Air Pollution and Brain Damage

Abstract

Exposure to complex mixtures of air pollutants produces in ammation in the upper and lower respiratory tract. Because the nasal cavity is a common portal of entry, respiratory and olfactory epithelia are vulnerable targets for toxicological damage. This study has evaluated, by light and electron microscopy and immunohistochemica l expression of nuclear factor-kappa beta (NF-j B) and inducible nitric oxide synthase (iNOS), the olfactory and respiratory nasal mucosae, olfactory bulb, and cortical and subcortical structures from 32 healthy mongrel canine residents in Southwest Metropolitan Mexico City (SWMMC), a highly polluted urban region. Findings were compared to those in 8 dogs from Tlaxcala, a less polluted, control city. In SWMMC dogs, expression of nuclear neuronal NF-j B and iNOS in cortical endothelial cells occurred at ages 2 and 4 weeks; subsequen t damage included alterations of the blood-brain barrier (BBB), degenerating cortical neurons, apoptotic glial white matter cells, deposition of apolipoprotein E (apoE)-positive lipid droplets in smooth muscle cells and pericytes, nonneuritic plaques, and neuro brillary tangles. Persistent pulmonary in ammation and deteriorating olfactory and respiratory barriers may play a role in the neuropatholog y observed in the brains of these highly exposed canines. Neurodegenerativ e disorders such as Alzheimer's may begin early in life with air pollutants playing a crucial role.

Brain Inflammation and Alzheimer's-Like Pathology in Individuals Exposed to Severe Air Pollution

“…Breakdown of the nasal olfactory epithelial (nose-brain) barrier is also likely in Mexico City residents, because this has been observed in dogs (Calderón-Garcidueñas et al, 2002, 2003a. Breakdown of respiratory epithelial barriers may contribute to brain inflammation by increasing the access of air pollutants to the brain, both directly through the olfactory pathway and indirectly through the systemic circulation (Calderón-Garcidueñas et al, 2002;Dorman et al, 2002;Calderón-Garcidueñas et al, 2003a;Oberdorster et al, 2004). The olfactory bulb is the first synaptic relay of neurons that reside in the olfactory epithelium and that are directly exposed to air pollutants.…”

Under the Dome: Air Pollution, Wellbeing, and Pro-Environmental Behaviour Among Beijing Residents

“…But there are many high concentrations of small and fine particulate pollution components of air pollution that are particularly associated with high numbers of deaths from heart disease and stroke, as well as respiratory illnesses and cancers (WHO, 2014a). In addition, air pollution may damage cognitive function (e.g., Anderson, Thundiyil, & Stolbach, 2012;Calderón-Garcidueñas et al, 2008;Fonken et al, 2011) and the brain (e.g., Calderón-Garcidueñas et al, 2002;Calderón-Garcidueñas et al, 2007;Calderón-Garcidueñas et al, 2004). According to the WHO (2014b), around 7 million premature deaths globally every year are due to outdoor air pollution.…”

Nitrogen Oxides Induced Neurodegeneration as Examined by Nuclear Magnetic Resonance

“…It has been reported that olfactory dysfunction due to ambient airborne pollutant exposure is associated with neurodegenerative diseases [6]. The nasal epithelium is also vulnerable to damage by air pollutants, and there is a correlation with increased deposition of apolipoprotein E and neurofibrillary tangles [7]. Nitrogen oxides can be inhaled into the lung, where it induces the expression of inflammatory cytokines [8].…”