Global gene expression changes in human embryonic lung fibroblasts induced by organic extracts from respirable air particles

Abstract

BackgroundRecently, we used cell-free assays to demonstrate the toxic effects of complex mixtures of organic extracts from urban air particles (PM2.5) collected in four localities of the Czech Republic (Ostrava-Bartovice, Ostrava-Poruba, Karvina and Trebon) which differed in the extent and sources of air pollution. To obtain further insight into the biological mechanisms of action of the extractable organic matter (EOM) from ambient air particles, human embryonic lung fibroblasts (HEL12469) were treated with the same four EOMs to assess changes in the genome-wide expression profiles compared to DMSO treated controls.MethodFor this purpose, HEL cells were incubated with subtoxic EOM concentrations of 10, 30, and 60 μg EOM/ml for 24 hours and global gene expression changes were analyzed using human whole genome microarrays (Illumina). The expression of selected genes was verified by quantitative real-time PCR.ResultsDose-dependent increases in the number of significantly deregulated transcripts as well as dose-response relationships in the levels of individual transcripts were observed. The transcriptomic data did not differ substantially between the localities, suggesting that the air pollution originating mainly from various sources may have similar biological effects. This was further confirmed by the analysis of deregulated pathways and by identification of the most contributing gene modulations. The number of significantly deregulated KEGG pathways, as identified by Goeman's global test, varied, depending on the locality, between 12 to 29. The Metabolism of xenobiotics by cytochrome P450 exhibited the strongest upregulation in all 4 localities and CYP1B1 had a major contribution to the upregulation of this pathway. Other important deregulated pathways in all 4 localities were ABC transporters (involved in the translocation of exogenous and endogenous metabolites across membranes and DNA repair), the Wnt and TGF-β signaling pathways (associated particularly with tumor promotion and progression), Steroid hormone biosynthesis (involved in the endocrine-disrupting activity of chemicals), and Glycerolipid metabolism (pathways involving the lipids with a glycerol backbone including lipid signaling molecules).ConclusionThe microarray data suggested a prominent role of activation of aryl hydrocarbon receptor-dependent gene expression.

Analysis of gene expression changes in A549 cells induced by organic compounds from respirable air particles

“…In our previous studies, we have focused on comparison of genotoxic dose-responses (determined as DNA adduct formation) with induction of AhR activation in A549 cells [7] and global gene expression in human lung fibroblasts HEL cells treated with the same set of EOM samples [6]. Here, we attempted to identify gene expression changes induced in human alveolar carcinoma A549 cells by a complex mixture of air pollutants adsorbed on PM2.5, and to compare the effects of EOMs originating from distinct localities and sources.…”

“…We recently demonstrated that extractable organic matter (EOM) from these PM2.5 samples induced significant gene expression changes in normal human lung fibroblasts (HEL 12469) [6]. In this study numerous biological processes and signaling pathways have been found to be deregulated in response to various organic extracts from PM2.5, and the key role of the activated AhR has been identified.…”

“…PM collection, extraction of organic matter and chemical characterization has been extensively described in our previous studies [6,7]. The basic characteristics of PM2.5 sampling are shown in Table 3.…”

“…The rapid development of toxicogenomics has provided a tool to gather mechanistic information on the changes occurring simultaneously in the cellular transcriptome in response to xenobiotic exposure, including complex mixtures of environmental pollutants, such as whole aiborne particles or their extracts [5,6].…”

Air Pollution Exposure

“…46,47 In human lung fi broblasts, the TGF-b signaling pathway is deregulated in a dose-dependent manner by exposure to extractable organic matter from ambient air pollution. 48 Th is occurs via both up-and downregulation of specifi c genes responsible for TGF-b signaling, highlighting the complex relationship between the exposure and downstream protein activity. Taken together, these data provide biologic plausibility that air pollution could be associated with the development, progression, or exacerbation of ILD via mechanisms of oxidative stress, dysregulated fi brogenesis, and/or infl ammation ( Fig 1 ).…”