Gene expression profiling of DEHP-treated cardiomyocytes reveals potential causes of phthalate arrhythmogenicity

The mitochondrial link: Phthalate exposure and cardiovascular disease

Phthalates' pervasive presence in everyday life poses concern as they have been revealed to induce perturbing health defects. Utilized as a plasticizer, phthalates are riddled throughout many common consumer products including personal care products, food packaging, home furnishings, and medical supplies. Phthalates permeate into the environment by leaching out of these products which can subsequently be taken up by the human body. It is previously established that a connection exists between phthalate exposure and cardiovascular disease (CVD) development; however, the specific mitochondrial link in this scenario has not yet been described. Prior studies have indicated that one possible mechanism for how phthalates exert their effects is through mitochondrial dysfunction. By disturbing mitochondrial structure, function, and signaling, phthalates can contribute to the development of the foremost cause of death worldwide, CVD. This review will examine the potential link among phthalates and their effects on the mitochondria, permissive of CVD development.

Mono-2-ethylhexylphthalate (MEHP) is a potent agonist of human TRPA1 channel

Phthalates are extensively used as plasticizers in diverse consumer care products but have been reported to cause adverse health effects in humans. A commonly used phthalate, di-2-ethylhexylphthalate (DEHP) causes developmental and reproductive toxicities in humans, but the associated molecular mechanisms are not fully understood. Mono-2-ethylhexylphthalate (MEHP), a hydrolytic product of DEHP generated by cellular esterases, is proposed to be the active toxicant. We conducted a screen for sensory irritants among compounds used in consumer care using an assay for human Transient Receptor Potential A1 (hTRPA1). We have identified MEHP as a potent agonist of hTRPA1. MEHP-induced hTRPA1 activation was blocked by the TRPA1 inhibitor A-967079. Patch clamp assays revealed that MEHP induced inward currents in cells expressing hTRPA1. In addition, the N855S mutation in hTRPA1 associated with familial episodic pain syndrome decreased MEHP-induced hTRPA1 activation. In summary, we report that MEHP is a potent agonist of hTRPA1 which generates new possible mechanisms for toxic effects of phthalates in humans.

Evidence for the cardiodepressive effects of the plasticizer di-2-ethylhexyl phthalate

Di-2-ethylhexyl phthalate (DEHP) is commonly used in the manufacturing of plastic materials, including intravenous bags, blood storage bags, and medical-grade tubing. DEHP can leach from plastic medical products, which can result in inadvertent patient exposure. DEHP concentrations were measured in red blood cell units stored between 7 and 42 days (17-119 μg/ml). Using these concentrations as a guide, Langendorff-perfused rat heart preparations were acutely exposed to DEHP. Sinus activity remained stable with lower doses of DEHP (25-50 μg/ml), but sinus rate declined by 43% and sinus node recovery time (SNRT) prolonged by 56.5% following 30-min exposure to 100 μg/ml DEHP. DEHP exposure also exerted a negative dromotropic response, as indicated by a 69.4% longer PR interval, 108.5% longer Wenckebach cycle length (WBCL), and increased incidence of atrioventricular (AV) uncoupling (60-min exposure). Pretreatment with doxycycline partially rescued the effects of DEHP on sinus activity, but did not ameliorate the effects on AV conduction. DEHP exposure also prolonged the ventricular action potential and effective refractory period, but had no measurable effect on intracellular calcium transient duration. Follow-up studies using human-induced pluripotent stem cell-derived cardiomyocytes confirmed that DEHP slows electrical conduction in a time (15 min-3 h) and dose-dependent manner (10-100 μg/ml). Previous studies have suggested that phthalate toxicity is specifically attributed to metabolites of DEHP, including mono-2-ethylhexylphthalate. This study demonstrates that DEHP exposure also contributes to cardiac dysfunction in a dose- and time-dependent manner. Future work is warranted to investigate the impact of DEHP (and its metabolites) on human health, with special consideration for clinical procedures that employ plastic materials.

Adverse cardiovascular effects of long-term exposure to diethyl phthalate in the rat aorta

Phthalates are classified as priority environmental pollutants, since they are ubiquitous in the environment, have endocrine disrupting properties and can contribute to impaired health. Used primarily in personal care products and excipients for pharmaceuticals, diethyl phthalate (DEP) is a short-chain alkyl phthalate that has been linked to decreased blood pressure, glucose tolerance, and increased gestational weight gain in humans, while in animals it has been associated with atherosclerosis and metabolic syndrome. Although all these findings are related to risk factors or cardiovascular diseases, DEP's vascular impacts still need to be clarified. Thus, performing ex vivo and in vitro experiments, we aimed to understand the vascular DEP effects in rat. To evaluate the vascular contractility of rat aorta exposed to different doses of DEP (0.001-1000 μM), an organs bath was used; and resorting to a cell line of the rat aorta vascular smooth muscle, electrophysiology experiments were performed to analyse the effects of a rapid (within minutes with no genomic effects) and a long-term (24 h with genomic effects) exposure of DEP on the L-type Ca2+ current (ICa,L), and the expression of several genes related with the vascular function. For the first time, vascular electrophysiological properties of an EDC were analysed after a long-term genomic exposure. The results show a hormetic response of DEP, inducing a Ca2+ current inhibition of the rat aorta, which may be responsible for impaired cardiovascular electrical health. Thus, these findings contribute to a greater scientific knowledge about DEP's effects in the cardiovascular system, specifically its implications in the development of electrical disturbances like arrhythmias and its possible mechanisms.

Evidence for the cardiodepressive effects of the plasticizer di-2-ethylhexylphthalate (DEHP)

Di-2-ethylhexylphthalate (DEHP) is commonly used in the manufacturing of plastic materials, including intravenous bags, blood storage bags, and medical-grade tubing. DEHP can leach from plastic medical products, which can result in inadvertent patient exposure. DEHP concentrations were measured in red blood cell (RBC) units stored between 7-42 days (23-119 μg/mL). Using these concentrations as a guide, Langendorff-perfused rat heart preparations were acutely exposed to DEHP. Sinus activity remained stable with lower doses of DEHP (25-50 μg/mL), but sinus rate declined by 43% and sinus node recovery time prolonged by 56.5% following 30-minute exposure to 100 μg/ml DEHP. DEHP exposure also exerted a negative dromotropic response, as indicated by a 69.4% longer PR interval, 108.5% longer Wenckebach cycle length, and increased incidence of atrioventricular uncoupling. Pretreatment with doxycycline partially rescued the effects of DEHP on sinus activity, but did not ameliorate the effects on atrioventricular conduction. DEHP exposure also prolonged the ventricular action potential and effective refractory period, but had no measurable effect on intracellular calcium transient duration. Follow-up studies using hiPSC-CM confirmed that DEHP slows electrical conduction in a time (15 min - 3 hours) and dose-dependent manner (10-100 μg/mL). Previous studies have suggested that phthalate toxicity is specifically attributed to metabolites of DEHP, including mono-2-ethylhexyl phthalate (MEHP). This study demonstrates that DEHP exposure also contributes to cardiac dysfunction in a dose- and time-dependent manner. Future work is warranted to investigate the impact of DEHP (and its metabolites) on human health, with special consideration for clinical procedures that employ plastic materials.

