The oxidative stress responses caused by phthalate acid esters increases mRNA abundance of base excision repair (BER) genes in vivo and in vitro

Mitochondrial DNA Stress-Mediated Health Risk to Dibutyl Phthalate Contamination on Zebrafish (Danio rerio) at Early Life Stage

Plastics contaminations are found globally and fit the exposure profile of the planetary boundary threat. The plasticizer of dibutyl phthalate (DBP) leaching has occurred and poses a great threat to human health and the ecosystem for decades, and its toxic mechanism needs further comprehensive elucidation. In this study, environmentally relevant levels of DBP were used for exposure, and the developmental process, oxidative stress, mitochondrial ultrastructure and function, mitochondrial DNA (mtDNA) instability and release, and mtDNA-cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway with inflammatory responses were measured in zebrafish at early life stage. Results showed that DBP exposure caused developmental impairments of heart rate, hatching rate, body length, and mortality in zebrafish embryo. Additionally, the elevated oxidative stress damaged mitochondrial ultrastructure and function and induced oxidative damage to the mtDNA with mutations and instability of replication, transcription, and DNA methylation. The stressed mtDNA leaked into the cytosol and activated the cGAS-STING signaling pathway and inflammation, which were ameliorated by co-treatment with DBP and mitochondrial reactive oxygen species (ROS) scavenger, inhibitors of cGAS or STING. Furthermore, the larval results suggest that DBP-induced mitochondrial toxicity of energy disorder and inflammation were involved in the developmental defects of impaired swimming capability. These results enhance the interpretation of mtDNA stress-mediated health risk to environmental contaminants and contribute to the scrutiny of mitochondrial toxicants.

Dibutyl phthalate exposure induced mitochondria-dependent ferroptosis by enhancing VDAC2 in zebrafish ZF4 cells

Dibutyl phthalate (DBP) contamination has raised global concern for decades, while its health risk with toxic mechanisms requires further elaboration. This study used zebrafish ZF4 cells to investigate the toxicity of ferroptosis with underlying mechanisms in response to DBP exposure. Results showed that DBP induced ferroptosis, characterized by accumulation of ferrous iron, lipid peroxidation, and decrease of glutathione peroxidase 4 levels in a time-dependent manner, subsequently reduced cell viability. Transcriptome analysis revealed that voltage-dependent anion-selective channel (VDAC) in mitochondrial outer membrane was upregulated in ferroptosis signaling pathways. Protecting mitochondria with a VDAC2 inhibitor or siRNAs attenuated the accumulation of mitochondrial superoxide and lipid peroxides, the opening of mitochondrial permeability transition pore (mPTP), and the overload of iron levels, suggesting VDAC2 oligomerization mediated the influx of iron into mitochondria that is predominant and responsible for mitochondria-dependent ferroptosis under DBP exposure. Furthermore, the pivotal role of activating transcription factor 4 (ATF4) was identified in the transcriptional regulation of vdac2 by ChIP assay. And the intervention of atf4b inhibited DBP-induced VDAC2 upregulation and oligomerization. Taken together, this study reveals that ATF4-VDAC2 signaling pathway is involved in the DBP-induced ferroptosis in zebrafish ZF4 cells, contributing to the in-depth understanding of biotoxicity and the ecological risk assessment of phthalates.

Biotoxicity responses of zebrafish in environmentally relevant concentration of di (2-ethylhexyl) phthalate

As an emerging environmental contaminant, di (2-ethylhexyl) phthalate (DEHP) is widely present in the aquatic environment, however, the effects and underlying mechanisms of DEHP on the aquatic organisms are poorly understood. This study systematically investigated the ecotoxicity induced by chronic exposure to environmental relevant concentrations of DEHP (0.03 mg/L, 0.1 mg/L, and 0.3 mg/L) on zebrafish brain. Results indicated that DEHP exposure significantly increased the levels of ROS and disturbance of the antioxidant enzymes activities in the brain, which may further enhance lipid peroxidation and DNA damage. Furthermore, acetylcholinesterase activity was first stimulated and inhibited by exposure to DEHP, and the antioxidant and apoptosis related genes were mainly upregulated. Risk assessment indicated that the ecotoxicity of DEHP on the zebrafish showed an "enhancement-reduction" trend as the exposure time was prolonged. Overall, these results provided new insights and useful information to ecological risk assessment and environmental management of DEHP pollution.

