Elevated glutathione in researchers exposed to engineered nanoparticles due to potential adaptation to oxidative stress.

Aim: To find a practical biomonitoring method for researchers exposed to nanoparticles causing oxidative stress. Methods: In a continuation of a study in 2016-2018, biological samples (plasma, urine and exhaled breath condensate [EBC]) were collected in 2019-2020 from 43 researchers (13.8 ± 3.0 years of exposure) and 45 controls. Antioxidant status was assessed using glutathione (GSH) and ferric-reducing antioxidant power, while oxidative stress was measured as thiobarbituric acid reactive substances, all using spectrophotometric methods. Researchers' personal nanoparticle exposure was monitored. Results: Plasma GSH was elevated in researchers both before and after exposure (p < 0.01); postexposure plasma GSH correlated with nanoparticle exposure, and GSH in EBC increased. Conclusion: The results suggest adaptation to chronic exposure to nanoparticles, as monitored by plasma and EBC GSH.

What is this study about? Identifying markers of oxidative stress and/or adaptation to oxidation stress could offer tools for monitoring exposure to nanoparticles in exposed researchers. In this study, we question whether these markers correlate with their personal exposure during the shift. What were the results? We found that exposure to nanoparticles correlated with the antioxidant marker glutathione, which is higher in workers who are already pre-exposed. What do the results mean? This study suggests that the researchers have adapted to nanoparticle exposure and are ready to combat oxidative stress. However, the similarity with increased markers of oxidative stress from asbestos and silica exposure, including nucleic acid oxidation, previously found in these researchers highlights the need for further research in this area to better understand and prevent potential future effects.

Effects of various environments on epigenetic settings and chromosomal damage.

Air pollution is a dominant environmental exposure factor with significant health consequences. Unexpectedly, research in a heavily polluted region of the Czech Republic, with traditional heavy industry, revealed repeatedly the lowest frequency of micronuclei in the season with the highest concentrations of air pollutants including carcinogenic benzo[a]pyrene (B[a]P). Molecular findings have been collected for more than 10 years from various locations of the Czech Republic, with differing quality of ambient air. Preliminary conclusions have suggested adaptation of the population from the polluted locality (Ostrava, Moravian-Silesian Region (MSR)) to chronic air pollution exposure. In this study we utilize the previous findings and, for the first time, investigate micronuclei (MN) frequency by type: (i) centromere positive (CEN+) MN, representing chromosomal losses, and (ii) centromere negative (CEN-) MN representing chromosomal breaks. As previous results indicated differences between populations in the expression of XRCC5, a gene involved in the non-homologous end-joining (NHEJ) repair pathway, possible variations in epigenetic settings in this gene were also investigated. This new research was conducted in two seasons in the groups from two localities with different air quality levels (Ostrava (OS) and Prague (PG)). The obtained new results show significantly lower frequencies of chromosomal breaks in the OS subjects, related to the highest air pollution levels (p < 0.001). In contrast, chromosomal losses were comparable between both groups. In addition, significantly lower DNA methylation was found in 14.3% of the analyzed CpG loci of XRCC5 in the population from OS. In conclusion, the epigenetic adaptation (hypomethylation) in XRCC5 involved in the NHEJ repair pathway in the population from the polluted region, was suggested as a reason for the reduced level of chromosomal breaks. Further research is needed to explore the additional mechanisms, including genetic adaptation.

Oxidative Stress and Antioxidant Response in Populations of the Czech Republic Exposed to Various Levels of Environmental Pollutants.

