Association of Inflammatory and Oxidative Status Markers with Metabolic Syndrome and Its Components in 40-to-45-Year-Old Females: A Cross-Sectional Study.

Oxidative stress and sterile inflammation play roles in the induction and maintenance of metabolic syndrome (MetS). This study cohort included 170 females aged 40 to 45 years who were categorized according to the presentation of MetS components (e.g., central obesity, insulin resistance, atherogenic dyslipidemia, and elevated systolic blood pressure) as controls not presenting a single component (n = 43), those with pre-MetS displaying one to two components (n = 70), and females manifesting MetS, e.g., ≥3 components (n = 53). We analyzed the trends of seventeen oxidative and nine inflammatory status markers across three clinical categories. A multivariate regression of selected oxidative status and inflammatory markers on the components of MetS was performed. Markers of oxidative damage (malondialdehyde and advanced-glycation-end-products-associated fluorescence of plasma) were similar across the groups. Healthy controls displayed lower uricemia and higher bilirubinemia than females with MetS; and lower leukocyte counts, concentrations of C-reactive protein, interleukine-6, and higher levels of carotenoids/lipids and soluble receptors for advanced glycation end-products than those with pre-MetS and MetS. In multivariate regression models, levels of C-reactive protein, uric acid, and interleukine-6 were consistently associated with MetS components, although the impacts of single markers differed. Our data suggest that a proinflammatory imbalance precedes the manifestation of MetS, while an imbalance of oxidative status accompanies overt MetS. Further studies are needed to elucidate whether determining markers beyond traditional ones could help improve the prognosis of subjects at an early stage of MetS.

Genotoxic effects of occupational exposure to glass fibres - A human biomonitoring study.

As part of a large human biomonitoring study, we conducted occupational monitoring in a glass fibre factory in Slovakia. Shopfloor workers (n = 80), with a matched group of administrators in the same factory (n = 36), were monitored for exposure to glass fibres and to polycyclic aromatic hydrocarbons (PAHs). The impact of occupational exposure on chromosomal aberrations, DNA damage and DNA repair, immunomodulatory markers, and the role of nutritional and lifestyle factors, as well as the effect of polymorphisms in metabolic and DNA repair genes on genetic stability, were investigated. The (enzyme-modified) comet assay was employed to measure DNA strand breaks (SBs) and apurinic sites, oxidised and alkylated bases. Antioxidant status was estimated by resistance to H2O2-induced DNA damage. Base excision repair capacity was measured with an in vitro assay (based on the comet assay). Exposure of workers to fibres was low, but still was associated with higher levels of SBs, and SBs plus oxidised bases, and higher sensitivity to H2O2. Multivariate analysis showed that exposure increased the risk of high levels of SBs by 20%. DNA damage was influenced by antioxidant enzymes catalase and glutathione S-transferase (measured in blood). DNA repair capacity was inversely correlated with DNA damage and positively with antioxidant status. An inverse correlation was found between DNA base oxidation and the percentage of eosinophils (involved in the inflammatory response) in peripheral blood of both exposed and reference groups. Genotypes of XRCC1 variants rs3213245 and rs25487 significantly decreased the risk of high levels of base oxidation, to 0.50 (p = 0.001) and 0.59 (p = 0.001), respectively. Increases in DNA damage owing to glass fibre exposure were significant but modest, and no increases were seen in chromosome aberrations or micronuclei. However, it is of concern that even low levels of exposure to these fibres can cause significant genetic damage.

DNA damage in circulating leukocytes measured with the comet assay may predict the risk of death.

The comet assay or single cell gel electrophoresis, is the most common method used to measure strand breaks and a variety of other DNA lesions in human populations. To estimate the risk of overall mortality, mortality by cause, and cancer incidence associated to DNA damage, a cohort of 2,403 healthy individuals (25,978 person-years) screened in 16 laboratories using the comet assay between 1996 and 2016 was followed-up. Kaplan-Meier analysis indicated a worse overall survival in the medium and high tertile of DNA damage (p < 0.001). The effect of DNA damage on survival was modelled according to Cox proportional hazard regression model. The adjusted hazard ratio (HR) was 1.42 (1.06-1.90) for overall mortality, and 1.94 (1.04-3.59) for diseases of the circulatory system in subjects with the highest tertile of DNA damage. The findings of this study provide epidemiological evidence encouraging the implementation of the comet assay in preventive strategies for non-communicable diseases.

