Genetic alteration profiling in middle-aged women acutely exposed during the mechanical processing of dental nanocomposites

Nanoparticles (NPs) have become an important part of everyday life, including their application in dentistry. Aside from their undoubted benefits, questions regarding their risk to human health, and/or genome have arisen. However, studies concerning cytogenetic effects are completely absent. A group of women acutely exposed to an aerosol released during dental nanocomposite grinding was sampled before and after the work. Exposure monitoring including nano (PM0.1) and respirable (PM4) fractions was performed. Whole-chromosome painting for autosomes #1, #4, and gonosome X was applied to estimate the pattern of cytogenetic damage including structural and numerical alterations. The results show stable genomic frequency of translocations (FG/100), in contrast to a significant 37.8% (p<0.05) increase of numerical aberrations caused by monosomies (p<0.05), but not trisomies. Monosomies were mostly observed for chromosome X. In conclusion, exposure to nanocomposites in stomatology may lead to an increase in numerical aberrations which can be dangerous for dividing cells.

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.

Metal Nanoparticles with Antimicrobial Properties: The Toxicity Response in Mouse Mesenchymal Stem Cells

Some metal nanoparticles (NP) are characterized by antimicrobial properties with the potential to be used as alternative antibiotics. However, NP may negatively impact human organism, including mesenchymal stem cells (MSC), a cell population contributing to tissue growth and regeneration. To address these issues, we investigated the toxic effects of selected NP (Ag, ZnO, and CuO) in mouse MSC. MSC were treated with various doses of NP for 4 h, 24 h, and 48 h and multiple endpoints were analyzed. Reactive oxygen species were generated after 48 h CuO NP exposure. Lipid peroxidation was induced after 4 h and 24 h treatment, regardless of NP and/or tested dose. DNA fragmentation and oxidation induced by Ag NP showed dose responses for all the periods. For other NP, the effects were observed for shorter exposure times. The impact on the frequency of micronuclei was weak. All the tested NP increased the sensitivity of MSC to apoptosis. The cell cycle was most affected after 24 h, particularly for Ag NP treatment. In summary, the tested NP induced numerous adverse changes in MSC. These results should be taken into consideration when planning the use of NP in medical applications where MSC are involved.

Effects of antimicrobial metal nanoparticles on characteristics and function properties of mouse mesenchymal stem cells

Nanoparticles (NPs) have a wide use in various field of industry and in medicine, where they represent a promise for their antimicrobial effects. Simultaneous application of NPs and therapeutic stem cells can speed up tissue regeneration and improve healing process but there is a danger of negative impacts of NPs on stem cells. Therefore, we tested effects of four types of metal antimicrobial NPs on characteristics and function properties of mouse mesenchymal stem cells (MSCs) in vitro. All types of tested NPs, i.e. zinc oxide, silver, copper oxide and titanium dioxide, exerted negative effects on the expression of phenotypic markers, metabolic activity, differentiation potential, expression of genes for immunoregulatory molecules and on production of cytokines and growth factors by MSCs. However, there were apparent differences in the impact of individual types of NPs on tested characteristics and function properties of MSCs. The results showed that individual types of NPs influence the activity of MSCs, and thus the use of metal NPs during tissue regeneration and in combination with stem cell therapy should be well considered.

A possible link between cognitive development in 5 years old children and prenatal oxidative stress

BACKGROUND

To study the impact of oxidative damage associated with particulate matter< 2.5 µm (PM2.5) during prenatal period on the cognitive development in five years old children.

METHODS

Two cohorts of children aged five years, born in the years 2013 and 2014, were studied for their cognitive development in the polluted district Karvina and the control district Ceske Budejovice. Exposure to PM2.5 in the ambient air was measured for each mother during the 3rd trimester of pregnancy. Oxidative damage was determined from the level of biomarkers at delivery in mothers´ and newborns´ urine as 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG) and in plasma as 15-F2t-isoprostane levels (15-F2t-IsoP). The Bender Visual Motor Gestalt Test (BG test) and the Raven Colored Progressive Matrices (RCPM test) were used as psychological cognitive tests.

RESULTS

Average concentrations of PM2.5 ± SD in the 3rd trimester of mothers´ pregnancies were 37.7 ± 14.7 µg/m3 and 17.1 ± 4.8 µg/m3 in Karvina and Ceske Budejovice, respectively (p < 0.001). The maternal level of 15-F2t-IsoP in plasma at the time of delivery was significantly associated with the results of the RCPM test (p < 0.05) and the BG test (p < 0.05) in five years old children.

CONCLUSIONS

Lipid peroxidation in maternal plasma at the time of delivery has an adverse effect on the results of psychological cognitive tests in five years old children.

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-1β, 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.

Genome-Wide DNA Methylation in Policemen Working in Cities Differing by Major Sources of Air Pollution

DNA methylation is the most studied epigenetic mechanism that regulates gene expression, and it can serve as a useful biomarker of prior environmental exposure and future health outcomes. This study focused on DNA methylation profiles in a human cohort, comprising 125 nonsmoking city policemen (sampled twice), living and working in three localities (Prague, Ostrava and Ceske Budejovice) of the Czech Republic, who spent the majority of their working time outdoors. The main characterization of the localities, differing by major sources of air pollution, was defined by the stationary air pollution monitoring of PM2.5, B[a]P and NO₂. DNA methylation was analyzed by a genome-wide microarray method. No season-specific DNA methylation pattern was discovered; however, we identified 13,643 differentially methylated CpG loci (DML) for a comparison between the Prague and Ostrava groups. The most significant DML was cg10123377 (log₂FC = −1.92, p = 8.30 × 10⁻⁴) and loci annotated to RPTOR (total 20 CpG loci). We also found two hypomethylated loci annotated to the DNA repair gene XRCC5. Groups of DML annotated to the same gene were linked to diabetes mellitus (KCNQ1), respiratory diseases (PTPRN2), the dopaminergic system of the brain and neurodegenerative diseases (NR4A2). The most significant possibly affected pathway was Axon guidance, with 86 potentially deregulated genes near DML. The cluster of gene sets that could be affected by DNA methylation in the Ostrava groups mainly includes the neuronal functions and biological processes of cell junctions and adhesion assembly. The study demonstrates that the differences in the type of air pollution between localities can affect a unique change in DNA methylation profiles across the human genome.

