MEHP promotes liver fibrosis by down-regulating STAT5A in BRL-3A hepatocytes

OBJECTIVE

As an environmental endocrine disruptor, mono-2-ethylhexyl phthalate (MEHP) can interfere with liver metabolism and lead to liver diseases. We aimed to investigate the role of MEHP in liver fibrosis and its molecular mechanism.

METHODS

BRL-3A hepatocytes were exposed to MEHP (0, 10, 50, 100 and 200 μM) for 24 h. STAT5A gene was overexpressed by lentivirus transfection. The reactive oxygen species (ROS) was tested by the flow cytometer. The malondialdehyde (MDA), glutathione peroxidase (GSH-PX), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were detected by commercial kits. Real-Time PCR and Western blot were performed to test the relative mRNA and proteins levels, respectively.

RESULTS

MEHP exposure significantly induced oxidative damage in BRL-3A cells, which inhibited the expression of STAT5A and promoted the expression of fibrosis related proteins MMP2, MMP9, TIMP2 and CTGF. After over-expression of STAT5A gene in BRL-3A cells, the elevated expression levels of CTGF, MMP2, MMP9 and TIMP2 induced by MEHP exposure were significantly reversed.

CONCLUSION

This study demonstrated that MEHP exposure inhibited the expression of STAT5A by causing oxidative damage in BRL-3A hepatocytes, thus accelerating the expression of key molecules in fibrosis and promoting the occurrence of liver fibrosis.

Impacts of diethylhexyl phthalate and overfeeding on physical fitness and lipid mobilization in Danio rerio (zebrafish)

As the prevalence of obesity has steadily increased on a global scale, research has shifted to explore potential contributors to this pandemic beyond overeating and lack of exercise. Environmental chemical contaminants, known as obesogens, alter metabolic processes and exacerbate the obese phenotype. Diethylhexyl phthalate (DEHP) is a common chemical plasticizer found in medical supplies, food packaging, and polyvinyl materials, and has been identified as a probable obesogen. This study investigated the hypothesis that co-exposure to DEHP and overfeeding would result in decreased lipid mobilization and physical fitness in Danio rerio (zebrafish). Four treatment groups were randomly assigned: Regular Fed (control, 10 mg/fish/day with 0 mg/kg DEHP), Overfed (20 mg/fish/day with 0 mg/kg DEHP), Regular Fed + DEHP (10 mg/fish/day with 3 mg/kg DEHP), Overfed + DEHP (20 mg/fish/day with 3 mg/kg DEHP). After 24 weeks, swim tunnel assays were conducted on half of the zebrafish from each treatment to measure critical swimming speeds (U_crit); the other fish were euthanized without swimming. Body mass index (BMI) was measured, and tissues were collected for blood lipid characterization and gene expression analyses. Co-exposure to DEHP and overfeeding decreased swim performance as measured by U_crit. While no differences in blood lipids were observed with DEHP exposure, differential expression of genes related to lipid metabolism and utilization in the gastrointestinal and liver tissue suggests alterations in metabolism and lipid packaging, which may impact utilization and ability to mobilize lipid reserves during physical activity following chronic exposures.

Comparison of the exposure assessment of di(2-ethylhexyl) phthalate between the PBPK model-based reverse dosimetry and scenario-based analysis: A Korean general population study

Di (2-ethylhexyl) phthalate (DEHP), classified as a reproductive toxicant, is a ubiquitous pollutant in foodstuffs, dust, and commercial products. In this study, to provide a useful cross-check on the accuracy of the exposure assessment, the estimated daily intake of DEHP was compared using reverse dosimetry with a physiologically-based pharmacokinetic (PBPK) model and a scenario-based probabilistic estimation model for six subpopulations in Korea. For reverse dosimetry analysis, the concentrations of urinary DEHP metabolites, namely mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono (2-ethyl-5-oxohexyl)phthalate (MEOHP), from three human biomonitoring program datasets were used. For the scenario-based model, we evaluated the various exposure sources of DEHP, including diet, air, indoor dust, soil, and personal care products (PCPs), and also determined its levels based on the literature review and measurements of indoor dust. The DEHP exposure doses using both exposure assessment approaches were similar in all cases, except for the 95th percentile exposure doses in toddlers (1-2 years) and young children (3-6 years). The PBPK-reverse dosimetry estimated daily intakes at the 95th percentile ranged between 22.53 and 29.90 μg/kg/day for toddlers and young children. These exceeded the reference dose (RfD) of 20 μg/kg bw/day of the US Environmental Protection Agency (EPA) based on the increased relative liver weight. Although, food was considered the primary source of DEHP, contributing to a total exposure of 50.8-75.1%, the effect of exposure to indoor dust should not be overlooked. The occurrence of high levels of DEHP in indoor dust collected from Korean homes suggests the use of a wide variety of consumer products containing DEHP. Furthermore, more attention should be paid to the high exposure levels of DEHP, especially in young children. Therefore, it is necessary to perform continuous monitoring of the indoor dust, consumer products, and the body burden of children.

