N-acetylcysteine prevents cytotoxic effects induced by man-made mineral fibers in a human bronchial epithelial cell line

Toxicological evaluation of polycrystalline wools in human lung cells

Aim: Polycrystalline wools (PCW) are included with Refractory ceramic fibers (RCF) in the alumino-silicates family of High Temperature Insulation Wools (HTIW). IARC includes PCW in the ceramic fibers group and considers them as possible human carcinogens (GROUP 2B). Since PCW toxicity is not yet clear, our aim was to evaluate their toxic and inflammatory effects and to compare them with the known RCF effects.Method: We exposed human bronchial (BEAS-2B) and alveolar (A549) cells to 2-100 µg/mL (2.4 × 10³-1.2 × 10⁵ fibers/mL; 2.51 × 10³-1.26 × 10⁵ fibers/cm² of PCW and 7.4 × 10³-3.7 × 10⁵ fibers/mL; 7.75 × 10³-3.87 × 10⁵ fibers/cm² of RCF) of the tested fibers to evaluate potential viability reduction, apoptosis, membrane damage, direct/oxidative DNA-damage, cytokine release.Results: In A549, PCW did not induce cytotoxicity and apoptosis but they induced significant dose-dependent DNA-damage, although lower than RCF; only RCF induced oxidative effects. PCW also induced an increase in IL-6 release at 100 µg/mL (1.2 × 10⁵ fibers/mL; 1.26 × 10⁵ fibers/cm²). In BEAS-2B, PCW did not induce cell-viability reduction RCF induced a dose-dependent cell-viability decrease. Both fibers show a dose-dependent increase of apoptosis. In BEAS-2B, PCW also induced dose-dependent DNA-damage, although lower than RCF, and slight oxidative effects similar to RCF. PCW also induced an increase of IL-6 release; RCF induced a decrease of IL-8. Summarizing, PCW induce direct-oxidative DNA-damage although to a lower extent than RCF observed by both mass-based and fiber number-based analysis.Conclusion: For the first time, the study shows the potential toxicity of PCW, usually considered safe, and suggests to perform further in vitro studies, also on other cell types, to confirm these findings.

Modulation of cigarette smoke extract-induced human bronchial epithelial damage by eucalyptol and curcumin

Smoking is one of the most important leading death cause worldwide. From a toxicological perspective, cigarette smoke serves hazards especially for the human being exposed to passive smoke. Over the last decades, the effects of natural compounds on smoking-mediated respiratory diseases such as COPD, asthma, and lung cancer have been under investigation, as well as the mechanistic aspects of disease progression. In the present study, the protective mechanism of eucalyptol (EUC), curcumin (CUR), and their combination on BEAS-2B cells were investigated in vitro to understand their impact on cell death, oxidative cell injury, and inflammatory response induced by 3R4F reference cigarette extract (CSE). According to the present findings, EUC, CUR, and their combination improved cell viability, attenuated CSE-induced apoptosis, and LC3B expression. Further, CSE-induced oxidative damage and inflammatory response in human bronchial epithelial cells were remarkably reduced by the combination treatment through modification of enzymatic antioxidant activity, GSH, MDA, and intracellular ROS levels as well as nitrite and IL-6 levels. In addition, nuclear translocation of Nrf2, a regulatory protein involved in the indirect antioxidant response, was remarkably up-regulated with the combination pre-treatment. In conclusion, EUC and CUR in combination might be a potential therapeutic against smoking-induced lung diseases through antioxidant and inflammatory pathways and results represent valuable background for future in vivo pulmonary toxicity studies.