Biomonitoring of 89 POPs in blood serum samples of Czech city policemen

In this biomonitoring study, we evaluated the concentrations of 8 polychlorinated biphenyls (PCBs), 11 organochlorinated pesticides (OCPs), 33 brominated flame retardants (BFRs), 7 novel brominated and chlorinated flame retardants (novel FRs) and 30 per- and polyfluoroalkylated substances (PFAS) in human serum samples (n = 274). A total of 89 persistent organic pollutants (POPs) were measured in blood serum samples of city policemen living in three large cities and their adjacent areas (Ostrava, Prague, and Ceske Budejovice) in the Czech Republic. All samples were collected during the year 2019 in two sampling periods (spring and autumn). The identification/quantification of PCBs, OCPs, BFRs, novel FRs and PFAS was performed by means of gas chromatography coupled to (tandem) mass spectrometry (GC-MS/(MS)) and ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). The most frequently detected pollutants were perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), 2,2',3,4,4',5'-hexachlorobiphenyl (CB 138), 2,2',4,4',5,5'-hexachlorobiphenyl (CB 153), 2,2',3,3',4,4',5-heptachlorobiphenyl (CB 170), 2,2',3,4,4',5,5'-heptachlorobiphenyl (CB 180), hexachlorobenzene (HCB), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) quantified in 100% of serum samples. In the serum samples, the concentrations of determined POPs were in the range of 0.108-900 ng g^-1 lipid weight (lw) for PCBs, 0.106-1016 ng g^-1 lw for OCPs, <0.1-618 ng g^-1 lw for FRs and <0.01-18.3 ng mL^-1 for PFAS, respectively. Locality, sampling season, and age were significantly associated with several POP concentrations. One of the important conclusions was that within the spring sampling period, statistically significant higher concentrations of CB 170 and CB 180 were observed in the samples from Ostrava (industrial area) compared to Prague and Ceske Budejovice. Older policemen had higher concentrations of five PCBs and two OCPs in blood serum.

Markers of lipid oxidation and inflammation in bronchial cells exposed to complete gasoline emissions and their organic extracts

Road traffic emissions consist of gaseous components, particles of various sizes, and chemical compounds that are bound to them. Exposure to vehicle emissions is implicated in the etiology of inflammatory respiratory disorders. We investigated the inflammation-related markers in human bronchial epithelial cells (BEAS-2B) and a 3D model of the human airways (MucilAir™), after exposure to complete emissions and extractable organic matter (EOM) from particles generated by ordinary gasoline (E5), and a gasoline-ethanol blend (E20; ethanol content 20% v/v). The production of 22 lipid oxidation products (derivatives of linoleic and arachidonic acid, AA) and 45 inflammatory molecules (cytokines, chemokines, growth factors) was assessed after days 1 and 5 of exposure, using LC-MS/MS and a multiplex immunoassay, respectively. The response observed in MucilAir™ exposed to E5 gasoline emissions, characterized by elevated levels of pro-inflammatory AA metabolites (prostaglandins) and inflammatory markers, was the most pronounced. E20 EOM exposure was associated with increased levels of AA metabolites with anti-inflammatory effects in this cell model. The exposure of BEAS-2B cells to complete emissions reduced lipid oxidation, while E20 EOM tended to increase concentrations of AA metabolite and chemokine production; the impacts on other inflammatory markers were limited. In summary, complete E5 emission exposure of MucilAir™ induces the processes associated with the pro-inflammatory response. This observation highlights the potential negative health impacts of ordinary gasoline, while the effects of alternative fuel are relatively weak.

In vitro exposure to complete engine emissions - a mini-review

Outdoor air pollution is classified as carcinogenic to humans and exposure to it contributes to increased incidence of various diseases, including cardiovascular, neurological or pulmonary disorders. Vehicle engine emissions represent a significant part of outdoor air pollutants, particularly in large cities with high population density. Considering the potentially negative health impacts of engine emissions exposure, the application of reliable test systems allowing assessment of the biological effects of these pollutants is crucial. The exposure systems should use relevant, preferably multicellular, cell models that are treated with the complete engine exhaust (i.e. a realistic mixture of particles, chemical compounds bound to them and gaseous phase) at the air-liquid interface. The controlled delivery and characterization of chemical and/or particle composition of the exhaust should be possible. In this mini-review we report on such exposure systems that have been developed to date. We focus on a brief description and technical characterization of the systems, and discuss the biological parameters detected following exposure to a gasoline/diesel exhaust. Finally, we summarize and compare findings from the individual systems, including their advantages/limitations.

Individual DNA Methylation Pattern Shifts in Nanoparticles-Exposed Workers Analyzed in Four Consecutive Years

A DNA methylation pattern represents an original plan of the function settings of individual cells and tissues. The basic strategies of its development and changes during the human lifetime are known, but the details related to its modification over the years on an individual basis have not yet been studied. Moreover, current evidence shows that environmental exposure could generate changes in DNA methylation settings and, subsequently, the function of genes. In this study, we analyzed the effect of chronic exposure to nanoparticles (NP) in occupationally exposed workers repeatedly sampled in four consecutive years (2016-2019). A detailed methylation pattern analysis of 14 persons (10 exposed and 4 controls) was performed on an individual basis. A microarray-based approach using chips, allowing the assessment of more than 850 K CpG loci, was used. Individual DNA methylation patterns were compared by principal component analysis (PCA). The results show the shift in DNA methylation patterns in individual years in all the exposed and control subjects. The overall range of differences varied between the years in individual persons. The differences between the first and last year of examination (a three-year time period) seem to be consistently greater in the NP-exposed subjects in comparison with the controls. The selected 14 most differently methylated cg loci were relatively stable in the chronically exposed subjects. In summary, the specific type of long-term exposure can contribute to the fixing of relevant epigenetic changes related to a specific environment as, e.g., NP inhalation.

The genotoxic effects in the leukocytes of workers handling nanocomposite materials

The extensive development of nanotechnologies and nanomaterials poses a number of questions to toxicologists about the potential health risks of exposure to nanoparticles (NP). In this study, we analysed DNA damage in the leukocytes of 20 workers who were long-term exposed (18 ± 10 years) to NP in their working environment. Blood samples were collected in September 2016, before and after a shift, to assess (i) the chronic effects of NP on DNA (pre-shift samples) and (ii) the acute effects of exposure during the shift (the difference between pre- and post-shift samples). The samples from matched controls were taken in parallel with workers before the shift. Leukocytes were isolated from heparinised blood on a Ficoll gradient. The enzyme-modified comet assay (DNA formamido-pyrimidine-glycosylase and endonuclease III) demonstrated a considerable increase of both single- and double-strand breaks in DNA (DNA-SB) and oxidised bases when compared with the controls (2.4× and 2×, respectively). Acute exposure induced a further increase of DNA-SB. The welding and smelting of nanocomposites represented a higher genotoxic risk than milling and grinding of nanocomposite surfaces. Obesity appeared to be a factor contributing to an increased risk of oxidative damage to DNA. The data also indicated a higher susceptibility of males vs. females to NP exposure. The study was repeated in September 2017. The results exhibited similar trend, but the levels of DNA damage in the exposed subjects were lower compared to previous year. This was probably associated with lower exposure to NP in consequence of changes in nanomaterial composition and working operations. The further study involving also monitoring of personal exposures to NP is necessary to identify (i) the main aerosol components responsible for genotoxic effects in workers handling nanocomposites and (ii) the primary cause of gender differences in response to NP action.

