Gestation and lactation triphenyl phosphate exposure disturbs offspring gut microbiota in a sex-dependent pathway.

Triphenyl phosphate (TPhP) is an Organophosphate flame retardant (OPFR) that has been widely used in many commercial products. Following its widely usage, its health risk has been concerned. In this study, mice were exposed to TPhP (1 mg/kg) during pregnancy and lactation (E0-PND21), the effect of TPhP on gut microbiota and its role in TPhP mediated lipid metabolism disturbance of offspring was investigated. Our results showed that TPhP disturbed the gut microbiota in dam or offspring at different extent, with male offspring experiencing major effects. Both the composition, abundance or network of gut microbiome was affected in male offspring. In male offspring, expression of genes along gut-liver axis including FXR, CYP7A1, SREBP-1c and ChREBP was significantly up-regulated, and expression of SHP, FGF15 and ASBT was significantly down-regulated. Consistent with this, lipid accumulation in the liver, and increased level of triglyceride, total cholestrol and total bile acid in the serum was observed. The changed abundance of Ruminococcaceae, Clostridiaceae, and Bacteroidaceae shows strong correlation with disturbed lipid metabolism in male offspring. Our research showed that indirect TPhP exposure during early life stage could affect the gut microbiota and gene expression along gut-liver axis in offspring at sex-dependent pathways, with males experiencing more effects.

Triphenyl phosphate disturbs placental tryptophan metabolism and induces neurobehavior abnormal in male offspring.

Epidemiological studies have shown that prenatal triphenyl phosphate (TPhP) exposure is related to abnormal neurobehavior in children. However, the neurodevelopmental toxicity of TPhP in mammals is limited. To study the neurodevelopmental toxicity of TPhP in mammals and investigate the underlying mechanism, we used a mouse intrauterine TPhP exposure model. We measured the inflammatory factors (IL-6, TNFα) and NFκB levels, and tryptophan metabolism in placentae, detected the fetal brain transcriptome, hippocampal neuron development and neurobehavioral in the male offspring. The results showed that the protein level of IL-6, TNFα and NFκB in the placenta of the TPhP treatment group (1, 5 mg/kg) were significantly increased. Change of the protein level of these pro-inflammatory factors in maternal serum or fetal brain was not observed. Expression of genes along tryptophan-serotonin metabolism pathway were significantly decreased. While, the concentration of 5-HT levels in the placenta or fetal brain were significantly increased. Consistent with the increased 5-HT, the Nissl body was reduced in the hippocampus of treatment group. The expression of serotonergic neuron gene markers including Tph2, Htr1A, Htr2A, Pet1 and Lmx1b in the hippocampus of treatment group was significantly decreased. The neurobehavioral test showed that TPhP decreased center time that represent anxiety-like behavior, and reduced learning and memory in male offspring. Meanwhile, expression of genes along tryptophan-kynurenine metabolism pathway were significantly increased. The result of the transcriptome analysis of fetal brain showed that the differentially expressed genes are mainly involved in the transcription regulation of DNA as a template in the nucleus, and the enriched pathways are mainly signal pathways regulated by axon guidance and neurotrophic factors, dopaminergic and cholinergic synapses, suggest that not only serotonergic neuronal was affected. Overall, this study demonstrates that TPhP has the potential to induce placental inflammatory response in the placenta, disturb placental tryptophan metabolism, compromise the neuronal development and synaptic transmission, and cause abnormal neurobehavior in male offspring.

Effects of long-term exposure to TDCPP in zebrafish (Danio rerio) - Alternations of hormone balance and gene transcriptions along hypothalamus-pituitary axes.

