Evaluation of the Toxicity on Lung Cells of By-Products Present in Naphthalene Secondary Organic Aerosols

Abstract

In 2018, seven million people died prematurely due to exposure to pollution. Polycyclic aromatic hydrocarbons (PAHs) are a significant source of secondary organic aerosol (SOA) in urban areas. We investigated the toxic effects of by-products of naphthalene SOA on lung cells. These by-products were 1,4-naphthoquinone (1,4-NQ), 2-hydroxy-1,4-naphthoquinone (2-OH-NQ), phthalic acid (PA) and phthaldialdehyde (OPA). Two different assessment methodologies were used to monitor the toxic effects: real-time cell analysis (RTCA) and the Holomonitor, a quantitative phase contrast microscope. The chemicals were tested in concentrations of 12.5 to 100 µM for 1,4-NQ and 1 to 10 mM for 2-OH-NQ, PA and OPA. We found that 1,4-NQ is toxic to cells from 25 to 100 µM (EC50: 38.7 µM ± 5.2); 2-OH-NQ is toxic from 1 to 10mM (EC50: 5.3 mM ± 0.6); PA is toxic from 5 to 10 mM (EC50: 5.2 mM ± 0.3) and OPA is toxic from 2.5 to 10 mM (EC50: 4.2 mM ± 0.5). Only 1,4-NQ and OPA affected cell parameters (migration, motility, motility speed and optical volume). Furthermore, 1,4-NQ is the most toxic by-product of naphthalene, with an EC50 value that was one hundred times higher than those of the other compounds. RTCA and Holomonitor analysis showed a complementarity when studying the toxicity induced by chemicals.

Pathogenic Mechanisms of Secondary Organic Aerosols

“…A series of cell culture studies reported the capacity of SOA to induce cell toxicity. ,,,,,, Moreover, it has also been reported that SOA have the capacity to alter transcriptomic profiles of lungs cells (e.g., upregulation of tumor protein 53 (p53) signaling pathway). , The latter, known as the guardian of the genome, regulates various processes in response to stress detection. Indeed, p53-targeted genes can induce cell cycle arrest, apoptosis, or autophagy in a dependent manner of SOA.…”

Weight loss and abnormal lung inflammation in mice chronically exposed to secondary organic aerosols

“…11 In fact, it is one of the most abundant and volatile precursors of SOAs and is particularly studied in the literature. 8,[12][13][14] In this regard, a series of studies mainly cell culture studies revealed a role for SOAs in cell oxidative stress, toxicity and inammation. 12,15 While data from these cell culture systems studies are very informative, they do not translate the complex inammatory response of human diseased situations especially following a long-term exposure to SOAs.…”

“…8,[12][13][14] In this regard, a series of studies mainly cell culture studies revealed a role for SOAs in cell oxidative stress, toxicity and inammation. 12,15 While data from these cell culture systems studies are very informative, they do not translate the complex inammatory response of human diseased situations especially following a long-term exposure to SOAs. Also, the scant in vivo studies that were carried out over a short period of time (few days) of exposure to SOAs were inconclusive in that a minor or no inammatory response was observed.…”

The Toxic Effect of Water-Soluble Particulate Pollutants from Biomass Burning on Alveolar Lung Cells

“…Second, the quantitative phase microscope Holomonitor produces 3D reconstructive images of cells, and measures the structural and behavioral parameters of cells, such as their area and migration. Third, the multi-mode brightfield microscope Cytation 3 provides images of cells, allowing the visualization of cell division and death [23][24][25]. All three, flaming, smoldering and pyrolysis stages, can occur during wood fires.…”