Granulocyte-colony stimulating factor ameliorates di-ethylhexyl phthalate-induced cardiac muscle injury via stem cells recruitment, Desmin protein regulation, antifibrotic and antiapoptotic mechanisms

Phthalates are common plasticizers present in medical-grade plastics and other everyday products. Di-ethylhexyl phthalate (DEHP) has been noted as a causative risk factor for the initiation and augmentation of cardiovascular functional disorders. G-CSF is a glycoprotein found in numerous tissues throughout the body and is currently applied in clinical practice and has been tested in congestive heart failure. We aimed to examine in depth the effect of DEHP on the histological and biochemical structure of the cardiac muscle in adult male albino rats and the mechanisms underlying the possible ameliorative effect of G-CSF. Forty-eight adult male albino rats were divided into control group, DEHP group, DEHP+ G-CSF group and DEHP-recovery group. We measured serum levels of aspartate aminotransferase (AST), creatine kinase MB isoenzyme (CK-MB) and lactate dehydrogenase (LDH). Left ventricular sections were processed for light and electron microscope examination, and immunohistochemical staining of Desmin, activated Caspase-3 and CD34. DEHP significantly increased enzyme levels, markedly distorted the normal architecture of cardiac muscle fibers, downregulated Desmin protein levels and enhanced fibrosis, and apoptosis. G-CSF treatment significantly decreased the enzyme levels compared to DEHP group. It enhanced CD34 positive stem cells recruitment to injured cardiac muscle, therefore improved the ultrastructural features of most cardiac muscle fibers via anti-fibrotic and anti-apoptotic effects in addition to increased Desmin protein expression levels. The recovery group showed partial improvement due to persistent DEHP effect. In conclusion, administration of G-CSF effectively corrected the histopathological, immunohistochemical and biochemical alterations in the cardiac muscle after DEHP administration by stem cells recruitment, Desmin protein regulation, antifibrotic and antiapoptotic mechanisms.

Phthalates' exposure leads to an increasing concern on cardiovascular health

Being an essential component in the plastics industry, phthalates are ubiquitous in the environment and in everyday life. They are considered environmental contaminants that have been classified as endocrine-disrupting compounds. Despite di-2-ethylhexyl phthalate (DEHP) being the most common plasticizer and the most studied to date, there are many others that, in addition to being widely used in the plastic, are also applied in the medical and pharmaceutical industries and cosmetics. Due to their wide use, phthalates are easily absorbed by the human body where they can disrupt the endocrine system by binding to molecular targets and interfering with hormonal homeostasis. Thus, phthalates exposure has been implicated in the development of several diseases in different age groups. Collecting information from the most recent available literature, this review aims to relate human phthalates' exposure with the development of cardiovascular diseases throughout all ages. Overall, most of the studies presented demonstrated an association between phthalates and several cardiovascular diseases, either from prenatal or postnatal exposure, affecting foetuses, infants, children, young and older adults. However, the mechanisms underlying these effects remain poorly explored. Thus, considering the cardiovascular diseases incidence worldwide and the constant human exposure to phthalates, this topic should be extensively studied to understand the mechanisms involved.

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

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

Association of phthalate exposure with all-cause and cause-specific mortality among people with hypertension: The U.S. National Health and Nutrition Examination Survey, 2003-2014

There is growing evidence that phthalate exposure results in a deteriorated effect on human health, while very few studies directly investigate the relationship of phthalate metabolites with mortality among people with hypertension. We aimed to explore whether exposure to phthalates is associated with all-cause and cause-specific mortality among people with hypertension. This study included 4012 people with hypertension from the National Health and Nutrition Examination Survey from 2003 to 2014. Death information was obtained from the National Death Index until 2015. A total of 577 deaths including 196 deaths due to cardiovascular disease (CVD) and 119 deaths due to cancer were documented. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). After adjustment for potential covariates, participants exposed to mono-ethyl phthalate (MEP) had a higher risk of cancer mortality (HR, 2.06; 95% CI, 1.07-3.95). Participants exposed to mono-n-butyl phthalate (MnBP) had higher risks of all-cause (HR, 1.83; 95% CI, 1.28-2.60), CVD (HR, 2.19; 95% CI, 1.21-3.95), and cancer (HR, 2.35; 95% CI, 1.07-5.17) mortality. Participants exposed to mono-benzyl phthalate (MBzP) had higher risks of all-cause (HR, 2.19; 95% CI, 1.58-3.05) and CVD (HR, 2.36; 95% CI, 1.35-4.13) mortality. Participants exposed to di-2-ethylhexylphthalate (DEHP) had a higher risk of all-cause mortality (HR, 1.69; 95% CI, 1.19-2.39). Our findings suggested that higher levels of specific phthalates were significantly associated with increased risks of all-cause, CVD, and cancer mortality among people with hypertension. Further studies are needed to confirm these findings and identify the underlying mechanisms.

DEHP-induced mitophagy and mitochondrial damage in the heart are associated with dysregulated mitochondrial biogenesis

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in agricultural and industrial plastic products. Many researchers have demonstrated that DEHP can cause varying degrees of harm to the heart. This research investigated the mechanism by which DEHP causes heart damage in quail. The quail were treated with DEHP (250 mg/kg BW/day, 500 mg/kg BW/day or 750 mg/kg BW/day) for 45 days. The present study suggested that DEHP could cause varying levels of heart damage, including disordered myocardial fiber arrangements, myocardial fiber breakage and myocardial cell swelling. The results showed that DEHP induced mitochondrial damage, such as cavitation lesions and mitochondrial crest breakage. DEHP damaged mitochondria and inhibited nuclear respiratory factor 1 (Nrf1)-mediated mitochondrial biogenesis, which led to mitochondrial damage. DEHP caused oxidative stress in the heart and activated the defense mechanism of the nuclear factor red blood cell 2 related factor 2 (Nrf2) system. DEHP-induced mitophagy was related to a decline in mitochondrial biogenesis and disordered mitochondrial dynamics. The data indicated that DEHP exposure damaged cardiac mitochondria and caused mitophagy and cardiotoxicity. Of note, this study showed that DEHP-induced mitophagy and mitochondrial damage are associated with the dysregulation of mitochondrial biogenesis.

Phthalates and attributable mortality: A population-based longitudinal cohort study and cost analysis

CONTEXT

Accelerating evidence of endocrine-related morbidity has raised alarm about the ubiquitous use of phthalates in the human environment, but studies have not directly evaluated mortality in relation to these exposures.

OBJECTIVES

To evaluate associations of phthalate exposure with mortality, and quantify attributable mortality and lost economic productivity in 2013-4 among 55-64 year olds.

DESIGN

This nationally representative cohort study included 5303 adults aged 20 years or older who participated in the US National Health and Nutrition Examination Survey 2001-2010 and provided urine samples for phthalate metabolite measurements. Participants were linked to mortality data from survey date through December 31, 2015. Data analyses were conducted in July 2020.

MAIN OUTCOME MEASURES

Mortality from all causes, cardiovascular disease, and cancer.

RESULTS

Multivariable models identified increased mortality in relation to high-molecular weight (HMW) phthalate metabolites, especially those of di-2-ethylhexylphthalate (DEHP). Hazard ratios (HR) for continuous HMW and DEHP metabolites were 1.14 (95% CI 1.06-1.23) and 1.10 (95% CI 1.03-1.19), respectively, with consistently higher mortality in the third tertile (1.48, 95% CI 1.19-1.86; and 1.42, 95% CI 1.13-1.78). Cardiovascular mortality was significantly increased in relation to a prominent DEHP metabolite, mono-(2-ethyl-5-oxohexyl)phthalate. Extrapolating to the population of 55-64 year old Americans, we identified 90,761-107,283 attributable deaths and $39.9-47.1 billion in lost economic productivity.

CONCLUSIONS

In a nationally representative sample, phthalate exposures were associated with all-cause and cardiovascular mortality, with societal costs approximating $39 billion/year or more. While further studies are needed to corroborate observations and identify mechanisms, regulatory action is urgently needed.