BACKGROUND: TDCPP is one of the major chemical of organophosphate flame retardants (OPFRs) that has been detected ubiquitously in both the environment and biota. Previously we observed that it influenced the concentrations of sex and thyroid hormones in a sex-dependent pattern, leading to reproductive impairments after short-term exposure in zebrafish. Here we investigate the consequences of longer-term exposure to TDCPP on the hypothalamic-pituitary-gonad (HPG), hypothalamic-pituitary-interrenal (HPI), and hypothalamic-pituitary-thyroid (HPT) axes of zebrafish (Danio rerio). METHODS: A 120-day exposure test to 0.005, 0.05 and 0.5 mg/L TDCPP was initiated with fertilized eggs. Sex steroid hormones in the treated fishes were measured and transcriptional changes were analyzed. RESULTS: In female fish, exposure to TDCPP resulted in increases in plasma cortisol, follicle stimulating hormone (FSH), luteinizing hormone (LH), 17ß-estradiol (E2), cortisol, thyroxine (T4), and triiodothyronine (T3). Transcription of most target genes along HPG, HPI and HPT axes were increased by the exposure. While in male fish the exposure led to decreases in cortisol, FSH, LH, T4, T3, testosterone (T), and 11-ketotestosterone (11-KT). Transcription of genes along HPG, HPI and HPT axes, especially steroidogenic genes, were inhibited in male zebrafish. While, E2/T or E2/11-KT ratio was increased in both female and females. The sex-dependent changes in hormones might be due to differential responses to TDCPP induced stresses. An increase in cortisol level coincided with increases in E2 and THs in female fish, while in males decreases in cortisol as well as T, 11-KT and THs were observed. Long-term exposure to TDCPP at very low (µg/L) concentrations could disrupt hormone balances in a sex dependent way. CONCLUSION: This study revealed that TDCPP could affect endocrine axes - HPG, HPI and HPT - in zebrafish, and impair zebrafish development.

Prenatal exposure to triphenyl phosphate activated PPARγ in placental trophoblasts and impaired pregnancy outcomes.

The health risks of triphenyl phosphate (TPhP) have increased since its widespread application. Using placental trophoblast cell line JEG-3, we demonstrated that TPhP could induce endoplasmic reticulum stress (ERS) and cell apoptosis through PPARγ-mediated lipid metabolism. However, the developmental toxicity of TPhP through the placenta is not known. In this study, prenatal TPhP exposure to mice was investigated. Pregnant mice were orally exposed to TPhP (1 and 5 mg/kg) from embryonic day 0 (E0) until delivery. The results showed that TPhP could accumulate in placenta and impair pregnancy outcomes. After exposure, at E18, placental hormone chorionic gonadotrophin and testosterone levels were significantly decreased, but progesterone and estradiol levels were significantly increased, and placental angiogenesis was activated in the low-dose exposure group. While, in the high-dose exposure group, only estradiol levels were significantly increased. Different with the effect on hormone level or angiogenesis, TPhP significantly increased PPARγ and its regulated lipid transport proteins FABP, FATP, and CD36, and induced lipid accumulation in placental trophoblasts of both low- and high-exposure group. RNA-seq analysis of the placenta identified differentially expressed genes that were mainly involved in the ERS and MAPK signaling pathways. Western blot analysis verified that the protein levels related to ERS stress and apoptosis were significantly increased. To further confirm the role of PPARγ in TPhP mediated placental toxicity, pregnant mice were orally exposed to TPhP (1 mg/kg) or TPhP (1 mg/kg) + GW9662 (PPARγ inhibitor, 2 mg/kg) from E0 until delivery. The results showed that GW9662 could ameliorate the effect of TPhP on placental lipid accumulation, ERS and cell apoptosis, suggesting that PPARγ mediated the placental toxicity of TPhP. Overall, our results indicated that prenatal TPhP exposure impaired pregnancy outcomes, at least partly through PPARγ regulated function of trophoblast.

Removal efficiencies and risk assessment of endocrine-disrupting chemicals at two wastewater treatment plants in South China.

