Toxicological responses of BEAS‐2B cells to repeated exposures to benzene, toluene, m‐xylene, and mesitylene using air–liquid interface method

Abstract

In order to reduce exposure to toxic chemicals, the European REACH regulation (1907/2006) recommends substituting toxic molecules with compounds that are less harmful to human health and the environment. Toluene is one of the most frequently used solvents in industries despite its toxicity. The objective of this study is to better understand and compare the toxicity of toluene and its homologues in a bronchial cell model. Thus, human bronchial BEAS‐2B cells were exposed to steams of toluene, m‐xylene, mesitylene (1,3,5‐trimethylbenzene), and benzene (20 and 100 ppm). Exposure was carried out using an air–liquid interface (ALI) system (Vitrocell) during 1 h/day for 1, 3, or 5 days. Cytotoxicity, xenobiotic metabolism enzyme gene expression, and inflammatory response were evaluated following cell exposures. BEAS‐2B cell exposure to toluene and its homologues revealed the involvement of major (CYP2E1) and minor metabolic pathways (CYP1A1). A late induction of genes (EPHX1, DHDH, ALDH2, and ALDH3B1) was measured from Day 3 and can be linked to the formation of metabolites. An increase in the secretion level of inflammatory markers (TNF‐α, IL‐6, IL‐8, MCP‐1, and GM‐CSF) was also observed. In parallel, regulation between inflammatory mediators and the expression of transmembrane glycoprotein mucin MUC1 was also studied. This in vitro approach with ALI system points out the relevance of conducting repeated exposures to detect potential late effects. The difference recorded after cell exposure to toluene and its homologues highlights the importance of substitution principle.

In Vitro Systems for Toxicity Evaluation of Microbial Volatile Organic Compounds on Humans: Current Status and Trends

“…With new molecular and genetic techniques, new cell lines for inhalatory purposes have been made available through artificial immortalization. The BEAS-2B cell line, generated in 1989 by immortalization of bronchial epithelium [170], has been used for toxicological studies of industrial VOCs such as toluene, benzene, m-xylene [113,171]. It has also been used for risk assessment of air pollutants in urban areas [172].…”

“…Tumor derived [157] Yes [5,56,57,[158][159][160][161][162][163] Calu-3 Epithelial adenocarcinoma Tumor derived [166] Yes [165,167,168] BEAS-2B Bronchial epithelium SV40 T-antigen [170] Yes [113,171,172] 16HBE14o-Bronchial epithelium SV40 T-antigen [187] Yes [173][174][175][176] NuLi-1 Bronchial epithelium hTERT [188] Yes [181,189] HBEC3-KT Bronchial epithelium hTERT [190] No BCi-NS1.1 Large airways basal cell hTERT [182] No hAELVI Primary alveolar epithelim Lentivirus [185] Yes [186] hSABCi-NS1.1 Small airway basal cell hTERT [183] No…”

Boosting VOCs elimination by coupling different techniques

“…These enzymes have a certain substrate specificity, and the results show that the effluents of the tested catalysts contained small amounts of polycyclic organic compounds of the PAH type. By measuring the activation of XMEs classically induced by polycyclic organic compounds, as well as the activation of AhR, in lung cells exposed to emissions from the catalytic degradation of toluene, we could thus suggest the formation of high molecular weight compounds that may confer residual toxicity to the catalyst emissions [Figure 3] [39] . These compounds were not detected in the routine micro-GC analysis used in the chemical optimization of catalyst systems.…”

“…Experimental setup of the coupling of the cell exposure system to the catalyst formulated for the catalytic degradation of toluene [38] . ) and analyzed by ∆∆Ct method [39] using air-exposed cells as reference and 18S as a normalization gene. Data are shown as median RQ values vs. controls and interquartile range.…”

“…Expression of the 12 genes was measured by RT-qPCR (n = 3) and analyzed by the ΔΔCt method [39] using cells exposed to filtered air as a reference and the geometric mean Ct of 18S, GAPDH, and B2M as normalization genes (=, no significant gene expression change; -, RQ < 0.5 ; +, RQ > 2 ; ++, RQ > 4).…”