Comparative proteomics and pulmonary toxicity of instilled single-walled carbon nanotubes, crocidolite asbestos, and ultrafine carbon black in mice

Our plain-English summary of Comparative proteomics and pulmonary toxicity of instilled single-walled carbon nanotubes, crocidolite asbestos, and ultrafine carbon black in mice, by J.G. Teeguarden, B.J. Webb-Robertson, K.M. Waters, et al (Toxicological Sciences, 2011).

The study

• Authors: J.G. Teeguarden, B.J. Webb-Robertson, K.M. Waters, A.R. Murray, E.R. Kisin, S.M. Varnum, J.M. Jacobs, J.G. Pounds, R.C. Zanger, A.A. Shvedova
• Journal: Toxicological Sciences
• Published: 2011;120(1):123-35
• Cited by: 68 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Reflecting their exceptional potential to advance a range of biomedical, aeronautic, and other industrial products, carbon nanotube (CNT) production and the potential for human exposure to aerosolized CNTs are increasing. CNTs have toxicologically significant structural and chemical similarities to asbestos (AB) and have repeatedly been shown to cause pulmonary inflammation, granuloma formation, and fibrosis after inhalation/instillation/aspiration exposure in rodents, a pattern of effects similar to those observed following exposure to AB. To determine the degree to which responses to single-walled CNTs (SWCNT) and AB are similar or different, the pulmonary response of C57BL/6 mice to repeated exposures to SWCNTs, crocidolite AB, and ultrafine carbon black (UFCB) were compared using high-throughput global high performance liquid chromatography fourier transform ion cyclotron resonance mass spectrometry (HPLC-FTICR-MS) proteomics, histopathology, and bronchoalveolar lavage cytokine analyses. Mice were exposed to material suspensions (40 micrograms per mouse) twice a week for 3 weeks by pharyngeal aspiration. Histologically, the incidence and severity of inflammatory and fibrotic responses were greatest in mice treated with SWCNTs. SWCNT treatment affected the greatest changes in abundance of identified lung tissue proteins. The trend in number of proteins affected (SWCNT [376] > AB [231] > UFCB [184]) followed the potency of these materials in three biochemical assays of inflammation (cytokines). SWCNT treatment uniquely affected the abundance of 109 proteins, but these proteins largely represent cellular processes affected by AB treatment as well, further evidence of broad similarity in the tissue-level response to AB and SWCNTs. Two high-sensitivity markers of inflammation, one (S100a9) observed in humans exposed to AB, were found and may be promising biomarkers of human response to SWCNT exposure.

In plain English

This was an animal experiment comparing lung responses in C57BL/6 mice given repeated pharyngeal aspiration of single-walled carbon nanotubes (SWCNT), crocidolite asbestos (AB) or ultrafine carbon black (UFCB), each at 40 micrograms per mouse twice weekly for 3 weeks (total 240 micrograms), while control mice received 50 microlitres of PBS vehicle; animals were killed 24 h after the last dose. Endpoints were lung histopathology, bronchoalveolar lavage cell counts and cytokines, lung collagen, and global HPLC-FTICR-MS proteomics. Moderate multifocal pyogranulomatous inflammation was present in all SWCNT lungs (7/7); AB-exposed lungs had mild to moderate inflammation with multinucleated giant cells but no classic granulomas; UFCB lungs showed mainly histiocytosis. Collagen was greatest after SWCNT, with smaller but statistically significant rises for AB and UFCB versus control. Three cytokines (TARC, IL-12, MDC) followed the order SWCNT greater than AB greater than UFCB. Proteins changed in abundance: SWCNT 376, AB 231, UFCB 184; 96% of AB-affected proteins were also affected by SWCNT. The authors concluded responses to SWCNT and crocidolite asbestos were broadly similar, but generally greater on a mass-dose basis for SWCNT.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Controlled animal (mouse) toxicology experiment with repeated pharyngeal aspiration exposure, combining histopathology, bronchoalveolar lavage cytokine/cell analysis and global proteomics
• Who was studied: Adult female C57BL/6 mice, 8-10 weeks old, housed at NIOSH facilities; each treatment group had six mice for lavage, six for histopathology and six for proteomics (26 samples analysed by proteomics); lavage and collagen figures state n = 12 mice per group
• Exposure: Purified SWCNT (99.7% elemental carbon, 0.23% Fe; diameter 0.4-1.2 nm; surface area 1040 m2/g), UICC crocidolite asbestos (18% Fe; mean diameter 210 nm; surface area 8.3 m2/g; length 0.8-12 micrometres) or ultrafine carbon black (mean diameter 14.3 nm; surface area 253.9 m2/g), 40 micrograms per mouse in 50 microlitres PBS by pharyngeal aspiration, six doses over 3 weeks (total 240 micrograms); control mice received 50 microlitres of PBS vehicle
• Main results:
  • All SWCNT-exposed mice had moderate multifocal inflammation with granuloma and pyogranuloma formation; in AB-exposed mice multinucleated giant cells were common but classic granulomas were not seen
  • In lavage fluid, SWCNT produced a significantly greater inflammatory cell response (PMNs and total cells) than crocidolite AB or UFCB
  • Crocidolite AB raised total cells and PMNs in lavage fluid but not alveolar macrophages, whereas UFCB raised all three
  • Lung collagen was highest in SWCNT-treated mice; AB and UFCB also raised collagen significantly above control but less than SWCNT
  • Three lavage cytokines followed the order SWCNT greater than AB greater than UFCB; MMP-2 and MIP-1 gamma rose with SWCNT and AB but did not differ significantly between those two
  • Number of lung tissue proteins significantly changed by treatment: 376 for SWCNT, 231 for crocidolite AB, 184 for UFCB (from 398 proteins differing from control)
  • Overlap between treatments: nearly all AB-affected proteins were also affected by SWCNT
  • Proteins affected by only one material: 109 for SWCNT, six for AB, 12 for UFCB; of 22 GO processes represented by the 109 SWCNT-only proteins, only six were unique to SWCNT
  • Partial least squares discriminant analysis separated the four treatment groups, classifying 24 of 26 samples correctly using the first three latent variables
  • S100a9 abundance followed the inflammation pattern SWCNT greater than AB greater than UFCB; the authors state this is the first report of S100a9 being affected by asbestos in a rodent lung model
• The authors' conclusion: The authors concluded that lung tissue and lung infiltrate responses to SWCNT and crocidolite asbestos were broadly similar, with the response generally greater on a mass-dose basis for SWCNT than for AB or UFCB
• Limitations the authors state:
  • The authors state that this single-dose, single-time-point design cannot distinguish whether differences between materials reflect potency, timing of response, or dose
  • The authors note the surface area doses of SWCNT and UFCB were 125 and 30 times higher than that of asbestos, so comparisons of potency depend on the dose metric used
  • The authors state the findings may not apply to other SWCNT batches and types
  • The authors note that doses could not be adjusted so that lung regional deposition matched that after inhalation, because of insufficient deposition information
  • The authors state there is no accepted basis for comparing doses of fibres with doses of non-fibre particles

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Crocidolite, Inflammation, Granuloma, Fibrosis, Histopathology, Bronchoalveolar Lavage (BAL), Cytokine, Biomarker.

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• Fibrous nanocellulose, crystalline nanocellulose, carbon nanotubes, and crocidolite asbestos elicit disparate immune responses upon pharyngeal aspiration in mice — E.J. Park, T.O. Khaliullin, et al. (2018)
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