Yoon Cho

Analysis of dose-response to hexanal-induced gene expression in A549 human alveolar cells

The problems of analyzing dose effects on gene expression are gaining attention in toxicological research. Determining how gene expression profiles change with toxicant dose will improve the utility of arrays in identifying biomarkers and elucidating their modes of toxic action. In the present study, we focused on determining the dose-dependent alterations of gene expression profiles with hexanal exposure and we identified the possible biomarkers of hexanal in A549 human alveolar cells. A549 cells were exposed to a 5% inhibitory concentration (IC5) and a 20% inhibitory concentration (IC20) of hexanal for 48 h. Through microarray analysis using an oligonucleotide chip, we identified that the gene expression patterns were differentially shown in the control group and the hexanalexposed groups. The hexanal-exposed groups are more sensitive to gene alteration than the control group, and gene expressions are more significantly altered in the IC20 exposure group than in the IC5 exposure group. With clustering analysis of gene expression profiles, we identified 2,929 IC5− and 3,678 IC20-specific genes, and 302 dose-dependently expressed genes. Gene ontology (GO) analysis with 246 annotated genes of the 302 dosedependent expressed genes showed correlation with the key biological processes involved in neurological system processes, immune system development, cell activation, and cell-cell signaling. In conclusion, current study describes alterations in gene expression profiles in response to exposure to different doses of hexanal and related toxic pathways induced by significantly expressed genes. Moreover, novel genes and pathways that could potentially play a role in the prevention of respiratory disease due to aldehydes are identified.

Integrative analysis of mRNA and microRNA expression of a human alveolar epithelial cell(A549) exposed to water and organic-soluble extract from particulate matter (PM)2.5

MicroRNA (miRNA) is now attracting attention as a powerful negative regulator of messenger RNA(mRNA) levels, and is implicated in the modulation of important mRNA networks involved in toxicity. In this study, we assessed the effects of particulate matter 2.5 (PM2.5), one of the most significant air pollutants, on miRNA and target gene expression. We exposed human alveolar epithelial cell (A549) to two types of PM2.5[water (W‐PM2.5) and organic (O‐PM2.5) soluble extracts] and performed miRNA microarray analysis. A total of 37 miRNAs and 62 miRNAs were altered 1.3‐fold in W‐PM2.5 and O‐PM2.5, respectively. Integrated analyses of miRNA and mRNA expression profiles identified negative correlations between miRNA and mRNA in both W‐PM2.5 and O‐PM2.5 exposure groups. Gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses showed that the 35 W‐PM2.5 target genes are involved in responses to nutrients, positive regulation of biosynthetic processes, positive regulation of nucleobase, nucleoside, and nucleotide, and nucleic acid metabolic processes; while the 69 O‐PM2.5 target genes are involved in DNA replication, cell cycle processes, the M phase, and the cell cycle check point. We suggest that these target genes may play important roles in PM2.5‐induced respiratory toxicity by miRNA regulation. These results demonstrate an integrated miRNA‐mRNA approach for identifying molecular events induced by environmental pollutants in an in vitro human model.

Epidermal growth factor receptor (EGFR)—MAPK—nuclear factor(NF)‐κB—IL8: A possible mechanism of particulate matter(PM) 2.5‐induced lung toxicity

Airway inflammation plays a central role in the pathophysiology of diverse pulmonary diseases. In this study, we investigated whether exposure to particulate matter (PM) 2.5, a PM with an aerodynamic diameter of less than 2.5 µm, enhances inflammation‐related toxicity in the human respiratory system through activation of the epidermal growth factor receptor (EGFR) signaling pathway. Through cytokine antibody array analysis of two extracts of PM2.5 [water (W‐PM2.5) and organic (O‐PM2.5) soluble extracts] exposed to A549 (human alveolar epithelial cell), we identified eight cytokines changed their expression with W‐PM2.5 and three cytokines with O‐PM2.5. Among them, epidermal growth factor (EGF) was commonly up‐regulated by W‐PM2.5 and O‐PM2.5. Then, in both groups, we can identify the increase in EGF receptor protein levels. Likewise, increases in the phosphorylation of ERK1/2 MAP kinase and acetylation of nuclear factor(NF)‐κB were detected. We also detected an increase in IL‐8 that was related to inflammatory response. And using the erlotinib as an inhibitor of EGFR, we identified the erlotinib impaired the phosphorylation of EGFR, ERK1/2, acetylation of NF‐κB proteins and decreased IL‐8. Furthermore, at in vivo model, we were able to identify similar patterns. These results suggest that PM2.5 may contribute to an abnormality in the human respiratory system through EGFR, MAP kinase, NF‐κB, and IL‐8 induced toxicity signaling.