Crosstalk between aryl hydrocarbon receptor and Wnt/β-catenin signaling pathway: Possible culprit of di (2-ethylhexyl) phthalate-mediated cardiotoxicity in zebrafish larvae

Typical plasticizer di (2-ethylhexyl) phthalate (DEHP) has been demonstrated to induce cardiotoxicity in zebrafish, but the potential molecular mechanisms involved have not been fully elucidated. Aryl hydrocarbon receptor (AhR), an essential protein for inducing developmental abnormalities, has been demonstrated to be activated by DEHP in other species, but whether the AhR signaling pathway also contributes to DEHP-mediated cardiac developmental toxicity in zebrafish remains unclear. Firstly, molecular docking simulations initially confirmed the possibility that DEHP has AhR agonistic activity. To further confirm this conjecture, this work analyzed the changes of cardiac-related indexes in zebrafish stressed by DEHP at individual, protein, and gene levels. The results showed that DEHP mediated cardiac phenotypic developmental defects, increased CYP1A1 activity, and oxidative stress as well as significant changes in the expression levels of key proteins and genes of AhR, Wnt/β-catenin, and Nrf2-Keap1 signaling pathways. Notably, the addition of AhR inhibitors effectively alleviated the above negative effects, indicating that the AhR signaling pathway and its crosstalk with the Wnt/β-catenin signaling pathway is an essential pathway for DEHP-mediated cardiac developmental toxicity. Overall, this work enriches the molecular mechanism of DEHP-mediated cardiac developmental defects in zebrafish and provides a reliable biomarker for future environmental risk assessment of DEHP.

Oxidatively generated DNA damage mediates the associations of exposure to phthalates with uterine fibroids and endometriosis: Findings from TREE cohort

BACKGROUND

Epidemiological studies on phthalate exposures in associations with uterine fibroids (UF) and endometriosis (EMT) are inconsistent. The underlying mechanisms are poorly understood.

OBJECTIVES

To investigate the relationships of urinary phthalate metabolites with UF and EMT risks, and further to examine the mediating role of oxidative stress.

METHODS

This study included 83 and 47 women separately diagnosed with UF and EMT, as well as 226 controls from the Tongji Reproductive and Environmental (TREE) cohort. Two spot urine samples from each woman were analyzed for two oxidative stress indicators and eight urinary phthalate metabolites. Unconditional logistic regression models or multivariate regression models were fitted to evaluate the associations among phthalate exposures, oxidative stress indicators, and the risks of UF and EMT. The potential mediating role of oxidative stress was estimated by the mediation analyses.

RESULTS

We observed that each ln-unit increase in urinary mono-benzyl phthalate (MBzP) concentrations was associated with increased UF risk [adjusted OR (aOR): 1.56, 95% CI: 1.20, 2.02], and that each ln-unit increase in urinary MBzP (aOR: 1.48, 95% CI: 1.09, 1.99), mono-isobutyl phthalate (MiBP) (aOR: 1.83, 95% CI: 1.19, 2.82), and mono-2-ethylhexyl phthalate (MEHP) (aOR: 1.66, 95% CI: 1.19, 2.31) concentrations were associated with increased EMT risk (all FDR-adjusted P < 0.05). Moreover, we observed that all tested urinary phthalate metabolites were positively associated with two oxidative stress indicators [4-hydroxy-2-nonenal-mercapturic acid (4-HNE-MA) and 8-hydroxy-2-deoxyguanosine (8-OHdG)], in which 8-OHdG was associated with increased risks of UF and EMT (all FDR-adjusted P < 0.05). The mediation analyses showed that 8-OHdG mediated the positive relationships of MBzP with UF risk, and of MiBP, MBzP, and MEHP with EMT risk, with the estimated intermediary proportion ranging from 32.7% to 48.1%.

CONCLUSIONS

Oxidatively generated DNA damage may mediate the positive associations of certain phthalate exposures with the risks of UF and EMT. However, further investigation is warranted to confirm these findings.