Airborne Benzo[a]Pyrene may contribute to divergent Pheno-Endotypes in children

BACKGROUND

Asthma represents a syndrome for which our understanding of the molecular processes underlying discrete sub-diseases (i.e., endotypes), beyond atopic asthma, is limited. The public health needs to characterize etiology-associated endotype risks is becoming urgent. In particular, the roles of polyaromatic hydrocarbon (PAH), globally distributed combustion by-products, toward the two known endotypes - T helper 2 cell high (Th2) or T helper 2 cell low (non-Th2) - warrants clarification.

OBJECTIVES

To explain ambient B[a]P association with non-atopic asthma (i.e., a proxy of non-Th2 endotype) is markedly different from that with atopic asthma (i.e., a proxy for Th2-high endotype).

METHODS

In a case-control study, we compare the non-atopic as well as atopic asthmatic boys and girls against their respective controls in terms of the ambient Benzo[a]pyrene concentration nearest to their home, plasma 15-Ft2-isoprostane (15-Ft2-isoP), urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), and lung function deficit. We repeated the analysis for i) dichotomous asthma outcome and ii) multinomial asthma-overweight/obese (OV/OB) combined outcomes.

RESULTS

The non-atopic asthma cases are associated with a significantly higher median B[a]P (11.16 ng/m3) compared to that in the non-atopic controls (3.83 ng/m3; P-value < 0.001). In asthma-OV/OB stratified analysis, the non-atopic girls with lean and OV/OB asthma are associated with a step-wisely elevated B[a]P (median,11.16 and 18.00 ng/m3, respectively), compared to the non-atopic lean control girls (median, 4.28 ng/m3, P-value < 0.001). In contrast, atopic asthmatic children (2.73 ng/m3) are not associated with a significantly elevated median B[a]P, compared to the atopic control children (2.60 ng/m3; P-value > 0.05). Based on the logistic regression model, on ln-unit increate in B[a]P is associated with 4.7-times greater odds (95% CI, 1.9-11.5, P = 0.001) of asthma among the non-atopic boys. The same unit increase in B[a]P is associated with 44.8-times greater odds (95% CI, 4.7-428.2, P = 0.001) among the non-atopic girls after adjusting for urinary Cotinine, lung function deficit, 15-Ft2-isoP, and 8-oxodG.

CONCLUSIONS

Ambient B[a]P is robustly associated with non-atopic asthma, while it has no clear associations with atopic asthma among lean children. Furthermore, lung function deficit, 15-Ft2-isoP, and 8-oxodG are associated with profound alteration of B[a]P-asthma associations among the non-atopic children.

The hCOMET project: International database comparison of results with the comet assay in human biomonitoring. Baseline frequency of DNA damage and effect of main confounders

The alkaline comet assay, or single cell gel electrophoresis, is one of the most popular methods for assessing DNA damage in human population. One of the open issues concerning this assay is the identification of those factors that can explain the large inter-individual and inter-laboratory variation. International collaborative initiatives such as the hCOMET project - a COST Action launched in 2016 - represent a valuable tool to meet this challenge. The aims of hCOMET were to establish reference values for the level of DNA damage in humans, to investigate the effect of host factors, lifestyle and exposure to genotoxic agents, and to compare different sources of assay variability. A database of 19,320 subjects was generated, pooling data from 105 studies run by 44 laboratories in 26 countries between 1999 and 2019. A mixed random effect log-linear model, in parallel with a classic meta-analysis, was applied to take into account the extensive heterogeneity of data, due to descriptor, specimen and protocol variability. As a result of this analysis interquartile intervals of DNA strand breaks (which includes alkali-labile sites) were reported for tail intensity, tail length, and tail moment (comet assay descriptors). A small variation by age was reported in some datasets, suggesting higher DNA damage in oldest age-classes, while no effect could be shown for sex or smoking habit, although the lack of data on heavy smokers has still to be considered. Finally, highly significant differences in DNA damage were found for most exposures investigated in specific studies. In conclusion, these data, which confirm that DNA damage measured by the comet assay is an excellent biomarker of exposure in several conditions, may contribute to improving the quality of study design and to the standardization of results of the comet assay in human populations.

Biomarkers of nucleic acid oxidation - A summary state-of-the-art

Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. Increasingly, interest is also focusing upon the effects of damage to the other nucleic acids, RNA and the (2′-deoxy-)ribonucleotide pools, and evidence is growing that these too may have an important role in disease. LC-MS/MS has the ability to provide absolute quantification of specific biomarkers, such as 8-oxo-7,8-dihydro-2′-deoxyGuo (8-oxodG), in both nuclear and mitochondrial DNA, and 8-oxoGuo in RNA. However, significant quantities of tissue are needed, limiting its use in human biomonitoring studies. In contrast, the comet assay requires much less material, and as little as 5 μL of blood may be used, offering a minimally invasive means of assessing oxidative stress in vivo, but this is restricted to nuclear DNA damage only. Urine is an ideal matrix in which to non-invasively study nucleic acid-derived biomarkers of oxidative stress, and considerable progress has been made towards robustly validating these measurements, not least through the efforts of the European Standards Committee on Urinary (DNA) Lesion Analysis. For urine, LC-MS/MS is considered the gold standard approach, and although there have been improvements to the ELISA methodology, this is largely limited to 8-oxodG. Emerging DNA adductomics approaches, which either comprehensively assess the totality of adducts in DNA, or map DNA damage across the nuclear and mitochondrial genomes, offer the potential to considerably advance our understanding of the mechanistic role of oxidatively damaged nucleic acids in disease.

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Oxidatively damaged nucleic acids are implicated in the pathogenesis of disease.

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LC-MS/MS, comet assay and ELISA are often used to study oxidatively damaged DNA.

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Urinary oxidatively damaged nucleic acids non-invasively reflect oxidative stress.

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DNA adductomics will aid understanding the role of ROS damaged DNA in disease.

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.