We aimed to identify the variables that modify levels of oxidatively damaged DNA and lipid peroxidation in subjects living in diverse localities of the Czech Republic (a rural area, a metropolitan locality, and an industrial region). The sampling of a total of 126 policemen was conducted twice in two sampling seasons. Personal characteristics, concentrations of particulate matter of aerodynamic diameter <2.5 µm and benzo[a]pyrene in the ambient air, activities of antioxidant mechanisms (superoxide dismutase, catalase, glutathione peroxidase, and antioxidant capacity), levels of pro-inflammatory cytokines (TNF-α, IL-1ß, and IL-6), concentrations of persistent organic pollutants in blood plasma, and urinary levels of polycyclic aromatic hydrocarbon metabolites were investigated as parameters potentially affecting the markers of DNA oxidation (8-oxo-7,8-dihydro-2'-deoxyguanosine) and lipid peroxidation (15-F2t-isoprostane). The levels of oxidative stress markers mostly differed between the localities in the individual sampling seasons. Multivariate linear regression analysis revealed IL-6, a pro-inflammatory cytokine, as a factor with the most pronounced effects on oxidative stress parameters. The role of other variables, including environmental pollutants, was minor. In conclusion, our study showed that oxidative damage to macromolecules was affected by processes related to inflammation; however, we did not identify a specific environmental factor responsible for the pro-inflammatory response in the organism.

The Impact of Air Pollution Exposure on the MicroRNA Machinery and Lung Cancer Development.

Small non-coding RNA molecules (miRNAs) play an important role in the epigenetic regulation of gene expression. As these molecules have been repeatedly implicated in human cancers, they have been suggested as biomarkers of the disease. Additionally, miRNA levels have been shown to be affected by environmental pollutants, including airborne contaminants. In this review, we searched the current literature for miRNAs involved in lung cancer, as well as miRNAs deregulated as a result of exposure to air pollutants. We then performed a synthesis of the data and identified those molecules commonly deregulated under both conditions. We detected a total of 25 miRNAs meeting the criteria, among them, miR-222, miR-21, miR-126-3p, miR-155 and miR-425 being the most prominent. We propose these miRNAs as biomarkers of choice for the identification of human populations exposed to air pollution with a significant risk of developing lung cancer.

Telomere length in peripheral blood lymphocytes related to genetic variation in telomerase, prognosis and clinicopathological features in breast cancer patients.

Disruption of telomere length (TL) homeostasis in peripheral blood lymphocytes has been previously assessed as a potential biomarker of breast cancer (BC) risk. The present study addressed the relationship between lymphocyte TL (LTL), prognosis and clinicopathological features in the BC patients since these associations are insufficiently explored at present. LTL was measured in 611 BC patients and 154 healthy controls using the monochrome multiplex quantitative Polymerase Chain Reaction assay. In addition, we genotyped nine TL-associated single-nucleotide polymorphisms that had been identified through genome-wide association studies. Our results showed that the patients had significantly (P = 0.001, Mann-Whitney U-test) longer LTL [median (interquartile range); 1.48 (1.22-1.78)] than the healthy controls [1.27 (0.97-1.82)]. Patients homozygous (CC) for the common allele of hTERT rs2736108 or the variant allele (CC) of hTERC rs16847897 had longer LTL. The latter association remained statistically significant in the recessive genetic model after the Bonferroni correction (P = 0.004, Wilcoxon two-sample test). We observed no association between LTL and overall survival or relapse-free survival of the patients. LTL did not correlate with cancer staging based on Union for International Cancer Control (UICC), The tumor node metastasis (TNM) staging system classification, tumour grade or molecular BC subtypes. Overall, we observed an association between long LTL and BC disease and an association of the hTERC rs16847897 CC genotype with increased LTL. However, no association between LTL, clinicopathological features and survival of the patients was found.

Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface.

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.

The Differential Effect of Carbon Dots on Gene Expression and DNA Methylation of Human Embryonic Lung Fibroblasts as a Function of Surface Charge and Dose.