Environmental occurrence and ecotoxicity of aquaculture-derived plastic leachates

Plastic products such as fishing nets and foam buoys have been widely used in aquaculture. To enhance the desirable characteristics of the final equipment, plastic gear for aquaculture is mixed with a wide range of additives. Recent studies have shown that additives could be leached out to the environment with a long-term use of aquaculture plastics, forming aquaculture-derived plastic leachates. It should be emphasized that some leachates such as phthalic acid esters (PAEs) and organophosphate esters (OPEs) are endocrine disruptors, which could increase the exposure risk of aquatic products and subsequently display potential threats to human health via food chain. However, systematic studies on the release, occurrence, bioaccumulation, and toxic effects of aquaculture-derived plastic leachates are missing, overlooking their potential sources and ecotoxicological risks in aquatic environments. We have reviewed and compared the concentrations of major plastic leachates in the water environment and organisms of global aquaculture and non-farmed areas, confirming that aquaculture leachate is an important source of contaminants in the environment. Moreover, the toxic effects of aquaculture-derived plastic additives and the related mechanisms are summarized with fish as a representative, revealing their potential health risk. In addition, we proposed current challenges and future research needs, which provides scientific guidance for the use and management of plastic products in aquaculture industries.

Assessing CaMPARI as new approach methodology for evaluating neurotoxicity

Developmental exposure to environmental toxicants has been linked to the onset of neurological disorders and diseases. Despite substantial advances in the field of neurotoxicology, there remain significant knowledge gaps in our understanding of cellular targets and molecular mechanisms that mediate the neurotoxicological endpoints associated with exposure to both legacy contaminants and emerging contaminants of concern. Zebrafish are a powerful neurotoxicological model given their high degree sequence conservation with humans and the similarities they share with mammals in micro- and macro-level brain structures. Many zebrafish studies have effectively utilized behavioral assays to predict the neurotoxic potential of different compounds, but behavioral phenotypes are rarely able to predict the brain structures, cell types, or mechanisms affected by chemical exposures. Calcium-modulated photoactivatable ratiometric integrator (CaMPARI), a recently developed genetically-encoded calcium indicator, undergoes a permanent green to red switch in the presence of elevated intracellular Ca2+ concentrations and 405-nm light, which allows for a "snapshot" of brain activity in freely-swimming larvae. To determine whether behavioral results are predictive of patterns of neuronal activity, we assessed the effects of three common neurotoxicants, ethanol, 2,2',3,5',6-pentachlorobiphenyl (PCB 95), and monoethylhexyl phthalate (MEHP), on both brain activity and behavior by combining the behavioral light/dark assay with CaMPARI imaging. We demonstrate that brain activity profiles and behavioral phenotypes are not always concordant and, therefore, behavior alone is not sufficient to understand how toxicant exposure affects neural development and network dynamics. We conclude that pairing behavioral assays with functional neuroimaging tools such as CaMPARI provides a more comprehensive understanding of the neurotoxic endpoints of compounds while still offering a relatively high throughput approach to toxicity testing.

Assessment of the benefits of essential fatty acids and risks associated with antimicrobial residues in aquatic products: A case study of Chinese mitten crab (Eriocheir sinensis)

Much attention has been given to the safety and quality of aquatic products, including consuming Chinese mitten crab (Eriocheir sinensis), which offers both nutritional benefits and toxicological risks. Eighteen sulfonamides, 9 quinolones and 37 fatty acids were analyzed in 92 crab samples from primary aquaculture provinces in China. Enrofloxacin and ciprofloxacin have been mentioned as typical antimicrobials occurring at the greatest concentrations (>100 μg/kg, wm). By use of an in vitro method, the proportions of enrofloxacin, ciprofloxacin and essential fatty acids (EFAs, DHA and EPA) in ingested nutrients were determined to be 12 %, none and 95 %, respectively. The risk-benefit quotient (HQ) between the adverse effects of antimicrobials and nutritional benefits of EFAs in crabs found that HQs based on data after digestion were significantly less (HQ = 0.0086) than that of the control group where no digestion occurred (HQ = 0.055). This result suggested that (1) there was less risk posed by antimicrobials due to the consumption of crab, and (2) ignoring the bioaccessible fraction of antimicrobials in crabs might overestimate risks to the health of humans due to dietary exposure. Meaning bioaccessibility can improve the accuracy of the risk assessment process. Realistic risk evaluation should be recommended to achieve a quantified assessment of the dietary risks and benefits of aquatic products.