Association between Levels of Urine Di-(2-ethylhexyl)phthalate Metabolites and Heart Rate Variability in Young Adults

Phthalate exposure is associated with cardiovascular risk. Among the various phthalates, di-(2-ethylhexyl) phthalate (DEHP) is a deleterious plasticizer in our daily lives. This study investigated the association between DEHP exposure and the alteration of heart rate variability (HRV). During 2017–2019, we recruited 974 young adults to investigate the effects of living environments and dietary habits on cardiometabolic disorders in Taiwan. We quantitatively analyzed urinary metabolites of DHEP. A continuous electrocardiogram was recorded to obtain a 5-min ECG. Time-domain and frequency-domain HRV analyses were performed. Multiple linear regression showed that urinary oxidized DEHP metabolites MEHHP and MEOHP were associated with decreased HRV after controlling for associated cardiovascular risk factors. A higher MEHHP level was associated with a lower triangular interpolation of NN interval histogram (TINN), very low frequency (VLF), and low frequency/high frequency (LF/HF) ratio. A higher MEOHP level was associated with a decreased LF/HF ratio. In addition, trend analysis showed that higher MEHHP and MEOHP quantiles were significantly associated with a decreased LF/HF ratio. DEHP is a potentially harmful and invisible chemical. The urinary DEHP metabolites MEHHP and MEOHP are associated with decreased HRV, indicating an adverse effect on autonomic balance in young adults in Taiwan.

Association of urinary phthalate metabolites with cardiovascular disease among the general adult population

OBJECTIVE

This study aims to explore the relationship between urinary phthalate metabolites and total and specific cardiovascular disease (CVD) among the general adult population.

METHODS

This cross-sectional study analyzed 11 urinary phthalates in the general population from the 2005-2016 National Health and Nutrition Examination Survey (NHANES) (n = 10,427). Multivariate logistic regression and weighted quantile sum (WQS) regression were applied to examine the relationship between phthalate metabolites and mixtures and the prevalence rates of total and specific CVD.

RESULTS

Compared to the lowest quartile, mono-isobutyl phthalate (MiBP) (OR 1.37; 95% CI 1.03-1.83, P for trend = 0.032) and mono-benzyl phthalate (MBzP) (OR 1.44; 95% CI 1.10-1.88, P for trend = 0.013) in the highest quartile were independently associated with increased total CVD. The WQS index of phthalate mixtures was independently correlated with total CVD (adjusted OR 1.17; 95% CI 1.01-1.36, P = 0.039), and MBzP (weight = 0.392) was the most heavily weighted component. In addition, restricted cubic spline regression demonstrated that the MBzP level had a positive correlation and linear association with total CVD (P for nonlinearity = 0.182).

CONCLUSIONS

Our findings suggest that high phthalate mixture levels are associated with an increased prevalence of CVD, with the greatest influence coming from MBzP.

Chronic perinatal hypoxia delays cardiac maturation in a mouse model for cyanotic congenital heart disease

Compared with acyanotic congenital heart disease (CHD), cyanotic CHD has an increased risk of lifelong mortality and morbidity. These adverse outcomes may be attributed to delayed cardiomyocyte maturation, since the transition from a hypoxic fetal milieu to oxygen-rich postnatal environment is disrupted. We established a rodent model to replicate hypoxic myocardial conditions spanning perinatal development, and tested the hypothesis that chronic hypoxia impairs cardiac development. Pregnant mice were housed in hypoxia beginning at embryonic day 16. Pups stayed in hypoxia until postnatal day (P)8 when cardiac development is nearly complete. Global gene expression was quantified at P8 and at P30, after recovering in normoxia. Phenotypic testing included electrocardiogram, echocardiogram, and ex vivo electrophysiology study. Hypoxic P8 animals were 47% smaller than controls with preserved heart size. Gene expression was grossly altered by hypoxia at P8 (1,427 genes affected), but normalized after recovery (P30). Electrocardiograms revealed bradycardia and slowed conduction velocity in hypoxic animals at P8, with noticeable resolution after recovery (P30). Notable differences that persisted after recovery (P30) included a 65% prolongation in ventricular effective refractory period, sinus node dysfunction, 23% reduction in ejection fraction, and 16% reduction in fractional shortening in animals exposed to hypoxia. We investigated the impact of chronic hypoxia on the developing heart. Perinatal hypoxia was associated with changes in gene expression and cardiac function. Persistent changes to the electrophysiological substrate and contractile function warrant further investigation and may contribute to adverse outcomes observed in the cyanotic CHD population.NEW & NOTEWORTHY We utilized a new mouse model of chronic perinatal hypoxia to simulate the hypoxic myocardial conditions present in cyanotic congenital heart disease. Hypoxia caused numerous abnormalities in cardiomyocyte gene expression, the electrophysiologic substrate of the heart, and contractile function. Taken together, alterations observed in the neonatal period suggest delayed cardiac development immediately following hypoxia.

Di(2-ethylhexyl) adipate plasticizer triggers hepatic, brain, and cardiac injury in rats: Mitigating effect of Peganum harmala oil

Di(2-ethylhexyl) adipate (DEHA) is a widely used plasticizer and prevalent environmental contaminant. In this study, DEHA concentrations in the milk, cheese, and butter samples wrapped with food-grade commercial polyethylene films and stored at 4 °C for 30 days were detected using gas chromatographic analysis. Also, the effects of exposure to a high dose of DEHA for a long duration on the liver, brain, and heart of Wistar rats were assessed. Besides, the possible beneficial effect of Peganum harmala oil (PGO), in relieving DEHA induced adverse effects was explored. For this purpose, four groups (8 rats/group) were orally given physiological saline, PGO (320 mg/kg bwt), DEHA (2000 mg/kg bwt), or PGO + DEHA for 60 days. The results revealed that the DEHA concentrations in the tested dairy products were ordered as follows: (butter > cheese > milk). Notably, the detected levels in butter were higher than the specific migration limit in foods. DEHA induced a significant increase in the serum levels of glucose, alanine transaminase, aspartate transaminase, acetylcholine esterase, creatine kinase-myocardium bound, malondialdehyde, tumor necrosis factor-α, and interleukin-1β. But, significant hypoproteinemia, hypoalbuminemia, hypoglobulinemia, and hypocholesterolemia were evident following DEHA exposure. A significant reduction in the serum level of superoxide dismutase, reduced glutathione, and brain-derived neurotrophic factor was recorded. Besides, a significant downregulation in hepatic CYP2E1, brain glial fibrillary acidic protein, and cardiac troponin I gene expression was noticed. Moreover, DEHA exposure induced a significant decrease in Bcl-2 immunolabeling, but Caspase-3 immunoexpression was increased. On the contrary, PGO significantly recused DEHA injurious impacts. Therefore, PGO could represent a promising agent for preventing DEHA-induced hepatotoxicity, neurotoxicity, and cardiotoxicity.

