Air pollution and the brain

Subchronic diesel exhaust exposure causes neuroinflammation and elevates early markers of neurodegenerative disease

Shannon Levesque, Michael J. Surace, Jacob McDonald, Michelle Block

Research output: Contribution to journalArticle

123 Citations (Scopus)

Abstract

Background: Increasing evidence links diverse forms of air pollution to neuroinflammation and neuropathology in both human and animal models, but the effects of long-term exposures are poorly understood.Objective: We explored the central nervous system consequences of subchronic exposure to diesel exhaust (DE) and addressed the minimum levels necessary to elicit neuroinflammation and markers of early neuropathology.Methods: Male Fischer 344 rats were exposed to DE (992, 311, 100, 35 and 0 μg PM/m3) by inhalation over 6 months.Results: DE exposure resulted in elevated levels of TNFα at high concentrations in all regions tested, with the exception of the cerebellum. The midbrain region was the most sensitive, where exposures as low as 100 μg PM/m3 significantly increased brain TNFα levels. However, this sensitivity to DE was not conferred to all markers of neuroinflammation, as the midbrain showed no increase in IL-6 expression at any concentration tested, an increase in IL-1β at only high concentrations, and a decrease in MIP-1α expression, supporting that compensatory mechanisms may occur with subchronic exposure. Aβ42 levels were the highest in the frontal lobe of mice exposed to 992 μg PM/m3 and tau [pS199] levels were elevated at the higher DE concentrations (992 and 311 μg PM/m3) in both the temporal lobe and frontal lobe, indicating that proteins linked to preclinical Alzheimer's disease were affected. α Synuclein levels were elevated in the midbrain in response to the 992 μg PM/m3 exposure, supporting that air pollution may be associated with early Parkinson's disease-like pathology.Conclusions: Together, the data support that the midbrain may be more sensitive to the neuroinflammatory effects of subchronic air pollution exposure. However, the DE-induced elevation of proteins associated with neurodegenerative diseases was limited to only the higher exposures, suggesting that air pollution-induced neuroinflammation may precede preclinical markers of neurodegenerative disease in the midbrain.

Original languageEnglish (US)
Article number105
JournalJournal of Neuroinflammation
Volume8
DOIs
StatePublished - Aug 24 2011
Externally publishedYes

Fingerprint

Vehicle Emissions
Air Pollution
Neurodegenerative Diseases
Mesencephalon
Brain
Frontal Lobe
Synucleins
Inbred F344 Rats
Temporal Lobe
Interleukin-1
Cerebellum
Inhalation
Parkinson Disease
Interleukin-6
Alzheimer Disease
Proteins
Central Nervous System
Animal Models
Pathology

Keywords

  • α synuclein
  • Aβ42
  • Air pollution
  • Diesel exhaust
  • Midbrain
  • Tau hyperphosphorylation
  • TNFα

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Neurology
  • Immunology
  • Neuroscience(all)

Cite this

Air pollution and the brain : Subchronic diesel exhaust exposure causes neuroinflammation and elevates early markers of neurodegenerative disease. / Levesque, Shannon; Surace, Michael J.; McDonald, Jacob; Block, Michelle.

In: Journal of Neuroinflammation, Vol. 8, 105, 24.08.2011.

Research output: Contribution to journalArticle

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abstract = "Background: Increasing evidence links diverse forms of air pollution to neuroinflammation and neuropathology in both human and animal models, but the effects of long-term exposures are poorly understood.Objective: We explored the central nervous system consequences of subchronic exposure to diesel exhaust (DE) and addressed the minimum levels necessary to elicit neuroinflammation and markers of early neuropathology.Methods: Male Fischer 344 rats were exposed to DE (992, 311, 100, 35 and 0 μg PM/m3) by inhalation over 6 months.Results: DE exposure resulted in elevated levels of TNFα at high concentrations in all regions tested, with the exception of the cerebellum. The midbrain region was the most sensitive, where exposures as low as 100 μg PM/m3 significantly increased brain TNFα levels. However, this sensitivity to DE was not conferred to all markers of neuroinflammation, as the midbrain showed no increase in IL-6 expression at any concentration tested, an increase in IL-1β at only high concentrations, and a decrease in MIP-1α expression, supporting that compensatory mechanisms may occur with subchronic exposure. Aβ42 levels were the highest in the frontal lobe of mice exposed to 992 μg PM/m3 and tau [pS199] levels were elevated at the higher DE concentrations (992 and 311 μg PM/m3) in both the temporal lobe and frontal lobe, indicating that proteins linked to preclinical Alzheimer's disease were affected. α Synuclein levels were elevated in the midbrain in response to the 992 μg PM/m3 exposure, supporting that air pollution may be associated with early Parkinson's disease-like pathology.Conclusions: Together, the data support that the midbrain may be more sensitive to the neuroinflammatory effects of subchronic air pollution exposure. However, the DE-induced elevation of proteins associated with neurodegenerative diseases was limited to only the higher exposures, suggesting that air pollution-induced neuroinflammation may precede preclinical markers of neurodegenerative disease in the midbrain.",
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