New Insights into How Melatonin Ameliorates Bisphenol A-Induced Colon Damage: Inhibition of NADPH Oxidase

Bisphenol A (BPA) is an endocrine disruptor, widely employed, and detected in many consumer products and food items. Oral intake poses a great threat to intestinal health. Melatonin (MT) stands out as an endogenous, dietary, and therapeutic molecule with potent antioxidant capacity. To explore the protective effect of MT against BPA-induced colon damage and the role of NADPH oxidase (NOX) in this process, we established mice and colonic epithelial cell (NCM460) models of BPA exposure and treated with MT. In vitro and in vivo results showed that MT ameliorated BPA-induced oxidative stress, DNA damage, and the G2/M cell cycle arrest. MT also downregulated the expression of NOX family-related genes, reversed the inhibition of the base excision repair (BER) pathway, promoted the activation of non-homologous end-joining (NHEJ) pathway, and suppressed the mRNA and protein expression of ATM, Chk1/2, and p53. Diphenyleneiodonium chloride (DPI), a NOX-specific inhibitor, also attenuated the toxic effects of BPA on NCM460 cells. Furthermore, molecular docking revealed that MT could bind to NOX. Conclusively, our finding suggested that MT can ameliorate BPA-induced colonic DNA damage by scavenging NOX-derived ROS, which further attenuates G2/M cell cycle arrest dependent on the ATM-Chk1/2-p53 axis.

Prenatal exposure to phthalates and polybrominated diphenyl ethers on neonatal health: A birth cohort study in Guangxi, China

Few epidemiological studies have focused on prenatal phthalates (PAEs) and polybrominated diphenyl ethers (PBDEs) exposure to neonatal health in China. This study aimed to assess the associations between prenatal PAEs and PBDEs exposure and neonatal health in Guangxi, a Zhuang autonomous region of China. Concentrations of 4 PAEs metabolites (mPAEs) and 5 PBDEs congeners were measured in the serum of 267 healthy pregnant women. Birth outcomes and clinical data of neonates were collected after delivery. Mono-(2-Ethylhexyl) phthalate (MEHP) (81.52%) and BDE47 (35.21%) were the mPAEs and PBDEs congeners with the highest detection rate in serum. Prenatal exposures to mono-n-butyl phthalate (MBP), MEHP, and ΣmPAEs were negatively associated with birth weight (BW), birth length (BL), and gestational age (GA). Higher exposures to MBP, MEHP, and ΣmPAEs were associated with an increased odds ratio (OR) for low birth weight (LBW), but exposure to BDE28 exhibited the opposite effect. Moreover, higher exposures to MBP, MEHP, ΣmPAEs, BDE99, and ΣPBDEswere associated with an increased OR for premature birth (PTB) (P < 0.05). In contrast to MBP exposure, BDE28 exposure was associated with a higher OR for neonatal jaundice (NNJ) (P < 0.05). The interaction analysis showed a positive interaction between monoethyl phthalate (MEP) and BDE28 on the risk of NNJ and positive interaction between ΣmPAEs and BDE47 on the risk of NNJ. In addition, there are ethnicity-specific associations of prenatal PBDEs exposure with neonatal health in individuals of Zhuang and Han nationalities, and boy neonates were more sensitive to prenatal PBDEs exposure than girl neonates. The results revealed that prenatal exposure to mPAEs and PBDEs might have adverse effects on neonatal development, and the effects might be ethnicity- and sex-specific.

