Project description:There is a growing need to understand the potential neurotoxicity of organophosphate ester flame retardants (OPFRs) and plasticizers because use and, consequently, human exposure, is rapidly expanding. We have previously shown in rats that developmental exposure to the commercial FR mixture Firemaster® 550 (FM 550), which contains OPFRs, results in sex-specific behavioral effects, and identified the placenta as a potential target of toxicity. The placenta is a critical coordinator of fetal growth and neurodevelopment, and a source of neurotransmitters (NTs) for the developing brain. We have shown in rats and humans that FRs accumulate in placental tissue, and induce functional changes, including altered neurotransmitter (NT) production. Here we sought to establish if OPFRs (triphenyl phosphate, TPHP, and a mixture of isopropylated triarylphosphate isomers, ITPs) alter placental function and fetal forebrain development, with disruption of tryptophan (Trp) metabolism as a primary pathway of interest. Wistar rat dams were orally exposed to OPFRs (0, 500, 1,000, or 2,000 μg/day) or a serotonin (5-HT) agonist (5-MT) for 14 days during gestation and placenta and fetal forebrain tissues collected for analysis by transcriptomics and metabolomics. Relative abundance of genes responsible for the transport and synthesis of placental 5-HT were disrupted, and multiple neuroactive metabolites in the 5-HT and kynurenine (Kyn) metabolic pathways were upregulated. Additionally, 5-HTergic projections were significantly longer in the fetal forebrains of exposed males. These findings suggest that OPFRs have the potential to impact the 5-HTergic system in the fetal forebrain by disrupting placental Trp metabolism.
Project description:Exposure to environmental chemicals can impair neurodevelopment, and oligodendrocytes may be particularly vulnerable as their development extends from gestation into adulthood. However, few environmental chemicals have been assessed for potential risks to oligodendrocytes. Here, using a high-throughput developmental screen in cultured cells, we identified environmental chemicals in two classes that disrupt oligodendrocyte development through distinct mechanisms. Quaternary compounds, ubiquitous in disinfecting agents and personal care products, were potently and selectively cytotoxic to developing oligodendrocytes, whereas organophosphate flame retardants, commonly found in household items such as furniture and electronics, prematurely arrested oligodendrocyte maturation. Chemicals from each class impaired oligodendrocyte development postnatally in mice and in a human 3D organoid model of prenatal cortical development. Analysis of epidemiological data showed that adverse neurodevelopmental outcomes were associated with childhood exposure to the top organophosphate flame retardant identified by our screen. This work identifies toxicological vulnerabilities for oligodendrocyte development and highlights the need for deeper scrutiny of these compounds’ impacts on human health.
Project description:Alzheimer's disease is the most common form of dementia characterized on cognitive impairment. Autophagy-lysosome dysfunction is linked to AD pathology. Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used organophosphorus flame retardants with the potential to induce neuronal damage. We found that TDCIPP significantly increased expression of BACE1 and of Aβ42. TMT labeled proteomic study were used to reveal profile changes of N2a-APPswe cells after exposure by TDCIPP. Proteomic and bioinformatic analysis revealed that lysosomal proteins were dysregulated after TDCIPP treatment in N2a-APPswe cells. LC3, P62, CTSD, and LAMP1 were increased, while STAT1 was decreased after TDCIPP exposure and dysregulated proteins were validated by Western blotting. Our results, for the first time revealed that TDCIPP could be one of potential environment risk factors for AD development. Autophagy dysregulation may take an important role on TDCIPP induced Aβ42 production.
Project description:Exposure to environmental chemicals can impair neurodevelopment. Oligodendrocytes that wrap around axons to boost neurotransmission may be particularly vulnerable to chemical toxicity as they develop throughout fetal development and into adulthood. However, few environmental chemicals have been assessed for potential risks to oligodendrocyte development. Here, we utilized a high-throughput developmental screen and human cortical brain organoids, which revealed environmental chemicals in two classes that disrupt oligodendrocyte development. Quaternary compounds, ubiquitous in disinfecting agents, hair conditioners, and fabric softeners, were potently and selectively cytotoxic to developing oligodendrocytes through activation of the integrated stress response. Organophosphate flame retardants, commonly found in household items such as furniture and electronics, were non-cytotoxic but prematurely arrested oligodendrocyte maturation. Chemicals from each of the two classes impaired human oligodendrocyte development in a 3D organoid model of prenatal cortical development. In analysis of epidemiological data from the CDC’s National Health and Nutrition Examination Survey, adverse neurodevelopmental outcomes were associated with childhood exposure to the top organophosphate flame retardant identified in our oligodendrocyte toxicity platform. Collectively, our work identifies toxicological vulnerabilities specific to oligodendrocyte development and highlights common household chemicals with high exposure risk to children that warrant deeper scrutiny for their impact on human health.
