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Reduced repressive epigenetic marks, increased DNA damage and Alzheimer's disease hallmarks in the brain of humans and mice exposed to particulate urban air pollution
Calderón-Garcidueñas L, Herrera-Soto A, Jury N, Maher BA, González-Maciel A, Reynoso-Robles R, Ruiz-Rudolph P, van Zundert B et al.. Environmental research, 2020-02-04
Topic: Air pollution and environmental exposures
Exposure to air pollutants is associated with an increased risk of developing Alzheimer's disease (AD). AD pathological hallmarks and cognitive deficits are documented in children and young adults in polluted cities (e.g. Metropolitan Mexico City, MMC). Iron-rich combustion- and friction-derived nanoparticles (CFDNPs) that are abundantly present in airborne particulate matter pollution have been detected in abundance in the brains of young urbanites. Epigenetic gene regulation has emerged as a candidate mechanism linking exposure to air pollution and brain diseases. A global decrease of the repressive histone post-translational modifications (HPTMs) H3K9me2 and H3K9me3 (H3K9me2/me3) has been described both in AD patients and animal models. Here, we evaluated nuclear levels of H3K9me2/me3 and the DNA double-strand-break marker γ-H2AX by immunostaining in post-mortem prefrontal white matter samples from 23 young adults (age 29 ± 6 years) who resided in MMC (n = 13) versus low-pollution areas (n = 10). Lower H3K9me2/me3 and higher γ-H2A.X staining were present in MMC urbanites, who also displayed the presence of hyperphosphorylated tau and amyloid-β (Aβ) plaques. Transmission electron microscopy revealed abundant CFDNPs in neuronal, glial and endothelial nuclei in MMC residents' frontal samples. In addition, mice exposed to particulate air pollution (for 7 months) in urban Santiago (Chile) displayed similar brain impacts; reduced H3K9me2/me3 and increased γ-H2A.X staining, together with increased levels of AD-related tau phosphorylation. Together, these findings suggest that particulate air pollution, including metal-rich CFDNPs, impairs brain chromatin silencing and reduces DNA integrity, increasing the risk of developing AD in young individuals exposed to high levels of particulate air pollution.
Key findings
- Exposure to air pollutants is associated with an increased risk of developing Alzheimer's disease (AD).
- Here, we evaluated nuclear levels of H3K9me2/me3 and the DNA double-strand-break marker γ-H2AX by immunostaining in post-mortem prefrontal white matter samples from 23 young adults (age 29 ± 6 years) who resided in MMC (n = 13) versus low-pollution areas (n = 10).
- Transmission electron microscopy revealed abundant CFDNPs in neuronal, glial and endothelial nuclei in MMC residents' frontal samples.
- Together, these findings suggest that particulate air pollution, including metal-rich CFDNPs, impairs brain chromatin silencing and reduces DNA integrity, increasing the risk of developing AD in young individuals exposed to high levels of particulate air pollution.
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Study details
- Participants13
- Evidence strengthLow
How this study scored 40/100
Published in a peer-reviewed journal. Scored zero for study design, effect reported and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 23 of the 58 points we could judge it on, which is 40 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Environmental research) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2020 — within 10 year(s) of the newest study here |
| Sample size | 1 / 4 | 13 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Laboratory or animal study (title names “mice”) — scores zero |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 32045727) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 23 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 23 of the 58 points we could judge it on is 40 out of 100. |
| Total | 40 / 100 | — |
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APA 7th
Calderón-Garcidueñas, L., Herrera-Soto, A., Jury, N., Maher, B. A., González-Maciel, A., Reynoso-Robles, R., et al. (2020). Reduced repressive epigenetic marks, increased DNA damage and Alzheimer's disease hallmarks in the brain of humans and mice exposed to particulate urban air pollution. Environmental research. https://doi.org/10.1016/j.envres.2020.109226
Vancouver
Calderón-Garcidueñas L, Herrera-Soto A, Jury N, Maher BA, González-Maciel A, Reynoso-Robles R, et al. Reduced repressive epigenetic marks, increased DNA damage and Alzheimer's disease hallmarks in the brain of humans and mice exposed to particulate urban air pollution. Environmental research. 2020. doi:10.1016/j.envres.2020.109226. PMID: 32045727.
BibTeX
@article{calderongarciduenas2020-32045727,
author = {Calderón-Garcidueñas, L. and Herrera-Soto, A. and Jury, N. and Maher, B. A. and González-Maciel, A. and Reynoso-Robles, R. and Ruiz-Rudolph, P. and van Zundert, B. and others},
title = {{Reduced repressive epigenetic marks, increased DNA damage and Alzheimer's disease hallmarks in the brain of humans and mice exposed to particulate urban air pollution}},
journal = {Environmental research},
year = {2020},
doi = {10.1016/j.envres.2020.109226},
pmid = {32045727},
url = {https://doi.org/10.1016/j.envres.2020.109226}
}
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