DNA repair genes play a variety of roles in the development of fish embryos

Embryogenesis is one of the most important life stages because it determines an organism's healthy growth. However, embryos of externally fertilizing species, such as most fish, are directly exposed to the environment during development and may be threatened by DNA damaging factors (pollutants, UV, reactive oxygen species). To counteract the negative effects of DNA fragmentation, fish embryos evolved complex damage response pathways. DNA repair pathways have been extensively studied in some fish species, such as zebrafish (Danio rerio). Our literature review, on the other hand, revealed a paucity of knowledge about DNA damage response and repair in non-model aquaculture fish species. Further, several pieces of evidence underlie the additional role of DNA repair genes and proteins in organogenesis, spatiotemporal localization in different tissue, and its indispensability for normal embryo development. In this review, we will summarize features of different DNA repair pathways in course of fish embryo development. We describe how the expression of DNA repair genes and proteins is regulated during development, their organogenetic roles, and how the expression of DNA repair genes changes in response to genotoxic stress. This will aid in addressing the link between genotoxic stress and embryo phenotype. Furthermore, available data indicate that embryos can repair damaged DNA, but the effects of early-life stress may manifest later in life as behavioral changes, neoplasia, or neurodegeneration. Overall, we conclude that more research on DNA repair in fish embryos is needed.

Silver nanoparticles induce developmental toxicity via oxidative stress and mitochondrial dysfunction in zebrafish (Danio rerio)

Sliver nanoparticles (AgNPs) are widely used in industry, agriculture, and medicine, potentially resulting in adverse effects on human health and aquatic environments. Here, we investigated the developmental toxicity of zebrafish embryos with acute exposure to AgNPs. Our results demonstrated developmental defects in 4 hpf zebrafish embryos after exposure to different concentrations of AgNPs for 72 h. In addition, RNA-seq profiling of zebrafish embryos after AgNPs treatment. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that the differentially expressed genes (DEGs) were enriched in DNA replication initiation, oxidoreductase activity, DNA replication, cellular senescence, and oxidative phosphorylation signaling pathways in the AgNPs-treated group. Notably, we also found that AgNPs exposure could result in the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), the inhibition of superoxide dismutase (SOD), catalase (CAT), and mitochondrial complex I-V activities, and the downregulated expression of SOD, CAT, and mitochondrial complex I-IV chain-related genes. Moreover, the expression of mitochondrion-mediated apoptosis signaling pathway-related genes, such as bax, bcl2, caspase-3, and caspase-9, was significantly regulated after AgNPs exposure in zebrafish. Therefore, these findings demonstrated that AgNPs exposure could cause oxidative stress, induce mitochondrial dysfunction, and ultimately lead to developmental toxicity.

Polystyrene Nanoplastic Exposure Induces Developmental Toxicity by Activating the Oxidative Stress Response and Base Excision Repair Pathway in Zebrafish (Danio rerio)

The widespread accumulation of nanoplastics is a growing concern for the environmental and human health. However, studies on the mechanisms of nanoplastic-induced developmental toxicity are still limited. Here, we systematically investigated the potential biological roles of nanoplastic exposure in zebrafish during the early developmental stage. The zebrafish embryos were subjected to exposure to 100 nm polystyrene nanoplastics with different concentrations (0, 100, 200, and 400 mg/L). The results indicated that nanoplastic exposure could decrease the hatching and survival rates of zebrafish embryos. In addition, the developmental toxicity test indicated that nanoplastic exposure exhibits developmental toxicity via the inhibition of the heart rate and body length in zebrafish embryos. Besides, behavioral activity was also significantly suppressed after 96 h of nanoplastic exposure in zebrafish larvae. Further biochemical assays revealed that nanoplastic-induced activation of the oxidative stress responses, including reactive oxygen species accumulation and enhanced superoxide dismutase and catalase activities, might affect developmental toxicity in zebrafish embryos. Furthermore, a quantitative polymerase chain reaction assay demonstrated that the mRNA levels of the base excision repair (BER) pathway-related genes, including lig1, lig3, polb, parp1, pold, fen1, nthl1, apex, xrcc1, and ogg1, were altered in zebrafish embryos for 24 h after nanoplastic exposure, indicating that the activation of the BER pathway would be stimulated after nanoplastic exposure in zebrafish embryos. Therefore, our findings illustrated that nanoplastics could induce developmental toxicity through activation of the oxidative stress response and BER pathways in zebrafish.

