Focused X-Ray Histological Analyses to Reveal Asbestos Fibers and Bodies in Lungs and Pleura of Asbestos-Exposed Subjects

Our plain-English summary of Focused X-Ray Histological Analyses to Reveal Asbestos Fibers and Bodies in Lungs and Pleura of Asbestos-Exposed Subjects, by L. Pascolo, A. Gianoncelli, C. Rizzardi, et al (Microscopy and Microanalysis, 2016).

The study

• Authors: L. Pascolo, A. Gianoncelli, C. Rizzardi, M. de Jonge, D. Howard, D. Paterson, F. Cammisuli, M. Salomé, P. De Paoli, M. Melato, V. Canzonieri
• Journal: Microscopy and Microanalysis
• Published: 2016;22(5):1062-1071
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos bodies are the histological hallmarks of asbestos exposure. Both conventional and advanced techniques are used to evaluate abundance and composition in histological samples. We previously reported the possibility of using synchrotron X-ray fluorescence microscopy (XFM) for analyzing the chemical composition of asbestos bodies directly in lung tissue samples. Here we applied a high-performance synchrotron X-ray fluorescence (XRF) set-up that could allow new protocols for fast monitoring of the occurrence of asbestos bodies in large histological sections, improving investigation of the related chemical changes. A combination of synchrotron X-ray transmission and fluorescence microscopy techniques at different energies at three distinct synchrotrons was used to characterize asbestos in paraffinated lung tissues. The fast chemical imaging of the XFM beamline (Australian Synchrotron) demonstrates that asbestos bodies can be rapidly and efficiently identified as co-localization of high calcium and iron, the most abundant elements of these formations inside tissues (Fe up to 10% w/w; Ca up to 1%). By following iron presence, we were also able to hint at small asbestos fibers in pleural spaces. XRF at lower energy and at higher spatial resolution was afterwards performed to better define small fibers. These analyses may predispose for future protocols to be set with laboratory instruments.

In plain English

This laboratory methods study tested whether synchrotron X-ray fluorescence imaging could quickly locate asbestos bodies and fibers in paraffin-embedded lung tissue sections. The authors examined autopsy lung tissue from six people: four former naval shipyard workers from Monfalcone, Italy, who had asbestosis (one also with mesothelioma), and two people not exposed to asbestos. At three synchrotron facilities, they mapped elements including iron, calcium and zinc. Asbestos bodies appeared where high iron and high calcium overlapped. Iron was generally below 0.1% in unaffected tissue but reached up to 10% in asbestos bodies. In a control sample, dust (anthracotic) deposits had iron up to 1.3%, but calcium did not overlap with it. In the pleura of one exposed patient, iron maps pointed to small fibers 2 to 20 micrometres long. Further analysis found silicon and magnesium but not sodium, which the authors said was compatible with chrysotile. The authors concluded the approach could help estimate asbestos body burden. They added that limited access to synchrotrons makes it unsuitable for routine clinical use.

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: Laboratory methods study (technical feasibility) using synchrotron X-ray fluorescence and transmission microscopy on autopsy lung tissue sections
• Who was studied: Autopsy lung tissue from six patients. Four were asbestos-exposed men aged 74 to 83, naval shipyard workers from Monfalcone, Italy, with asbestosis; one of them (A4) also had mesothelioma. They came from the St. Polo Hospital of Monfalcone and had been analyzed in an earlier study. Two were asbestos-unexposed patients from the archive of the Centro di Riferimento Oncologico (CRO), Aviano, Italy.
• Exposure: Occupational asbestos exposure as naval shipyard workers. No fiber type is stated for the exposure. Previously reported asbestos body counts were 1,209,375 bodies/g of tissue (A1), 25,600 (A2), 2,700 (A3) and 557,685 (A4).
• Main results:
  • In lung tissue from a patient with asbestosis, an area of about 2 by 1.3 mm was scanned in about 2 hours and revealed several tens of asbestos bodies. The bodies were identified where high calcium and high iron occurred together.
  • In the asbestos-exposed tissue, iron was generally below 0.1% in unaffected tissue, reached up to 10% in asbestos bodies, and was close to 1% in many zones, particularly in areas next to asbestos.
  • Calcium in asbestos bodies reached concentrations ten times higher than in the surrounding fibrotic tissue.
  • Calcium in the asbestosis tissue region appeared generally higher than in nonpathological tissue or control samples.
  • In a control (unexposed) sample, iron reached up to 0.3% in vessels and was below 0.05% in the rest of the tissue.
  • In the control sample, an anthracotic dust area had iron up to 1.3%, but calcium did not co-localize with iron in the dust. This was the basis the authors gave for telling asbestos bodies apart from other dust.
  • In the pleural space of an exposed patient, higher-resolution iron mapping identified fibers ranging from 2 to 20 micrometres in length.
  • Low-energy analysis suggested a pleural fiber diameter of 400 nm or less. Most fiber-shaped structures revealed by iron also contained silicon and magnesium and lacked sodium, which the authors said suggested a composition compatible with chrysotile asbestos.
• The authors' conclusion: The authors concluded that synchrotron methods are valuable tools for detecting and characterizing asbestos fibers and bodies in tissue. They believed that fluorescence analysis detecting calcium and iron promises great efficiency in evaluating asbestos body burden, competing with current techniques such as light microscopy. They suggested the method could in future be transferred to laboratory instruments.
• Limitations the authors state:
  • Access to synchrotron facilities is limited, so the authors stated the approach cannot be a convenient protocol for routine clinical investigations.
  • The fast screening can only suggest possible fibers in the pleura; final confirmation requires higher-resolution and low-energy fluorescence analysis.
  • Depending on dose, X-ray exposure, especially to soft X-rays, may affect the biochemical response of the tissue, though the authors did not expect changes in elemental distribution.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleura, Asbestos Bodies, Asbestos Exposure.

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