Role of PARP1 on DNA damage induced by mineral silicate chrysotile in bronchial epithelial and pleural mesothelial cells

To investigate whether poly (ADP ribose) polymerase-1 (PARP1) is involved in chrysotile-induced DNA damage in pleural mesothelial cells (MeT-5A) and bronchial epithelial cells (BEAS-2B), two PARP1-deficient cell lines were established. Efficiencies of RNA interference on PARP1 were detected by western blot and qPCR. Here, normal cells and PARP1-deficient cells were exposed to chrysotile, and DNA damage and DNA repair were detected by alkaline comet assay. All cells were treated with chrysotile at the indicated concentrations (5, 10, 20, and 40 μg/cm²) for 24 h and then the DNA repair capacity was observed for 12 and 24 h, respectively. The results showed that chrysotile caused DNA damage at an obvious dose-dependent manner in MeT-5A and BEAS-2B cells. In addition, MeT-5A cells had more persistent DNA damage than BEAS-2B. Compared to normal cells, the PARP1-deficient cells were more sensitive to DNA damage caused by chrysotile. In DNA repair experiments, all cell lines recovered from the damage over time. The results of relative repair percentage (RRP) of MeT-5A and BEAS-2B were higher than those of MeT-5A shPARP1 and BEAS-2B shPARP1 cells at all experimental concentrations (except 5 μg/cm²) at 12-h repair. However, RRP of BEAS-2B and BEAS-2B shPARP1 tended to be closer, and RRP of MeT-5A shPARP1 was still lower than that of MeT-5A at 24-h repair. All results suggest that PARP1 plays an important role in early repair of DNA damage in BEAS-2B and MeT-5A cells exposed to chrysotile.

Sub-ohm vaping increases the levels of carbonyls, is cytotoxic, and alters gene expression in human bronchial epithelial cells exposed at the air-liquid interface

Background

Exposure to electronic-cigarette (e-cig) aerosols induces potentially fatal e-cig or vaping-associated lung injury (EVALI). The cellular and molecular mechanisms underlying these effects, however, are unknown. We used an air–liquid interface (ALI) in vitro model to determine the influence of two design characteristics of third-generation tank-style e-cig devices—resistance and voltage—on (1) e-cig aerosol composition and (2) cellular toxicity.

Methods

Human bronchial epithelial cells (H292) were exposed to either butter-flavored or cinnamon-flavored e-cig aerosols at the ALI in a Vitrocell exposure system connected to a third-generation e-cig device. Exposures were conducted following a standard vaping topography profile for 2 h per day, for 1 or 3 consecutive days. 24 h after ALI exposures cellular and molecular outcomes were assessed.

Results

We found that butter-flavored e-cig aerosol produced under ‘sub-ohm’ conditions (< 0.5 Ω) contains high levels of carbonyls (7–15 μg/puff), including formaldehyde, acetaldehyde and acrolein. E-cig aerosol produced under regular vaping conditions (resistance > 1 Ω and voltage > 4.5 V), contains lower carbonyl levels (< 2 μg/puff). We also found that the levels of carbonyls produced in the cinnamon-flavored e-cig aerosols were much lower than that of the butter-flavored aerosols. H292 cells exposed to butter-flavored or cinnamon-flavored e-cig aerosol at the ALI under ‘sub-ohm’ conditions for 1 or 3 days displayed significant cytotoxicity, decreased tight junction integrity, increased reactive oxygen species production, and dysregulated gene expression related to biotransformation, inflammation and oxidative stress (OS). Additionally, the cinnamon-flavored e-cig aerosol induced pro-oxidant effects as evidenced by increases in 8-hydroxy-2-deoxyguanosine protein levels. Moreover, we confirmed the involvement of OS as a toxicity process for cinnamon-flavored e-cig aerosol by pre-treating the cells with N-acetyl cysteine (NAC), an antioxidant that prevented the cells from the OS-mediated damage induced by the e-cig aerosol.

Conclusion

The production of high levels of carbonyls may be flavor specific. Overall, inhaling e-cig aerosols produced under ‘sub-ohm’ conditions is detrimental to lung epithelial cells, potentially via mechanisms associated with OS. This information could help policymakers take the necessary steps to prevent the manufacturing of sub-ohm atomizers for e-cig devices.