Di-(2-ethylhexyl) Phthalate Triggers Proliferation, Migration, Stemness, and Epithelial-Mesenchymal Transition in Human Endometrial and Endometriotic Epithelial Cells via the Transforming Growth Factor-β/Smad Signaling Pathway

Di-(2-ethylhexyl) phthalate (DEHP) is a frequently used plasticizer that may be linked to the development of endometriosis, a common gynecological disorder with a profound impact on quality of life. Despite its prevalence, vital access to treatment has often been hampered by a lack of understanding of its pathogenesis as well as reliable disease models. Recently, epithelial–mesenchymal transition (EMT) has been suggested to have a significant role in endometriosis pathophysiology. In this study, we found that DEHP treatment enhanced proliferation, migration, and inflammatory responses, along with EMT and stemness induction in human endometrial and endometriotic cells. The selective transforming growth factor-β (TGF-β) receptor type 1/2 inhibitor LY2109761 reversed the DEHP-induced cell proliferation and migration enhancement as well as the increased expression of crucial molecules involved in inflammation, EMT, and stemness, indicating that DEHP-triggered phenomena occur via the TGF-β/Smad signaling pathway. Our study clearly defines the role of DEHP in the etiology and pathophysiological mechanisms of endometriosis and establishes an efficient disease model for endometriosis using a biomimetic 3D cell culture technique. Altogether, our data provide novel etiological and mechanistic insights into the role of DEHP in endometriosis pathogenesis, opening avenues for developing novel preventive and therapeutic strategies for endometriosis.

The associations of urinary DEHP metabolite levels, serum thyroid hormones, and thyroid-related genes among the adolescent students from China: a cross-sectional study

Our study aimed to investigate the associations between DEHP exposure and serum thyroid hormone levels in 347 adolescents and young adults. We measured DEHP metabolites including mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono(2-carboxymethyl)hexyl phthalate (MCMHP) in their urine. Total thyroxine (TT4), total triiodothyronine, free triiodothyronine, free thyroxine (FT4), thyroid-stimulating hormone and the mRNA levels of thyroid peroxidase (TPO), thyroglobulin (TG), sodium iodide symporter (NIS), thyroid transcription factor 1 (TTF-1), and paired box gene 8 (PAX-8) in serum were measured. The results of statistical analysis showed that urinary DEHP metabolites were generally negatively associated with TT4 levels in serum. In the males, the FT4 levels showed positive associations with urinary MEHP, MECPP, MCMHP, and ∑DEHP. The mRNA level of TG was significantly positively correlated with the levels of MECPP, MCMHP, and ∑DEHP, while the levels of TTF-1 and PAX-8 mRNA were significantly positively correlated with the levels of DEHP metabolites. Taken together, DEHP may affect the synthesis of TG by altering the normal transcription of TTF-1 and PAX-8, leading to decreased TT4 levels in Chinese adolescents.

Overcompensation of CoA Trapping by Di(2-ethylhexyl) Phthalate (DEHP) Metabolites in Livers of Wistar Rats

Di(2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in various industrial and household plastic products, ensuring widespread human exposures. Its routine detection in human bio-fluids and the propensity of its monoester metabolite to activate peroxisome proliferator activated receptor-α (PPARα) and perturb lipid metabolism implicate it as a metabolic disrupter. In this study we evaluated the effects of DEHP exposure on hepatic levels of free CoA and various CoA esters, while also confirming the metabolic activation to CoA esters and partial β-oxidation of a DEHP metabolite (2-ethyhexanol). Male Wistar rats were exposed via diet to 2% (^w/_w) DEHP for fourteen-days, following which hepatic levels of free CoA and various CoA esters were identified using liquid chromatography-mass spectrometry. DEHP exposed rats showed significantly elevated free CoA and increased levels of physiological, DEHP-derived and unidentified CoA esters. The physiological CoA ester of malonyl-CoA and DEHP-derived CoA ester of 3-keto-2-ethylhexanoyl-CoA were the most highly elevated, at eighteen- and ninety eight-times respectively. We also detected sixteen unidentified CoA esters which may be derivative of DEHP metabolism or induction of other intermediary metabolism metabolites. Our results demonstrate that DEHP is a metabolic disrupter which affects production and sequestration of CoA, an essential cofactor of oxidative and biosynthetic reactions.