Compartmentalized regulation of NAD+ by Di (2-ethyl-hexyl) phthalate induces DNA damage in placental trophoblast

Di (2-ethyl-hexyl) phthalate (DEHP) is a wildly used plasticizer. Maternal exposure to DEHP during pregnancy blocks the placental cell cycle at the G2/M phase by reducing the efficiency of the DNA repair pathways and affects the health of offsprings. However, the mechanism by which DEHP inhibits the repair of DNA damage remains unclear. In this study, we demonstrated that DEHP inhibits DNA damage repair by reducing the activity of the DNA repair factor recruitment molecule PARP1. NAD+ and ATP are two substrates necessary for PARP1 activity. DEHP abated NAD+ in the nucleus by reducing the level of NAD+ synthase NMNAT1 and elevated NAD+ in the mitochondrial by promoting synthesis. Furthermore, DEHP destroyed the mitochondrial respiratory chain, affected the structure and quantity of mitochondria, and decreased ATP production. Therefore, DEHP inhibits PARP1 activity by reducing the amount of NAD+ and ATP, which hinders the DNA damage repair pathways. The supplement of NAD+ precursor NAM can partially rescue the DNA and mitochondria damage. It provides a new idea for the prevention of health problems of offsprings caused by DEHP injury to the placenta.

Effects of di-(2-ethylhexyl) phthalate (DEHP) on behavior and dopamine signaling in zebrafish (Danio rerio)

Di (2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer, also known as a developmental toxicant, but its neurobehavioral toxicity remains elusive. This study evaluated the neurobehavioral toxicity and its possible mechanism in larval zebrafish. Embryos at gastrula period (~6 h post fertilization, hpf) were exposure to DEHP (0, 1, 2.5, 5 and 10 mg/L) for 7 days. Spontaneous tail movement in embryos and swimming activity in larvae were monitored. Alterations in the mRNA expression of genes involved in dopamine signaling and apoptosis pathway were assessed. In situ apoptotic cells were assessed by Acridine orange staining, and oxidative damage were measured using enzymatic assay. The behavior results showed that DEHP inhibited spontaneous tail movement and decreased locomotor activities in the light/dark behavioral test. Meanwhile, behavioral changes were accompanied by increased apoptosis and malondialdehyde (MDA) content, decreased superoxide dismutase (SOD) activity and dopamine (DA) content, and perturbed the expression of genes associated with the synthesis (th), reuptake (dat) and metabolism (mao) of DA, with dopamine receptors (DRs), and with the apoptosis pathway (p53, bax, bcl2, caspase-3, caspase-8, caspase-9). The findings will help to illuminate the possible neurobehavioral toxicity mechanisms of organism exposure to DEHP.

Hindbrain defects induced by Di-butyl phthalate (DBP) in developing zebrafish embryos

Di-butyl phthalate (DBP) is a globally used plasticizer found in alarmingly high concentrations in soil and water ecosystems. As phthalates are non-covalently bound to plastic polymers, phthalates easily leach into the aquatic environment. The effects of DBP on aquatic organisms is concerning, most notably, studies have focused on the endocrine-disrupting effects. However, reports on the developmental neurotoxicity of DBP are rare. Using the zebrafish vertebrate model system, we treated pre-gastrulation staged embryos with 2.5 μM DBP, a concentration environmentally noted. We find that general hindbrain structure and rhombomere patterning is disrupted at 72 h post fertilization (hpf). We investigated hindbrain specific neural patterning of cranial motor neurons and find defects in branchiomotor neuron patterning and migration. Furthermore, defects in r4 specific Mauthner neuron development were also noted. Thus, we conclude that DBP exposure during embryonic development induces defects to the hindbrain and concomitantly the neurons that are born and differentiate there.

Ecotoxicological evaluation of zebrafish liver (Danio rerio) induced by dibutyl phthalate

Dibutyl phthalate (DBP), one of the most commonly applied plasticizers, has been frequently detected in the aquatic environment, posing potential risks to aquatic organisms. Currently, reports about the toxicity of zebrafish liver with DBP exposure are rare, and the toxic mechanism is still not clear. In this study, zebrafish (Danio rerio) were used to explore the ecotoxicological effects of DBP from the physiological, biochemical, genetic, and molecular levels. The results showed oxidative stress, lipid peroxidation, and DNA damage occurred in zebrafish liver according to changes in antioxidant enzymes, MDA and 8-OHdG content. AchE activity was always active, and negatively correlated with the DBP concentration. The expression of Cu/Zn-sod and gpx genes were similar to that of antioxidant enzymes from 7 to 21 days, while in the end, the inconsistent result appeared due to the time lag effect in protein modification, gene transcription and translation. Besides, the mRNA abundance of Caspase-3 and p53 were upregulated, showing a "dose-response" relationship. The integrated biomarker reaction indicated that the effects of exposure time on zebrafish liver was 14th day> 28th day> 7th day> 21th day. These results are of great significance to evaluate the toxicological effects and explore the toxic mechanism of DBP on aquatic organisms.