DNA Repair Gene Polymorphisms and Chromosomal Aberrations in Exposed Populations.

DNA damage and unrepaired or insufficiently repaired DNA double-strand breaks as well as telomere shortening contribute to the formation of structural chromosomal aberrations (CAs). Non-specific CAs have been used in the monitoring of individuals exposed to potential carcinogenic chemicals and radiation. The frequency of CAs in peripheral blood lymphocytes (PBLs) has been associated with cancer risk and the association has also been found in incident cancer patients. CAs include chromosome-type aberrations (CSAs) and chromatid-type aberrations (CTAs) and their sum CAtot. In the present study, we used data from our published genome-wide association studies (GWASs) and extracted the results for 153 DNA repair genes for 607 persons who had occupational exposure to diverse harmful substances/radiation and/or personal exposure to tobacco smoking. The analyses were conducted using linear and logistic regression models to study the association of DNA repair gene polymorphisms with CAs. Considering an arbitrary cutoff level of 5 × 10-3, 14 loci passed the threshold, and included 7 repair pathways for CTA, 4 for CSA, and 3 for CAtot; 10 SNPs were eQTLs influencing the expression of the target repair gene. For the base excision repair pathway, the implicated genes PARP1 and PARP2 encode poly(ADP-ribosyl) transferases with multiple regulatory functions. PARP1 and PARP2 have an important role in maintaining genome stability through diverse mechanisms. Other candidate genes with known roles for CSAs included GTF2H (general transcription factor IIH subunits 4 and 5), Fanconi anemia pathway genes, and PMS2, a mismatch repair gene. The present results suggest pathways with mechanistic rationale for the formation of CAs and emphasize the need to further develop techniques for measuring individual sensitivity to genotoxic exposure.

DNA repair gene polymorphisms and chromosomal aberrations in healthy, nonsmoking population.

Nonspecific structural chromosomal aberrations (CAs) can be found at around 1% of circulating lymphocytes from healthy individuals but the frequency may be higher after exposure to carcinogenic chemicals or radiation. The frequency of CAs has been measured in occupational monitoring and an increased frequency of CAs has also been associated with cancer risk. Alterations in DNA damage repair and telomere maintenance are thought to contribute to the formation of CAs, which include chromosome type of aberrations and chromatid type of aberrations. In the present study, we used the result of our published genome-wide association studies to extract data on 153 DNA repair genes from 866 nonsmoking persons who had no known occupational exposure to genotoxic substances. Considering an arbitrary cut-off level of P< 5 × 10-3, single nucleotide polymorphisms (SNPs) tagging 22 DNA repair genes were significantly associated with CAs and they remained significant at P < 0.05 when adjustment for multiple comparisons was done by the Binomial Sequential Goodness of Fit test. Nucleotide excision repair pathway genes showed most associations with 6 genes. Among the associated genes were several in which mutations manifest CA phenotype, including Fanconi anemia, WRN, BLM and genes that are important in maintaining genome stability, as well as PARP2 and mismatch repair genes. RPA2 and RPA3 may participate in telomere maintenance through the synthesis of the C strand of telomeres. Errors in NHEJ1 function may lead to translocations. The present results show associations with some genes with known CA phenotype and suggest other pathways with mechanistic rationale for the formation of CAs in healthy nonsmoking population.

Impact of genetic polymorphisms in kinetochore and spindle assembly genes on chromosomal aberration frequency in healthy humans.

