Attenuation of oxidative stress and chromosomal aberrations in cultured macrophages and pulmonary cells following self-sustained high temperature synthesis of asbestos

Maurizio Ferretti,Laura Gaggero,Sebastiano La Maestra,Rosanna T Micale,Alberto Izzotti

doi:10.1038/s41598-020-65620-x

Maurizio Ferretti, Laura Gaggero + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-65620-x

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Abstract

Inhalation of asbestos fibres can cause lung and pleural diseases in humans and constitutes a severe public health threat worldwide. The aim of the present study was to assess the biological effects induced in both pulmonary cells (A549) and monocyte/macrophage (RAW 264.7) cell lines by combustion slags obtained from asbestos through a self-sustained high-temperature synthesis (SHS) reaction. The SHS reaction involves rapid thermal treatment and displays great ability to neutralise asbestos. Cytotoxicity, redox status imbalance, lipid peroxide production, DNA strand breaks (comet assay) and chromosomal aberrations (cytokinesis block micronucleus test) were evaluated in cells exposed either to untreated asbestos fibres or to grinded SHS-generated slags of different granulometry, tested in cultured cells at varying doses and for varying exposure times. Our results show that asbestos fibres cause redox status imbalance, especially in monocyte/macrophage cell lines. Moreover, they promote lipid peroxidation and trigger genomic alterations. When the cells were exposed to slag powders, which are the products of SHS asbestos treatment, generation of lipid peroxides and induction of DNA strand breaks still persisted, due to the high content in iron and other metals detected in these samples. However, there was an attenuation of redox status imbalance and an absence of chromosomal aberrations, which probably reflects the loss of the asbestos fibrous structure following SHS reaction, as demonstrated by electron microscopy analyses. In conclusions, SHS-treated asbestos wastes can potentially have deleterious health effects due to the oxidative stress induced by inhaled powders but they loose the asbestos ability to induce chromosomal alterations.

Highlights

Inhalation of asbestos fibres can cause lung and pleural diseases in humans and constitutes a severe public health threat worldwide
The volatile substances released from chrysotile or embedded calcite as breakdown products induced a swirling vesicular texture
There was an attenuation of oxidative alterations, which occurred in the absence of any lipid peroxidation alterations, as well as a decrease of the DNA damaging activity and especially of chromosomal aberrations

Summary

Introduction

Inhalation of asbestos fibres can cause lung and pleural diseases in humans and constitutes a severe public health threat worldwide. Our results show that asbestos fibres cause redox status imbalance, especially in monocyte/macrophage cell lines They promote lipid peroxidation and trigger genomic alterations. The number of industries that still use asbestos is decreasing, the workers with the highest risks today are likely to be those subject to incidental exposures, for example construction workers and tunnel excavation workers. Awareness of this issue has increased, and advanced preventive monitoring in the workplace is currently carried out[4]. In Italy, the quantity of asbestos-containing waste (ACW) is thought to be as much as 30 million tons, i.e., 18 million m3, about half of which is pure asbestos[11], and the situation in other European countries is similar

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