Prenatal triphenyl phosphate exposure impairs placentation and induces preeclampsia-like symptoms in mice.

Triphenyl phosphate (TPhP) is an organophosphate flame retardant that is widely used in many commercial products. The United States Environmental Protection Agency has listed TPhP as a priority compound that requires health risk assessment. We previously found that TPhP could accumulate in the placentae of mice and impair birth outcomes by activating peroxisome proliferator-activated receptor gamma (PPARγ) in the placental trophoblast. However, the underlying mechanism remains unknown. In this study, we used a mouse intrauterine exposure model and found that TPhP induced preeclampsia (PE)-like symptoms, including new on-set gestational hypertension and proteinuria. Immunofluorescence analysis showed that during placentation, PPARγ was mainly expressed in the labyrinth layer and decidua of the placenta. TPhP significantly decreased placental implantation depth and impeded uterine spiral artery remodeling by activating PPARγ. The results of the in vitro experiments confirmed that TPhP inhibited extravillous trophoblast (EVT) cell migration and invasion by activating PPARγ and inhibiting the PI3K-AKT signaling pathway. Overall, our data demonstrated that TPhP could activate PPARγ in EVT cells, inhibit cell migration and invasion, impede placental implantation and uterine spiral artery remodeling, then induce PE-like symptom and impair birth outcomes. Although the exposure doses used in this study was several orders of magnitude higher than human daily intake, our study highlights the placenta as a potential target organ of TPhP worthy of further research.

Triphenyl phosphate disrupts placental tryptophan metabolism by activating MAOA/ROS/NFκB.

Triphenyl phosphate (TPhP) is an organophosphate flame retardant widely distributed in the environment. The neurodevelopmental toxicity of TPhP has been observed in animals and humans. Previously, we found that prenatal TPhP exposure disturbed placental tryptophan metabolism, impaired neurodevelopment in male offspring, and induced abnormal neurobehavior; however, the underlying mechanisms are unknown. In this study, using the trophoblast cell line JEG-3, we found that TPhP altered gene and protein expression in the tryptophan metabolism pathway, inhibited the tryptophan-serotonin pathway, and activated the tryptophan-kynurenine pathway. Meanwhile, TPhP induced oxidative stress by activating monoamine oxidase A (MAOA), promoting inflammatory factors including nuclear factor kappa-B (NFκB), interleukin-6, and tumor necrosis factor α. The NFκB inhibitor sulfasalazine could alleviate the effects of TPhP on tryptophan metabolism disturbance. The MAOA inhibitor clorgyline or the antioxidant N-acetylcysteine can mitigate oxidative stress and eliminate TPhP-induced inflammatory factors and tryptophan metabolism disturbances. The data above suggest that TPhP disturbed tryptophan metabolism by activating NFκB through MAOA-mediated oxidative stress. Finally, using the mouse intrauterine exposure model, the results confirmed that TPhP induced oxidative stress, activated inflammatory factors, disturbed tryptophan metabolism, and increased the levels of the tryptophan metabolites serotonin, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid in the placenta during the second trimester of pregnancy. Overall, TPhP can disturb placental tryptophan metabolism by activating the inflammatory factor NFκB, which was induced by MAOA-induced oxidative stress. The results of this study confirm that indirect exposure to xenobiotic compounds at an early life stage can impair offspring development and provide a novel perspective on the neurodevelopmental toxicity of TPhP.

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.

Triphenyl phosphate disturbs the lipidome and induces endoplasmic reticulum stress and apoptosis in JEG-3 cells.