Genomic instability is a characteristic of a majority of human malignancies. Chromosomal instability is a common form of genomic instability that can be caused by defects in mitotic checkpoint genes. Chromosomal aberrations in peripheral blood are also indicative of genotoxic exposure and potential cancer risk. We evaluated associations between inherited genetic variants in 33 mitotic checkpoint genes and the frequency of chromosomal aberrations (CAs) in the presence and absence of environmental genotoxic exposure. Associations with both chromosome and chromatid type of aberrations were evaluated in two cohorts of healthy individuals, namely an exposed and a reference group consisting of 607 and 866 individuals, respectively. Binary logistic and linear regression analyses were performed for the association studies. Bonferroni-corrected significant p-value was 5 × 10-4 for 99 tests based on the number of analyzed genes and phenotypes. In the reference group the most prominent associations were found with variants in CCNB1, a master regulator of mitosis, and in genes involved in kinetochore function, including CENPH and TEX14, whereas in the exposed group the main association was found with variants in TTK, also an important gene in kinetochore function. How the identified variants may affect the fidelity of mitotic checkpoint remains to be investigated, however, the present study suggests that genetic variation may partly explain interindividual variation in the formation of CAs.

Distinct pathways associated with chromosomal aberration frequency in a cohort exposed to genotoxic compounds compared to general population.

Non-specific structural chromosomal aberrations (CAs) observed in peripheral blood lymphocytes of healthy individuals can be either chromosome-type aberrations (CSAs) or chromatid-type aberrations (CTAs) depending on the stage of cell division they are induced in and mechanism of formation. It is important to study the genetic basis of chromosomal instability as it is a marker of genotoxic exposure and a predictor of cancer risk. For that purpose, we conducted two genome-wide association studies (GWASs) on healthy individuals in the presence and absence of apparent genotoxic exposure from the Czech Republic and Slovakia. The pre-GWAS cytogenetic analysis reported the frequencies of CSA, CTA and total CA (CAtot). We performed both linear and binary logistic regression analysis with an arbitrary cut-off point of 2% for CAtot and 1% for CSA and CTA. Using the statistical threshold of 1.0 × 10-5, we identified five loci with in silico predicted functionality in the reference group and four loci in the exposed group, with no overlap between the associated regions. A meta-analysis on the two GWASs identified further four loci with moderate associations in each of the studies. From the reference group mainly loci within genes related to DNA damage response/repair were identified. Other loci identified from both the reference and exposed groups were found to be involved in the segregation of chromosomes and chromatin modification. Some of the discovered regions in each group were implicated in tumourigenesis and autism.

Titanium dioxide nanoparticles tested for genotoxicity with the comet and micronucleus assays in vitro, ex vivo and in vivo.

The genotoxicity of TiO2 nanoparticles (NPs) was assessed with the cytokinesis-block micronucleus (CBMN) assay in TK6 lymphoblastoid cells, lymphocytes from human volunteers, and bone marrow erythrocytes from rats exposed in vivo; and with the comet assay (detecting both strand breaks and oxidised purines) in human and rat peripheral blood mononuclear cells (PBMCs). NPs were dispersed using three different methods giving different size distribution and stability. On average, TiO2 NPs caused no increase in micronuclei in TK6 cells, rat bone marrow erythrocytes or human lymphocytes (though lymphocytes from 3 out of 13 human subjects showed significant increases). PBMCs from rats treated in vivo with a single dose of NPs dispersed by a method with low agglomeration showed an increase in strand breaks after 1 day. TiO2 NPs dispersed in a stable, non-agglomerated state induced DNA strand breaks at 75 µg/cm2 after 4 h exposure of human PBMCs and at 15 µg/cm2 and 75 µg/cm2 after 24 h exposure, but no increase in DNA oxidation was seen. Overall, NPs in an agglomerated state did not cause DNA damage. However, at the individual level, significant increases in strand breaks were seen in PBMCs from most of the volunteers. Cells from one volunteer showed positive effects in all conditions and both tests, while cells from another volunteer appeared to be completely resitant to TiO2 NPs. The implication is that some individuals may be more sensitive than others to effects of this nanomaterial. Differences seen in results obtained with the micronucleus and the comet assay may be due to the mechanisms underlying the genotoxic effects of TiO2 NPs and the different endpoints represented by the two assays.

Genetic variation associated with chromosomal aberration frequency: A genome-wide association study.