Activation of forkhead box O3a by mono(2-ethylhexyl)phthalate and its role in protection against mono(2-ethylhexyl)phthalate-induced oxidative stress and apoptosis in human cardiomyocytes

Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of di(2-ethylhexyl)phthalate (DEHP), is known to exert cardiotoxicity. The aim of the present study was to investigate the role of forkhead box O3a (FOXO3a) in MEHP-induced human AC16 cardiomyocyte injuries. MEHP reduced cell viability and mitochondrial membrane potential (ΔΨm), whereas it increased lactate dehydrogenase (LDH) leakage, production of reactive oxygen species (ROS), and apoptosis in cardiomyocytes. The expression of FOXO3a and its target genes, mitochondrial superoxide dismutase (Mn-SOD) and apoptosis repressor with caspase recruitment domain (ARC), increased after MEHP exposure, but the expression of p-FOXO3a protein was decreased. Overexpression of FOXO3a decreased the production of ROS and the apoptosis rate induced by MEHP, and the expression of Mn-SOD and ARC was further increased after MEHP exposure. In contrast, knockdown of FOXO3a resulted in increased ROS production and apoptosis and suppressed the expression of Mn-SOD and ARC in the presence of MEHP. However, overexpression or knockdown of FOXO3a did not affect MEHP-induced loss of ΔΨm. In conclusion, the loss of ΔΨm and apoptosis are involved in MEHP-induced cardiomyocyte toxicity. Activation of FOXO3a defends against MEHP-induced oxidative stress and apoptosis by upregulating the expression of Mn-SOD and ARC in AC16 cardiomyocytes.

A multi-omics approach reveals molecular mechanisms by which phthalates induce cardiac defects in zebrafish (Danio rerio)

The potential risks of phthalates affecting human and animal health as well as the environment are emerging as serious concerns worldwide. However, the mechanism by which phthalates induce developmental effects is under debate. Herein, we found that embryonic exposure of zebrafish to di-(2-ethylhexyl) phthalate (DEHP) and di-butyl phthalate (DBP) increased the rate of heart defects including abnormal heart rate and pericardial edema. Changes in the transcriptional profile demonstrated that genes involved in the development of the heart, such as tbx5b, nppa, ctnt, my17, cmlc1, were significantly altered by DEHP and DBP at 50 μg/L, which agreed with the abnormal cardiac outcomes. Methylated DNA immunoprecipitation sequencing (MeDIP-Seq) further showed that significant hypomethylation of nppa and ctnt was identified after DEHP and DBP exposure, which was consistent with the up-regulation of these genes. Notably, hypermethylation on the promoter region (<1 kb) of tbx5b was found after DEHP and DBP exposure, which might be responsible for its decrease in transcription. In conclusion, phthalates have the potential to induce cardiac birth defects, which might be associated with the transcriptional regulation of the involved developmental factors such as tbx5b. These findings would contribute to understand the molecular pathways that mediated the cardiac defects caused by phthalates.

Phthalates Implications in the Cardiovascular System

Today’s sedentary lifestyle and eating habits have been implicated as some of the causes of the increased incidence of several diseases, including cancer and cardiovascular diseases. However, environmental pollutants have also been identified as another possible cause for this increase in recent decades. The constant human exposure to plastics has been raising attention regarding human health, particularly when it comes to phthalates. These are plasticizers used in the manufacture of industrial and consumer products, such as PVC (Polyvinyl Chloride) plastics and personal care products, with endocrine-disrupting properties, as they can bind molecular targets in the body and interfere with hormonal function. Since these compounds are not covalently bound to the plastic, they are easily released into the environment during their manufacture, use, or disposal, leading to increased human exposure and enhancing health risks. In fact, some studies have related phthalate exposure with cardiovascular health, having already shown a positive association with the development of hypertension and atherosclerosis in adults and some cardiometabolic risk factors in children and adolescents. Therefore, the main purpose of this review is to present and relate the most recent studies concerning the implications of phthalates effects on the cardiovascular system.

Bisphenols and phthalates: Plastic chemical exposures can contribute to adverse cardiovascular health outcomes

Phthalates and bisphenols are high production volume chemicals that are used in the manufacturing of consumer and medical products. Given the ubiquity of bisphenol and phthalate chemicals in the environment, biomonitoring studies routinely detect these chemicals in 75-90% of the general population. Accumulating evidence suggests that such chemical exposures may influence human health outcomes, including cardiovascular health. These associations are particularly worrisome for sensitive populations, including fetal, infant and pediatric groups-with underdeveloped metabolic capabilities and developing organ systems. In the presented article, we aimed to review the literature on environmental and clinical exposures to bisphenols and phthalates, highlight experimental work that suggests that these chemicals may exert a negative influence on cardiovascular health, and emphasize areas of concern that relate to vulnerable pediatric groups. Gaps in our current knowledge are also discussed, so that future endeavors may resolve the relationship between chemical exposures and the impact on pediatric cardiovascular physiology.

TGF-β1 relieves epithelial-mesenchymal transition reduction in hypospadias induced by DEHP in rats

BACKGROUNDS

To investigate the potential mechanism of hypospadias induced by DEHP in rats to reveal the preventative effect of TGF-β1 in hypospadias induced by DEHP via the reduction of EMT.

METHODS

Time-mated Sprague-Dawley rats underwent cesarean section, and the penises of male pups were collected after exposure to corn oil or DEHP to establish a rat model of hypospadias and to further study the molecular mechanisms of hypospadias in vivo. In addition, the penises were cultured and treated with MEHP or MEHP+TGF-β1 in vitro. Subsequently, histomorphology and elements in TGF-β/Smad signaling pathway changes were evaluated using scanning electron microscopy, immunofluorescence, polymerase chain reaction, and western blot.

RESULTS

The development of rat penis and urethral seam fusion were delayed after the treatment with DEHP in vivo or MEHP in vitro compared with the Control group. Moreover, TGF-β1, Smad2/Smad3, and the mesenchymal biomarkers, including α-SMA, N-cadherin, and Vimentin, were decreased. However, the epithelial biomarkers, including E-cadherin, ZO-1, β-catenin, and occludin, were increased. In addition, TGF-β1 could relieve all of the above changes.

CONCLUSION

Gestational DEHP exposure could lead to hypospadias by reducing urethral EMT. Moreover, TGF-β1 could prevent it by regenerating EMT through activating the TGF-β/Smad signal pathway.

Di-(2-ethylhexyl) phthalate induced an increase in blood pressure via activation of ACE and inhibition of the bradykinin-NO pathway

Epidemiological studies and animal experiments have suggested that exposure to Di-(2-ethylhexyl) phthalate (DEHP) is strongly associated with an increase in blood pressure. However, the mechanisms that result in the detrimental effects of DEHP exposure on blood pressure are unclear. In our study, mice were orally exposed to DEHP dosages of 0.1, 1, 10 mg/kg/day for 6 weeks. The results showed that DEHP could induce a significant increase in systolic blood pressure (SBP) and heart rate, and a significant thickening of the ventricular wall. To explore the underlying mechanism, we measured the level of: angiotensin converting enzyme (ACE); bradykinin B2 receptor (BK2R); endothelial nitric oxide synthase (eNOS); bradykinin and Ca²⁺ in cardiac cytoplasm as well as in serum nitric oxide (NO). The results suggested that DEHP could induce an increase in ACE levels, and a decrease in bradykinin levels. Moreover, BK2R, Ca²⁺, eNOS and NO decreased when mice were exposed to 10 mg/kg/day DEHP. Interestingly, 5 mg/kg/day angiotensin converting enzyme inhibitor (ACEI) treatment inhibited the increase in blood pressure, and inhibited the decrease in the levels of BK2R, Ca²⁺, eNOS, and NO, that were induced by DEHP exposure. Our results suggest that DEHP might increase blood pressure by activating ACE expression, and inhibiting the bradykinin-NO pathway.

