Pathological Cardiopulmonary Evaluation of Rats Chronically Exposed to Traffic-Related Air Pollution

Abstract

Background: Traffic-related air pollution (TRAP) is made up of complex mixtures of particulate matter, gases and volatile compounds. However, the effects of TRAP on the cardiopulmonary system in most animal studies have been tested using acute exposure to singular pollutants. The cardiopulmonary effects and molecular mechanisms in animals that are chronically exposed to unmodified air pollution as a whole have yet to be studied. Additionally, sex-dependent toxicity of TRAP exposure has rarely been evaluated. Objectives: This study sought to assess the cardiopulmonary effect of chronic exposure to unmodified, real-world TRAP in both female and male rats. Methods: Four-week-old male and female rats were exposed to TRAP or filtered air for 14 months in a novel facility drawing air from a major freeway tunnel system in Northern California. Inflammation and oxidative stress markers were examined in the lung, heart, spleen, and plasma, and TRAP deposits were quantified in the lungs of both male and female rats. Results: Elemental analysis showed higher levels of eight elements in the female lungs and one element in the male lungs. Expression of genes related to fibrosis, aging, oxidative stress, and inflammation were higher in the rat hearts exposed to TRAP, with female rats being more susceptible than males. Enhanced collagen accumulation was found only in the TRAP-exposed female hearts. Plasma cytokine secretion was higher in both female and male rats, but inflammatory macrophages were higher only in TRAP-exposed male spleens. Discussion: Our results in rats suggest pathological consequences from chronic TRAP exposure, including sex differences indicating females may be more susceptible to TRAP-induced cardiac fibrosis. https://doi.org/10.1289/EHP7045

The Effects of Chronic Exposure to Ambient Traffic-Related Air Pollution on Alzheimer’s Disease Phenotypes in Wildtype and Genetically Predisposed Male and Female Rats

“…An important finding is that the mean maximum refractive intensity of the particles in the brains of TRAP animals was significantly greater than those in the brains of FA controls, suggesting differences in elemental composition. Although chemical analysis of these tissue-embedded particles was beyond the scope of this study, our previous characterization of TRAP collected from this facility showed that elemental, organic, and total carbon levels, as well as levels of copper, titanium, zinc, iron, sulfur, and silicon were significantly elevated in air from TRAP compared with FA exposure chambers ( Edwards et al. 2020 ; Patten et al.…”

“…The tunnel vivarium, which has been previously described ( Berg et al. 2020 ; Edwards et al. 2020 ; Patten et al.…”

“…TRAP was delivered unchanged in real time to exposure chambers within the tunnel vivarium. FA control animals were exposed to background ambient air collected from a storage shed immediately adjacent to the vivarium that was subjected to multiple emission control technologies to remove residual air pollutants as previously described ( Edwards et al. 2020 ).…”

“…Emissions controls used to purify FA included coarse filtration for removing large debris and dust, inline activated carbon for removing volatile organic compounds (VOCs), barium oxide-based catalytic converters for removing nitrogen oxides ( ), and a 6-port ultrahigh-efficiency particle filtering system for removing ultrafine [PM with aerodynamic diameter less than or equal to 10 micrometers ( ), fine [PM with aerodynamic diameter less than or equal to 2.5 micrometers ( )], and coarse mode PM; see Supplemental Materials, “Tunnel Exposure Facility” and Edwards et al. ( 2020 ) for further details on the exposure facility. The airflow rate in the exposure chambers was 35 cubic feet per min, in accordance with IACUC specifications.…”

Potential Mechanisms behind Air Pollution Toxicity: Findings from Real-World Chronic Exposures

“…In a recent pilot study reported in Environmental Health Perspectives, investigators sought to address this issue using a real-world model of TRAP exposure in rats. 2 Worldwide, ambient air pollution is estimated to cause 3.8 million premature deaths per year due to cardiovascular and respiratory diseases. 3,4 Several studies have reported an association between acute exposure to highly concentrated PM and development of cardiopulmonary dysfunction in humans and animals.…”