Chromosomal aberrations (CAs) in human peripheral blood lymphocytes (PBL) measured with the conventional cytogenetic assay have been used for human biomonitoring of genotoxic exposure for decades. CA frequency in peripheral blood is a marker of cancer susceptibility. Previous studies have shown associations between genetic variants in metabolic pathway, DNA repair and major mitotic checkpoint genes and CAs. We conducted a genome-wide association study on 576 individuals from the Czech Republic and Slovakia followed by a replication in two different sample sets of 482 (replication 1) and 1288 (replication 2) samples. To have a broad look at the genetic susceptibility associated with CA frequency, the sample sets composed of individuals either differentially exposed to smoking, occupational/environmental hazards, or they were untreated cancer patients. Phenotypes were divided into chromosome- and chromatid-type aberrations (CSAs and CTAs, respectively) and total chromosomal aberrations (CAtot). The arbitrary cutoff point between individuals with high and low CA frequency was 2% for CAtot and 1% for CSA and CTA. The data were analyzed using age, sex, occupation/cancer and smoking history as covariates. Altogether 11 loci reached the P-value of 10-5 in the GWAS. Replication 1 supported the association of rs1383997 (8q13.3) and rs2824215 (21q21.1) in CAtot and rs983889 (5p15.1) in CTA analysis. These loci were found to be associated with genes involved in mitosis, response to environmental and chemical factors and genes involved in syndromes linked to chromosomal abnormalities. Identification of new genetic variants for the frequency of CAs offers prediction tools for cancer risk in future. Environ. Mol. Mutagen. 60:17-28, 2019. © 2018 Wiley Periodicals, Inc.

Automotive airborne brake wear debris nanoparticles and cytokinesis-block micronucleus assay in peripheral blood lymphocytes: A pilot study.

Motor vehicle exhaust and non-exhaust processes play a significant role in environmental pollution, as they are a source of the finest particulate matter. Emissions from non-exhaust processes include wear-products of brakes, tires, automotive hardware, road surface, and traffic signs, but still are paid little attention to. Automotive friction composites for brake pads are composite materials which may consist of potentially hazardous materials and there is a lack of information regarding the potential influence of the brake wear debris (BWD) on the environment, especially on human health. Thus, we focused our study on the genotoxicity of the airborne fraction of BWD using a brake pad model representing an average low-metallic formulation available in the EU market. BWD was generated in the laboratory by a full-scale brake dynamometer and characterized by Raman microspectroscopy, scanning electron microscopy, and transmission electron microscopy showing that it contains nano-sized crystalline metal-based particles. Genotoxicity tested in human lymphocytes in different testing conditions showed an increase in frequencies of micronucleated binucleated cells (MNBNCs) exposed for 48h to BWD nanoparticles (NPs) (with 10% of foetal calf serum in culture medium) compared with lymphocytes exposed to medium alone, statistically significant only at the concentration 3µg/cm(2) (p=0.032).

Immunotoxicity and genotoxicity testing of PLGA-PEO nanoparticles in human blood cell model.

A human blood cell model for immunotoxicity and genotoxicity testing was used to measure the response to polylactic-co-glycolic acid (PLGA-PEO) nanoparticle (NP) (0.12, 3, 15 and 75 µg/cm(2) exposure in fresh peripheral whole blood cultures/isolated peripheral blood mononuclear cell cultures from human volunteers (n = 9-13). PLGA-PEO NPs were not toxic up to dose 3 µg/cm(2); dose of 75 µg/cm(2) displays significant decrease in [(3)H]-thymidine incorporation into DNA of proliferating cells after 4 h (70% of control) and 48 h (84%) exposure to NPs. In non-cytotoxic concentrations, in vitro assessment of the immunotoxic effects displayed moderate but significant suppression of proliferative activity of T-lymphocytes and T-dependent B-cell response in cultures stimulated with PWM > CON A, and no changes in PHA cultures. Decrease in proliferative function was the most significant in T-cells stimulated with CD3 antigen (up to 84%). Cytotoxicity of natural killer cells was suppressed moderately (92%) but significantly in middle-dosed cultures (4 h exposure). On the other hand, in low PLGA-PEO NPs dosed cultures, significant stimulation of phagocytic activity of granulocytes (119%) > monocytes (117%) and respiratory burst of phagocytes (122%) was recorded. Genotoxicity assessment revealed no increase in the number of micronucleated binucleated cells and no induction of SBs or oxidised DNA bases in PLGA-PEO-treated cells. To conclude on immuno- and genotoxicity of PLGA-PEO NPs, more experiments with various particle size, charge and composition need to be done.