Di (2-ethylhexyl) phthalate induces cardiac disorders in BALB/c mice

Because of the extensive use of phthalates for domestic, medical, and industrial applications, the evaluation of their toxic effects is of major concern to public health. The aim of the present study was to assess the propensity of di (2-ethylhexyl) phthalate (DEHP), one of the most used phthalates, to cause oxidative cardiac damage in mice. DEHP was administered intraperitoneally at doses of 5, 50, and 200 mg/kg body weight for 30 consecutive days in BALB/c mice. We assessed the effect of DEHP on cardiac injury using biochemical profile (such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatinine phosphokinase (CPK), total cholesterol (T-CHOL), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)), parameters related to myocardiac oxidative stress, such as malondialdehyde (MDA) level, protein carbonyl (PC) concentration, and DNA fragmentation. In addition, we evaluated antioxidant status; enzymatic (catalase (CAT) and superoxide dismutase (SOD) activities) and non-enzymatic (protein-bound sulfhydryl concentration (PSH)) antioxidants. Acetylcholinesterase (AChE) activity and histopathological changes were also assessed in heart mice treated with DEHP. Our results showed that DEHP induced an elevation of serum marker enzymes and perturbated the lipid profile. In addition, this phthalate increased lipid peroxidation, protein carbonyl levels, and DNA fragmentation in the heart in a dose-dependent manner. Antioxidant status was also perturbated by the increase of the CAT and SOD activities and the decrease of the protein-bound sulfhydryl concentration. AChE activity was also inhibited in the heart following the treatment with DEHP. These biochemical alterations were also confirmed by histopathological changes. Increased free radical production at various doses of DEHP would result in impairment of the redox status leading to an enhanced dose-dependent cardiotoxicity.

Cardiovascular Response of Rat Aorta to Di-(2-ethylhexyl) Phthalate (DEHP) Exposure

Phthalates are one of the main constituents of plastic, reaching up to 40% of the total plastic weight, and their main function is to impart flexibility/elasticity to polymers that would otherwise be rigid. Phthalates are known as endocrine disruptors, since they can interfere with hormone homeostasis. Regarding the cardiovascular system, it was already shown the effects of di-(2-ethylhexyl) phthalate (DEHP) exposure with significant changes in several calcium-handling proteins and an increase in the blood pressure of mice offspring, suggesting that DEHP leads to vasocontraction. However, the mechanisms involved were not elucidated yet. The aim of this study is to analyse the involvement of calcium channels in the effects induced by DEHP on vascular smooth muscle cells. Endothelium-denuded aorta artery rings were prepared from male Wistar rats and incubated in an organ bath, and the whole-cell configuration of Patch Clamp technique was used to measure the activity of L-type Ca²⁺ channels (LTCC) in A7r5 cells. Overall, DEHP caused relaxation on KCl-induced contraction at higher concentrations and inhibited the basal and BAY K8644-stimulated calcium current, indicating that this drug blocks LTCC. These results suggest that DEHP induces relaxation on vascular smooth muscle cells due to the inhibition of calcium channels.

Modulation of heat-shock response is associated with Di (2-ethylhexyl) phthalate (DEHP)-induced cardiotoxicity in quail (Coturnix japonica)

Di(2-ethylhexyl) phthalate (DEHP) is an omnipresent environmental pollutant with endocrine disrupting properties. As a plasticizer, DEHP can be leach from the plastic to transfer the external environment and thus enters the animal food chain, causing serious damage to the animal organs. The heat-shock response (HSR) comprising heat-shock protein (HSPs) and heat-shock transcription factor (HSFs) plays a pivotal role in various toxic stress conditions. For the sake of investigating the effects of DEHP exposure on cardiac toxicity and the regulation of HSR, male quail were fed the diet with 0, 250, 500 and 750 mg/kg DEHP by gavage administration for 45 days. Histopathological changes including cardiomyocyte swelling and muscle fiber dilatation were observed in the hearts exposed to DEHP. During the DEHP treatment, the mRNA expression of HSP60 and HSP70 were universally reduced, while the expression of other HSPs (HSP10, HSP25, HSP27, HSP40, HSP47, HSP90, HSP110) had different degrees of growth. In addition, the levels of HSF1, HSF2, and HSF3 were significantly increased. Given the facts above, DEHP exposure induced the toxic effects of quail heart. DEHP exposure did great harm to HSR via affecting the synthesis of HSFs to mediate the transcription of the HSPs. Ultimately, this study provided new evidence that DEHP-induced cardiotoxicity in quail was related to activation of HSR and playing a protective role.

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

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

Food Additives and Child Health

Increasing scientific evidence suggests potential adverse effects on children's health from synthetic chemicals used as food additives, both those deliberately added to food during processing (direct) and those used in materials that may contaminate food as part of packaging or manufacturing (indirect). Concern regarding food additives has increased in the past 2 decades in part because of studies that increasingly document endocrine disruption and other adverse health effects. In some cases, exposure to these chemicals is disproportionate among minority and low-income populations. This report focuses on those food additives with the strongest scientific evidence for concern. Further research is needed to study effects of exposure over various points in the life course, and toxicity testing must be advanced to be able to better identify health concerns prior to widespread population exposure. The accompanying policy statement describes approaches policy makers and pediatricians can take to prevent the disease and disability that are increasingly being identified in relation to chemicals used as food additives, among other uses.

Food Additives and Child Health

Our purposes with this policy statement and its accompanying technical report are to review and highlight emerging child health concerns related to the use of colorings, flavorings, and chemicals deliberately added to food during processing (direct food additives) as well as substances in food contact materials, including adhesives, dyes, coatings, paper, paperboard, plastic, and other polymers, which may contaminate food as part of packaging or manufacturing equipment (indirect food additives); to make reasonable recommendations that the pediatrician might be able to adopt into the guidance provided during pediatric visits; and to propose urgently needed reforms to the current regulatory process at the US Food and Drug Administration (FDA) for food additives. Concern regarding food additives has increased in the past 2 decades, in part because of studies in which authors document endocrine disruption and other adverse health effects. In some cases, exposure to these chemicals is disproportionate among minority and low-income populations. Regulation and oversight of many food additives is inadequate because of several key problems in the Federal Food, Drug, and Cosmetic Act. Current requirements for a "generally recognized as safe" (GRAS) designation are insufficient to ensure the safety of food additives and do not contain sufficient protections against conflict of interest. Additionally, the FDA does not have adequate authority to acquire data on chemicals on the market or reassess their safety for human health. These are critical weaknesses in the current regulatory system for food additives. Data about health effects of food additives on infants and children are limited or missing; however, in general, infants and children are more vulnerable to chemical exposures. Substantial improvements to the food additives regulatory system are urgently needed, including greatly strengthening or replacing the "generally recognized as safe" (GRAS) determination process, updating the scientific foundation of the FDA's safety assessment program, retesting all previously approved chemicals, and labeling direct additives with limited or no toxicity data.