Paternal preconception phthalate exposure alters sperm methylome and embryonic programming

Preconception environmental conditions have been demonstrated to shape sperm epigenetics and subsequently offspring health and development. Our previous findings in humans showed that urinary anti-androgenic phthalate metabolites in males were associated with altered sperm methylation and blastocyst-stage embryo development. To corroborate this, we examined the effect of preconception exposure to di(2-ethylhexyl) phthalate (DEHP) on genome-wide DNA methylation and gene expression profiles in mice. Eight-week old C57BL/6J male mice were exposed to either a vehicle control, low, or high dose of DEHP (2.5 and 25 mg/kg/weight, respectively) for 67 days (~2 spermatogenic cycles) and were subsequently mated with unexposed females. Reduced representation bisulfite sequencing (RRBS) of epididymal sperm was performed and gastrulation stage embryos were collected for RRBS and transcriptome analyses in both embryonic and extra-embryonic lineages. Male preconception DEHP exposure resulted in 704 differentially methylated regions (DMRs; q-value < 0.05; ≥10% methylation change) in sperm, 1,716 DMRs in embryonic, and 3,181 DMRs in extra-embryonic tissue. Of these, 29 DMRs overlapped between sperm and F1 tissues, half of which showed concordant methylation changes between F0 and F1 generations. F1 transcriptomes at E7.5 were also altered by male preconception DEHP exposure including developmental gene families such as Hox, Gata, and Sox. Additionally, gene ontology analyses of DMRs and differentially expressed genes showed enrichment of multiple developmental processes including embryonic development, pattern specification and morphogenesis. These data indicate that spermatogenesis in adult may represent a sensitive window in which exposure to DEHP alters the sperm methylome as well as DNA methylation and gene expression in the developing embryo.

Protective effect of Lycium barbarum polysaccharide on di-(2-ethylhexyl) phthalate-induced toxicity in rat liver

Di-(2-ethylhexyl)-phthalate (DEHP) is the most commonly used plasticizer and it has been a ubiquitous environmental contaminant which affects health. The purpose of this study was to investigate the protective effect of the Lycium barbarum polysaccharide (LBP) at dosages of 100, 200, and 300 mg/kg bw on DEHP-induced (3000 mg/kg) toxicity in rat liver through a 28-day animal experiment. The results showed that LBP attenuated oxidative stress slightly by lowering the production of ROS and improving the activity of SOD and GSH-Px in liver and serum of DEHP treatment rats. At the same time, the levels of PXR, CYP450, CYP2E1, CYP3A1, UGT1, and GST were reduced after LBP treatment. Moreover, LBP decreased the mRNA expression of PXR, UGT1, and GST significantly. These findings suggested that LBP might ameliorate DEHP-induced liver injury by down-regulating the expression of PXR in liver, further down-regulating the downstream phase I and II detoxification enzymes, thus reducing the damage caused by DEHP. Therefore, LBP may have the potential to become an auxiliary therapeutic agent as a natural ingredient of health food.

DEHP Down-Regulates Tshr Gene Expression in Rat Thyroid Tissues and FRTL-5 Rat Thyrocytes: A Potential Mechanism of Thyroid Disruption

BACKGROUND

Di-2-ethylhexyl phthalate (DEHP) is known to disrupt thyroid hormonal status. However, the underlying molecular mechanism of this disruption is unclear. Therefore, we investigated the direct effects of DEHP on the thyroid gland.

METHODS

DEHP (vehicle, 50 mg/kg, and 500 mg/kg) was administered to Sprague-Dawley rats for 2 weeks. The expression of the thyroid hormone synthesis pathway in rat thyroid tissues was analyzed through RNA sequencing analysis, quantitative reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemical (IHC) staining. DEHP was treated to FRTL-5 rat thyroid cells, and an RT-PCR analysis was performed. A reporter gene assay containing the promoter of thyroid stimulating hormone receptor (TSHR) in Nthy-ori 3-1 human thyroid cells was constructed, and luciferase activity was determined.

RESULTS

After DEHP treatment, the free thyroxine (T4) and total T4 levels in rats significantly decreased. RNA sequencing analysis of rat thyroid tissues showed little difference between vehicle and DEHP groups. In the RT-PCR analysis, Tshr expression was significantly lower in both DEHP groups (50 and 500 mg/kg) compared to that in the vehicle group, and IHC staining showed that TSHR expression in the 50 mg/kg DEHP group significantly decreased. DEHP treatment to FRTL-5 cells significantly down-regulated Tshr expression. DEHP treatment also reduced luciferase activity in a reporter gene assay for TSHR.

CONCLUSION

Although overall genetic changes in the thyroid hormone synthesis pathway are not clear, DEHP exposure could significantly down-regulate Tshr expression in thyroid glands. Down-regulation of Tshr gene appears to be one of potential mechanisms of thyroid disruption by DEHP exposure.