Triphenyl phosphate (TPP) is a frequently used aryl organophosphate flame retardant. Epidemiological studies have shown that TPP and its metabolite diphenyl phosphate (DPP) can accumulate in the placenta, and positively correlated with abnormal birth outcomes. TPP can disturb placental hormone secretion through the peroxisome proliferator-activated receptor γ (PPARγ) pathway. However, the extent and mechanism of placental toxicity mediation by TPP remains unknown. In this study, we used JEG-3 cells to investigate the role of PPARγ-regulated lipid metabolism in TPP-mediated placental toxicity. The results of lipidomic analysis showed that TPP increased the production of triglycerides (TG), fatty acids (FAs), and phosphatidic acid (PA), but decreased the levels of phosphatidylethanol (PE), phosphatidylserine (PS), and sphingomyelin (SM). TG accumulation was accompanied by increased levels of sterol regulatory element binding transcription factor 1 (SREBP1), acetyl-coA carboxylase (ACC), and fatty acid transport protein (CD36). Although PPARγ and its target CCAAT/enhancer binding proteins (C/EBPα) was decreased, the TG content and gene expression of SREBP1, ACC, and CD36 decreased when TPP was co-exposed to the PPARγ antagonist GW9662. TPP also induced inflammatory responses, endoplasmic reticulum stress (ERS), and cell apoptosis. Expression of genes related to ERS and apoptosis were attenuated by GW9662. Together, these results show that TPP can disturb lipid metabolism and cause lipid accumulation through PPARγ, induce ERS, and cell apoptosis. Our findings reveal that the developmental toxicity of TPP through placental toxicity should not be ignored.

Triphenyl phosphate permeates the blood brain barrier and induces neurotoxicity in mouse brain.

Concerns have been raised over the neurotoxicity of triphenyl phosphate (TPP), but there have been few studies of the neurotoxic effects of TPP on mammals and the underlying mechanisms. In this study, weaned male mice (C57/BL6) were used and exposed to 0, 50, or 150 mg/kg TPP daily by oral gavage for 30 days. The blood brain barrier (BBB) permeability of TPP and its metabolite diphenyl phosphate (DPP) in the brain, and TPP induced metabolomic and transcriptomic changes of the brain were investigated. The results showed that TPP and DPP can cross the BBB of mice. Histopathological examination of the brain revealed abnormalities in the hippocampus, cortex and thalamus, and mice treated with high doses showed a potential inflammation in the thalamus and hippocampus. Untargeted metabolomic results revealed that the changed level of glutamic acid, N-acetyl CoA metabolites, and organic acid in the brain of treated mice, suggest that amino acid and lipid metabolism was interfered. RNA-seq data indicated that neuronal transcription processes and cell apoptosis pathway (forkhead box (FOXO), and mitogen-activated protein kinase (MAPK) signaling pathways) were significantly affected by TPP exposure. RT-PCR showed proinflammation cytokine tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6)) levels were increased, while antioxidant genes including nuclear factor-E2-related factor 2 (Nrf2), heme oxygenase1 (HO-1) and superoxide dismutase (SOD1) decreased. These results suggest that TPP could cause a degree of neurotoxicity by inducing neuroinflammation and neuronal apoptosis, which are related to oxidative stress. The potential implications for neurophysiology and behavioral regulation cannot be ignored.

A high-resolution computed tomography-based scoring system to differentiate the most infectious active pulmonary tuberculosis from community-acquired pneumonia in elderly and non-elderly patients.

OBJECTIVE: The objective of this study was to use high-resolution computed tomography (HRCT) imaging to predict the presence of smear-positive active pulmonary tuberculosis (PTB) in elderly (at least 65 years of age) and non-elderly patients (18-65 years of age). METHODS: Patients with active pulmonary infections seen from November 2010 through December 2011 received HRCT chest imaging, sputum smears for acid-fast bacilli and sputum cultures for Mycobacterium tuberculosis. Smear-positive PTB was defined as at least one positive sputum smear and a positive culture for M. tuberculosis. Multivariate logistic regression analyses were performed to determine the HRCT predictors of smear-positive active PTB, and a prediction score was developed on the basis of receiver operating characteristic curve analysis. RESULTS: Of 1,255 patients included, 139 were diagnosed with smear-positive active PTB. According to ROC curve analysis, the sensitivity, specificity, positive predictive value, negative predictive value, false positive rates and false negative rates were 98.6 %, 95.8 %, 78.5 %, 99.8 %, 4.2 % and 1.4 %, respectively, for diagnosing smear-positive active PTB in elderly patients, and 100.0 %, 96.9 %, 76.5 %, 100.0 %, 3.1 % and 0.0 %, respectively, for non-elderly patients. CONCLUSIONS: HRCT can assist in the early diagnosis of the most infectious active PTB, thereby preventing transmission and minimizing unnecessary immediate respiratory isolation. KEY POINTS: • HRCT can assist in the early diagnosis of the infectious active PTB • HRCT imaging is useful to predict the presence of smear-positive active PTB • Predictions from the HRCT imaging are valid even before sputum smear or culture results.