Exposure to air particulate matter (PM) present in urban environments have been shown to induce systemic prooxidant and proinflammatory effects in apolipoprotein E knockout (ApoE-/-) mice and proinflammatory central nervous system (CNS) effects in BALB/c mice. We hypothesize that ApoE-/- mice would exhibit a greater propensity to develop PM-induced CNS effects due to their greater susceptibility to CNS inflammation. We studied the brains of ApoE-/- mice exposed in a previous study to concentrated air particles of different sizes (fine vs. ultrafine) or filtered-air to evaluate the effect of PM exposure on the development of CNS proinflammatory effects in a genetically susceptible background. This was important because, although the use of nano-sized materials opens an exciting potential for their use as diagnostic or therapeutic tools, not much is known about the possible CNS toxicity of these particles. Neuroinflammation has been shown to exacerbate progression of neurodegeneration. Since the onset and progression of idiopathic forms of neurodegenerative disorders are likely to be multifactorial and involve gene-environment interactions, we determined the possibility of particles in ambient air pollution to enhance neuroinflammation. Our results indicate that in the brain, there was significant modulation in the activation of the transcription factors NF-kappaB and AP-1 after exposure to the ultrafine fractions. Levels of two pro-inflammatory cytokines (TNF-alpha and IL-1alpha) were also increased in the brain of exposed animals and this was independent of the size fraction of PM. Since inflammatory processes have been shown to contribute to the pathology associated with neurodegenerative diseases, it will be important to further evaluate the role ambient particles may play in the potentiation of existing CNS damage and progression of neurodegenerative disorders.
"Air pollutants with an aerodynamic diameter of <2.5 m (PM 2.5 ) have been lately found to be related with increased cardiovascular , respiratory and pro-inflammatory effects associated with death and diseases (Campbell et al., 2009). Vital two regarding adverse health effects (Donaldson et al., 2005). "
[Show abstract][Hide abstract] ABSTRACT: Air pollution has persistently been the major cause of respiratory-related illness and death. Environmental pollutants such as diesel and petrol exhaust particles (PEPs) are the major contributors to urban air pollution. The aim of the present study was to characterize and investigate the in vitro cytotoxicity, oxidative stress, DNA damage and inflammation induced by PEPs. Cultured type II epithelium cells (human A549 lung cells) and alveolar macrophages (murine RAW 264.7 cells) were exposed to control, vehicle control and to different concentrations of PEPs for up to 24h. Each treatment was evaluated by cell viability, cytotoxicity, oxidative stress, DNA damage and inflammatory parameters. Overall in vitro studies demonstrated that both cell lines showed similar patterns in response to the above studies induced by petrol exhaust nanoparticles (PENPs). Vehicle control showed no changes compared with the control. In both cell lines, significant changes at the dose of 20 and 50μg/mL (A549 cell lines) and 10and 20μg/mL (macrophages) for PENPs were found. The reactive oxygen species production in both cell lines shot up in minutes, reached the maximum within an hour and came down after 4h. Hence, exposure to PENPs resulted in dose-dependent toxicity in cultured A549 cells and RAW 264.7 cells and was closely correlated to increased oxidative stress, DNA damage and inflammation.
"A very critical component of air pollution exposure is neuroinflammation [8, 50–52]. MCMA young urbanites exhibit an important frontal imbalance in genes essential for inflammation, innate and adaptive immune responses, oxidative stress, cell proliferation and apoptosis, when compared to age-matched residents in low pollution cities . "
[Show abstract][Hide abstract] ABSTRACT: Chronic exposure to particulate matter air pollution is known to cause inflammation leading to respiratory- and cardiovascular-related sickness and death. Mexico City Metropolitan Area children exhibit an early brain imbalance in genes involved in oxidative stress, inflammation, and innate and adaptive immune responses. Early dysregulated neuroinflammation, brain microvascular damage, production of potent vasoconstrictors, and perturbations in the integrity of the neurovascular unit likely contribute to progressive neurodegenerative processes. The accumulation of misfolded proteins coincides with the anatomical distribution observed in the early stages of both Alzheimer's and Parkinson's diseases. We contend misfolding of hyperphosphorylated tau (HP π ), alpha-synuclein, and beta-amyloid could represent a compensatory early protective response to the sustained systemic and brain inflammation. However, we favor the view that the chronic systemic and brain dysregulated inflammation and the diffuse vascular damage contribute to the establishment of neurodegenerative processes with childhood clinical manifestations. Friend turns Foe early; therefore, implementation of neuroprotective measures to ameliorate or stop the inflammatory and neurodegenerative processes is warranted in exposed children. Epidemiological, cognitive, structural, and functional neuroimaging and mechanistic studies into the association between air pollution exposures and the development of neuroinflammation and neurodegeneration in children are of pressing importance for public health.
"TNFα is a "potent" pro-inflammatory cytokine elevated in both AD and PD patients, where it is implicated to play a causal role in neurotoxicity . Consistent with previous reports on short term and high exposures to air pollution [18,28,46] and chronic human studies , here we show a general pro-inflammatory response in the brain with subchronic DE exposure, which we propose may be due in large part to a systemic/peripheral effect that reaches the entire brain, rather than solely through the olfactory bulb, a favored pathway of PM entry into the brain [47,48]. This is evidenced by the fact that the olfactory bulb showed a blunted TNFα response when compared to other regions and TNFα levels were elevated in most regions tested, with the exception of the cerebellum (Figure 1). "
[Show abstract][Hide abstract] ABSTRACT: 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.
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.
Male Fischer 344 rats were exposed to DE (992, 311, 100, 35 and 0 μg PM/m³) by inhalation over 6 months.
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.
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.
Journal of Neuroinflammation 08/2011; 8(1):105. DOI:10.1186/1742-2094-8-105 · 5.41 Impact Factor
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