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Adamson A, Ilieva N, Stone WJ, De Miranda BR. Low-dose inhalation exposure to trichloroethylene induces dopaminergic neurodegeneration in rodents. Toxicol Sci 2023; 196:218-228. [PMID: 37669148 DOI: 10.1093/toxsci/kfad090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023] Open
Abstract
Trichloroethylene (TCE) is one of the most pervasive environmental contaminants in the world and is associated with Parkinson disease (PD) risk. Experimental models in rodents show that TCE is selectively toxic to dopaminergic neurons at high doses of ingestion, however, TCE is a highly volatile toxicant, and the primary pathway of human exposure is inhalation. As TCE is a highly lipophilic, volatile organic compound (VOC), inhalation exposure results in rapid diffusion throughout the brain, avoiding first-pass hepatic metabolism that necessitated high doses to recapitulate exposure conditions observed in human populations. We hypothesized that inhalation of TCE would induce significantly more potent neurodegeneration than ingestion and better recapitulate environmental conditions of vapor intrusion or off gassing from liquid TCE. To this end, we developed a novel, whole-body passive exposure inhalation chamber in which we exposed 10-month-old male and female Lewis rats to 50 ppm TCE (time weighted average, TWA) or filtered room air (control) over 8 weeks. In addition, we exposed 12-month-old male and female C57Bl/6 mice to 100 ppm TCE (TWA) or control over 12 weeks. Both rats and mice exposed to chronic TCE inhalation showed significant degeneration of nigrostriatal dopaminergic neurons as well as motor and gait impairments. TCE exposure also induced accumulation of pSer129-αSyn in dopaminergic neurons as well as microglial activation within the substantia nigra of rats. Collectively, these data indicate that TCE inhalation causes highly potent dopaminergic neurodegeneration and recapitulates some of the observed neuropathology associated with PD, providing a future platform for insight into the mechanisms and environmental conditions that influence PD risk from TCE exposure.
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Affiliation(s)
- Ashley Adamson
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Neda Ilieva
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - William J Stone
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Briana R De Miranda
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Petroff RL, Cavalcante RG, Langen ES, Dolinoy DC, Padmanabhan V, Goodrich JM. Mediation effects of DNA methylation and hydroxymethylation on birth outcomes after prenatal per- and polyfluoroalkyl substances (PFAS) exposure in the Michigan mother-infant Pairs cohort. Clin Epigenetics 2023; 15:49. [PMID: 36964604 PMCID: PMC10037903 DOI: 10.1186/s13148-023-01461-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/05/2023] [Indexed: 03/26/2023] Open
Abstract
BACKGROUND Per- and polyfluoroalkyl substances (PFAS) are chemicals that are resistant to degradation and ubiquitous in our environments. PFAS may impact the developing epigenome, but current human evidence is limited to assessments of total DNA methylation. We assessed associations between first trimester PFAS exposures with newborn DNA methylation, including 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC). DNA methylation mediation of associations between PFAS and birth outcomes were explored in the Michigan Mother Infant Pairs cohort. Nine PFAS were measured in maternal first trimester blood. Seven were highly detected and included for analysis: PFHxS, PFOA, PFOS, PFNA, PFDA, PFUnDA, and MeFOSAA. Bisulfite-converted cord blood DNA (n = 141) and oxidative-bisulfite-converted cord blood (n = 70) were assayed on Illumina MethylationEPIC BeadChips to measure total DNA methylation (5-mC + 5-hmC) and 5-mC/5-hmC. Correcting for multiple comparisons, beta regressions were used to assess associations between levels of PFAS and total methylation, 5-mC, or 5-hmC. Nonlinear mediation analyses were used to assess the epigenetic meditation effect between PFAS and birth outcomes. RESULTS PFAS was significantly associated with total methylation (q < 0.05: PFHxS-12 sites; PFOS-19 sites; PFOA-2 sites; PFNA-3 sites; PFDA-4 sites). In 72 female infants and 69 male infants, there were sex-specific associations between five PFAS and DNA methylation. 5-mC and 5-hmC were each significantly associated with thousands of sites for PFHxS, PFOS, PFNA, PFDA, PFUnDA, and MeFOSAA (q < 0.05). Clusters of 5-mC and 5-hmC sites were significant mediators between PFNA and PFUnDA and decreased gestational age (q < 0.05). CONCLUSIONS This study demonstrates the mediation role of specific types of DNA methylation on the relationship between PFAS exposure and birth outcomes. These results suggest that 5-mC and 5-hmC may be more sensitive to the developmental impacts of PFAS than total DNA methylation.