Endocrine-disrupting chemicals (EDCs) in the effluent from wastewater treatment plants (WWTPs) are an important pollutant sources of the aquatic system. In this study, the removal efficiencies of eight typical EDCs at two domestic WWTPs in Dongguan City, China, are reported based on instrumental analysis and bioassay results. Bioactivities, including steroidogenesis-disrupting effects, estrogen receptor (ER)-binding activity, and aryl hydrocarbon receptor (AhR)-binding activity were evaluated using the H295R, MVLN, and H4IIE cell bioassays, respectively. The potential environmental risks of these residual EDCs were also evaluated. The results of instrumental analysis showed that nonylphenol was the major chemical type present among the eight tested EDCs. Meanwhile, concentrations of estrogen compounds including estrone, 17ß-estradiol (E2), estriol, 17α-ethinyl estradiol, and diethylstilbestrol were relatively low. The removal rates of all eight EDCs were relatively high. Although the chemical analysis indicated high removal efficiency, the bioassay results showed that steroidogenesis-disrupting effects as well as ER-binding and AhR-binding activities remained, with E2-equivalent values of effluent samples ranging from 0.16 to 0.9 ng·L-1, and 2,3,7,8-tetrachlorodibenzo-p-dioxin-equivalent values ranging from 0.61 to 4.09 ng L-1. Principal component analysis combined with regression analysis suggests that the chemicals analyzed in this study were partly responsible for these ER and AhR activities. Ecological risk assessment of the residual EDCs showed that estrone was the most hazardous chemical among the eight EDCs tested, with a risk quotient of 1.44-5.50. Overall, this study suggests that, despite high apparent removal efficiencies of typical EDCs, their bioactivities and potential ecological risks cannot be ignored.

An in vitro investigation of endocrine disrupting potentials of ten bisphenol analogues.

The endocrine disruption potency of BPA was reported elsewhere, but the mechanisms of its analogues have not been fully resolved. In this study, endocrine disruption potentials of nine alternative bisphenol analogues, namely 2,2-bis(4-hydroxyphenyl)butane (BPB), 2,2-Bis(4-hydroxy-3-methylphenyl)propane (BPC), 4,4'-dihydroxydiphenylmethane (BPF), 4,4'-(1,3-Phenylene diisopropylidene)bisphenol (BPM), 4,4'-(1,4-phenylenediisopropylidene)bisphenol (BPP), 4,4'- sulfonyldiphenol (BPS), 4,4' cyclohexylidenebisphenol (BPZ), 4,4' (hexafluoroisopropylidene)-diphenol (BPAF) and 4,4'-(1-phenylethylidene)bisphenol (BPAP), plus 2,2-bis(4-hydroxyphenyl)propane (BPA) were investigated by H295R cell and MVLN cell bioassays. In the H295R cell assay, the endpoints included hormone production and key genes for steroidogenesis (CYP11A, CYP17, CYP19 and 3ßHSD2) or metabolism sulfotransferase (SULT1A1, SULT2A1 and SULT2B1) at the molecular level. The results indicated that except for BPP or BPAF, the eight other bisphenols significantly increased the E2/T ratio. In addition, BPB, BPF and BPS significantly up-regulate CYP19 gene expression, and only BPB significantly reduced sulfotransferase gene expression. In the MVLN luciferase gene reporter assay, seven bisphenols induced luciferase activity alone, and are 104 to 108-fold less potent than E2. Their nuclear ERα binding activity is in the order of BPAF > BPZ > BPP > BPB > BPA > BPF > BPS. In summary, all nine tested bisphenols showed endocrine toxicity through different mechanisms. Some had similar potency as BPA, but some had even higher potency. Further research is necessary to evaluate the toxicity of these potential BPA substitutes.

Rational design of conformationally constrained oxazolidinone-fused 1,2,3,4-tetrahydroisoquinoline derivatives as potential PDE4 inhibitors.

Improvement of subtype selectivity of an inhibitor's binding activity using the conformational restriction approach has become an effective strategy in drug discovery. In this study, we applied this approach to PDE4 inhibitors and designed a series of novel oxazolidinone-fused 1,2,3,4-tetrahydroisoquinoline derivatives as conformationally restricted analogues of rolipram. The bioassay results demonstrated the oxazolidinone-fused tetrahydroisoquinoline derivatives exhibited moderate to good inhibitory activity against PDE4B and high selectivity for PDE4B/PDE4D. Among these derivatives, compound 12 showed both the strongest inhibition activity (IC50=0.60µM) as well as good selectivity against PDE4B and good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. The primary SAR study showed that restricting the conformation of the catechol moiety in rolipram with the scaffold of oxazolidinone-fused tetrahydroisoquinoline could lead to an increase in selectivity for PDE4B over PDE4D, which was consistent with the observed docking simulation.