Gene expression profiling of human alveolar epithelial cells (A549 cells) exposed to atmospheric particulate matter 2.5 (PM2.5) collected from Seoul, Korea

Many epidemiological and in vitro studies have shown that particulate matter 2.5 (PM2.5) is associated with adverse health effects in humans, especially respiratory morbidity and mortality1–3. While the mechanisms for these effects have been vigorously investigated for many years, they still remain uncertain. In previous studies, we collected PM2.5 samples in Seoul, Korea, where pollution results from a high level of automobile traffic, and analyzed the chemical composition of PM2.5. In the present study, we used gene expression profiling and gene ontology (GO) analysis to identify the gene expression changes in A549 human alveolar epithelial cells induced by exposure to water and organic extracts of PM2.5 (W-PM2.5 and O-PM2.5) in order to evaluate the adverse health effects of PM2.5. Transcriptomic profiling indicates that the O-PM2.5 exposure group was more sensitive in gene alterations than the W-PM2.5 exposure group. Through analysis of gene expression profiles, we identified 149 W-PM2.5-specific genes and 516 O-PM2.5-specific genes, as well as 173 commonly expressed genes in both the W-PM2.5 and O-PM2.5 exposure groups. After gene ontology (GO) analysis on the O-PM2.5-specific genes, we determined several key pathways that are known to be related to increasing pulmonary toxicity, such as immune response, regulation of inflammatory response, metabolism of xenobiotics by cytochrome P450, and retinol metabolism. However, we did not find the pulmonary toxicity-related pathways through GO analysis on the W-PM2.5-specific genes. In addition, 173 commonly expressed genes are involved in tyrosine catabolic process, retinol metabolism pathway, and steroid hormone biosynthesis — all of which are known to induce adverse health effects. In conclusion, this report describes changes in gene expression profiles in an in vitro respiratory system in response to exposure to PM2.5 water and organic extracts and relates these gene expression changes to pulmonary toxicity related pathways. This experiment adds to the understanding of how cells respond to PM2.5 exposure through transcriptional regulation.

Expression of exosomal and cellular microRNAs: as biomarkers for toluene, ethylbenzene, xylene (TEX) exposure

Exosomes, small vesicles released by many cells, are associated with various biological processes and they can potentially be used for prognosis and therapy and as biomarkers of health. Thus, they are gaining attention in toxicological and pathological research. miRNA is also considered as a useful tool to predict health risk caused by environmental toxicants. Volatile organic compounds (VOCs), including toluene (T), xylene (X), and ethylbenzene (E), have been reported to be harmful. Although VOCs are prevalent in the environment, the mechanisms underlying their toxicity are not understood. In this study, a microarray analysis identified 50 miRNAs that were differentially expressed in exosomes and cytosols of HL-60 cell line exposed to three VOCs (TEX). A total of 3,355 putative target genes were classified according to the miRWalk 2.0 database. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the putative target genes showed a correlation with biological processes involved in the regulation of myeloid leukocyte differentiation, MAPK signaling pathway, and pathways in cancer. In conclusion, this study describes alterations in miRNA expression profiles in response to exposure to VOCs and related toxicity affected by significantly expressed target genes. Moreover, it illustrates the value of exosomes as diagnostic biomarkers of toxicity.

Comparative analysis of microRNA and mRNA expression profiles in cells and exosomes under toluene exposure

Recent studies have illustrated the growing importance of exosomes (small extracellular vesicles) and their constituent microRNAs (miRNAs) in the fields of toxicology and pathology. The mechanism of toxicity of toluene, a highly-prevalent and volatile organic compound, is largely unknown. To examine the role of miRNAs in toluene-induced toxicity, we investigated miRNAs and toluene-induced gene expression in HL-60 human promyelocytic leukemia cells and exosomes using microarrays. A total of 54 miRNAs were differentially expressed in HL-60 cell lines exposed to toluene and exosomes from the cells. Four out of the 54 miRNAs (hsa-miR-1290, hsa-miR-718, hsa-miR-3663-3p, and hsa-miR-320c) were subsequently validated by qRT-PCR. Integrated analysis of miRNA and mRNA expression profiles identified 8 miRNA-mRNA correlations. By performing Comparative Toxicogenomics Database analysis, we found that the eight putative target genes of the differentially expressed miRNAs under toluene exposure (EXOSC6, RHOH, GFER, HERC2, GOLGA4, SLC7A11, GCLM, and BACH1) are related to diverse disease categories such as nervous system disease, cancer, cardiovascular disease, and respiratory tract disease. In conclusion, our data demonstrated that miRNA-mRNA networks provide a better understanding of toxicological mechanism caused by environmental pollutants in vitro using HL-60 cells and exosomes.