Coating-dependent induction of cytotoxicity and genotoxicity of iron oxide nanoparticles.

Surface coatings of nanoparticles (NPs) are known to influence advantageous features of NPs as well as potential toxicity. Iron oxide (Fe3O4) NPs are applied for both medical diagnostics and targeted drug delivery. We investigated the potential cytotoxicity and genotoxicity of uncoated iron oxide (U-Fe3O4) NPs in comparison with oleate-coated iron oxide (OC-Fe3O4) NPs. Testing was performed in vitro in human lymphoblastoid TK6 cells and in primary human blood cells. For cytotoxicity testing, relative growth activity, trypan blue exclusion, (3)H-thymidine incorporation and cytokinesis-block proliferation index were assessed. Genotoxicity was evaluated by the alkaline comet assay for detection of strand breaks and oxidized purines. Particle characterization was performed in the culture medium. Cellular uptake, morphology and pathology were evaluated by electron microscopy. U-Fe3O4 NPs were found not to be cytotoxic (considering interference of NPs with proliferation test) or genotoxic under our experimental conditions. In contrast, OC-Fe3O4 NPs were cytotoxic in a dose-dependent manner, and also induced DNA damage, indicating genotoxic potential. Intrinsic properties of sodium oleate were excluded as a cause of the toxic effect. Electron microscopy data were consistent with the cytotoxicity results. Coating clearly changed the behaviour and cellular uptake of the NPs, inducing pathological morphological changes in the cells.

Health effects of selected nanoparticles in vivo: liver function and hepatotoxicity following intravenous injection of titanium dioxide and Na-oleate-coated iron oxide nanoparticles in rodents.

The study determined the effect of intravenous administration of acutely toxic or sub-lethal doses of Na-oleate-coated Fe3O4 (OC-Fe3O4) nanoparticles (NPs) on liver structure and function in Wistar rats, compared to titanium dioxide (TiO2) NPs and saline-injected controls. The acute study, using a modified OECD 425 progressive dosing procedure, found LD50 values of 59.22 and 36.42 mg/kg for TiO2 and OC-Fe3O4 NPs, respectively. In the sub-lethal study, rats were either injected with saline (negative controls), a sub-lethal reference (0.592 mg/kgTiO2 NPs, equal to 1% of LD50 on a body weight basis) or OC-Fe3O4 NPs in doses equivalent to 0.1, 1 or 10% of the LD50, respectively (corresponding to 0.0364, 0.364 and 3.64 mg Fe3O4/kg body weight). Animals were sampled 24 h, 1, 2 and 4 weeks post-injection for adverse effects. Mitochondrial respiration was significantly increased 2 weeks after injection of 10% OC-Fe3O4 NPs compared to controls, but the effect was transient. Cholesterol and triacylglycerol concentrations in the liver tissue did not increase in any treatment. There were some disturbances to antioxidant enzymes after OC-Fe3O4 NPs treatment in the livers of animals 1 week post-exposure; with the most sensitive changes occurring in glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities. Lipidosis and mild necrosis with changes in sinusoid space were also observed in histological sections of the liver. Overall, these data suggest that the liver likely retains functional integrity with acute and sub-lethal doses of OC-Fe3O4 NPs, albeit with some stimulation of redox defences and evidence of some tissue injury.

Comprehensive assessment of nephrotoxicity of intravenously administered sodium-oleate-coated ultra-small superparamagnetic iron oxide (USPIO) and titanium dioxide (TiO2) nanoparticles in rats.