Combining in vivo pathohistological and redox status analysis with in silico toxicogenomic study to explore the phthalates and bisphenol A mixture-induced testicular toxicity

The aim of this study was to: (i) determine and compare the capacity of bis (2 -ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), bisphenol A (BPA), and their mixture to produce testicular toxicity after the subacute exposure; (ii) explore the mechanisms behind the observed changes using in silico toxicogenomic approach. Male rats were randomly split into groups (n = 6): (1) Control (corn oil); (2) DEHP (50 mg/kg b.w./day); (3) DBP (50 mg/kg b.w./day); (4) BPA (25 mg/kg b.w./day); and (5) MIX (50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA). Animals were sacrificed after 28 days of oral exposure, testes were extracted and prepared for histological assessments under the light microscope (haematoxylin and eosin staining) and redox status analysis. The Comparative Toxicogenomics Database (CTD; http://CTD.mdibl.org), Cytoscape software (https://cytoscape.org) and ToppGene Suite (https://toppgene.cchmc.org) were used for data-mining. Present pathohistological study has demonstrated more pronounced testicular toxicity of the MIX group (desquamated germinal epithelium cells, enlarged cells with hyperchromatic nuclei, multinucleated cell forms and intracytoplasmic vacuoles) in comparison with the single substances, while effects on redox status parameters were either more prominent, or present only in the MIX group. In silico investigation revealed 20 genes linked to male reproductive disorders, affected by all three investigated substances. Effects on metabolism, AhR pathway, apoptosis and oxidative stress could be singled out as the most probable mechanisms involved in the subacute DEHP, DBP and BPA mixture testicular toxicity, while the effect on oxidative stress parameters was confirmed by in vivo experiment.

LncRNAs activate longevity regulation pathway due to aging of Leydig cells caused by DEHP exposure: A transcriptome-based study

Di-(2-ethylhexyl) phthalate (DEHP), one of the most commonly used endocrine-disrupting chemicals, has been shown to cause reproductive dysfunction in humans and animal models. However, very few studies have investigated the impact of DEHP at the post-transcriptional level in mouse testes, and the underlying mechanisms remain unclear. In the present research, TM3 Leydig cells were treated with 200 µM phthalic acid mono-2-ethylhexyl ester (MEHP, bio-metabolite of DEHP), and then the mRNA and lncRNA sequencing of TM3 Leydig cells was performed. Mice were exposed prepubertally to 0 or 500 mg DEHP/kg/day. RNA sequencing of mouse testes was performed to verify the RNA-seq results in vitro. The expression patterns of relevant genes and proteins were verified using real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting. DEHP and MEHP exposure led to testicular damage and accelerated cell aging via ROS accumulation. RNA sequencing analyses indicated that FOXO signaling and longevity regulation pathways were activated in resistance to ROS accumulation. FOXO signaling and longevity regulation pathway-related genes and proteins were also activated. By constructing a competing endogenous RNA (ceRNA) network, we observed that the ceRNA network might play a role in regulating FOXO signaling and longevity regulation pathways in response to excessive ROS accumulation and cell aging. In summary, our data here suggests that the ceRNA network may play a role in regulating FOXO signaling and longevity pathways in response to DEHP exposure in mouse testes.

Effects of Fe-Mn oxide-modified biochar composite applications on phthalate esters (PAEs) accumulation in wheat grains and grain quality under PAEs-polluted brown soil

Phthalate esters (PAEs), such as dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), are used extensively as additives and plasticizers, and have become ubiquitous in the environment. PAEs in the soil could have adverse effects on crop plants as well as humans via accumulations in food chain. Thus, it is important to explore strategies to reduce the bioavailability of phthalate esters. We investigated the effects of Fe-Mn oxide-modified biochar composite (FMBC) applications on the quality of wheat grown in DBP- and DEHP-polluted brown soil. The application of FMBC and biochar (BC) increased the wheat grain biomass by 9.71-223.01% and 5.40-120.15% in the DBP-polluted soil, and 10.52-186.21% and 4.50-99.53% in the DEHP-spiked soil in comparison to the controls. All FMBC treatments were better than the BC treatments, in terms of decreasing DBP and DEHP bioavailability for the wheat grains. The activities of the glutamine synthetase and glutamic-pyruvic transaminase in the flag leaves at the filling stage and of granule-bound starch synthase, soluble starch synthase, and adenosine diphosphate-glucose pyrophosphorylase in the grains at maturity increased significantly with increases in either the BC or FMBC applications. This, in turn, increased the starch, protein, and amino acid content in the wheat grains. Compared with the BC treatment, the FMBC amendment induced only slight increases in the aforementioned factors. This study offers novel insights into potential strategies for decreasing PAEs bioavailability in soil, with potential positive implications for crop quality and environmental health improvements.