Sub-ohm vaping increases the levels of carbonyls, is cytotoxic, and alters gene expression in human bronchial epithelial cells exposed at the air-liquid interface

BACKGROUND

Exposure to electronic-cigarette (e-cig) aerosols induces potentially fatal e-cig or vaping-associated lung injury (EVALI). The cellular and molecular mechanisms underlying these effects, however, are unknown. We used an air-liquid interface (ALI) in vitro model to determine the influence of two design characteristics of third-generation tank-style e-cig devices-resistance and voltage-on (1) e-cig aerosol composition and (2) cellular toxicity.

METHODS

Human bronchial epithelial cells (H292) were exposed to either butter-flavored or cinnamon-flavored e-cig aerosols at the ALI in a Vitrocell exposure system connected to a third-generation e-cig device. Exposures were conducted following a standard vaping topography profile for 2 h per day, for 1 or 3 consecutive days. 24 h after ALI exposures cellular and molecular outcomes were assessed.

RESULTS

We found that butter-flavored e-cig aerosol produced under 'sub-ohm' conditions (< 0.5 Ω) contains high levels of carbonyls (7-15 μg/puff), including formaldehyde, acetaldehyde and acrolein. E-cig aerosol produced under regular vaping conditions (resistance > 1 Ω and voltage > 4.5 V), contains lower carbonyl levels (< 2 μg/puff). We also found that the levels of carbonyls produced in the cinnamon-flavored e-cig aerosols were much lower than that of the butter-flavored aerosols. H292 cells exposed to butter-flavored or cinnamon-flavored e-cig aerosol at the ALI under 'sub-ohm' conditions for 1 or 3 days displayed significant cytotoxicity, decreased tight junction integrity, increased reactive oxygen species production, and dysregulated gene expression related to biotransformation, inflammation and oxidative stress (OS). Additionally, the cinnamon-flavored e-cig aerosol induced pro-oxidant effects as evidenced by increases in 8-hydroxy-2-deoxyguanosine protein levels. Moreover, we confirmed the involvement of OS as a toxicity process for cinnamon-flavored e-cig aerosol by pre-treating the cells with N-acetyl cysteine (NAC), an antioxidant that prevented the cells from the OS-mediated damage induced by the e-cig aerosol.

CONCLUSION

The production of high levels of carbonyls may be flavor specific. Overall, inhaling e-cig aerosols produced under 'sub-ohm' conditions is detrimental to lung epithelial cells, potentially via mechanisms associated with OS. This information could help policymakers take the necessary steps to prevent the manufacturing of sub-ohm atomizers for e-cig devices.

Therapeutic effect of N- acetyl cysteine as an antioxidant on rainbow trout's brain in cypermethrin toxicity

The aim of this study was to investigate the therapeutic effect of N-acetylcystein (NAC) against oxidative stress induced by Cypermethrin pesticide in rainbow trout (Oncorhynchus mykiss). The experiment was designed as 5 groups (A, B, C, D, and E). Group A was organized as control group and had no treatment. The other groups were treated with Cypermethrin for 14 days. At the end of this period, Groups B (1.0 mM NAC) and D (0.5 mM NAC) was performed with NAC for 96 h. Group C was not administered NAC, the recovery process was evaluated with this group. Group E was exposed to cypermethrin during 14 days and sampled. Acetylcholinesterase (AChE), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO) activities, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), caspase-3 levels, and trace elements contents analyses were performed in all fish brains. According to the results, MDA, MPO, 8-OHdG and caspase-3 levels were significantly decreased compared to the other groups (pesticide and recovery) (p < 0.05), AChE, SOD, CAT, GPx, PON, and AR activities increased (p < 0.05). In brain tissue, no statistically significant difference was observed in trace element analysis of all application groups. According to the obtained data, the positive effect of N-acetylcysteine on protein synthesis, detoxification, and diverse metabolic functions against cypermethrin toxicity has been more effective in 1.0 mM NAC. NAC has important therapeutic effect on pesticide-induced neurotoxicity for fish in terms of all data. It was concluded that NAC has an antioxidant effect against pesticide-induced oxidative stress and the selected biochemical markers are useful for such studies.