Plastics and cardiovascular health: phthalates may disrupt heart rate variability and cardiovascular reactivity

Plastics have revolutionized medical device technology, transformed hematological care, and facilitated modern cardiology procedures. Despite these advances, studies have shown that phthalate chemicals migrate out of plastic products and that these chemicals are bioactive. Recent epidemiological and research studies have suggested that phthalate exposure adversely affects cardiovascular function. Our objective was to assess the safety and biocompatibility of phthalate chemicals and resolve the impact on cardiovascular and autonomic physiology. Adult mice were implanted with radiofrequency transmitters to monitor heart rate variability, blood pressure, and autonomic regulation in response to di-2-ethylhexyl-phthalate (DEHP) exposure. DEHP-treated animals displayed a decrease in heart rate variability (-17% SD of normal beat-to-beat intervals and -36% high-frequency power) and an exaggerated mean arterial pressure response to ganglionic blockade (31.5% via chlorisondamine). In response to a conditioned stressor, DEHP-treated animals displayed enhanced cardiovascular reactivity (-56% SD major axis Poincarè plot) and prolonged blood pressure recovery. Alterations in cardiac gene expression of endothelin-1, angiotensin-converting enzyme, and nitric oxide synthase may partly explain these cardiovascular alterations. This is the first study to show an association between phthalate chemicals that are used in medical devices with alterations in autonomic regulation, heart rate variability, and cardiovascular reactivity. Because changes in autonomic balance often precede clinical manifestations of hypertension, atherosclerosis, and conduction abnormalities, future studies are warranted to assess the downstream impact of plastic chemical exposure on end-organ function in sensitive patient populations. This study also highlights the importance of adopting safer biomaterials, chemicals, and/or surface coatings for use in medical devices.NEW & NOTEWORTHY Phthalates are widely used in the manufacturing of consumer and medical products. In the present study, di-2-ethylhexyl-phthalate exposure was associated with alterations in heart rate variability and cardiovascular reactivity. This highlights the importance of investigating the impact of phthalates on health and identifying suitable alternatives for medical device manufacturing.

In Utero and Lactational Exposure Study in Rats to Identify Replacements for Di(2-ethylhexyl) Phthalate

Di(2-ethylhexyl) phthalate (DEHP) and other phthalates are ubiquitous environmental contaminants with endocrine disrupting properties. Two novel plasticizers, 1,4 butanediol dibenzoate (BDB) and dioctyl succinate (DOS), have been proposed as potential replacements. Both have desirable properties as plasticizers and minimal in vitro biological effects. Herein, we present an in utero and lactational exposure study comparing DEHP with BDB, DOS, and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), a commercial alternative. Timed-pregnant Sprague-Dawley rats were gavaged with vehicle or one of these chemicals at 30 or 300 mg/kg/day from gestational day 8 until postnatal day (PND) 21. The offspring were examined for effects on developmental and endocrine markers until PND 46. DEHP treatment (300 mg/kg) decreased heart weights in dams and induced a significant decrease in anogenital index and an increase in hemorrhagic testes and multinucleated gonocytes in PND 3 male pups. An increase in the incidence of hemorrhagic testes was also observed on PND 8 after exposure to DINCH (30 and 300 mg/kg). The only other effects observed were decreases in serum alanine transaminase and magnesium in BDB 30 exposed dams. These data suggest that both BDB and DOS are viable alternative plasticizers.

The effects of phthalates in the cardiovascular and reproductive systems: A review

Every year millions of tons of plastic are produced around the world and humans are increasingly exposed to them. This constant exposure to plastics has raised some concerns against human health, particularly when it comes to phthalates. These compounds have endocrine-disrupting properties, as they have the ability to bind molecular targets in the body and interfere with hormonal function and quantity. The main use of phthalates is to give flexibility to polyvinyl chloride (PVC) polymers. Phthalates are found in a variety of industrial and consumer products, and as they are not covalently bound to the plastic, phthalates contaminate the environment from which human exposure occurs. Studies in human and animal populations suggest a correlation between phthalate exposure and adverse health outcomes, particularly at the reproductive and cardiovascular systems, however there is much less information about the phthalate toxicity of the later. Thus, the main purpose of this review is to present the studies relating the effects already stated of phthalates on the cardiovascular and reproductive systems, and also present the link between these two systems.

The adverse cardiac effects of Di(2-ethylhexyl)phthalate and Bisphenol A

The ubiquitous nature of plastics has raised concerns pertaining to continuous exposure to plastic polymers and human health risks. Of particular concern is the use of endocrine-disrupting chemicals in plastic production, including di(2-ethylhexyl)phthalate (DEHP) and bisphenol A (BPA). Widespread and continuous exposure to DEHP and BPA occurs through dietary intake, inhalation, dermal and intravenous exposure via consumer products and medical devices. This article reviews the literature examining the relationship between DEHP and BPA exposure and cardiac toxicity. In vitro and in vivo experimental reports are outlined, as well as epidemiological studies which examine the association between these chemicals and cardiovascular outcomes. Gaps in our current knowledge are also discussed, along with future investigative endeavors that may help resolve whether DEHP and/or BPA exposure has a negative impact on cardiovascular physiology.

The effects of environmental chemicals on renal function

The global incidence of chronic kidney disease (CKD) is increasing among individuals of all ages. Despite advances in proteomics, genomics and metabolomics, there remains a lack of safe and effective drugs to reverse or stabilize renal function in patients with glomerular or tubulointerstitial causes of CKD. Consequently, modifiable risk factors that are associated with a progressive decline in kidney function need to be identified. Numerous reports have documented the adverse effects that occur in response to graded exposure to a wide range of environmental chemicals. This Review summarizes the effects of such chemicals on four aspects of cardiorenal function: albuminuria, glomerular filtration rate, blood pressure and serum uric acid concentration. We focus on compounds that individuals are likely to be exposed to as a consequence of normal consumer activities or medical treatment, namely phthalates, bisphenol A, polyfluorinated alkyl acids, dioxins and furans, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Environmental exposure to these chemicals during everyday life could have adverse consequences on renal function and might contribute to progressive cumulative renal injury over a lifetime. Regulatory efforts should be made to limit individual exposure to environmental chemicals in an attempt to reduce the incidence of cardiorenal disease.

Parental occupational exposures to endocrine disruptors and the risk of simple isolated congenital heart defects

This study aims to explore the associations between parental occupational exposures to endocrine disruptors (EDs) and simple isolated congenital heart defects (CHDs). A case-control study with standardized data collection involving 761 children with isolated CHDs and 609 children without any congenital malformations was conducted in Sichuan Province of China from March in 2012 to August in 2013. An adjusted job exposure matrix was used for occupational EDs exposure assessment. Logistic regression analysis was performed to assess the associations between parental occupational EDs exposures and CHDs. Maternal age at births, maternal education level, gravity, parity, induced abortion, folic acid use, medication use, drinking capacity and area of residence periconceptionally were selected as confounding factors for mothers. For fathers, we selected the following confounding factors: paternal education level, smoking, drinking frequencies and drinking capacity periconceptionally. Maternal occupational exposures to phthalates are associated with perimembranous ventricular septal defect (PmVSD) (P = 0.001, adjusted OR 3.7, 95 % CI 1.7-8.0), patent ductus arteriosus (PDA) (P = 0.002, adjusted OR 3.8, 95 % CI 1.6-8.9), secundum atrial septal defect (s-ASD) (P = 0.008, adjusted OR 3.5, 95 % CI 1.4-8.7) and pulmonary valve stenosis (PS) (P = 0.035, adjusted OR 4.2, 95 % CI 1.1-16.0), to alkylphenolic compounds and PmVSD (P = 0.003, adjusted OR 2.2, 95 % CI 1.3-3.6), PDA (P = 0.005, adjusted OR 2.0, 95 % CI 1.1-3.5) and PS (P = 0.004, adjusted OR 3.8, 95 % CI 1.5-9.4), to heavy metals with PmVSD (P = 0.003, adjusted OR 7.3, 95 % CI 2.0-27.6) and s-ASD (P = 0.034, adjusted OR 6.5, 95 % CI 1.1-36.7). Paternal occupational exposures to phthalates are associated with PmVSD (P = 0.035, adjusted OR 1.6, 95 % CI 1.0-2.4) and PS (P = 0.026, adjusted OR 2.4, 95 % CI 1.1-5.2), to alkylphenolic compounds (P = 0.027, adjusted OR 1.5, 95 % CI 1.0-2.2) with PmVSD. In conclusion, parental occupational exposures to some specific EDs, in particular phthalates and alkylphenolic compounds, are associated with an increased risk of some CHD phenotypes. However, the findings need to be considered more circumspectly regarding a crude measure of exposure probabilities and small numbers.