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 Impact of Cesarean and Vaginal Delivery on Results of Psychological Cognitive Test in 5 Year Old Children

Background and objectives: The impact of cesarean and vaginal delivery on cognitive development was analyzed in 5 year old children. Materials and Methods: Two cohorts of 5 year old children born in the years 2013 and 2014 in Karvina (Northern Moravia) and Ceske Budejovice (Southern Bohemia) were studied for their cognitive development related to vaginal (n = 117) and cesarean types of delivery (n = 51). The Bender Visual Motor Gestalt Test (BG test) and the Raven Colored Progressive Matrices (RCPM test) were used as psychological tests. Results: In the comparison of vaginal delivery vs. cesarean section, the children delivered by cesarean section scored lower and, therefore, achieved poorer performance in cognitive tests compared to those born by vaginal delivery, as shown in the RCPM (p < 0.001) and in the BG test (p < 0.001). When mothers' education level was considered, the children whose mothers achieved a university degree scored higher in both the RCPM test (p < 0.001) and the BG test (p < 0.01) compared to the children of mothers with lower secondary education. When comparing mothers with a university degree to those with higher secondary education, there was a significant correlation between level of education and score achieved in the RCPM test (p < 0.001), but not in the BG test. Conclusions: According to our findings, the mode of delivery seems to have a significant influence on performance in psychological cognitive tests in 5 year old children in favor of those who were born by vaginal delivery. Since cesarean-born children scored notably below vaginally born children, it appears possible that cesarean delivery may have a convincingly adverse effect on children's further cognitive development.

The Molecular Mechanisms of Adaptive Response Related to Environmental Stress

The exposure of living organisms to environmental stress triggers defensive responses resulting in the activation of protective processes. Whenever the exposure occurs at low doses, defensive effects overwhelm the adverse effects of the exposure; this adaptive situation is referred to as “hormesis”. Environmental, physical, and nutritional hormetins lead to the stimulation and strengthening of the maintenance and repair systems in cells and tissues. Exercise, heat, and irradiation are examples of physical hormetins, which activate heat shock-, DNA repair-, and anti-oxidative-stress responses. The health promoting effect of many bio-actives in fruits and vegetables can be seen as the effect of mildly toxic compounds triggering this adaptive stimulus. Numerous studies indicate that living organisms possess the ability to adapt to adverse environmental conditions, as exemplified by the fact that DNA damage and gene expression profiling in populations living in the environment with high levels of air pollution do not correspond to the concentrations of pollutants. The molecular mechanisms of the hormetic response include modulation of (a) transcription factor Nrf2 activating the synthesis of glutathione and the subsequent protection of the cell; (b) DNA methylation; and (c) microRNA. These findings provide evidence that hormesis is a toxicological event, occurring at low exposure doses to environmental stressors, having the benefit for the maintenance of a healthy status.

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.

The processes associated with lipid peroxidation in human embryonic lung fibroblasts, treated with polycyclic aromatic hydrocarbons and organic extract from particulate matter

Polycyclic aromatic hydrocarbons (PAHs) may cause lipid peroxidation via reactive oxygen species generation. 15-F2t-isoprostane (IsoP), an oxidative stress marker, is formed from arachidonic acid (AA) by a free-radical induced oxidation. AA may also be converted to prostaglandins (PG) by prostaglandin-endoperoxide synthase (PTGS) induced by NF-κB. We treated human embryonic lung fibroblasts (HEL12469) with benzo[a]pyrene (B[a]P), 3-nitrobenzanthrone (3-NBA) and extractable organic matter (EOM) from ambient air particulate matter <2.5 µm for 4 and 24 h. B[a]P and 3-NBA induced expression of PAH metabolising, but not antioxidant enzymes. The concentrations of IsoP decreased, whereas the levels of AA tended to increase. Although the activity of NF-κB was not detected, the tested compounds affected the expression of prostaglandin-endoperoxide synthase 2 (PTGS2). The levels of prostaglandin E2 (PGE2) decreased following exposure to B[a]P, whereas 3-NBA exposure tended to increase PGE2 concentration. A distinct response was observed after EOM exposure: expression of PAH-metabolising enzymes was induced, IsoP levels increased after 24-h treatment but AA concentration was not affected. The activity of NF-κB increased after both exposure periods, and a significant induction of PTGS2 expression was found following 4-h treatment. Similarly to PAHs, the EOM exposure was associated with a decrease of PGE2 levels. In summary, exposure to PAHs with low pro-oxidant potential results in a decrease of IsoP levels implying 'antioxidant' properties. For such compounds, IsoP may not be a suitable marker of lipid peroxidation.

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.

Inhalation of ZnO Nanoparticles: Splice Junction Expression and Alternative Splicing in Mice

Despite the wide application of nanomaterials, toxicity studies of nanoparticles (NP) are often limited to in vitro cell models, and the biological impact of NP exposure in mammals has not been thoroughly investigated. Zinc oxide (ZnO) NPs are commonly used in various consumer products. To evaluate the effects of the inhalation of ZnO NP in mice, we studied splice junction expression in the lungs as a proxy to gene expression changes analysis. Female ICR mice were treated with 6.46 × 104 and 1.93 × 106 NP/cm3 for 3 days and 3 months, respectively. An analysis of differential expression and alternative splicing events in 298 targets (splice junctions) of 68 genes involved in the processes relevant to the biological effects of ZnO NP was conducted using next-generation sequencing. Three days of exposure resulted in the upregulation of IL-6 and downregulation of BID, GSR, NF-kB2, PTGS2, SLC11A2, and TXNRD1 splice junction expression; 3 months of exposure increased the expression of splice junctions in ALDH3A1, APAF1, BID, CASP3, DHCR7, GCLC, GCLM, GSR, GSS, EHHADH, FAS, HMOX-1, IFNγ, NF-kB1, NQO-1, PTGS1, PTGS2, RAD51, RIPK2, SRXN1, TRAF6, and TXNRD1. Alternative splicing of TRAF6 and TXNRD1 was induced after 3 days of exposure to 1.93 × 106 NP/cm3. In summary, we observed changes of splice junction expression in genes involved in oxidative stress, apoptosis, immune response, inflammation, and DNA repair, as well as the induction of alternative splicing in genes associated with oxidative stress and inflammation. Our data indicate the potential negative biological effects of ZnO NP inhalation.

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.