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Affiliation(s)
- Rebekah L Petroff
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Raymond G Cavalcante
- Epigenomics Core, Biomedical Research Core Facilities, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Elizabeth S Langen
- Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Dana C Dolinoy
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
- Epigenomics Core, Biomedical Research Core Facilities, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Vasantha Padmanabhan
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
- Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Pediatrics Medical School, University of Michigan, Ann Arbor, MI, USA
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA.
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Jiang L, Greenlaw K, Ciampi A, Canty AJ, Gross J, Turecki G, Greenwood CMT. A Bayesian hierarchical model for improving measurement of 5mC and 5hmC levels: Toward revealing associations between phenotypes and methylation states. Genet Epidemiol 2022; 46:446-462. [PMID: 35753057 DOI: 10.1002/gepi.22489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 04/20/2022] [Accepted: 05/04/2022] [Indexed: 11/09/2022]
Abstract
5-hydroxymethylcytosine (5hmC) is a methylation state linked with gene regulation, commonly found in cells of the central nervous system. 5hmC is associated with demethylation of cytosines from 5-methylcytosine (5mC) to the unmethylated state. The presence of 5hmC can be inferred by a paired experiment involving bisulfite and oxidation-bisulfite treatments on the same sample, followed by a methylation assay using a platform such as the Illumina Infinium MethylationEPIC BeadChip (EPIC). Existing methods for analysis of the resulting EPIC data are not ideal. Most approaches ignore the correlation between the two experiments and any imprecision associated with DNA damage from the additional treatment. Estimates of 5mC/5hmC levels free from these limitations are desirable to reveal associations between methylation states and phenotypes. We propose a hierarchical Bayesian method called Constrained HYdroxy Methylation Estimation (CHYME) to simultaneously estimate 5mC/5hmC signals as well as any associations between these signals and covariates or phenotypes, while accounting for the potential impact of DNA damage and dependencies induced by the experimental design. Simulations show that CHYME has valid type 1 error and better power than a range of alternative methods, including the popular OxyBS method and linear models on transformed proportions. Other methods we examined suffer from hugely inflated type 1 error for inference on 5hmC proportions. We use CHYME to explore genome-wide associations between 5mC/5hmC levels and cause of death in postmortem prefrontal cortex brain tissue samples. These analyses indicate that CHYME is a useful tool to reveal phenotypic associations with 5mC/5hmC levels.
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Affiliation(s)
- Lai Jiang
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada
| | - Keelin Greenlaw
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada
| | - Antonio Ciampi
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada
| | - Angelo J Canty
- Department of Mathematics and Statistics, McMaster University, Hamilton, Ontario, Canada
| | - Jeffrey Gross
- Department of Psychiatry, Douglas Institute, McGill University, Montréal, Québec, Canada
| | - Gustavo Turecki
- Department of Psychiatry, Douglas Institute, McGill University, Montréal, Québec, Canada
| | - Celia M T Greenwood
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada.,Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada.,Gerald Bronfman Department of Oncology, McGill University, Montréal, Québec, Canada.,Department of Human Genetics, McGill University, Montréal, Québec, Canada
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Tiedemann RL, Eden HE, Huang Z, Robertson KD, Rothbart SB. Distinguishing Active Versus Passive DNA Demethylation Using Illumina MethylationEPIC BeadChip Microarrays. Methods Mol Biol 2021; 2272:97-140. [PMID: 34009611 DOI: 10.1007/978-1-0716-1294-1_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The 5-carbon positions on cytosine nucleotides preceding guanines in genomic DNA (CpG) are common targets for DNA methylation (5mC). DNA methylation removal can occur through both active and passive mechanisms. Ten-eleven translocation enzymes (TETs) oxidize 5mC in a stepwise manner to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). 5mC can also be removed passively through sequential cell divisions in the absence of DNA methylation maintenance. In this chapter, we describe approaches that couple TET-assisted bisulfite (TAB) and oxidative bisulfite (OxBS) conversion to the Illumina MethylationEPIC BeadChIP (EPIC array) and show how these technologies can be used to distinguish active versus passive DNA demethylation. We also describe integrative bioinformatics pipelines to facilitate this analysis.
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Affiliation(s)
| | - Hope E Eden
- Center for Epigenetics, Van Andel Institute, Grand Rapids, MI, USA
| | - Zhijun Huang
- Center for Epigenetics, Van Andel Institute, Grand Rapids, MI, USA
| | - Keith D Robertson
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Scott B Rothbart
- Center for Epigenetics, Van Andel Institute, Grand Rapids, MI, USA.