Exposure to Di-2-ethylhexyl Phthalate and Benign Prostatic Hyperplasia, NHANES 2001-2008

30% of men suffer from benign prostatic hyperplasia (BPH) worldwide. As one of the most important members of Phthalate esters, previous studies suggested ubiquitous Di-(2-ethylhexyl) phthalate (DEHP) exposure is associated with such male disorders by interfering with endocrine system, however, little is known about the association between DEHP exposure and BPH. The objective of this study was to study the potential association by the 2001-2008 National Health and Nutrition Examination Survey (NHANES) data. The data was collected, and multiple logistic regression was adapted to measure the association. The concentrations of DEHP (∑DEHP) were calculated by each metabolite and split into quartiles for analysis. Results showed that the odds ratio (OR) decreased with increased ∑DEHP concentration. In the crude model, the OR for the second quartile (OR = 1.60, 95%CI [1.24, 2.07]) was obviously higher compared with the lowest quartile. However, the OR for the highest quartile (OR = 0.55, 95%CI [0.44,0.69]) was lower than that for the third quartile (OR = 0.77, 95%CI [0.61, 0.97]), and the OR for the third and the highest quartile were significantly lower than that of the lowest quartile, which suggested biphasic effects of DEHP based on concentration. The results showed the same trend after adjusting confounding factors. The study suggested that the DEHP exposure is associated with DEHP, and the results adds limited evidence to study this topic, however, further researches are needed to determine if the status of BPH can be changed by controlling DEHP exposure.

DEHP induce cholesterol imbalance via disturbing bile acid metabolism by altering the composition of gut microbiota in rats

Di(2-ethylhexyl) phthalate (DEHP) is one of the most widespread environmental contaminants worldwide because of its massive production, extensive use in common products, and liability to leach from products. This study investigated the mechanisms of DEHP mediated alteration of lipid metabolism. Rats were treated with 0.5 mg kg^-1 d^-1 of DEHP for 23 weeks. Results showed that the treatment induced cholesterol imbalance. Further fecal transplantation experiments corroborated the involvement of gut microbiota in DEHP-induced cholesterol imbalance. In addition, 16S rRNA gene sequencing analysis of cecal contents showed that DEHP disrupted the gut microbiota diversity in rats and increased the ratio of Firmicutes to Bacteroidetes. Further cecal metabolomic analyses, bile salt hydrolase enzyme activity, and gene expression examination revealed that chronic DEHP exposure generated a bile acid profile in the gut that is a more potent activator of farnesoid X receptor (FXR). The activation of FXR in the gut induced the expression of fibroblast growth factor 15, which subsequently suppressed cytochrome P450 family 7 subfamily A member 1 in the liver and bile acid synthesis. These results suggest that DEHP might induce cholesterol imbalance by regulating bile acid metabolism via the remodeling of the gut microbiota.

Physiological responses of Arthrobacter sp. JQ-1 cell interfaces to co-existed di-(2-ethylhexyl) phthalate (DEHP) and copper

Arthrobacter sp. JQ-1 can completely degrade 500 mg/L of DEHP within 3 days. The minimum inhibitory concentrations (MICs) of Cu²⁺ could reach 1.56 mM, however, 5.0 mg/L Cu²⁺ apparently inhibited DEHP degradation and bacterial growth. Consequently, JQ-1 was exposed to the DEHP-copper environment to verify the toxicity mechanism based on the physiological responses of cellular multiple interfaces (cellular surface, membrane and intracellular characteristics). The results showed the combination of 500 mg/L DEHP and 5.0 mg/L Cu²⁺ significantly decreased cell surface hydrophobicity (CSH) and the absolute value of zeta potential, which implied the bioavailability of DEHP was decreased. The cellular surface changes were mainly due to the interaction between Cu²⁺ and some functional groups (CH₂, CH₃, aromatic rings, and amide). The weakened proton-motive force (PMF) across the plasma membrane may interfere the formation and utilization of energy, which is not conducive to the repair process of cellular damages. In this study, Non-invasive micro-test technology (NMT) was applied to the research of combined toxicity of DEHP and heavy metal ions for the first time. DEHP-copper intensified K⁺ efflux and Ca²⁺ influx across the plasma membrane, which disturbed ion homeostasis of K⁺ and Ca²⁺ and might induce apoptosis and further inhibit DEHP degradation. The decline of intracellular esterase activity indicated that the metabolic capacity is apparently restrained. This study enhances our understanding of cellular different interface processes responding to combined pollutants.

The phthalate DEHP modulates the estrogen receptors α and β increasing lactotroph cell population in female pituitary glands

Humans are exposed to numerous endocrine disruptors on a daily basis, which may interfere with endogenous estrogens, with Di-(2-ethylhexyl) phthalate (DEHP) being one of the most employed. The anterior pituitary gland is a target of 17β-estradiol (E2) through the specific estrogen receptors (ERs) α and β, whose expression levels fluctuate in the gland under different contexts, and the ERα/β index is responsible for the final E2 effect. The aim of the present study was to evaluate in vivo and in vitro the DEHP effects on ERα and β expression in the pituitary cell population, and also its impact on lactotroph and somatotroph cell growth. Our results revealed that perinatal exposure to DEHP altered the ERα and β expression pattern in pituitary glands from prepubertal and adult female rats and increased the percentage of lactotroph cells in adulthood. In the in vitro system, DEHP down-regulated ERα and β expression, and as a result increased the ERα/β ratio and decreased the percentages of lactotrophs and somatotrophs expressing ERα and β. In addition, DEHP increased the S + G2M phases, Ki67 index and cyclin D1 in vitro, leading to a rise in the lactotroph and somatotroph cell populations. These results showed that DEHP modified the pituitary ERα and β expression in lactotrophs and somatotrophs from female rats and had an impact on the pituitary cell growth. These changes in ER expression may be a mechanism underlying DEHP exposure in the pituitary gland, leading to cell growth deregulation.