Project description:Background: Organophosphate esters (OPEs), used as flame retardants and plasticizers, are present ubiquitously in the environment. Previous studies suggested that exposure to OPEs may be detrimental to female fertility in humans. However, no experimental information is available on the effects of OPE mixtures on ovarian granulosa cells, which play essential roles in female reproduction. Objectives: The goal of this study was to elucidate the effects of OPE mixtures representative of those found in Canadian house dust on ovarian granulosa cells. Methods: We used high-content imaging to investigate the effects an environmentally relevant OPE mixtures on KGN human granulosa cell phenotypes. Perturbation to steroidogenesis was assessed using ELISA and qRT-PCR. A high-throughput transcriptomic approach, TempO-Seq, was used to identify transcriptional changes in a targeted panel of genes. Effects on lipid homeostasis were explored using cholesterol assay and global lipidomic profiling. Results: OPE mixtures with distinct structural characteristics altered multiple phenotypic features of KGN cells with different potencies. The mixtures increased basal production of steroid hormones; this was mediated by significant changes in the expression of critical transcripts involved in steroidogenesis. Further, the total-OPE mixture disrupted cholesterol homeostasis and the composition of intracellular lipid droplets. Discussion: Exposure to house dust-derived mixtures of OPEs may adversely affect female reproductive health by altering a multitude of phenotypic and functional endpoints in granulosa cells. This study provides novel insights into the mechanisms of actions underlying the toxicity induced by OPE mixtures and highlights the need to examine the effects of human relevant chemical mixtures.
Project description:Human HepG2/C3A cells were exposed to indoor dust reference material SRM2585; DMBA (dimethylbenzanthracene); HBCD (hexabromocyclododecane); two different mixtures of flame retardants (all dissolved in 0.1% DMSO) or 0.1% DMSO alone for 72h. RNA was prepared and labeled with Cy3 then hybridized to Agilent SurePrint G3 Human GE v2 8x60k Microarrays, Agilent design ID 039494.
Project description:To investigate the potential underlying neurotoxic effect of developmental exposure to flame retardant mixture, Fire Master 550, or it brominated and organophosphate we performed gene expression profiling in PND1 rat prefrontal cortex.
Project description:RNA-seq provided a general overview of the gene expression profiles of the digestive glands of Mactra veneriformis exposed to 2, 2′,4,4′-tetrabromodiphenyl ether (BDE-47, a type of widely used brominated flame retardants).
Project description:Organophosphate esters (OPEs) are used widely as flame retardants and plasticizers but much remains unknown about their potential toxicity. Previously, we reported that four individual OPEs suppress endochondral ossification in murine limb bud cultures. However, real-life exposure is to complex OPE mixtures. In the present study, we tested the hypothesis that a Canadian household dust-based OPE mixture will affect endochondral ossification in gestation day 13 CD1 mouse embryo limb buds expressing fluorescent markers for the major cell populations involved in the process: COL2A1-ECFP (proliferative chondrocytes), COL10A1-mCherry (hypertrophic chondrocytes), and COL1A1-YFP (osteoblasts). Limbs were cultured for six days in the presence of vehicle or dilutions of the OPE mixture (1/1,000,000, 1/600,000, and 1/300,000). All three OPE mixture dilutions affected cartilage template development and the progression of endochondral ossification, as indicated by the fluorescent markers. The expression of Sox9, the master regulator of chondrogenesis, was unchanged, but the expression of Runx2 and Sp7, which drive chondrocyte hypertrophy and osteoblastogenesis, was dilution-dependently suppressed. RNA sequencing revealed that exposure to the 1/300,000 dilution of the OPE mixture for 24 h downregulated 153 transcripts and upregulated 48 others by at least 1.5-fold. Downregulated transcripts were enriched for those related to the immune system and bone formation. In contrast, upregulated transcripts were enriched for those with stress response functions known to be regulated by ATF4 activation. Thus, exposure to the mixture of OPEs commonly found in house dust may have adverse effects on bone formation.