence of other phthalates on other cytokines has only been investigated in few studies. Thus, in vitro studies on primary human monocytes/macrophages as well as more in vivo studies are needed to confirm or dispute these findings.

Effects of phthalate exposure on asthma may be mediated through alterations in DNA methylation

Background

Phthalates may increase the asthma risk in children. Mechanisms underlying this association remain to be addressed. This study assesses the effect of phthalate exposures on epigenetic changes and the role of epigenetic changes for asthma. In the first step, urine and blood samples from 256 children of the Childhood Environment and Allergic diseases Study (CEAS) were analyzed. Urine 5OH-MEHP levels were quantified as an indicator of exposure, and asthma information was collected. DNA methylation (DNA-M) was measured by quantitative PCR. In the screening part of step 1, DNA-M of 21 potential human candidate genes suggested by a toxicogenomic data were investigated in 22 blood samples. Then, in the testing part of step 1, positively screened genes were tested in a larger sample of 256 children and then validated by protein measurements. In step 2, we replicated the association between phthalate exposure and gene-specific DNA-M in 54 children in the phthalate contaminated food event. In step 3, the risk of DNA-M for asthma was tested in 256 children from CEAS and corroborated in 270 children from the Isle of Wight (IOW) birth cohort.

Results

Differential methylation in three genes (AR, TNFα, and IL-4) was identified through screening. Testing in 256 children showed that methylation of the TNFα gene promoter was lower when children had higher urine 5OH-MEHP values (β = −0.138, P = 0.040). Functional validation revealed that TNFα methylation was inversely correlated with TNFα protein levels (β = −0.18, P = 0.041). In an additional sample of 54 children, we corroborated that methylation of the TNFα gene promoter was lower when urine 5OH-MEHP concentrations were higher. Finally, we found that a lower methylation of 5′CGI region of TNFα was associated with asthma in 256 CEAS children (OR = 2.15, 95% CI = 1.01 to 4.62). We replicated this in 270 children from the IOW birth cohort study. Methylation of the CpG site cg10717214 was negatively associated with asthma, when children had ‘AA’ or ‘AG’ genotype of the TNFα single nucleotide rs1800610.

Conclusions

Effects of phthalate exposure on asthma may be mediated through alterations in DNA methylation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0060-x) contains supplementary material, which is available to authorized users.

Exposure to bisphenol A, but not phthalates, increases spontaneous diabetes type 1 development in NOD mice

Type 1 diabetes mellitus (T1DM) is an autoimmune destruction of insulin producing pancreatic beta-cells due to a genetic predisposition and can be triggered by environmental factors. We have previously shown that bisphenol A (BPA) accelerates the spontaneous development of diabetes in non-obese diabetic (NOD) mice. Here, we hypothesized that oral exposure to a mixture of the endocrine disruptors BPA and phthalates, relevant for human exposure, would accelerate diabetes development compared to BPA alone. NOD mice were exposed to BPA (1 mg/l), a mixture of phthalates (DEHP 1 mg/l, DBP 0.2 mg/l, BBP 10 mg/l and DiBP 20 mg/l) or a combination of BPA and the phthalate mixture through drinking water from conception and throughout life. Previous observations that BPA exposure increased the prevalence of diabetes and insulitis and decreased the number of tissue resident macrophages in pancreas were confirmed, and extended by demonstrating that BPA exposure also impaired the phagocytic activity of peritoneal macrophages. None of these effects were observed after phthalate exposure alone. The phthalate exposure in combination with BPA seemed to dampen the BPA effects on macrophage number and function as well as diabetes development, but not insulitis development. Exposure to BPA alone or in combination with phthalates decreased cytokine release (TNFα, IL-6, IL-10, IFNγ, IL-4) from in vitro stimulated splenocytes and lymph node cells, indicating systemic changes in immune function. In conclusion, exposure to BPA, but not to phthalates or mixed exposure to BPA and phthalates, accelerated diabetes development in NOD mice, apparently in part via systemic immune alterations including decreased macrophage function.

Home renovation, family history of atopy, and respiratory symptoms and asthma among children living in China

OBJECTIVES

To investigate the association of indoor air pollution with the respiratory health of children, we evaluated the associations of children's respiratory symptoms with asthma and recent home renovation.

METHODS

We conducted a cross-sectional survey in a school recruitment sample of 31,049 children aged 2 to 14 years in 25 districts of 7 cities of northeast China in 2008-2009. The children's parents completed standardized questionnaires characterizing the children's histories of respiratory symptoms and illness, recent home renovation information, and other associated risk factors.

RESULTS

The effects of home renovation in the past 2 years were significantly associated with cough, phlegm, current wheeze, doctor-diagnosed asthma, and current asthma. The associations we computed when combining the status of home renovation and family history of atopy were higher than were those predicted from the combination of the separate effects. However, the interactions between home renovation and family history of atopy on a multiplicative scale were not statistically significant (P>.05).

CONCLUSIONS

Home renovation is associated with increases in the prevalence of respiratory symptoms and asthma in children. The effects of different renovation materials on child respiratory health should be studied further.

Age- and species-dependent infiltration of macrophages into the testis of rats and mice exposed to mono-(2-Ethylhexyl) phthalate (MEHP)

The mechanism by which noninfectious testicular inflammation results in infertility is poorly understood. Here the infiltration of CD11b+ immunoreactive testicular interstitial cells (neutrophil, macrophages, dendritic cells) in immature (Postnatal Day [PND] 21, 28, and 35) and adult (PND 56) Fischer rats is described at 12, 24, and 48 h after an oral dose of 1 g/kg mono-(2-ethylhexyl) phthalate (MEHP), a well-described Sertoli cell toxicant. Increases of CD11b+ cells are evident 12 h after MEHP exposure in PND 21 and 28 rats. In PND 28 rats, CD11b+ cells remained significantly elevated at 48 h, while in PND 21 rats, it returned to control levels by 24 h. The peak number of CD11b+ cells in PND 35 rat testis is delayed until 24 h, but remains significantly elevated at 48 h. In PND 56 rats, no increase in CD11b+ cells occurs after MEHP exposure. In PND 21, 28, and 35 rats, a significant increase in monocyte chemoattractant protein-1 (MCP-1) by peritubular myoid cells occurs 12 h after MEHP. Interestingly, MEHP treatment of C57BL/6J mice did not incite an infiltration of CD11b+ cells at either PND 21 or 28. The peak level of germ cell apoptosis observed 24 h after MEHP exposure in young rats is not seen in mice at any age or in PND 56 rats. Taken together, these findings implicate MCP-1 released by peritubular myoid cells in provoking the migration of CD11b+ cells into the immature rat testis early after MEHP exposure and point to a role for CD11b+ cells in triggering germ cell apoptosis in an age- and species-dependent manner.