This study presents a toxicological evaluation of two types of carbon dots (CD), similar in size (<10 nm) but differing in surface charge. Whole-genome mRNA and miRNA expression (RNAseq), as well as gene-specific DNA methylation changes, were analyzed in human embryonic lung fibroblasts (HEL 12469) after 4 h and 24 h exposure to concentrations of 10 and 50 µg/mL (for positive charged CD; pCD) or 10 and 100 µg/mL (for negative charged CD, nCD). The results showed a distinct response for the tested nanomaterials (NMs). The exposure to pCD induced the expression of a substantially lower number of mRNAs than those to nCD, with few commonly differentially expressed genes between the two CDs. For both CDs, the number of deregulated mRNAs increased with the dose and exposure time. The pathway analysis revealed a deregulation of processes associated with immune response, tumorigenesis and cell cycle regulation, after exposure to pCD. For nCD treatment, pathways relating to cell proliferation, apoptosis, oxidative stress, gene expression, and cycle regulation were detected. The expression of miRNAs followed a similar pattern: more pronounced changes after nCD exposure and few commonly differentially expressed miRNAs between the two CDs. For both CDs the pathway analysis based on miRNA-mRNA interactions, showed a deregulation of cancer-related pathways, immune processes and processes involved in extracellular matrix interactions. DNA methylation was not affected by exposure to any of the two CDs. In summary, although the tested CDs induced distinct responses on the level of mRNA and miRNA expression, pathway analyses revealed a potential common biological impact of both NMs independent of their surface charge.

Genotoxicant exposure, activation of the aryl hydrocarbon receptor, and lipid peroxidation in cultured human alveolar type II A549 cells.

The aryl hydrocarbon receptor (AhR) transcription factor is activated by polycyclic aromatic hydrocarbons (PAH) and other ligands. Activated AhR binds to dioxin responsive elements (DRE) and initiates transcription of target genes, including the gene encoding prostaglandin endoperoxide synthase 2 (PTGS-2), which is also activated by the transcription factor NF-ĸB. PTGS-2 catalyzes the conversion of arachidonic acid (AA) into prostaglandins, thromboxanes or isoprostanes. 15-F2t-Isoprostane (IsoP), regarded as a universal marker of lipid peroxidation, is also induced by PAH exposure. We investigated the processes associated with lipid peroxidation in human alveolar basal epithelial cells (A549) exposed for 4 h or 24 h to model PAH (benzo[a]pyrene, BaP; 3-nitrobenzanthrone, 3-NBA) and organic extracts from ambient air particulate matter (EOM), collected in two seasons in a polluted locality. Both EOM induced the expression of CYP1A1 and CYP1B1; 24 h treatment significantly reduced PTGS-2 expression. IsoP levels decreased after both exposure periods, while the concentration of AA was not affected. The effects induced by BaP were similar to EOM except for increased IsoP levels after 4 h exposure and elevated AA concentration after 24 h treatment. In contrast, 3-NBA treatment did not induce CYP expression, had a weak effect on PTGS-2 expression, and, similar to BaP, induced IsoP levels after 4 h exposure and AA levels after 24 h treatment. All tested compounds induced the activity of NF-ĸB after the longer exposure period. In summary, our data suggest that EOM, and partly BaP, reduce lipid peroxidation by a mechanism that involves AhR-dependent inhibition of PTGS-2 expression. The effect of 3-NBA on IsoP levels is probably mediated by a different mechanism independent of AhR activation.

DNA Methylation Profiles in a Group of Workers Occupationally Exposed to Nanoparticles.

The risk of exposure to nanoparticles (NPs) has rapidly increased during the last decade due to the vast use of nanomaterials (NMs) in many areas of human life. Despite this fact, human biomonitoring studies focused on the effect of NP exposure on DNA alterations are still rare. Furthermore, there are virtually no epigenetic data available. In this study, we investigated global and gene-specific DNA methylation profiles in a group of 20 long-term (mean 14.5 years) exposed, nanocomposite, research workers and in 20 controls. Both groups were sampled twice/day (pre-shift and post-shift) in September 2018. We applied Infinium Methylation Assay, using the Infinium MethylationEPIC BeadChips with more than 850,000 CpG loci, for identification of the DNA methylation pattern in the studied groups. Aerosol exposure monitoring, including two nanosized fractions, was also performed as proof of acute NP exposure. The obtained array data showed significant differences in methylation between the exposed and control groups related to long-term exposure, specifically 341 CpG loci were hypomethylated and 364 hypermethylated. The most significant CpG differences were mainly detected in genes involved in lipid metabolism, the immune system, lung functions, signaling pathways, cancer development and xenobiotic detoxification. In contrast, short-term acute NP exposure was not accompanied by DNA methylation changes. In summary, long-term (years) exposure to NP is associated with DNA epigenetic alterations.