Hexanal-induced changes in miRNA-mRNA interactions in A549 human alveolar epithelial cells

Although hexanal is considered to be a major air pollutant the correlation between hexanal and health risk is largely unknown. Identifying aldehyde toxicity in eukaryotic cells will be useful for preventing and treating environmental diseases and disorders. However, it is important to note that previous microRNA (miRNA) studies of hexanal have not yet identified the functional relationship between miRNA and mRNA. The aim of this study is to investigate the modulation of the integrated miRNA-mRNA relationship following exposure to hexanal. A549 human alveolar epithelial cells were treated to a 20% inhibitory concentration (IC20) of hexanal for 48 h. The microarray analysis results showed that 6 miRNA were altered in the hexanal-exposed A549 cells. Integrated analysis of miRNA and mRNA expression profiles identified 445 miRNA-mRNA correlations. KEGG analysis of 445 putative target genes of hexanal-induced miRNAs indicated that 8 genes (ATP2B3, ATP2B4, CACNA1G, EDNRA, GRM5, ITPR2, ITPKB, PTGER3) are involved in the calcium signaling pathway, which plays an important role in Alzheimer’s and several inherited immunodeficiency diseases. Therefore, this study suggests the value of miRNA-mRNA networks in order to identify molecular regulation in response to hexanal exposure in an in vitro model. Furthermore, this approach provides insight into the potential biological process of toxicity and a better understanding of the toxicological mechanism of toxicants.

Role of total hip arthroplasty and resurfacing in Legg-Calvé-Perthes disease.

Hip replacement arthroplasty is a very reliable and effective therapeutic modality for patients with end-stage degenerative coxarthrosis secondary to Legg-Calvé-Perthes disease (LCPD). Long-term results of the conventional total hip arthroplasty for patients with LCPD have been reported to be satisfactory similar to those for patients with primary arthritis. For selective patients, resurfacing arthroplasty can be performed successfully. We described special aspects of patients with LCPD in conventional total hip arthroplasty and resurfacing arthroplasty.

A study of cytotoxicity and genotoxicity of particulate matter (PM 2.5 ) in human lung epithelial cells (A549)

BackgroundsExposure to airborne particulate matter (PM2.5), a PM with an aerodynamic diameter of less than 2.5 μm, is known to be associated with a variety of adverse health effects, particularly related to the respiratory system. However, the molecular mechanisms involved in fine PM toxicity are still not well-characterized. In this study, we estimate pulmonary toxic mechanism using two types (water soluble extract, WPM2.5, and organic soluble extract, O-PM2.5) of PM2.5 on human lung epithelial cells (A549).MethodsSamples were collected using a high-volume air sampler. Each sample was divided into two groups by its own types (water soluble extract, W-PM2.5, and organic soluble extract, O-PM2.5). In the present study, two types of PM2.5-induced cytotoxic and genotoxic effects and expression of toxicity-related genes were evaluated using human lung epithelial cells (A549). Also, the production of intracellular reactive oxygen species was measured to investigate the mechanism of cell death induced by PM2.5ResultsBoth W-PM2.5 and O-PM2.5 exposures significantly reduced the viability of A549 cells in a dosedependent manner, and expression of 17 cell deathrelated genes were significantly regulated in the PM2.5 exposure group. Exposure of PM2.5 significantly induced the production of ROS. Further, data obtained from the Comet assay indicated that two extracts of PM2.5 caused DNA damage in A549 cells in a dose-dependent manner.ConclusionOur study suggests that ROS-mediated DNA damage may play a major role in PM2.5-induced cell death. This finding represents the basis for further studies addressing the pathophysiological mechanisms of PM2.5 exposure.

Analysis of gene expression changes in relation to hepatotoxicity induced by perfluorinated chemicals in a human hepatoma cell line

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) represent a rising class of persistent organic pollutants termed perfluorinated chemicals (PFCs). In this study, hepatotoxic effects of PFCs were examined by microarray and gene ontology (GO) analysis. Human hepatocellular carcinoma (HepG2) cells were exposed to PFOS and PFOA for 48 h, and the RNA was collected. Global gene expression analysis using microarrays revealed 279 and 1,973 genes that changed greater than 1.5-fold after PFOS and PFOA exposure, respectively (P<0.05 for both), with 154 genes common to both PFCs. These genes were enriched in gene ontology (GO) terms and KEGG pathways associated with hepatotoxicity. Many genes were involved in complement and coagulation cascades, PPAR signaling pathway, and regulation of cell proliferation, which coincide with clinical evidence and indicate the critical hepatotoxicity of PFCs. These results show that transcriptome alterations induced by PFOS and PFOA could be possible signatures of the hepatotoxic effects of PFCs.