Screening of Cellular Stress Responses Induced by Ambient Aerosol Ultrafine Particle Fraction PM0.5 in A549 Cells.

Pavlína Šimečková,Lucie Králiková,Jiřina Procházková,Jiří Neča,Miroslav Machala,Pavel Kulich,Soňa Marvanová

doi:10.3390/ijms20246310

Pavlína Šimečková, Lucie Králiková + Show 5 more

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https://doi.org/10.3390/ijms20246310

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Abstract

Effects of airborne particles on the expression status of markers of cellular toxic stress and on the release of eicosanoids, linked with inflammation and oxidative damage, remain poorly characterized. Therefore, we proposed a set of various methodological approaches in order to address complexity of PM0.5-induced toxicity. For this purpose, we used a well-characterized model of A549 pulmonary epithelial cells exposed to a non-cytotoxic concentration of ambient aerosol particle fraction PM0.5 for 24 h. Electron microscopy confirmed accumulation of PM0.5 within A549 cells, yet, autophagy was not induced. Expression profiles of various cellular stress response genes that have been previously shown to be involved in early stress responses, namely unfolded protein response, DNA damage response, and in aryl hydrocarbon receptor (AhR) and p53 signaling, were analyzed. This analysis revealed induction of GREM1, EGR1, CYP1A1, CDK1A, PUMA, NOXA and GDF15 and suppression of SOX9 in response to PM0.5 exposure. Analysis of eicosanoids showed no oxidative damage and only a weak anti-inflammatory response. In conclusion, this study helps to identify novel gene markers, GREM1, EGR1, GDF15 and SOX9, that may represent a valuable tool for routine testing of PM0.5-induced in vitro toxicity in lung epithelial cells.

Highlights

Particulate matter (PM) in the ambient air is known to play an important role in the development of cardiovascular and respiratory diseases and is classified as carcinogenic to humans (Group 1; [1])
In order to determine whether the aerosol particles smaller than 0.5 μm are able to induce cellular stress responses, pulmonary A549 cells were exposed to PM0.5 in a concentration of 25 μg/cm2 for 24 h, which was chosen according to the study Gualtieri et al [3] and shown to be non-cytotoxic in the time frame of 72 h (WST-1 assay; data not shown)
To ensure that aerosol particles were taken into the cells, ultrathin sections of A549 cells exposed to PM0.5 were examined by transmission electron microscopy

Summary

Introduction

Particulate matter (PM) in the ambient air is known to play an important role in the development of cardiovascular and respiratory diseases and is classified as carcinogenic to humans (Group 1; [1]). In order to reveal the mechanism of PM-induced toxicity, in vitro studies in human airway cells have been performed using size segregated aerosol particles. In addition to well-known effects, such as oxidative stress and inflammation, other mechanisms of nanoparticle toxicity were suggested and encompass endoplasmic reticulum stress (ER stress), dysfunction of lysosomes and dysfunction of autophagy [13,14,15]. These intracellular events might be linked to cellular stress responses [16]

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