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

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

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

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.

Three-Year Study of Markers of Oxidative Stress in Exhaled Breath Condensate in Workers Producing Nanocomposites, Extended by Plasma and Urine Analysis in Last Two Years.

Human data concerning exposure to nanoparticles are very limited, and biomarkers for monitoring exposure are urgently needed. In a follow-up of a 2016 study in a nanocomposites plant, in which only exhaled breath condensate (EBC) was examined, eight markers of oxidative stress were analyzed in three bodily fluids, i.e., EBC, plasma and urine, in both pre-shift and post-shift samples in 2017 and 2018. Aerosol exposures were monitored. Mass concentration in 2017 was 0.351 mg/m3 during machining, and 0.179 and 0.217 mg/m3 during machining and welding, respectively, in 2018. In number concentrations, nanoparticles formed 96%, 90% and 59%, respectively. In both years, pre-shift elevations of 50.0% in EBC, 37.5% in plasma and 6.25% in urine biomarkers were observed. Post-shift elevation reached 62.5% in EBC, 68.8% in plasma and 18.8% in urine samples. The same trend was observed in all biological fluids. Individual factors were responsible for the elevation of control subjects' afternoon vs. morning markers in 2018; all were significantly lower compared to those of workers. Malondialdehyde levels were always acutely shifted, and 8-hydroxy-2-deoxyguanosine levels best showed chronic exposure effect. EBC and plasma analysis appear to be the ideal fluids for bio-monitoring of oxidative stress arising from engineered nanomaterials. Potential late effects need to be targeted and prevented, as there is a similarity of EBC findings in patients with silicosis and asbestosis.

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.

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.

Markers of Oxidative Stress in the Exhaled Breath Condensate of Workers Handling Nanocomposites.

Researchers in nanocomposite processing may inhale a variety of chemical agents, including nanoparticles. This study investigated airway oxidative stress status in the exhaled breath condensate (EBC). Nineteen employees (42.4 ± 11.4 y/o), working in nanocomposites research for 18.0 ± 10.3 years were examined pre-shift and post-shift on a random workday, together with nineteen controls (45.5 ± 11.7 y/o). Panels of oxidative stress biomarkers derived from lipids, nucleic acids, and proteins were analyzed in the EBC. Aerosol exposures were monitored during three major nanoparticle generation operations: smelting and welding (workshop 1) and nanocomposite machining (workshop 2) using a suite of real-time and integrated instruments. Mass concentrations during these operations were 0.120, 1.840, and 0.804 mg/m³, respectively. Median particle number concentrations were 4.8 × 104, 1.3 × 105, and 5.4 × 105 particles/cm³, respectively. Nanoparticles accounted for 95, 40, and 61%, respectively, with prevailing Fe and Mn. All markers of nucleic acid and protein oxidation, malondialdehyde, and aldehydes C6⁻C13 were elevated, already in the pre-shift samples relative to controls in both workshops. Significant post-shift elevations were documented in lipid oxidation markers. Significant associations were found between working in nanocomposite synthesis and EBC biomarkers. More research is needed to understand the contribution of nanoparticles from nanocomposite processing in inducing oxidative stress, relative to other co-exposures generated during welding, smelting, and secondary oxidation processes, in these workshops.

Neuroinflammation markers and methyl alcohol induced toxic brain damage.