Quantification of bis(2-ethylhexyl) phthalate released by medical devices during respiratory assistance and estimation of patient exposure

Bis(2-ethylhexyl) phthalate (DEHP) migration from polyvinyl chloride (PVC) has been studied with infusion, transfusion and extracorporeal oxygenation devices, but no study has been conducted to estimate its migration via respiratory medical devices (MDs). This work aims to develop an ex vivo model to quantify DEHP released doses by these MDs, which will then be used to estimate newborns DEHP exposure from respiratory assistance MDs. We followed the Frensh National Research and Safety Institute (INRS) recommendations for the validation of a collecting and analysing method of DEHP in air, which will be used to quantify DEHP in air passing through PVC respiratory assistance MDs. The developed method met all the validation criteria for DEHP determination in air. DEHP in air passing through MDs on the sixth day reached a cumulative quantity of 122.86 μg when using a flow rate of 4 L min^-1 of non-humidified air while it was of 49.22 μg; 58.12 μg and 29.61 μg with flow rates of 2 L min^-1 of humidified air, 2 L min^-1 of dry air and 4 L min^-1 of humidified air, respectively. Model application to two patients undergoing two different respiratory procedure demonstrated that noninvasive ventilation patient received higher dose of inhaled DEHP, confirmed by DEHP metabolites quantification in urine. Although the protective effect of air humidifiers on DEHP exposure was demonstrated, the effect of flow rate is difficult to be established. This developed method should be tested to verify its capacity to collect and quantify other plasticizers used in PVC MDs.

Uptake and toxicity of di-(2-ethylhexyl) phthalate in Brassica chinensis L

This work focuses on the bioaccumulation and toxic effects of di-(2-ethylhexyl) phthalate (DEHP) in the leafy vegetable Shanghaiqing (SHQ) (Brassica chinensis L.). The accumulated DEHP amount in the edible part and roots of SHQ increased as the DEHP concentration in the soil increased. DEHP accumulation was higher in the roots than in the edible part of the plant. The root concentration factors and bioaccumulation factors for DEHP in SHQ were 0.13-2.49 and 0.03-2.00, respectively. The DEHP translocation factors were below 1.0, indicating that DEHP preferentially accumulated in plant roots. The DEHP risk index in the edible part of SHQ in relation to the human body and in terms of dietary exposure risk assessment was also below 1.0, indicating a low health risk. High DEHP concentrations caused 1) inhibition of SHQ growth, 2) an increase in SHQ chlorophyll and malondialdehyde contents and 3) a decrease in soluble sugar and vitamin contents. Low DEHP concentrations stimulated total superoxide dismutase, peroxidase and catalase activities, while high DEHP levels showed an inhibitory effect. DEHP presence in soil affected not only SHQ growth but also quality. Our results provide the data needed for the proper assessment of food safety and the ecological impact of DEHP contamination in agricultural soils.

How does continuous venovenous hemofiltration theoretically expose (ex-vivo models) inpatients to diethylhexyladipate, a plasticizer of PVC medical devices?

Continuous venovenous hemofiltration (CVVH) is widely used in intensive care units to treat patients with acute kidney injury requiring renal replacement therapy. The medical devices (MD) used for CVVH include a hemofilter and tubings made of plasticized PVC. Due to its known reprotoxicity, diethylhexyl phthalate (DEHP) has been replaced by alternatives such as diethylhexyladipate (DEHA) in some of these tubings. The migration of DEHA from hemofiltration systems has not been assessed and thus the level of patient exposure to this DEHP-alternative remains unknown. In this study, 2 CVVH models were used to evaluate the potential migration of DEHA from PVC tubings, allowing the determination of (Rachoin and Weisberg, 2019) the highest rates of DEHA able to migrate into a simulant flowing in a marketed adult CVVH circuit by disregarding any metabolisation and (Krieter et al., 2013) the clinical-reflecting exposure of patients to this plasticizer and its metabolites by assessing their migration into blood. In the first model, we showed that patients undergoing a CVVH procedure may be exposed to high rates of DEHA. Moreover, DEHA is continuously hydrolyzed into its primary metabolite MEHA (monoethylhexyladipate), which may reach cytotoxic level in the patients' blood. When looking from a « safer » MD perspective, DEHA might not be the best alternative plasticizer for CVVH tubings. However, to reflect clinical conditions, this study should be completed by an in-vivo evaluation (biomonitoring) of the oxidized metabolites of DEHA in urines of inpatients undergoing CVVH.