In Vitro Transformation of Human Bronchial Epithelial Cells by Diesel Exhaust Particles: Gene Expression Profiling and Early Toxic Responses

Occupational exposure to diesel exhaust may cause lung cancer in humans. Mechanisms include DNA-damage and inflammatory responses. Here, the potential of NIST SRM2975 diesel exhaust particles (DEP) to transform human bronchial epithelial cells (HBEC3) in vitro was investigated. Long-term exposure of HBEC3 to DEP led to increased colony growth in soft agar. Several DEP-transformed cell lines were established and based on the expression of epithelial-to-mesenchymal-transition (EMT) marker genes, one of them (T2-HBEC3) was further characterized. T2-HBEC3 showed a mesenchymal/fibroblast-like morphology, reduced expression of CDH1, and induction of CDH2 and VIM. T2-HBEC3 had reduced migration potential compared with HBEC3 and little invasion capacity. Gene expression profiling showed baseline differences between HBEC3 and T2-HBEC3 linked to lung carcinogenesis. Next, to assess differences in sensitivity to DEP between parental HBEC3 and T2-HBEC3, gene expression profiling was carried out after DEP short-term exposure. Results revealed changes in genes involved in metabolism of xenobiotics and lipids, as well as inflammation. HBEC3 displayed a higher steady state of IL1B gene expression and release of IL-1β compared with T2-HBEC3. HBEC3 and T2-HBEC3 showed similar susceptibility towards DEP-induced genotoxic effects. Liquid-chromatography-tandem-mass-spectrometry was used to measure secretion of eicosanoids. Generally, major prostaglandin species were released in higher concentrations from T2-HBEC3 than from HBEC3 and several analytes were altered after DEP-exposure. In conclusion, long-term exposure to DEP-transformed human bronchial epithelial cells in vitro. Differences between HBEC3 and T2-HBEC3 regarding baseline levels and DEP-induced changes of particularly CYP1A1, IL-1β, PGE2, and PGF2α may have implications for acute inflammation and carcinogenesis.

The repeated cytogenetic analysis of subjects occupationally exposed to nanoparticles: a pilot study

The application of nanomaterials has been rapidly increasing during recent years. Inhalation exposure to nanoparticles (NP) may result in negative toxic effects but there is a critical lack of human studies, especially those related to possible DNA alterations. We analyzed pre-shift and post-shift a group of nanocomposite researchers with a long-term working background (17.8 ± 10.0 years) and matched controls. The study group consisted of 73.2% males and 26.8% females. Aerosol exposure monitoring during a working shift (involving welding, smelting, machining) to assess the differences in exposure to particulate matter (PM) including nanosized fractions <25–100 nm, and their chemical analysis, was carried out. A micronucleus assay using Human Pan Centromeric probes, was applied to distinguish between the frequency of centromere positive (CEN+) and centromere negative (CEN−) micronuclei (MN) in the binucleated cells. This approach allowed recognition of the types of chromosomal damage: losses and breaks. The monitoring data revealed differences in the exposure to NP related to individual working processes, and in the chemical composition of nanofraction. The cytogenetic results of this pilot study demonstrated a lack of effect of long-term (years) exposure to NP (total frequency of MN, P = 0.743), although this exposure may be responsible for DNA damage pattern changes (12% increase of chromosomal breaks—clastogenic effect). Moreover, short-term (daily shift) exposure could be a reason for the increase of chromosomal breaks in a subgroup of researchers involved in welding and smelting processes (clastogenic effect, P = 0.037). The gender and/or gender ratio of the study participants was also an important factor for the interpretation of the results. As this type of human study is unique, further research is needed to understand the effects of long-term and short-term exposure to NP.

Short-term and Long-term Exposure of the MucilAir™ Model to Polycyclic Aromatic Hydrocarbons

Cells grown in monocultures are widely used to model lung tissue. As a result of these culture conditions, these cells exhibit poor morphological similarity to those present in in vivo lung tissue. MucilAir™, a 3-D in vitro model comprising human basal, goblet and ciliated cells, represents a fully differentiated respiratory epithelium that can be used as an alternative and a more realistic system. The aim of our study was to compare the effects of short-term and long-term exposure to two polycyclic aromatic hydrocarbons (PAHs) - benzo[a]pyrene (B[a]P) and 3-nitrobenzanthrone (3-NBA) - using MucilAir as a model of human lung tissue. Two concentrations (0.1 μM and 1 μM) were tested at three time points (24 hours, 7 days and 28 days). Several aspects were assessed: cytotoxicity (lactate dehydrogenase (LDH) release), integrity of the cell layer (transepithelial electrical resistance (TEER)), induction of oxidative stress (reactive oxygen species production) and changes in the expression of selected genes involved in PAH metabolism (CYP1A1 and AKR1C2) and the antioxidant response (ALDH3A1, SOD1, SOD2, GPX1, CAT, HMOX1 and TXNRD1). The results showed that exposure to B[a]P caused a spike in LDH release at day 5. Exposure to 3-NBA caused a number of spikes in LDH release, starting at day 5, and a decrease in TEER after 11 days. CYP1A1 gene expression was upregulated after the 7-day and 28-day B[a]P exposures, as well as after the 24-hour and 7-day 3-NBA exposures. HMOX1 and SOD1 were downregulated after both 24-hour PAH treatments. HMOX1 was upregulated after a 1-week exposure to 3-NBA. There were no significant changes in the messenger RNA (mRNA) levels of AKR1C2, ALDH3A1, TXNRD1, SOD2, GPX1 or CAT. These results illustrate the potential use of this 3-D in vitro lung tissue model in studying the effects of chronic exposure to PAHs.

A murine model of the effects of inhaled CuO nanoparticles on cells of innate and adaptive immunity - a kinetic study of a continuous three-month exposure

The inhalation or application of nanoparticles (NPs) has serious impacts on immunological reactivity. However, the effects of NPs on the immune system are influenced by numerous factors, which cause a high variability in the results. Here, mice were exposed to a three month continuous inhalation of copper oxide (CuO) NPs, and at different time intervals (3, 14, 42 and 93 days), the composition of cell populations of innate and adaptive immunity was evaluated in the spleen by flow cytometry. The ability of spleen cells from exposed and control mice to respond to stimulation with T- or B-cell mitogens by proliferation and by production of cytokines IL-2, IL-6, IL-10, IL-17 and IFN-γ was characterized. The results showed that the inhalation of CuO NPs predominantly affects the cells of innate immunity (changes in the proportion of eosinophils, neutrophils, macrophages and antigen-presenting cells) with a minimal effect on the percentage of T and B lymphocytes. However, the proliferative and secretory activity of T cells was already significantly enhanced after 3 days from the start of inhalation, decreased on day 14 and normalized at the later time intervals. There was no correlation between the impacts of NPs on the cells of innate and adaptive immunity. The results have shown that the inhalation of CuO NPs significantly alters the composition of cell populations of innate immunity and modulates the proliferation and production of cytokines by cells of the adaptive immune system. However, the immunomodulatory effects of inhaled NPs strongly depend on the time of inhalation.

Greater susceptibility of girls to airborne Benzo[a]pyrene for obesity-associated childhood asthma

BACKGROUND

Sexually dimorphic risk of obesity-associated asthma is posited to accelerate around puberty. Yet, the role of air pollution on the lean and obese asthmatic children has never been examined.

