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Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

ABSTRACT: BACKGROUND:Little is known about the mechanism underlying the genotoxicity observed in the liver following pulmonary exposure to carbon black (CB) nanoparticles (NPs). The genotoxicity could be caused by the presence of translocated particles or by circulating inflammatory mediators released during pulmonary inflammation and acute-phase response. To address this, we evaluated induction of pulmonary inflammation, pulmonary and hepatic acute-phase response and genotoxicity following exposure to titanium dioxide (TiO2), cerium oxide (CeO2) or CB NPs. Female C57BL/6 mice were exposed by intratracheal instillation, intravenous injection or oral gavage to a single dose of 162 ?g NPs/mouse and terminated 1, 28 or 180 days post-exposure alongside vehicle control. RESULTS:Liver DNA damage assessed by the Comet Assay was observed after intravenous injection and intratracheal instillation of CB NPs but not after exposure to TiO2 or CeO2. Intratracheal exposure to NPs resulted in pulmonary inflammation in terms of increased neutrophils influx for all NPs 1 and 28 days post-exposure. Persistent pulmonary acute phase response was detected for all NPs at all three time points while only a transient induction of hepatic acute phase response was observed. All 3 materials were detected in the liver by enhanced darkfield microscopy up to 180 days post-exposure. In contrast to TiO2 and CeO2 NPs, CB NPs generated ROS in an acellular assay. CONCLUSIONS:Our results suggest that the observed hepatic DNA damage following intravenous and intratracheal dosing with CB NPs was caused by the presence of translocated, ROS-generating, particles detected in the liver rather than by the secondary effects of pulmonary inflammation or hepatic acute phase response.

SUBMITTER: Modrzynska J

PROVIDER: S-EPMC5753473 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

Modrzynska Justyna J Berthing Trine T Ravn-Haren Gitte G Jacobsen Nicklas Raun NR Weydahl Ingrid Konow IK Loeschner Katrin K Mortensen Alicja A Saber Anne Thoustrup AT Vogel Ulla U

Particle and fibre toxicology 20180103 1

<h4>Background</h4>Little is known about the mechanism underlying the genotoxicity observed in the liver following pulmonary exposure to carbon black (CB) nanoparticles (NPs). The genotoxicity could be caused by the presence of translocated particles or by circulating inflammatory mediators released during pulmonary inflammation and acute-phase response. To address this, we evaluated induction of pulmonary inflammation, pulmonary and hepatic acute-phase response and genotoxicity following exposu ...[more]

PMID: 29298701

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Project description:Environmental stimulation during brain development is an important risk factor for the development of neurodegenerative disease. Clinical evidence indicates that prenatal exposure to particulate air pollutants leads to diffuse damage to the neurovascular unit in the developing brain and accelerates neurodegeneration. Maternal exposure to carbon black nanoparticles (CB-NPs), used as a model for particulate air pollution, induces long-lasting diffuse perivascular abnormalities. We aimed to comprehensively characterize the perivascular abnormalities related to maternal NPs exposure using Fourier transform infrared microspectroscopy (in situ FT-IR) and classical staining analysis. Pregnant ICR mice were intranasally treated with a CB-NPs suspension (95 ?g/kg at a time) on gestational days 5 and 9. Brains were collected 6 weeks after birth and sliced to prepare 10-?m-thick serial sections. Reflective spectra of in situ FT-IR were acquired using lattice measurements (x-axis: 7, y-axis: 7, 30-?m apertures) around a centered blood vessel. We also performed mapping analysis of protein secondary structures. Serial sections were stained with using periodic acid-Schiff or immunofluorescence to examine the phenotypes of the perivascular areas. Peaks of amide I bands in spectra from perivascular areas were shifted by maternal NPs exposure. However, there were two types of peak-shift in one mouse in the exposure group. Some vessels had a large peak-shift and others had a small peak-shift. In situ FT-IR combined with traditional staining revealed that the large peak-shift was induced around blood vessel adjacent to astrocytes with glial fibrillary acidic protein and aquaporin-4 over-expression and perivascular macrophages (PVMs) with enlarged lysosome granules. Furthermore, protein secondary structural analysis indicated that maternal NPs exposure led to increases in ?-sheet content and decreases in ?-helix content in areas that are mostly close to the centered blood vessel displaying histopathological changes. These results suggest that ?-sheet-rich waste proteins, which are denatured by maternal NPs exposure, likely accumulate in the perivascular space as they are processed by the clearance systems in the brain. This may in turn lead the denaturation of PVMs and astrocyte activation. The risk of neurodegeneration may be enhanced by exposure to particulate air pollutants during brain development following the perivascular accumulation of ?-sheet-rich waste proteins.

Project description:Carbon black nanoparticles (CBNP) are the most widely produced nanomaterial and are thus a concern for occupational exposures. CBNPs are known to cause inflammation upon inhalation; however, detailed time course data to evaluate the changing nature of inflammatory responses have not been evaluated. In this study, we investigate the short- and longer-term effects of CBNP following a single intratracheal exposure. Female C57BL/6BomTac mice were exposed to CBNPs (printex 90) via a single intratracheal instillation of 162 µg/mouse alongside vehicle controls. Mice were examined 3 hours (hrs), and 1, 2, 3, 4, 5, 14, and 42 days (d) post-exposure. Global gene expression was assessed using DNA microarrays in parallel with analysis of pulmonary inflammation assessed as bronchoalveolar lavage (BAL) cell counts and DNA strand breaks assessed by the comet assay. Pulmonary inflammation in terms of increased neutrophil influx was obverved at all time points. Increased levels of DNA strand breaks were observed in BAL cells 3 hrs post exposure and in lung tissue 2-5 d post exposure. Approximately 2600 significant differentially expressed genes (±1.5 fold; p ≤0.05) across all of the time-points in the lungs of exposed mice were identified upon comparison to time-matched controls. Transcriptional alterations were enriched for genes involved in common respiratory infectious diseases. The perturbed biological processes and pathways were primarily related to immune-inflammatory responses and acute phase responses, consistent with the BAL inflammatory profiles. Gene and pathway analysis revealed a biphasic inflammatory response, with changes occurring as early as 3 hrs post-exposure and declining to base-levels by 3 d post-exposure, but with inflammatory pathways increasing in response again at 14 d and persisting to 42 d post-exposure. Other perturbed pathways included DNA repair and apoptosis, cell cycle regulation, and muscle contraction. Single CBNP exposure induced a biphasic inflammatory response that lasted until 42 d post-exposure. Such persistent inflammatory response raises concerns over the chronic effects of CBNP exposure since the administered dose corresponds to pulmonary deposition in mice during nine 8-hour working days at the current occupational exposure limit for carbon black.

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Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

Publications

Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

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