Gene Expression and Epigenetic Changes in Mice Following Inhalation of Copper(II) Oxide Nanoparticles.

We investigated the transcriptomic response and epigenetic changes in the lungs of mice exposed to inhalation of copper(II) oxide nanoparticles (CuO NPs) (8 × 105 NPs/m3) for periods of 3 days, 2 weeks, 6 weeks, and 3 months. A whole genome transcriptome and miRNA analysis was performed using next generation sequencing. Global DNA methylation was assessed by ELISA. The inhalation resulted in the deregulation of mRNA transcripts: we detected 170, 590, 534, and 1551 differentially expressed transcripts after 3 days, 2 weeks, 6 weeks, and 3 months of inhalation, respectively. Biological processes and pathways affected by inhalation, differed between 3 days exposure (collagen formation) and longer treatments (immune response). Periods of two weeks exposure further induced apoptotic processes, 6 weeks of inhalation affected the cell cycle, and 3 months of treatment impacted the processes related to cell adhesion. The expression of miRNA was not affected by 3 days of inhalation. Prolonged exposure periods modified miRNA levels, although the numbers were relatively low (17, 18, and 38 miRNAs, for periods of 2 weeks, 6 weeks, and 3 months, respectively). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis based on miRNA-mRNA interactions, revealed the deregulation of processes implicated in the immune response and carcinogenesis. Global DNA methylation was not significantly affected in any of the exposure periods. In summary, the inhalation of CuO NPs impacted on both mRNA and miRNA expression. A significant transcriptomic response was already observed after 3 days of exposure. The affected biological processes and pathways indicated the negative impacts on the immune system and potential role in carcinogenesis.

The Biological Effects of Complete Gasoline Engine Emissions Exposure in a 3D Human Airway Model (MucilAirTM) and in Human Bronchial Epithelial Cells (BEAS-2B).

The biological effects induced by complete engine emissions in a 3D model of the human airway (MucilAirTM) and in human bronchial epithelial cells (BEAS-2B) grown at the air-liquid interface were compared. The cells were exposed for one or five days to emissions generated by a Euro 5 direct injection spark ignition engine. The general condition of the cells was assessed by the measurement of transepithelial electrical resistance and mucin production. The cytotoxic effects were evaluated by adenylate kinase (AK) and lactate dehydrogenase (LDH) activity. Phosphorylation of histone H2AX was used to detect double-stranded DNA breaks. The expression of the selected 370 relevant genes was analyzed using next-generation sequencing. The exposure had minimal effects on integrity and AK leakage in both cell models. LDH activity and mucin production in BEAS-2B cells significantly increased after longer exposures; DNA breaks were also detected. The exposure affected CYP1A1 and HSPA5 expression in MucilAirTM. There were no effects of this kind observed in BEAS-2B cells; in this system gene expression was rather affected by the time of treatment. The type of cell model was the most important factor modulating gene expression. In summary, the biological effects of complete emissions exposure were weak. In the specific conditions used in this study, the effects observed in BEAS-2B cells were induced by the exposure protocol rather than by emissions and thus this cell line seems to be less suitable for analyses of longer treatment than the 3D model.

Micronucleus frequency and content in healthy relatives of cancer patients.

OBJECTIVE: To compare chromosomal damage in lymphocytes of individuals who did or did not report first-degree relatives with cancer. MATERIALS AND METHODS: Cases and controls (68 each) were matched for sex, age and radon exposure. Chromosomal damage was quantified as frequency of micronucleus-containing cells and proportion of centromere-free micronuclei. RESULTS: Individuals not reporting cancer in their families showed lower values of both the frequency of micronucleus-containing cells (n.s.) and the proportion of centromere-free micronuclei (p < 0.05) in some subgroups, but not in all. CONCLUSION: The chromosomal damage observed may be due to inheritable genomic instability, but environmental influences cannot be excluded.