Neurological effects of subchronic exposure to dioctyl phthalate (DOP), lead, and arsenic, individual and mixtures, in immature mice

Dioctyl phthalate (DOP) (200, 500, and 1000 mg kg^-1 bw, i.g.), Pb (Ac)₂ (50 mg L^-1, p.o.), and NaAsO₂ (10 mg L^-1, p.o.) were administered individually and as mixtures to weanling male mice for 8 weeks. It was observed that Pb, As, and DOP exposure could significantly inhibit the growth and development of mice. Compared with the Pb, As, and Pb + As groups, the activities of iNOS and TNOS were significantly increased, the levels of AChE and SOD were significantly decreased, and the level of MDA was significantly increased in the Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups. The factorial analysis shows that the iNOS, TNOS, and AChE present synergistic effects on Pb, As, and DOP. A significant increase of escape latency and a significant decrease of original platform quadrant stops were observed between Pb + As + DOP-H and Pb + As groups. The factorial analysis shows that there was a synergistic effect on Pb, As, and DOP. Compared with that of the control group, the expression levels of caspase-3 and Bax expression in Pb + As, DOP-H, Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups were significantly increased in the hippocampus. The expression levels of Bcl-2 expression decreased significantly and the Bax/Bcl-2 ratio increased significantly. Pathological alterations on the hippocampus were found in exposed groups. This result shows that combined exposure of Pb, As, and DOP could induce neurotoxicity, of which possible mechanism is hippocampal neuronal apoptosis. Graphical abstract This study shows that there were three components with eigenvalues greater than 1, which together explained 89.40% of total variance. The first component (PC1) showed high loadings on B-SOD, L-SOD, B-MDA, L-MDA, K-MDA, iNOS, tNOS, and AChE and accounted for 46.55% of the total variance after Varimax rotation. PC2 accounted for 23.81% of the total variance with high loadings on B-As, L-As, K-As, and K-SOD, whereas PC3 showed high loadings on B-Pb, L-Pb, and K-Pb and accounted for 19.04% of the total variance.

Identification and characterization of a novel phthalate-degrading hydrolase from a soil metagenomic library

Phthalate esters have raised public concerns owing to their effects on the environment and human health. We identified a novel phthalate-degrading hydrolase, EstJ6, from a metagenomic library using function-driven screening. Phylogenetic analysis indicated that EstJ6 is a member of family IV esterases. EstJ6 hydrolyzed various dialkyl and monoalkyl phthalate esters, and exhibited high hydrolytic activity (128 U/mg) toward dibutyl phthalate at 40 °C and pH 7.5. EstJ6 hydrolyzed not only common phthalate esters with simple side chains but also diethylhexyl phthalate and monoethylhexyl phthalate, which have complex and long side chains. Site-directed mutagenesis indicated that the catalytic triad residues of EstJ6 consists of Ser146, Glu240, and His270. EstJ6 is therefore a promising biodegradation enzyme, and our study illustrates the advantages of a metagenomic approach in identifying enzyme-coding genes for agricultural, food, and biotechnological applications.

Sources of clinically significant neonatal intensive care unit phthalate exposure

In the United States each year, more than 300,000 infants are admitted to neonatal intensive care units (NICU) where they are exposed to a chemical-intensive hospital environment during a developmentally vulnerable period. Although multiple studies have demonstrated elevated phthalate biomarkers in NICU patients, specific sources of NICU-based phthalate exposure have not been identified.In this study, premature newborns with birth weight <1500 g were recruited to participate in a prospective environmental health cohort during the NICU hospitalization. Exposure to specific NICU equipment was recorded daily during the NICU hospitalization. One hundred forty-nine urine specimens from 71 infants were analyzed for phthalate metabolites using high-performance liquid chromatography/tandem mass spectrometry.In initial analyses, exposure to medical equipment was directly related to phthalate levels, with DEHP biomarkers 95-132% higher for infants exposed to specific medical equipment types compared to those without that equipment exposure (p < 0.001-0.023). This association was mirrored for clinically relevant phthalate mixtures whether composed of DEHP metabolites or not (p = 0.002-0.007). In models accounting for concurrent equipment use, exposure to respiratory support was associated with DEHP biomarkers 50-136% higher in exposed compared to unexposed infants (p = 0.007-0.036). Phthalate mixtures clinically relevant to neurobehavioral development were significantly associated with non-invasive respiratory support (p = 0.008-0.026). Feeding supplies and intravenous lines were not significantly associated with clinically important phthalate mixtures.Respiratory support equipment may be a significant and clinically relevant NICU source of phthalate exposure. Although manufacturers have altered feeding and intravenous supplies to reduce DEHP exposure, other sources of exposure to common and clinically impactful phthalates persist in the NICU.