OBJECTIVE

To compare whether a unit exposure to airborne benzo[a]pyrene (B[a]P) is associated with altered risks of asthma across the overweight/obese (OV/OB) control, lean asthmatic, and OV/OB asthmatic children, respectively, compared to the lean controls, before and after adjusting for oxidant stress markers (i.e. 15‑F2t‑IsoP, 8‑oxo‑dG, and Carbonyl).

METHODS

Asthmatic and healthy control children, recruited from polluted urban and rural areas, were matched to ambient concentration of B[a]P. A unit increase in B[a]P and multinomial logistic regression on OV/OB control, lean asthmatic, and OV/OB asthma were compared across the sex- and age-groups.

RESULTS

The median B[a]P was associated with a linear increase among the female children, according to OV/OB and asthma, respectively, and together, compared to the lean control girls (p = 0.001). While B[a]P was associated with positive relationship with 15‑F2t‑IsoP level among the OV/OB boys, the same exposure-outcome association was inverse among the OV/OB girls. One natural log-unit increase in ambient B[a]P was associated with 10.5-times greater odds (95% CI, 2.6-39.6; p = 0.001) the adolescent OV/OB boys, compared to the unit odds among the lean controls. In contrast, the adolescent OV/OB girls were associated with highest adjusted odds of the asthma (aOR = 15.4; 95% CI, 2.9-29.1; p < 0.001) compared to the lean control girls. An adjustment for 15‑F2t‑IsoP, and Carbonyls was associated with greater odds of asthma per unit exposure for the adolescent OV/OB girls (aOR = 16.2; 95% CI, 1.4-181.8; p = 0.024).

CONCLUSIONS

B[a]P exposure was associated with a leap in the odds of asthma among the OV/OB adolescents, particularly the girls, after adjusting for 15‑F2t‑IsoP and Carbonyls.

Gene expression profiling in healthy newborns from diverse localities of the Czech Republic

Prenatal exposure to air pollution is associated with intrauterine growth restriction and low birth weight. Gene expression changes in newborns in relation to air pollution have not been sufficiently studied. We analyzed whole genome expression in cord blood leukocytes of 202 newborns from diverse localities of the Czech Republic, differing among other factors in levels of air pollution: the district of Karvina (characterized by higher concentration of air pollutants) and Ceske Budejovice (lower air pollution levels). We aimed to identify differentially expressed genes (DEGs) and pathways in relation to locality and concentration of air pollutants. We applied the linear model to identify the specific DEGs and the correlation analysis, to investigate the relationship between the concentrations of air pollutants and gene expression data. An analysis of biochemical pathways and gene set enrichment was also performed. In general, we observed modest changes of gene expression, mostly attributed to the effect of the locality. The highest number of DEGs was found in samples from the district of Karvina. A pathway analysis revealed a deregulation of processes associated with cell growth, apoptosis or cellular homeostasis, immune response-related processes or oxidative stress response. The association between concentrations of air pollutants and gene expression changes was weak, particularly for samples collected in Karvina. In summary, as we did not find a direct effect of exposure to air pollutants, we assume that the general differences in the environment, rather than actual concentrations of individual pollutants, represent a key factor affecting gene expression changes at delivery. Environ. Mol. Mutagen. 59:401-415, 2018. © 2018 Wiley Periodicals, Inc.

Altered vulnerability to asthma at various levels of ambient Benzo[a]Pyrene by CTLA4, STAT4 and CYP2E1 polymorphisms

BACKGROUND

Within fossil- and solid-fuel dependent geographic locations, mechanisms of air pollution-induced asthma remains unknown. In particular, sources of greater genetic susceptibility to airborne carcinogen, namely, benzo[a]pyrene (B[a]P) has never been investigated beyond that of a few well known genes.

OBJECTIVES

To deepen our understanding on how the genotypic variations within the candidate genes contribute to the variability in the children's susceptibility to ambient B[a]P on doctor-diagnosed asthma.

METHODS

Clinically confirmed asthmatic versus healthy control children (aged, 7-15) were enrolled from historically polluted and rural background regions in Czech Republic. Contemporaneous ambient B[a]P concentration was obtained from the routine monitoring network. The sputum DNA was genotyped for 95 genes. B[a]P interaction with SNPs was studied by two-stage, semi-agnostic screening of 621 SNPs.

RESULTS

The median B[a]P within the highly polluted urban center was 8-times higher than that in the background region (7.8 vs. 1.1 ng/m³) during the period of investigation. Within the baseline model, which considered B[a]P exposure-only, the second tertile range was associated with a significantly reduced odds (aOR = 0.28) of asthma (95% CI, 0.16 to 0.50) compared to those at the lowest range. However, the highest range of B[a]P was associated with 3.18-times greater odds of the outcome (95% CI, 1.77 to 5.71). Within the gene-environment interaction models, joint occurrence of a high B[a]P exposure range and having a high-risk genotype at CTLA4 gene (rs11571316) was associated with 9-times greater odds (95% CI, 4.56-18.36) of the asthma diagnosis. Similarly, rs11571319 at CTLA4 and a high B[a]P exposure range was associated with a 8-times greater odds (95% CI, 3.95-14.27) of asthma diagnosis. Furthermore, having TG + GG genotypes on rs1031509 near STAT4 was associated with 5-times (95% CI, 3.03-8.55) greater odds of asthma diagnosis at the highest B[a]P range, compared to the odds at the reference range. Also CYP2E1 AT + TT genotypes (rs2070673) was associated with 5-times (95% CI, 3.1-8.8) greater odds of asthma diagnosis at the highest B[a]P exposure.

CONCLUSIONS

The children, who jointly experience a high B[a]P exposure (6.3-8.5 ng/m3) as well as susceptible genotypes in CTLA4 (rs11571316 and rs11571319), STAT4 (rs1031509), and CYP2E1 (rs2070673), respectively, are associated with a significantly greater odds of having doctor-diagnosed asthma, compared to those with neither risk factors.