Physiological response of cardiac tissue to bisphenol A: alterations in ventricular pressure and contractility

Biomonitoring studies have indicated that humans are routinely exposed to bisphenol A (BPA), a chemical that is commonly used in the production of polycarbonate plastics and epoxy resins. Epidemiological studies have shown that BPA exposure in humans is associated with cardiovascular disease; however, the direct effects of BPA on cardiac physiology are largely unknown. Previously, we have shown that BPA exposure slows atrioventricular electrical conduction, decreases epicardial conduction velocity, and prolongs action potential duration in excised rat hearts. In the present study, we tested if BPA exposure also adversely affects cardiac contractile performance. We examined the impact of BPA exposure level, sex, and pacing rate on cardiac contractile function in excised rat hearts. Hearts were retrogradely perfused at constant pressure and exposed to 10(-9)-10(-4) M BPA. Left ventricular developed pressure and contractility were measured during sinus rhythm and during pacing (5, 6.5, and 9 Hz). Ca(2+) transients were imaged from whole hearts and from neonatal rat cardiomyocyte layers. During sinus rhythm in female hearts, BPA exposure decreased left ventricular developed pressure and inotropy in a dose-dependent manner. The reduced contractile performance was exacerbated at higher pacing rates. BPA-induced effects on contractile performance were also observed in male hearts, albeit to a lesser extent. Exposure to BPA altered Ca(2+) handling within whole hearts (reduced diastolic and systolic Ca(2+) transient potentiation) and neonatal cardiomyocytes (reduced Ca(2+) transient amplitude and prolonged Ca(2+) transient release time). In conclusion, BPA exposure significantly impaired cardiac performance in a dose-dependent manner, having a major negative impact upon electrical conduction, intracellular Ca(2+) handing, and ventricular contractility.

Exposure to phthalates affects calcium handling and intercellular connectivity of human stem cell-derived cardiomyocytes

Background

The pervasive nature of plastics has raised concerns about the impact of continuous exposure to plastic additives on human health. Of particular concern is the use of phthalates in the production of flexible polyvinyl chloride (PVC) products. Di-2-ethylhexyl-phthalate (DEHP) is a commonly used phthalate ester plasticizer that imparts flexibility and elasticity to PVC products. Recent epidemiological studies have reported correlations between urinary phthalate concentrations and cardiovascular disease, including an increased risk of high blood pressure and coronary risk. Yet, there is little direct evidence linking phthalate exposure to adverse effects in human cells, including cardiomyocytes.

Methods and Results

The effect of DEHP on calcium handling was examined using monolayers of gCAMP3 human embryonic stem cell-derived cardiomyocytes, which contain an endogenous calcium sensor. Cardiomyocytes were exposed to DEHP (5 – 50 μg/mL), and calcium transients were recorded using a Zeiss confocal imaging system. DEHP exposure (24 – 72 hr) had a negative chronotropic and inotropic effect on cardiomyocytes, increased the minimum threshold voltage required for external pacing, and modified connexin-43 expression. Application of Wy-14,643 (100 μM), an agonist for the peroxisome proliferator-activated receptor alpha, did not replicate DEHP’s effects on calcium transient morphology or spontaneous beating rate.

Conclusions

Phthalates can affect the normal physiology of human cardiomyocytes, including DEHP elicited perturbations in cardiac calcium handling and intercellular connectivity. Our findings call for additional studies to clarify the extent by which phthalate exposure can alter cardiac function, particularly in vulnerable patient populations who are at risk for high phthalate exposure.

Mechanisms mediating environmental chemical-induced endocrine disruption in the adrenal gland

Humans are continuously exposed to hundreds of man-made chemicals that pollute the environment in addition to multiple therapeutic drug treatments administered throughout life. Some of these chemicals, known as endocrine disruptors (EDs), mimic endogenous signals, thereby altering gene expression, influencing development, and promoting disease. Although EDs are eventually removed from the market or replaced with safer alternatives, new evidence suggests that early-life exposure leaves a fingerprint on the epigenome, which may increase the risk of disease later in life. Epigenetic changes occurring in early life in response to environmental toxicants have been shown to affect behavior, increase cancer risk, and modify the physiology of the cardiovascular system. Thus, exposure to an ED or combination of EDs may represent a first hit to the epigenome. Only limited information is available regarding the effect of ED exposure on adrenal function. The adrenal gland controls the stress response, blood pressure, and electrolyte homeostasis. This endocrine organ therefore has an important role in physiology and is a sensitive target of EDs. We review herein the effect of ED exposure on the adrenal gland with particular focus on in utero exposure to the plasticizer di(2-ethylehyl) phthalate. We discuss the challenges associated with identifying the mechanism mediating the epigenetic origins of disease and availability of biomarkers that may identify individual or population risks.

Impact of di-ethylhexylphthalate exposure on metabolic programming in P19 ECC-derived cardiomyocytes

Di(2-ethylhexyl)phthalate (DEHP) is the most common plasticizer in plastic devices of everyday use. It is a ubiquitous environmental contaminant and primarily known to impair male gonadal development and fertility. Studies concerning the long-term effects of prenatal DEHP exposure on certain diseases [The Developmental Origins of Health and Disease paradigm (DOHaD) hypothesis] are scarce although it is proven that DEHP crosses the placenta. Rising environmental pollution during the last centuries coincides with an increasing prevalence of cardiovascular and metabolic diseases. We have investigated the effects of an early embryonic DEHP exposure at different developmental stages on cardiomyogenesis. We used an in-vitro model, the murine P19 embryonic carcinoma cell line (P19 ECC), mimicking early embryonic stages up to differentiated beating cardiomyocytes. P19 ECC were exposed to DEHP (5, 50, 100 µg ml(-1)) at the undifferentiated stage for 5 days and subsequently differentiated to beating cardiomyocytes. We analyzed the expression of metabolic (Pparg1, Fabp4 and Glut4), cardiac (Myh6, Gja1) and methylation (Dnmt1, Dnmt3a) marker genes by quantitative real-time PCR (qRT-PCR), beating rate and the differentiation velocity of the cells. The methylation status of Pparg1, Ppara and Glut4 was investigated by pyrosequencing. DEHP significantly altered the expression of all investigated genes. The beating rate and differentiation velocity were accelerated. Exposure to DEHP led to small but statistically significant increases in methylation of specific CpGs within Ppara and Pparg1, which otherwise were generally hypomethylated, but methylation of Glut4 was unaltered. Early DEHP exposure of P19 ECC alters the expression of genes associated with cellular metabolism and the functional features of cardiomyocytes.

Plasticizer contamination of firefighter personal protective clothing--a potential factor in increased health risks in firefighters

Chemical exposures may be responsible for firefighters' elevated incidences of cancer and cardiovascular disease. This study characterized semivolatile chemical contamination on firefighter personal protective clothing to assess exposure of firefighters to these chemicals. Samples from used firefighter protective clothing, including gloves, hood, and one coat wristlet, were extracted with methylene chloride and analyzed by EPA method 8270 for semivolatile contaminants, including 20 polycyclic aromatic hydrocarbons (PAHs) and 6 phthalate diesters. Twenty-two of the chemicals of interest were found on at least one clothing swatch. Only di-(2-ethylhexyl) phthalate (DEHP), a plasticizer, added to polyvinyl chloride (PVC) to increase flexibility, was found on every swatch. DEHP concentrations were the highest of any chemical measured, and were 52 to 875 times higher than any PAH concentration measured. DEHP was also detected on most items of unused firefighter personal protective clothing, although at much lower levels. These findings suggest that firefighters are exposed to high levels of DEHP, a probable human carcinogen, and at levels much higher than PAHs, the semivolatile toxic combustion products most extensively studied historically. Firefighter exposure to DEHP and other phthalate diesters therefore merits further study.