Accumulation and metabolism of di(n-butyl) phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) in mature wheat tissues and their effects on detoxification and the antioxidant system in grain

Di(2-ethylhexyl) phthalate (DEHP) and di(n-butyl) phthalate (DBP) are the major phthalic acid esters to be used during the plastic manufacturing process; they have emerged as pollutants that result in serious environmental problems. However, their impacts on wheat at the reproductive stage remain unclear. Here, we examined the distribution of DEHP and DBP and their respective metabolites mono(2-ethylhexyl) phthalate (MEHP) and mono-n-butyl phthalate (MBP) in mature wheat, along with the mechanism of detoxification and oxidative burst in wheat grains under DBP and DEHP stress conditions in a pot experiment. High-performance liquid chromatography showed that the contents of DBP and DEHP, as well as their metabolites, i.e., MBP and MEHP, presented the highest values in the grain, followed by the stem, leaf, and root. Entry of DBP and DEHP into the grain from the soil induced the production of reactive oxygen species, accompanied by the upregulated expression and activity of the antioxidant enzymes (e.g., cytochrome P4503A4 and peroxidase). The metacaspase type I gene was also upregulated in response to DBP and DEHP stress in grains, which is indicative of programmed cell death to maintain normal physiological activities and to resist cell damage. DBP and DEHP stress-damaged cells in the grains underwent programmed cell death by upregulating the expression levels of the metacaspase type I gene. These results provide a new perspective for improving wheat tolerance to DBP and DEHP through the use of genetic engineering strategies.

Microstructure, bacterial community and metabolic prediction of multi-species biofilms following exposure to di-(2-ethylhexyl) phthalate (DEHP)

The occurrence and transportation of phthalate esters in biofilms from natural and engineered sources have attracted considerable research interest. However, little information is available highlighting the responses of multi-species biofilms in terms of their physicochemical structure and bacterial community induced by phthalate esters. Di-(2-ethylhexyl) phthalate (DEHP), a model phthalate eater, was selected to treat multi-species biofilm aggregates, including an attached biofilm from a moving bed bioreactor (MBBR), a periphytic biofilm from a natural source and activated sludge in short-term exposure experiments (120 h). The production of extracellular polymeric substances (EPS) from the three biofilms initially decreased and then slightly increased after exposure to DEHP, consistent with the variation of the most dominant fluorescent compounds consisting of humic-acid-like organic substances. The MBBR and periphytic biofilms secreted more fluorescence compounds than the activated sludge during the exposure period. The organic matter in the EPS was converted into smaller molecules, while limited variation was observed in the functional groups and secondary protein structures. Acinetobacter and Bacillus demonstrated significant increases and were likely the key genera responsible for DEHP degradation. The combined use of spectral, chromatographic and sequencing analyses indicated that the periphytic biofilm was more resistant to DEHP, possibly owing to the presence of more mature assemblages, including cells with higher metabolic activity and a higher diversity within the bacterial community. This study provides insights into the microstructural and bacterial responses of multi-species biofilms following exposure to phthalate esters, and provides important guidance for bioremediation of phthalate esters using periphytic biofilms.

Phthalate plasticizer di(2-ethyl-hexyl) phthalate induces cyclooxygenase-2 expression in gastric adenocarcinoma cells

The phthalate plasticizer, di(2-ethyl-hexyl) phthalate (DEHP), and its derived metabolites are common anthropogenic environmental toxins, which are known to act as endocrine disruptors. Numerous studies have associated DEHP with disruption of sex hormones, abnormal development of reproductive organs, allergies, and inflammation. Its role in promoting inflammation has been reported by both human epidemiological and animal studies. In stomach tissue, chronic inflammation is known to accompany mucosal damage, and pave the way to gastritis, stomach ulcers, and ultimately gastric cancer. Eastern Asian populations possess the highest gastric cancer incidences in the world. Coincidentally, East Asia is one of the world's major sites for plastics manufacture and export. Thus, possible correlations between DEHP, a common plasticizer, and gastric cancer are of great interest. Our study revealed several critical findings. First, even at very low dosage, mimicking the residual plasticizer exposure, detrimental effects of DEHP on gastric cells can be detected. Second, gastric cells treated with DEHP increased cyclooxygenase-2 (COX-2) in a time-dependent manner. Third, promoter deletion studies revealed a critical role of nuclear factor-kappa B (NF-κB) for COX-2 gene responses. Finally, our results indicated that a low concentration of DEHP is able to trigger COX-2 activation via the extracellular signal-regulated kinase (ERK1/2) and NF-κB signaling pathway. Taken together, we demonstrate that very low doses of DEHP enhance the expression of the prototypical inflammatory gene, COX-2, in gastric cancer cells via ERK1/2 and NF-κB activation. This study provides important insights into the inflammatory process and damages associated with phthalate plasticizers exposure.