As a main excretory organ, kidney is predisposed to direct/indirect injury. We addressed the potential nephrotoxic effects following expositions of healthy rats to nanoparticle (NP) loads relevant to humans in a situation of 100% bioavailability. Up to 4 weeks after administration, a single iv bolus of oleate-coated ultra-small superparamagnetic iron oxide NPs (in dose of 0.1%, 1.0% and 10.0% of LD50) or TiO2 NPs (1.0% of LD50) did not elicit decline in renal function, damage to proximal tubules, alterations in: renal histology or expression of pro-inflammatory/pro-fibrotic genes, markers of systemic or local renal micro-inflammation or oxidative damage. Antioxidant enzyme activities in renal cortex, mildly elevated at 24 h, completely restored at later time points. Data obtained by multifaceted approach enable the prediction of human nephrotoxicity during preclinical studies, and may serve as comparison for alternative testing strategies using in vitro and in silico methods essential for the NP-nephrotoxicity risk assessment.

Genotoxicity testing of PLGA-PEO nanoparticles in TK6 cells by the comet assay and the cytokinesis-block micronucleus assay.

The in vitro genotoxicity of PLGA-PEO (poly-lactic-co-glycolic acid-polyethylene oxide copolymer) nanoparticles was assessed in TK6 cells using the comet assay as well as cytokinesis-block micronucleus (CBMN) assay. The cells were exposed to 0.12-75µg/cm² of PLGA-PEO nanoparticles during 2 and 24h for analysis in the comet assay, and to 3-75µg/cm² of these nanoparticles during 4, 24, 48 and 72h, respectively, for analysis in the CBMN assay. Two different protocols for treatment with cytochalasin B were used. We found that PLGA-PEO was neither cytotoxic (measured by relative cell growth activity and cytokinesis-block proliferation index (CBPI)), nor did it induce DNA strand-breaks (detected by the comet assay) or oxidative DNA lesions (measured by the comet assay modified with lesion-specific enzyme formamidopyrimidine-DNA-glycosylase). There were no statistically significant differences in the frequencies of micronucleated binucleated cells (MNBNCs) between untreated and treated cells in either of the conditions used. This suggests that PLGA-PEO did not have potential genotoxicity. However, using two experimental protocols of the micronucleus assay, PLGA-PEO nanoparticles showed a weak but significant increase in the level of MN in mononucleated cells, in cells treated for 48h with PLGA-PEO nanoparticles when cytochalasin B was added for the last 24h (1st protocol), and in cells treated for 24h with PLGA-PEO nanoparticles followed by washing of NPs and addition of cytochalasin B for another 24h (2nd protocol). It remains unclear whether the increase of MNMNC after treatment with PLGA-PEO nanoparticles is the effect of a possible, weak aneugenic potential or early effect of these particles, or due to another reason. These results suggest that aneugenicity in addition to clastogenicity may be considered as an important biomarker when assessing the genotoxic potential of polymeric nanoparticles.

Association between the human immune response and body mass index.

The aim of this study was to determine the strength of the association between the human immune response and body mass index (BMI) and whether differences exist in the effects of obesity on selected immune parameters between men and women. Two hundred ninety participants were divided into groups according to sex and BMI. Parameters CD3, CD4, CD8, CD16+56, CD19, HLADR, CD11b, CD11c, and CD54 were quantified. Leukocyte and differential counts were performed. We observed elevation with regard to the normal weight group in the parameters of white blood cells, neutrophils, monocytes, CD3, CD4, CD19, and CD11b for the whole study group. A decrease was observed in the expression of CD16+56. The effect of BMI on the immune system was much more apparent in women. BMI was correlated with the majority of the measured parameters, reflecting a strong association between BMI and the human immune system.

Are glutathione S transferases involved in DNA damage signalling? Interactions with DNA damage and repair revealed from molecular epidemiology studies.

