Impact of air pollution on lung inflammation and the role of Toll-like receptors

Abstract

Abstract:The link between air pollution and adverse pulmonary health effects is well established. The National Ambient Air Quality Standards were formulated to protect human health. These standards are strictly enforced based on strong associations between elevated air pollution levels and increased emergency room visits and hospitalizations due to respiratory conditions. Impacts of air pollution on lung health occur due to the direct interaction between the external environment and internal biological systems and processes. The innate immune system is one of the first lines of defense against inhaled air contaminants and is characterized by activation of key signaling pathways and inflammatory cell recruitment to the lung. Numerous independent and often redundant pathways participate in innate and adaptive immune responses. Given the impact of air pollution on human health, extensive research efforts have aimed to characterize the mechanisms of response to various air pollutants and evaluate risk factors contributing to individual susceptibility. A significant body of evidence exists to document air pollution-induced alterations in proinflammatory or oxidative signaling molecules. However, the role of specific pathways participating in the propagation of the inflammatory effects remains unclear. One hypothesis for interindividual susceptibility to inhaled air pollutants is that genetic polymorphisms in inflammatory or oxidative stress pathways may contribute to the diverse range of the inflammatory response. Activation of numerous receptors associated with airway cells culminates in the translocation of nuclear factor-kappa B and other transcription factors to the nucleus, and therefore initiation of altered signaling of proinflammatory mediators. Alterations in the transcription and expression of inflammatory mediators following exposure to air pollution are well documented. However, the interaction between specific air pollutants and specific cell surface and intracellular receptors has not been clearly defined. Involvement of specific pathways in the innate immune response may be dependent on differential physical and chemical characteristics of air pollution. One pathway implicated in the response to inhaled air pollutants is initiated by the activation of Toll-like receptors (TLRs). TLRs and downstream proinflammatory mediators are well studied for their role in pathogen response, yet gaps in the understanding of TLR response to nonpathogenic agents, such as air pollution, exist. TLRs are associated with inflammation and allergy, and emerging evidence suggests they may also play a role in the response and susceptibility to air pollution. However, the specific component, exogenous or endogenous, responsible for the association between air pollution and TLR activation has yet to be clearly identified. Improved understanding of pulmonary response mechanisms and potential mediators of susceptibility to air pollution, including the role of TLRs, may contribute to a reduction of the health burden of air pollutio...

Bioaerosol-induced in vitro activation of toll-like receptors and inflammatory biomarker expression in waste workers

“…Results from in vitro experiments cannot fully explain exposure-related health outcomes in workers, as individual susceptibility naturally varies due to genetic polymorphisms, underlying health conditions, age, nicotine use, BMI, or external factors, such as long-term exposure to weak electro-magnetic fields (Hosseinabadi et al 2019 ; Plummer et al 2012 ; Schwartz and Cook 2005 ). However, based on the in vitro results in the present study, it can be assumed that occupational exposure during waste handling may elicit an immune response in susceptible workers.…”

Impact of the Airborne Particulate Matter onthe Human Health

“…To protect human health, the US EPA has established the NAQS to regulate "criteria" of air pollutants: O 3 , PM, NO x , SO x , lead, and carbon monoxide (CO). Regulation of these criteria through the Clean Air Act is based on the scientific evidence that exposure to air pollution is associated with the development (long-term effect) or exacerbation (short-term effect) of a variety of respiratory conditions (Plummer, Smiley-Jewell, and Pinkerton, 2012). Acute and chronic exposures to atmospheric gases and PM are associated with increased emergency room visits and hospital admissions for exacerbations of pulmonary conditions, including asthma and chronic obstructive pulmonary disease.…”

“…These effects may result from direct interaction of air pollutants with various receptors or via interactions with secondary mediators within these inflammatory pathways. Numerous investigations of air pollution-induced health effects are investigating the mechanism behind the inflammatory response to inhaled air pollutants using human, laboratory, and cellular systems (Plummer, Smiley-Jewell, and Pinkerton, 2012). It has just been reported (see Section 10.2) that PM physicochemical nature is influenced by many factors such as particle size, emission season, and site; in such a way it seems difficult to understand which is the contribution promoting the inflammatory pathways.…”

Hyperparameter-Optimization-Inspired Long Short-Term Memory Network for Air Quality Grade Prediction

“…A large number of epidemiological and pathological studies have shown that pollutants in the air can cause serious lung diseases [5], including particulate matter (PM 2.5 , PM 10 ), sulfur dioxide (SO 2 ), carbon monoxide (CO) and nitrogen oxide (NOx) being capable of causing asthma and tuberculosis. At the same time, other systems and organs of the body can also be harmed to varying degrees if people are exposed to air pollution for a long time [6][7][8][9], and when the amount and concentration of air pollutant increases obviously, even that can indirectly affect the health of human beings through permeation into food products that people usually eat [10,11]. This introduces an urgent need for people to have a certain degree of understanding of air quality in order to adopt operations to manage air quality.…”