DNA Damage Potential of Engine Emissions Measured In Vitro by Micronucleus Test in Human Bronchial Epithelial Cells.

Internal combustion engine emissions belong among the major anthropogenic sources of air pollution in urban areas. According to the International Agency for Research on Cancer, there is sufficient evidence of the carcinogenicity of diesel exhaust in human beings. Although alternative fuels, mainly biodiesel, have recently become popular, little is still known about the genotoxicity of emissions from these fuels. We analysed DNA damage expressed as the frequency of micronuclei (MN) in human bronchial epithelial cells (BEAS-2B), induced by extractable organic matter (EOM; tested concentrations: 1, 10 and 25 µg/ml) obtained from particle emissions from various blends of biodiesel with diesel fuels (including neat diesel fuel (B0), a blend of 70% B0 and 30% biodiesel (B30) and neat biodiesel (B100)). We also tested the effect of selected diesel exhaust organic/genotoxic components [benzo[a]pyrene (B[a]P) concentrations: 25, 100 and 200 µM; 1-nitropyrene (1-NP) concentrations: 1, 5 and 10 µM; 3-nitrobenzanthrone (3-NBA) concentrations: 1, 5 and 50 µM]. The cells were treated with the compounds for 28 and 48 hr. Our results showed that most of the tested compounds (except for the 25 µM B[a]P, 28-hr treatment) significantly increased MN frequency. The genotoxicity of EOMs from the engine emissions of diesel and biodiesel engines was comparable. Both nitro-PAH compounds demonstrated higher genotoxic potential in comparison with B[a]P. Considering our results and due to increasing popularity of alternative fuels, it is prudent that the potential genotoxic effects of various fuels are investigated across engine technologies and operating conditions in a relevant model system.

Evaluation of 11 polycyclic aromatic hydrocarbon metabolites in urine of Czech mothers and newborns.

Polycyclic aromatic hydrocarbons (PAHs) represent a large group of ubiquitous contaminants of the environment, including food chain where they are released as by-products of incomplete combustion of an organic matter. Epidemiological studies have shown that exposure to PAHs correlated with increased incidence of cancer. Carcinogenicity is associated mainly with metabolites that are formed during metabolic degradation of these substances in exposed organism. In this study monohydroxylated PAHs (OH-PAHs), the major metabolites excreted into urine, were determined in 531 urine samples collected from mothers and their newborns from two localities of the Czech Republic - heavily air polluted Karvina and control locality of Ceske Budejovice and in two sampling rounds - August-October 2013 (summer, less air polluted season) and January-April 2014 (winter, more air polluted season). From all targeted analytes, naphthalene-2-ol was the most abundant compound present in 100% of the samples and it represented also the analyte with the highest concentration. Median concentration of ΣOH-PAHs in the urine of children was on average 1.6 times lower compared to the respective mother which correlates with higher intake of PAHs by mothers. ΣOH-PAHs concentrations determined in mothers' urine collected in the summer were comparable in both localities. No significant increase occurred in Ceske Budejovice in winter, while in samples from the Karvina region a statistically significant difference (α=0.05) in the amount of ΣOH-PAHs was observed. The median concentrations of ΣOH-PAHs in mothers' urine samples in the winter were 1.5 times higher than in the summer in the same locality. The amounts of ΣOH-PAHs in newborns' urine from Karvina in the winter season were 1.5 times higher than in the summer collected in the same locality and 3.3 times higher when compared with the less polluted locality of Ceske Budejovice.

Systematic review of the use of the lymphocyte cytokinesis-block micronucleus assay to measure DNA damage induced by exposure to polycyclic aromatic hydrocarbons.

