Composition of Air Pollution Particles and Oxidative Stress in Cells, Tissues, and Living Systems

Abstract

Epidemiological studies demonstrated an association between increased levels of ambient air pollution particles and human morbidity and mortality. Production of oxidants, either directly by the air pollution particles or by the host response to the particles, appears to be fundamental in the biological effects seen after exposure to particulate matter (PM). However, the precise components and mechanisms responsible for oxidative stress following PM exposure are yet to be defined. Direct oxidant generation by air pollution particles is attributed to organic and metal components. Organic compounds generate an oxidative stress through redox cycling of quinone-based radicals, by complexing of metal resulting in electron transport, and by depletion of antioxidants by reactions between quinones and thiol-containing compounds. Metals directly support electron transport to generate oxidants and also diminish levels of antioxidants. In addition to direct generation of oxidants by organic and metal components, cellular responses contribute to oxidative stress after PM exposure. Reactive oxygen species (ROS) production occurs in the mitochondria, cell membranes, phagosomes, and the endoplasmic reticulum. Oxidative stress following PM exposure initiates a series of cellular reactions that includes activation of kinase cascades and transcription factors and release of inflammatory mediators, which ultimately lead to cell injury or apoptosis. Consequently, oxidative stress in cells and tissues is a central mechanism by which PM exposure leads to injury, disease, and mortality.

Cytotoxic response in human lung epithelial cells and ion characteristics of urban-air particles from Torino, a northern Italian city

“…A small amount of iron is bio-available (approximately 4 % of total Fe), and this fraction is involved in oxidant generation after PM exposure by directly supporting electron transport, thus producing ROS (Ghio et al 2012). Bio-available Fe showed a seasonal trend, with higher content of this metal in samples from the cold season compared with those from the warm seasons and was also correlated with the PM10 and PM2.5 concentrations.…”

“…organic carbon, are greater in urban environments, and specific metals may also be more prevalent in these areas. In an urban setting, approximately 40 % of the particle mass can be attributed to fossil fuel use (Ghio et al 2012). …”

Quinone compounds regulate the level of ROS production by the NADPH oxidase Nox4

“…They can be formed from benzene or polycyclic aromatic hydrocarbons and are toxicologically important components of air pollution [2] and cigarette smoke [3]. Among the enzymes that modulate quinone toxicity, the NAD(P)H quinone oxidoreductase type 1 (NQO1; EC 1.6.99.2) is one of the most important enzymes.…”

The Impact of Pollution on Skin and Proper Efficacy Testing for Anti-Pollution Claims

“…However, ROSs are unstable, so they can easily react with other molecules in the cell, causing damage. Each living cell also has defense mechanisms to neutralize the negative impact of ROS, such as antioxidant enzymes: catalase, superoxide dismutase, or glutathione peroxidase [24,25]. Air pollutants are known to deplete the antioxidant enzymes in epidermis.…”