Adaptation of the human population to the environment: Current knowledge, clues from Czech cytogenetic and "omics" biomonitoring studies and possible mechanisms

The human population is continually exposed to numerous harmful environmental stressors, causing negative health effects and/or deregulation of biomarker levels. However, studies reporting no or even positive impacts of some stressors on humans are also sometimes published. The main aim of this review is to provide a comprehensive overview of the last decade of Czech biomonitoring research, concerning the effect of various levels of air pollution (benzo[a]pyrene) and radiation (uranium, X-ray examination and natural radon background), on the differently exposed population groups. Because some results obtained from cytogenetic studies were opposite than hypothesized, we have searched for a meaningful interpretation in genomic/epigenetic studies. A detailed analysis of our data supported by the studies of others and current epigenetic knowledge, leads to a hypothesis of the versatile mechanism of adaptation to environmental stressors via DNA methylation settings which may even originate in prenatal development, and help to reduce the resulting DNA damage levels. This hypothesis is fully in agreement with unexpected data from our studies (e.g. lower levels of DNA damage in subjects from highly polluted regions than in controls or in subjects exposed repeatedly to a pollutant than in those without previous exposure), and is also supported by differences in DNA methylation patterns in groups from regions with various levels of pollution. In light of the adaptation hypothesis, the following points may be suggested for future research: (i) the chronic and acute exposure of study subjects should be distinguished; (ii) the exposure history should be mapped including place of residence during the life and prenatal development; (iii) changes of epigenetic markers should be monitored over time. In summary, investigation of human adaptation to the environment, one of the most important processes of survival, is a new challenge for future research in the field of human biomonitoring that may change our view on the results of biomarker analyses and potential negative health impacts of the environment.

The effects of grafted mesenchymal stem cells labeled with iron oxide or cobalt-zinc-iron nanoparticles on the biological macromolecules of rat brain tissue extracts

INTRODUCTION

Rat mesenchymal stem cells (rMSCs) labeled with 1) poly-l-lysine-coated superparamagnetic iron oxide nanoparticles or 2) silica-coated cobalt-zinc-iron nanoparticles were implanted into the left brain hemisphere of rats, to assess their effects on the levels of oxidative damage to biological macromolecules in brain tissue.

METHODS

Controls were implanted with unlabeled rMSCs. Animals were sacrificed 24 hours or 4 weeks after the treatment, and the implantation site along with the surrounding tissue was isolated from the brain. At the same intervals, parallel groups of animals were scanned in vivo by magnetic resonance imaging (MRI). The comet assay with enzymes of excision DNA repair (endonuclease III and formamidopyrimidine-DNA glycosylase) was used to analyze breaks and oxidative damage to DNA in the brain tissue. Oxidative damage to proteins and lipids was determined by measuring the levels of carbonyl groups and 15-F_2t-isoprostane (enzyme-linked immunosorbent assay). MRI displayed implants of labeled cells as extensive hypointense areas in the brain tissue. In histological sections, the expression of glial fibrillary acidic protein and CD68 was analyzed to detect astrogliosis and inflammatory response.

RESULTS

Both contrast labels caused a similar response in the T₂-weighted magnetic resonance (MR) image and the signal was clearly visible within 4 weeks after implantation of rMSCs. No increase of oxidative damage to DNA, lipids, or proteins over the control values was detected in any sample of brain tissue from the treated animals. Also, immunohistochemistry did not indicate any serious tissue impairment around the graft.

CONCLUSION

Both tested types of nanoparticles appear to be prospective and safe labels for tracking the transplanted cells by MR.

Perinatal health in the Danube region - new birth cohort justified

In 2013-2015, a consortium of European scientists - NEWDANUBE - was established to prepare a birth cohort in the Danube region, including most of the countries with the highest air pollution in Europe, the area being one-fifth of the European Union's (EU's) territory, including 14 countries (nine EU member states), over 100 million inhabitants, with numerous challenges: big socioeconomic disparities, and a region-specific environmental pollution. The consortium reflects the EU Strategy for the Danube Region Strategy (2010), which identified 11 thematic Priority Areas - one of which is the environmental risks. Birth cohorts have been established in all other areas of Europe and collaborative efforts in promoting maternal and fetal health by minimizing the environmental exposures have been initiated with national, European, and international financial support. A birth cohort in the Danube area could apply the established methodologies for prenatal exposure and birth outcome measurements and establish a platform for targeted health promotion in couples planning pregnancies. The consortium included a strong socioeconomic part focusing on the participant's active registration of exposures to environmental toxicants and health indicators of disease and wellbeing, combined with investigation of their risk-reducing behavior and interventions to change their lifestyle to avoid the adverse health risks. Willingness to pay for reducing the health risks in children is also proposed to be estimated. Further collaboration and networking is encouraged as the Danube region has several decades of experience and expertise in biomonitoring adult populations exposed environmentally or occupationally. Additionally, some countries in the Danube region launched small-scale birth cohorts encouraged by participation in several ongoing research projects.

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.

Oxidative stress in newborns by different modes of delivery

OBJECTIVES

The aim of our study is to investigate the impact of the type of delivery - vaginal vs. cesarean section on oxidative damage determined as the lipid peroxidation (15-F2t-isoprostane (15-F2t-IsoP) in the cord blood of newborns and venous blood from mothers in two localities with different levels of air pollution: Ceske Budejovice (CB), a locality with a clean air, and Karvina, a locality with high air pollution.

RESUTLS

In Karvina, the concentration of PM2.5 was higher than in CB in the summer 2013 (mean±SD: 20.41±6.28 vs. 9.45±3.62 µg/m3, p<0.001) and in the winter 2014 (mean±SD: 53.67±19.76 vs. 27.96±12.34 µg/m3, p<0.001). Similarly, the concentration of B[a]P was higher in Karvina than in CB in the summer 2013 (mean±SD: 1.16±0.91 vs. 0.16±0.26 ng/m3, p<0.001) and in the winter 2014 (5.36±3.64 vs. 1.45±1.19 ng/m3, p<0.001). Delivery procedures differed by the type of anesthesia; at the Cesarean section in CB was used general anesthesia in 73.8% vs. 20.8% in Karvina (p<0.001), epidural anesthesia in CB in 26.2% vs. 77.1% in Karvina (p<0.001), at vaginal delivery was local anesthesia used in CB in 58.9% vs. 14.1% in Karvina (p<0.001). In CB was oxidative stress higher after vaginal delivery (101.7±31.0 pg 15-F2t-isoP/ml plasma) vs. Cesarean section (83.9±26.9 pg 15-F2t-isoP/ml plasma, p<0.001), no difference between the type of delivery was observed in Karvina.

CONCLUSION

No difference between the types of delivery was observed in mothers in CB as well as in Karvina. Oxidative stress in newborns in Karvina was significantly affected by the concentrations of PM2.5 and B[a]P in the polluted air.

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.