The effect of exposure to polycyclic aromatic hydrocarbons (PAHs) to induce micronuclei (MN) measured using the lymphocytes cytokinesis-block micronucleus (CBMN) assay were evaluated in 34 studies according to the exposure: 20 studies in coke oven workers, 7 studies in different occupational exposures as alluminium industry workers, rubber factory workers, road construction workers, airport workers and diesel exposed workers, 6 studies on environmentaly exposed groups as police, volunteers and children. Reviewed papers indicate that the CBMN assay is a sensitive biomarker of PAHs exposure in polluted air. Reviewed studies confirmed previous conclusions, that the frequency of MN measured using the lymphocyte CBMN is not significantly affected by smoking, females are more sensitive to PAHs than males, the frequency of MN is increased with age.

Mapping the factors affecting the frequency and types of micronuclei in an elderly population from Southern Bohemia.

The micronucleus assay is one of the most common methods used to assess chromosomal damage (losses or breaks) in human peripheral blood lymphocytes (PBL) in genetic toxicology. Most studies have focused on analyzing total micronuclei (MN), but identifying the content of MN can provide more detailed information. The main aim of this study was to map the factors affecting the frequency and types of micronuclei in binucleated cells (BNC) in elderly population. Fluorescence in situ hybridization using Human Pan Centromeric Chromosome Paint was used to identify centromere positive (CEN+) or centromere negative (CEN-) MN. A group of 95 men from Southern Bohemia, Czech Republic (average age 68.0±6.8 years) was followed repeatedly, in spring and fall 2014. The study participants were former workers of the uranium plant "MAPE Mydlovary" (processing uranium ore from 1962 to 1991), and controls. The general profile of individual types of MN, and the effect of the season, former uranium exposure, age, smoking status, weight, and X-ray examination on the level and type of MN were analyzed. The results of this study showed: (i) a stable profile of BNC with MN based on the number of MN during two seasons; (ii) an increase of the number of CEN+ MN from spring to fall; (iii) a lower frequency of the total MN in the exposed group than in controls with a significant difference in the percentage of aberrant cells (%AB.C.) in the fall; (iv) no clear effect of age, smoking and BMI on DNA damage in this group; (v) lower DNA damage levels in former uranium workers who received X-ray examination later in life. In summary, the results indicate a trend of seasonal changes of individual types of MN and suggest that former exposure can have a protective effect on the level of DNA damage in case of future exposure.

Impact of Air Pollution to Genome of Newborns.

The Northern Moravia Region is the most polluted region in the Czech Republic by particulate matter (PM2.5) and carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) as benzo[a]pyrene (B[a]P) by heavy industry and local heating. This specific situation was used to study the impact of air pollution on newborns in the exposed Karviná district and control district of Ceské Budejovice. Biological material from newborns and mothers was collected in summer and winter seasons. This project is highly detailed, analyzing the concentrations of PAHs in ambient air and diet, in human breast milk, in the urine of mothers and newborns, using biomarkers of genetic damage as DNA adducts and gene expression analysis, biomarkers of oxidative stress as 8-oxodG adducts and lipid peroxidation (15-F2t-isoprostane immunoassay). All 400 children, for whom the biomarker data at delivery were obtained, will be followed for morbidity up to 2 years of age. The Northern Moravia Region seems to be to be a model area for studying the long-term impact of human health exposure to c-PAHs. Our observations will indicate possible genetic and oxidative damage in newborns, which may significantly affect their morbidity.

Day-to-day variability of toxic events induced by organic compounds bound to size segregated atmospheric aerosol.

This study quantified the temporal variability of concentration of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs), genotoxicity, oxidative DNA damage and dioxin-like activity of the extractable organic matter (EOM) of atmospheric aerosol particles of aerodynamic diameter (dae, µm) coarse (1 < dae < 10), upper- (0.5 < dae < 1) and lower-accumulation (0.17 < dae < 0.5) and ultrafine (<0.17) fractions. The upper accumulation fraction formed most of the aerosol mass for 22 of the 26 study days and contained ∼44% of total c-PAHs, while the ultrafine fraction contained only ∼11%. DNA adduct levels suggested a crucial contribution of c-PAHs bound to the upper accumulation fraction. The dioxin-like activity was also driven primarily by c-PAH concentrations. In contrast, oxidative DNA damage was not related to c-PAHs, as a negative correlation with c-PAHs was observed. These results suggest that genotoxicity and dioxin-like activity are the major toxic effects of organic compounds bound to size segregated aerosol, while oxidative DNA damage is not induced by EOM.