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Rygiel CA, Goodrich JM, Solano-González M, Mercado-García A, Hu H, Téllez-Rojo MM, Peterson KE, Dolinoy DC. Prenatal Lead (Pb) Exposure and Peripheral Blood DNA Methylation (5mC) and Hydroxymethylation (5hmC) in Mexican Adolescents from the ELEMENT Birth Cohort. Environ Health Perspect 2021; 129:67002. [PMID: 34152198 PMCID: PMC8216410 DOI: 10.1289/ehp8507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND Gestational lead (Pb) exposure can adversely affect offspring health through multiple mechanisms, including epigenomic alterations via DNA methylation (5mC) and hydroxymethylation (5hmC), an intermediate in oxidative demethylation. Most current methods do not distinguish between 5mC and 5hmC, limiting insights into their individual roles. OBJECTIVE Our study sought to identify the association of trimester-specific (T1, T2, T3) prenatal Pb exposure with 5mC and 5hmC levels at multiple cytosine-phosphate-guanine sites within gene regions previously associated with prenatal Pb (HCN2, NINJ2, RAB5A, TPPP) in whole blood leukocytes of children ages 11-18 years of age. METHODS Participants from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) birth cohorts were selected (n=144) for pyrosequencing analysis following oxidative or standard sodium bisulfite treatment. This workflow directly quantifies total methylation (5mC+5hmC) and 5mC only; 5hmC is estimated by subtraction. RESULTS Participants were 51% male, and mean maternal blood lead levels (BLL) were 6.43±5.16μg/dL in Trimester 1 (T1), 5.66±5.21μg/dL in Trimester 2 (T2), and 5.86±4.34μg/dL in Trimester 3 (T3). In addition, 5hmC levels were calculated for HCN2 (mean±standard deviation(SD), 2.08±4.18%), NINJ2 (G/C: 2.01±5.95; GG: 0.90±3.97), RAB5A (0.66±0.80%), and TPPP (1.11±6.67%). Furthermore, 5mC levels were measured in HCN2 (81.3±9.63%), NINJ2 (heterozygotes: 38.6±7.39%; GG homozygotes: 67.3±9.83%), RAB5A (1.41±1.21%), and TPPP (92.5±8.03%). Several significant associations between BLLs and 5mC/5hmC were identified: T1 BLLs with 5mC in HCN2 (β=-0.37, p=0.03) and 5hmC in NINJ2 (β=0.49, p=0.003); T2 BLLs with 5mC in HCN2 (β=0.37, p=0.03) and 5hmC in NINJ2 (β=0.27, p=0.008); and T3 BLLs with 5mC in HCN2 (β=0.50, p=0.01) and NINJ2 (β=-0.35, p=0.004) and 5hmC in NINJ2 (β=0.45, p<0.001). NINJ2 5mC was negatively correlated with gene expression (Pearson r=-0.5, p-value=0.005), whereas 5hmC was positively correlated (r=0.4, p-value=0.04). DISCUSSION These findings suggest there is variable 5hmC in human whole blood and that prenatal Pb exposure is associated with gene-specific 5mC and 5hmC levels at adolescence, providing evidence to consider 5hmC as a regulatory mechanism that is responsive to environmental exposures. https://doi.org/10.1289/EHP8507.
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Affiliation(s)
- Christine A. Rygiel
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Jaclyn M. Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | | | | | - Howard Hu
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | | | - Karen E. Peterson
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
- Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Dana C. Dolinoy
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
- Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
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Abstract
PURPOSE OF REVIEW The aims of this review are to evaluate the methods used to measure 5-hydroxymethylcytosine (5-hmC), and then summarize the available data investigating the impact of environmental factors on 5-hydroxymethylcytosine (5-hmC) in the brain. RECENT FINDINGS Recent research has shown that some environmental factors, including exposure to exogenous chemicals, stress, altered diet, and exercise, are all associated with 5-hmC variation in the brain. However, due to a lack of specificity in the methods used to generate a majority of the available data, it cannot be determined whether environment-induced changes in 5-hmC occur in specific biological pathways. Environment appears to shape 5-hmC levels in the brain, but the available literature is hampered by limitations in measurement methods. The field of neuroepigenetics needs to adopt new tools to increase the specificity of its data and enhance biological interpretation of exposure-related changes in 5-hmC. This will help improve understanding of the potential roles for environmental factors and 5-hmC in neurological disease.
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Affiliation(s)
- Joseph Kochmanski
- Department of Translational Neuroscience, Grand Rapids Research Center, Michigan State University College of Human Medicine, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Alison I Bernstein
- Department of Translational Neuroscience, Grand Rapids Research Center, Michigan State University College of Human Medicine, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA.
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