Urinary phthalates are associated with higher blood pressure in childhood

OBJECTIVE

To examine associations of urinary phthalate levels with blood pressure (BP) and serum triglyceride and lipoprotein levels in children.

STUDY DESIGN

We performed a cross-sectional analysis of a subsample of US children aged 6-19 years who participated in the National Health and Nutrition Examination Survey between 2003 and 2008. We quantified exposure to 3 families of phthalates--low molecular weight, high molecular weight and di-2-ethylhexylphthalate (DEHP)--based on molar concentration of urinary metabolites. We assessed descriptive, bivariate, and multivariate associations with BP and lipid levels.

RESULTS

Controlling for an array of sociodemographic and behavioral factors, as well as diet and body mass index, levels of metabolites of DEHP, a phthalate commonly found in processed foods, were associated with higher age-, sex-, and height-standardized BP. For each log unit (roughly 3-fold) increase in DEHP metabolites, a 0.041 SD unit increase in systolic BP z-score was identified (P = .047). Metabolites of low molecular weight phthalates commonly found in cosmetics and personal care products were not associated with BP. Phthalate metabolites were not associated with triglyceride levels, high-density lipoprotein level, or prehypertension.

CONCLUSIONS

Dietary phthalate exposure is associated with higher systolic BP in children and adolescents. Further work is needed to confirm these associations, as well as to evaluate opportunities for intervention.

Phthalate exposure changes the metabolic profile of cardiac muscle cells

BACKGROUND

Phthalates are common plasticizers present in medical-grade plastics and other everyday products. They can also act as endocrine-disrupting chemicals and have been linked to the rise in metabolic disorders. However, the effect of phthalates on cardiac metabolism remains largely unknown.

OBJECTIVES

We examined the effect of di(2-ethylhexyl)phthalate (DEHP) on the metabolic profile of cardiomyocytes because alterations in metabolic processes can lead to cell dysfunction.

METHODS

Neonatal rat cardiomyocytes were treated with DEHP at a concentration and duration comparable to clinical exposure (50-100 μg/mL, 72 hr). We assessed the effect of DEHP on gene expression using microarray analysis. Physiological responses were examined via fatty acid utilization, oxygen consumption, mitochondrial mass, and Western blot analysis.

RESULTS

Exposure to DEHP led to up-regulation of genes associated with fatty acid transport, esterification, mitochondrial import, and β-oxidation. The functional outcome was an increase in myocyte fatty acid-substrate utilization, oxygen consumption, mitochondrial mass, PPARα (peroxisome proliferator-activated receptor α) protein expression, and extracellular acidosis. Treatment with a PPARα agonist (Wy-14643) only partially mimicked the effects observed in DEHP-treated cells.

CONCLUSIONS

Data suggest that DEHP exposure results in metabolic remodeling of cardiomyocytes, whereby cardiac cells increase their dependence on fatty acids for energy production. This fuel switch may be regulated at both the gene expression and posttranscription levels. Our findings have important clinical implications because chronic dependence on fatty acids is associated with an accumulation in lipid intermediates, lactate, protons, and reactive oxygen species. This dependence can sensitize the heart to ischemic injury and ventricular dysfunction.

Dose response analysis of monophthalates in the murine embryonic stem cell test assessed by cardiomyocyte differentiation and gene expression

The embryonic stem cell test (EST) is based on compound-induced inhibition of cardiomyocyte differentiation of pluripotent stem cells. We examined the use of transcriptomics to assess concentration-effect relationships and performed potency ranking within a chemical class. Three embryotoxic phthalate monoesters, monobutyl phthalate (MBuP), monobenzyl phthalate (MBzP) and mono-(2-ethylhexyl) phthalate (MEHP) and the non-embryotoxic monomethyl phthalate (MMP) were studied for their effects on gene expression. Effects on gene expression were observed at concentrations that did not inhibit cardiomyocyte differentiation or induce cytotoxicity. The embryotoxic phthalate monoesters altered the expression of 668 commonly expressed genes in a concentration-dependent fashion. The same potency ranking was observed for morphology and gene expression (MEHP>MBzP>MBuP>MMP). These results indicate that integrating transcriptomics provides a sensitive method to measure the dose-dependent effects of phthalate monoester exposure and enables potency ranking based on a common mode of action within a class of compounds. Transcriptomic approaches may improve the applicability of the EST, in terms of sensitivity and specificity.

Bisphenol A and phthalates exhibit similar toxicogenomics and health effects

Plastics are widely used in modern life, and their unbound chemicals bisphenol A and phthalates can leach out into the surrounding environment. BPA and PAEs have recently attracted the special attention of the scientific community, regulatory agencies and the general public because of their high production volume, widespread use of plastics, and endocrine-disrupting effects. In The Comparative Toxicogenomics Database, BPA and five most frequently curated PAEs (DEHP/MEHP and DBP/BBP/MBP) were found to have 1932 and 484 interactions with genes/proteins, respectively. Five of their top ten toxicity networks were found to be involved in inflammation, and their top ten diseases included genital, prostatic, endomentrial, ovarian and breast diseases. BPA and PAEs were found to exhibit similar toxicogenomics and adverse effects on human health owning to their 89 common interacting genes/proteins. These 89 genes/proteins may serve as biomarkers to assay the toxicities of different chemicals leached out from the widely used plastics.

Transcriptomic effects of di-(2-ethylhexyl)-phthalate in Syrian hamster embryo cells: an important role of early cytoskeleton disturbances in carcinogenesis?

Background

Di-(2-ethylhexyl)-phthalate (DEHP) is a commonly used plasticizer in polyvinylchloride (PVC) formulations and a potentially non-genotoxic carcinogen. The aim of this study was to identify genes whose level of expression is altered by DEHP by using a global wide-genome approach in Syrian hamster embryo (SHE) cells, a model similar to human cells regarding their responses to this type of carcinogen. With mRNA Differential Display (DD), we analysed the transcriptional regulation of SHE cells exposed to 0, 12.5, 25 and 50 μM of DEHP for 24 hrs, conditions which induced neoplastic transformation of these cells. A real-time quantitative polymerase chain reaction (qPCR) was used to confirm differential expression of genes identified by DD.

Results

Gene expression profiling showed 178 differentially-expressed fragments corresponding to 122 genes after tblastx comparisons, 79 up-regulated and 43 down-regulated. The genes of interest were involved in many biological pathways, including signal transduction, regulation of the cytoskeleton, xenobiotic metabolism, apoptosis, lipidogenesis, protein conformation, transport and cell cycle. We then focused particularly on genes involved in the regulation of the cytoskeleton, one of the processes occurring during carcinogenesis and in the early steps of neoplastic transformation. Twenty one cytoskeleton-related genes were studied by qPCR. The down-regulated genes were involved in focal adhesion or cell junction. The up-regulated genes were involved in the regulation of the actin cytoskeleton and this would suggest a role of cellular plasticity in the mechanism of chemical carcinogenesis. The gene expression changes identified in the present study were PPAR-independent.

Conclusion

This study identified a set of genes whose expression is altered by DEHP exposure in mammalian embryo cells. This is the first study that elucidates the genomic changes of DEHP involved in the organization of the cytoskeleton. The latter genes may be candidates as biomarkers predictive of early events in the multistep carcinogenic process.