Methyl alcohol intoxication is a global problem with high mortality and long-term visual sequelae and severe brain damage in survivors. The role of neuroinflammation in the mechanisms of methyl alcohol-induced toxic brain damage has not been well studied. We measured the acute concentrations and dynamics of lipoxins LxA4 and LxB4 and the interleukins IL-4, IL-5, IL-9, IL-10, and IL-13 in the serum of patients treated with methyl alcohol poisoning and the follow-up concentrations in survivors two years after discharge from the hospital. A series of acute measurements was performed in 28 hospitalized patients (mean age 54.2 ±â€¯5.2 years, mean observation time 88 ±â€¯20 h) and the follow-up measurements were performed in 36 subjects who survived poisoning (including 12/28 survivors from the acute group). Visual evoked potentials (VEP) and magnetic resonance imaging of the brain (MRI) were performed to detect long-term visual and brain sequelae of intoxication. The acute concentrations of inflammatory mediators were higher than the follow-up concentrations: LxA4, 62.0 ±â€¯6.0 vs. 30.0 ±â€¯5.0 pg/mL; LxB4, 64.0 ±â€¯7.0 vs. 34.0 ±â€¯4.0 pg/mL; IL-4, 29.0 ±â€¯4.0 vs. 15.0 ±â€¯1.0 pg/mL; IL-5, 30.0 ±â€¯4.0 vs. 13.0 ±â€¯1.0 pg/mL; IL-9, 30.0 ±â€¯4.0 vs. 13.0 ±â€¯1.0 pg/mL; IL-10, 38.0 ±â€¯5.0 vs. 16.0 ±â€¯1.0 pg/mL; IL-13, 35.0 ±â€¯4.0 vs. 14.0 ±â€¯1.0 pg/mL (all p < 0.001). The patients with higher follow-up IL-5 concentration had prolonged latency P1 (r = 0.413; p = 0.033) and lower amplitude N1P1 (r = -0.498; p = 0.010) of VEP. The higher follow-up IL-10 concentration was associated with MRI signs of brain necrotic damage (r = 0.533; p = 0.001) and brain hemorrhage (r = 0.396; p = 0.020). Our findings suggest that neuroinflammation plays an important role in the mechanisms of toxic brain damage in acute methyl alcohol intoxication.

Role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning.

CONTEXT: The role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning has not been studied. OBJECTIVE: We measured the concentrations of lipid peroxidation markers in acutely intoxicated patients with known serum concentrations of methanol and leukotrienes. METHODS: Blood serum samples were collected from 28 patients hospitalized with acute intoxication and from 36 survivors 2 years after discharge. In these samples, concentrations of 4-hydroxy-trans-2-hexenal (HHE), 4-hydroxynonenal (HNE), and malondialdehyde (MDA) were measured using the method of liquid chromatography-electrospray ionization-tandem mass spectrometry. RESULTS: The maximum acute serum concentrations of all three lipid oxidative damage markers were higher than the follow-up serum concentrations: HNE 71.7 ± 8.0 ng/mL versus 35.4 ± 2.3 ng/mL; p < .001; HHE 40.1 ± 6.7 ng/mL versus 17.7 ± 4.1 ng/mL; p < .001; MDA 80.0 ± 7.2 ng/mL versus 40.9 ± 1.9 ng/mL; p < .001. The survivors without methanol poisoning sequelae demonstrated higher acute serum concentrations of the markers than the patients with sequelae. A correlation between measured markers and serum leukotrienes was present: HNE correlated with LTC4 (r = 0.663), LTD4 (r = 0.608), LTE4 (r = 0.771), LTB4 (r = 0.717), HHE correlated with LTC4 (r = 0.713), LTD4 (r = 0.676), LTE4 (r = 0.819), LTB4 (r = 0.746), MDA correlated with LTC4 (r = 0.785), LTD4 (r = 0.735), LTE4 (r = 0.814), LTB4 (r = 0.674); all p < .001. Lipid peroxidation markers correlated with anion gap (r= -0.428, -0.388, -0.334; p = .026, .045, .080 for HNE, HHE, MDA, respectively). The follow-up serum concentrations of lipid oxidation markers measured in survivors with and without visual/neurological sequelae 2 years after discharge did not differ. CONCLUSION: Our results demonstrate that lipid peroxidation plays a significant role in the mechanisms of acute methanol poisoning. The acute concentrations of three measured biomarkers were elevated in comparison with the follow-up concentrations. Neuronal membrane lipid peroxidation seems to activate leukotriene-mediated inflammation as a part of the neuroprotective mechanisms. No cases of persistent elevation were registered among the survivors 2 years after discharge.