Nucleotide excision repair is not induced in human embryonic lung fibroblasts treated with environmental pollutants.

The cellular response to genotoxic treatment depends on the cell line used. Although tumor cell lines are widely used for genotoxicity tests, the interpretation of the results may be potentially hampered by changes in cellular processes caused by malignant transformation. In our study we used normal human embryonic lung fibroblasts (HEL12469 cells) and tested their response to treatment with benzo[a]pyrene (B[a]P) and extractable organic matter (EOM) from ambient air particles <2.5 µm (PM2.5) collected in two Czech cities differing in levels and sources of air pollution. We analyzed multiple endpoints associated with exposure to polycyclic aromatic hydrocarbons (PAHs) including the levels of bulky DNA adducts and the nucleotide excision repair (NER) response [expression of XPE, XPC and XPA genes on the level of mRNA and proteins, unscheduled DNA synthesis (UDS)]. EOMs were collected in the winter and summer of 2011 in two Czech cities with different levels and sources of air pollution. The effects of the studied compounds were analyzed in the presence (+S9) and absence (-S9) of the rat liver microsomal S9 fraction. The levels of bulky DNA adducts were highest after treatment with B[a]P, followed by winter EOMs; their induction by summer EOMs was weak. The induction of both mRNA and protein expression was observed, with the most pronounced effects after treatment with B[a]P (-S9); the response induced by EOMs from both cities and seasons was substantially weaker. The expression of DNA repair genes was not accompanied by the induction of UDS activity. In summary, our results indicate that the tested compounds induced low levels of DNA damage and affected the expression of NER genes; however, nucleotide excision repair was not induced.

Health impact of air pollution to children.

Health impact of air pollution to children was studied over the last twenty years in heavily polluted parts of the Czech Republic during. The research program (Teplice Program) analyzed these effects in the polluted district Teplice (North Bohemia) and control district Prachatice (Southern Bohemia). Study of pregnancy outcomes for newborns delivered between 1994 and 1998 demonstrated that increase in intrauterine growth retardation (IUGR) was associated with PM10 and c-PAHs exposure (carcinogenic polycyclic aromatic hydrocarbons) in the first month of gestation. Morbidity was followed in the cohort of newborns (N=1492) up to the age of 10years. Coal combustion in homes was associated with increased incidence of lower respiratory track illness and impaired early childhood skeletal growth up to the age of 3years. In preschool children, we observed the effect of increased concentrations of PM2.5 and PAHs on development of bronchitis. The Northern Moravia Region (Silesia) is characterized by high concentrations of c-PAHs due to industrial air pollution. Exposure to B[a]P (benzo[a]pyrene) in Ostrava-Radvanice is the highest in the EU. Children from this part of the city of Ostrava suffered higher incidence of acute respiratory diseases in the first year of life. Gene expression profiles in leukocytes of asthmatic children compared to children without asthma were evaluated in groups from Ostrava-Radvanice and Prachatice. The results suggest the distinct molecular phenotype of asthma bronchiale in children living in polluted Ostrava region compared to children living in Prachatice. The effect of exposure to air pollution to biomarkers in newborns was analyzed in Prague vs. Ceske Budejovice, two locations with different levels of pollution in winter season. B[a]P concentrations were higher in Ceske Budejovice. DNA adducts and micronuclei were also elevated in cord blood in Ceske Budejovice in comparison to Prague. Study of gene expression profiles in the cord blood showed differential expression of 104 genes. Specifically, biological processes related to immune and defense response were down-regulated in Ceske Budejovice. Our studies demonstrate that air pollution significantly affect child health. Especially noticeable is the increase of respiratory morbidity. With the development of molecular epidemiology, we can further evaluate the health risk of air pollution using biomarkers.