Glutathione S-transferases (GSTs) are members of a multigene family of isoenzymes that are important in the control of oxidative stress and in phase II metabolism. Acting non-enzymically, GSTs can modulate signalling pathways of cell proliferation, cell differentiation and apoptosis. Using a molecular epidemiology approach, we have investigated a potential involvement of GSTs in DNA damage processing, specifically the modulation of DNA repair in a group of 388 healthy adult volunteers; 239 with at least 5 years of occupational exposure to asbestos, stone wool or glass fibre, and 149 reference subjects. We measured DNA damage in lymphocytes using the comet assay (alkaline single cell gel electrophoresis): strand breaks (SBs) and alkali-labile sites, oxidised pyrimidines with endonuclease III, and oxidised purines with formamidopyrimidine DNA glycosylase. We also measured GST activity in erythrocytes, and the capacity for base excision repair (BER) in a lymphocyte extract. Polymorphisms in genes encoding three GST isoenzymes were determined, namely deletion of GSTM1 and GSTT1 and single nucleotide polymorphism Ile105Val in GSTP1. Consumption of vegetables and wine correlated negatively with DNA damage and modulated BER. GST activity correlated with oxidised bases and with BER capacity, and differed depending on polymorphisms in GSTP1, GSTT1 and GSTM1. A significantly lower BER rate was associated with the homozygous GSTT1 deletion in all asbestos site subjects and in the corresponding reference group. Multifactorial analysis revealed effects of sex and exposure in GSTP1 Ile/Val heterozygotes but not in Ile/Ile homozygotes. These variants affected also SBs levels, mainly by interactions of GSTP1 genotype with exposure, with sex, and with smoking habit; and by an interaction between sex and smoking. Our results show that GST polymorphisms and GST activity can apparently influence DNA stability and repair of oxidised bases, suggesting a potential new role for these proteins in DNA damage processing via DNA damage signalling.

Occupational exposure to mineral fibres. Biomarkers of oxidative damage and antioxidant defence and associations with DNA damage and repair.

In order to study the effect of mineral wool exposure on oxidative DNA damage and lipid peroxidation, an epidemiological study was conducted in a mineral wool factory in Slovakia. Altogether 141 subjects were investigated (21-58 years old), 43 controls (20 men and 23 women: 27 non-smokers, 16 smokers) and 98 exposed (75 men and 23 women: 61 non-smokers, 37 smokers). We found higher malondialdehyde (MDA) levels in the group of all exposed workers (P = 0.025) and in exposed non-smokers (P = 0.003) and a significantly suppressed activity of ceruloplasmin oxidase (P = 0.02, P < 0.02, respectively) and catalase (CAT) (P = 0.04, P = 0.01, respectively) in these groups. The activity of glutathione S-transferase (GST) was affected by exposure to mineral wool; levels were significantly lower in all exposed subjects (P = 0.04), in the exposed non-smokers (P = 0.03) and in exposed men (P < 0.01). Concentrations of vitamin C in plasma and the ferric-reducing activity of plasma (FRAP) were not affected by the mineral wool exposure. There was a significant negative correlation between the activity of glutathione peroxidase (GPX) and MDA in the whole group (P < 0.01) and in the exposed group and between CAT activity and MDA in all subjects (P < 0.01). GST activity correlated inversely with oxidized pyrimidines in lymphocyte DNA, in almost all subgroups. We found significant negative correlations between DNA repair and GPX in all subjects (P = 0.03) as well as in control men (P < 0.03) and between DNA repair and CAT in all control subjects (P < 0.02) and in control men (P < 0.01). Interestingly, we found a positive correlation between DNA repair and MDA in all subjects (P < 0.01) and in all exposed subjects (P < 0.03). The presented results indicate that mineral wool exposure induces an increase in oxidative damage to biomolecules especially in the group of male non-smokers. However, optimal levels of antioxidants could have a protective effect. Biomarkers such as MDA, antioxidant enzymes and antioxidant vitamins measured in blood may be useful biomarkers of oxidative stress and antioxidant protection. We do not recommend FRAP as a marker of antioxidant status as interference from other constituents can provide false or confusing results. Our study supports the idea that there might also be other mechanisms by which antioxidant enzymes (especially GST) protect cells against oxidative DNA damage.