Toxic Effects of the Major Components of Diesel Exhaust in Human Alveolar Basal Epithelial Cells (A549)

We investigated the toxicity of benzo[a]pyrene (B[a]P), 1-nitropyrene (1-NP) and 3-nitrobenzanthrone (3-NBA) in A549 cells. Cells were treated for 4 h and 24 h with: B[a]P (0.1 and 1 μM), 1-NP (1 and 10 μM) and 3-NBA (0.5 and 5 μM). Bulky DNA adducts, lipid peroxidation, DNA and protein oxidation and mRNA expression of CYP1A1, CYP1B1, NQO1, POR, AKR1C2 and COX2 were analyzed. Bulky DNA adducts were induced after both treatment periods; the effect of 1-NP was weak. 3-NBA induced high levels of bulky DNA adducts even after 4-h treatment, suggesting rapid metabolic activation. Oxidative DNA damage was not affected. 1-NP caused protein oxidation and weak induction of lipid peroxidation after 4-h incubation. 3-NBA induced lipid peroxidation after 24-h treatment. Unlike B[a]P, induction of the aryl hydrocarbon receptor, measured as mRNA expression levels of CYP1A1 and CYP1B1, was low after treatment with polycyclic aromatic hydrocarbon (PAH) nitro-derivatives. All test compounds induced mRNA expression of NQO1, POR, and AKR1C2 after 24-h treatment. AKR1C2 expression indicates involvement of processes associated with reactive oxygen species generation. This was supported further by COX2 expression induced by 24-h treatment with 1-NP. In summary, 3-NBA was the most potent genotoxicant, whereas 1-NP exhibited the strongest oxidative properties.

Relationship between atmospheric pollution in the residential area and concentrations of polycyclic aromatic hydrocarbons (PAHs) in human breast milk

Human milk is an important source of beneficial nutrients and antibodies for newborns and infants and, under certain circumstances, its analysis may provide information on mothers' and infants' exposure to various contaminants. In the presented study, we have introduced the new analytical approach for analysis of 24 highly occurring polycyclic aromatic hydrocarbons (PAHs) in this indicator matrix. The sample preparation procedure is based on an ethyl acetate extraction of milk; the transfer of analytes into an organic layer is enhanced by addition of inorganic salts, i.e. sodium chloride and magnesium sulphate. Following the clean-up of a crude extract on silica SPE columns, gas chromatography coupled to triple quadrupole mass spectrometry is used for PAH identification and quantitation. The average recoveries of targeted PAHs from spiked samples were in the range of 68-110% with repeatabilities below 30% and method quantitation limits ranging from 0.03 to 0.3ng/g lipid weight. This newly validated method was successfully applied for analyses of 324 human milk samples collected from nonsmoking women during two sampling periods (summer and winter) in two residential areas in the Czech Republic differing in atmospheric pollution by PAHs. From 24 targeted analytes 17 were detected at least in one sample. Phenantherene, fluoranthrene, pyrene and fluorene were the most abundant compounds found at average concentration of 13.81, 1.80, 0.86, and 2.01ng/g lipid weight respectively. Comparing the data from two sampling periods, in both areas higher concentrations were measured in samples collected during winter. Also in the highly industrialized locality with heavily contaminated air PAH amounts in milk were higher than in the control locality. These first data on PAH concentrations in human milk collected in the Czech Republic are comparable with measurements for nonsmoking women reported earlier in the United States but significantly lower than results from China, Turkey or Italy.

Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine analysis by an improved ELISA: An inter-laboratory comparison study

ELISA is commonly used for the detection of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a marker of whole body oxidative stress. However, the method has been criticized for high inter-laboratory variability and poor agreement with chromatographic techniques. We performed an inter-laboratory comparison of 8-oxodG assessed in 30 urine samples and a urine spiked with four different concentrations of 8-oxodG by ELISA using standardized experimental conditions, including: sample pre-treatment with solid-phase extraction (SPE), performing analysis using a commercial kit from a single manufacturer and strict temperature control during the assay. We further compared the ELISA results with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and performed tentative identification of compounds that may contribute to the discrepancy between both methods. For all but one participating laboratory (Data 1) we observed consistent ELISA results lying mostly within 1SD of the mean 8-oxodG concentration. Mean 8-oxodG levels assessed by ELISA correlated with the data obtained by HPLC-MS/MS (R=0.679, p<0.001). The correlation improved when Data 1 were excluded from the analysis (R=0.749, p<0.001). We identified three outlying urine samples; one with an ELISA 8-oxodG concentration lower, and two with 8-oxodG levels higher, than those measured by HPLC-MS/MS. Omitting these samples further improved inter-methodology agreement (R=0.869, p<0.001). In the outliers with high 8-oxodG estimates various aromatic and heterocyclic compounds were tentatively identified using gas chromatography-mass spectrometry (GC-MS). Application of authentic standards revealed the presence of saccharides, including d-glucose and d-galactose as putative interfering substances. In summary, assay standardization improved ELISA inter-laboratory agreement, although some variability is still observed. There are still compounds contributing to overestimation of 8-oxodG by ELISA, but only in some urine samples. Thus, despite significant improvement, ELISA still should not be considered a robust alternative to chromatographic techniques.

Polymorphisms in DNA repair genes, traffic-related polycyclic aromatic hydrocarbon exposure and breast cancer incidence

Vehicular traffic polycyclic aromatic hydrocarbons (PAHs) have been associated with breast cancer incidence in epidemiologic studies, including our own. Because PAHs damage DNA by forming adducts and oxidative lesions, genetic polymorphisms that alter DNA repair capacity may modify associations between PAH-related exposures and breast cancer risk. Our goal was to examine the association between vehicular traffic exposure and breast cancer incidence within strata of a panel of nine biologically plausible nucleotide excision repair (NER) and base excision repair (BER) genotypes. Residential histories of 1,508 cases and 1,556 controls were assessed in the Long Island Breast Cancer Study Project between 1996 and 1997 and used to reconstruct residential traffic exposures to benzo[a]pyrene, as a proxy for traffic-related PAHs. Likelihood ratio tests from adjusted unconditional logistic regression models were used to assess multiplicative interactions. A gene-traffic interaction was evident (p = 0.04) for ERCC2 (Lys751); when comparing the upper and lower tertiles of 1995 traffic exposure estimates, the odds ratio (95% confidence interval) was 2.09 (1.13, 3.90) among women with homozygous variant alleles. Corresponding odds ratios for 1960-1990 traffic were also elevated nearly 2-3-fold for XRCC1(Arg194Trp), XRCC1(Arg399Gln) and OGG1(Ser326Cys), but formal multiplicative interaction was not evident. When DNA repair variants for ERCC2, XRCC1 and OGG1 were combined, among women with 4-6 variants, the odds ratios were 2.32 (1.22, 4.49) for 1995 traffic and 2.96 (1.06, 8.21) for 1960-1990 traffic. Our study is first to report positive associations between traffic-related PAH exposure and breast cancer incidence among women with select biologically plausible DNA repair genotypes.