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.

Di-butyl phthalate (DBP) induces defects during embryonic eye development in zebrafish

Di-butyl phthalate (DBP) is a phthalate ester (PAEs) added during the manufacturing of plastics to make them stronger, yet more pliable. DBP is noncovalently bound to plastics resulting in leaching into the environment. Concerning concentrations of DBP have been noted in surface and groundwater, aquatic ecosystems, soil and atmospheric environments globally. Global production of phthalates and thus concomitant exposure has increased over the years making studies on the ecological and environmental safety needed. Most of the literature on DBP focuses on the endocrine disrupting properties of phthalate esters, but the developmental toxicity of DBP is an understudied area. Here, we treat gastrula staged zebrafish embryos with environmentally relevant concentrations of DBP (2.5 µM). We find defects in eye development at 96 h post fertilization including a decrease in the size of the lens and retina in DBP-treated embryos. Defects in eye vascularization as well as loss of the optic nerve and optic tectum were also noted. Here we conclude that exposure to environmentally relevant doses of DBP during early embryonic development is toxic to eye development.

The Emerging Plasticizer Alternative DINCH and Its Metabolite MINCH Induce Oxidative Stress and Enhance Inflammatory Responses in Human THP-1 Macrophages

The use of the plasticizer bis(2-ethylhexyl)phthalate (DEHP) and other plasticizers in the manufacture of plastic products has been restricted due to adverse health outcomes such as obesity, metabolic syndrome, and asthma, for which inflammation has been described to be a driving factor. The emerging alternative plasticizer 1,2-cyclohexanedioic acid diisononyl ester (DINCH) still lacks information regarding its potential effects on the immune system. Here, we investigated the effects of DINCH and its naturally occurring metabolite monoisononylcyclohexane-1,2-dicarboxylic acid ester (MINCH) on the innate immune response. Human THP-1 macrophages were exposed to 10 nM–10 μM DINCH or MINCH for 4 h, 16 h, and 24 h. To decipher the underlying mechanism of action, we applied an untargeted proteomic approach that revealed xenobiotic-induced activation of immune-related pathways such as the nuclear factor κB (NF-κB) signaling pathway. Key drivers were associated with oxidative stress, mitochondrial dysfunction, DNA damage repair, apoptosis, and autophagy. We verified increased reactive oxygen species (ROS) leading to cellular damage, NF-κB activation, and subsequent TNF and IL-1β release, even at low nM concentrations. Taken together, DINCH and MINCH induced cellular stress and pro-inflammatory effects in macrophages, which may lead to adverse health effects.

Review on Toxic Effects of Di(2-ethylhexyl) Phthalate on Zebrafish Embryos

Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in consumer products. People are continuously exposed to DEHP through ingestion, inhalation and dermal absorption. From epidemiological studies, DEHP has been shown to associate with various adverse health effects, such as reproductive abnormalities and metabolic diseases. Health concerns have been raised regarding DEHP exposures; therefore, relevant risk assessment has become necessary through toxicological testing of DEHP. In the past 10 years, an increasing number of DEHP toxicity studies have been using zebrafish embryos as an in vivo model due to their high fecundity, rapid embryonic development as well as optical transparency, which have now been established as an alternative of the more conventional rodent model. The aim of the present paper is to review the effects of acute (from embryo stage to ≤1 week) and chronic (from embryo stage to >1 week) DEHP exposures on zebrafish, which start from the embryonic stage, and to analyze acute and potential long-term effects induced by acute exposure and effects induced by chronic exposure of DEHP upon subjecting to exposures, starting from the embryonic stage to different developmental stages, with a view to facilitate risk assessments on DEHP exposures.