Synchrotron soft X-ray imaging and fluorescence microscopy reveal novel features of asbestos body morphology and composition in human lung tissues

Our plain-English summary of Synchrotron soft X-ray imaging and fluorescence microscopy reveal novel features of asbestos body morphology and composition in human lung tissues, by L. Pascolo, A. Gianoncelli, B. Kaulich, et al (Particle and Fibre Toxicology, 2011).

The study

• Authors: L. Pascolo, A. Gianoncelli, B. Kaulich, C. Rizzardi, M. Schneider, C. Bottin, M. Polentarutti, M. Kiskinova, A. Longoni, M. Melato
• Journal: Particle and Fibre Toxicology
• Published: 2011;8(1):7
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Occupational or environmental exposure to asbestos fibres is associated with pleural and parenchymal lung diseases. A histopathologic hallmark of exposure to asbestos is the presence in lung parenchyma of the so-called asbestos bodies. They are the final product of biomineralization processes resulting in deposition of endogenous iron and organic matter (mainly proteins) around the inhaled asbestos fibres. For shedding light on the formation mechanisms of asbestos bodies it is of fundamental importance to characterize at the same length scales not only their structural morphology and chemical composition but also to correlate them to the possible alterations in the local composition of the surrounding tissues. Here we report the first correlative morphological and chemical characterization of untreated paraffinated histological lung tissue samples with asbestos bodies by means of soft X-ray imaging and X-Ray Fluorescence (XRF) microscopy, which reveals new features in the elemental lateral distribution.

Results: The X-ray absorption and phase contrast images and the simultaneously monitored XRF maps of tissue samples have revealed the location, distribution and elemental composition of asbestos bodies and associated nanometric structures. The observed specific morphology and differences in the local Si, Fe, O and Mg content provide distinct fingerprints characteristic for the core asbestos fibre and the ferruginous body. The highest Si content is found in the asbestos fibre, while the shell and ferruginous bodies are characterized by strongly increased content of Mg, Fe and O compared to the adjacent tissue. The XRF and SEM-EDX analyses of the extracted asbestos bodies confirmed an enhanced Mg deposition in the organic asbestos coating.

Conclusions: The present report demonstrates the potential of the advanced synchrotron-based X-ray imaging and microspectroscopy techniques for studying the response of the lung tissue to the presence of asbestos fibres. The new results obtained by simultaneous structural and chemical analysis of tissue specimen have provided clear evidence that Mg, in addition to Fe, is also involved in the formation mechanisms of asbestos bodies. This is the first important step to further thorough investigations that will shed light on the physiopathological role of Mg in tissue response to the asbestos toxicity.

In plain English

This laboratory study used synchrotron soft X-ray microscopy and X-ray fluorescence mapping to examine the structure and chemical makeup of asbestos bodies. Asbestos bodies are asbestos fibres that the lung has coated with iron-rich and protein material. The samples were post-mortem lung tissue from two patients in the pathology files of St. Polo Hospital, Monfalcone, Italy. Both had a similar history of asbestos exposure and pulmonary asbestosis, and one also had pleural mesothelioma. Asbestos bodies extracted from tissue were also examined by electron microscopy. The fibre cores appeared to be amosite, and some contained crocidolite. Silicon was concentrated in the fibre core. Iron was much higher in the coating, especially at the ends of the bodies. Magnesium was found in the coating, and also on its own in lung tissue near the bodies. The authors reported similar results in samples from two other patients but did not show the data. They also did not measure element amounts when comparing bodies in tissue with extracted bodies. The authors concluded that magnesium, like iron, takes part in building the coating, and that this needs further study.

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 microscopy study of post-mortem human lung tissue. It combined synchrotron soft X-ray imaging and X-ray fluorescence (XRF) mapping with electron microscopy and elemental analysis (SEM-EDX) of extracted asbestos bodies.
• Who was studied: Post-mortem lung tissue from two patients selected from the pathology files of St. Polo Hospital, Monfalcone, Italy, who had a similar history of asbestos exposure. Both had pulmonary asbestosis and one also had pleural mesothelioma. Tissue samples from two further patients were mentioned, but their data were not shown.
• Exposure: Asbestos, with no details given of jobs or doses. The elemental makeup of an uncoated fibre core suggested amosite.
• Main results:
  • Asbestos body counts in the two patients' lung tissues are printed as ranging from 50 × 103 to 500 × 103 bodies per gram of dry tissue (the exponents appear to have been lost in the text).
  • Some fibre cores of the extracted asbestos bodies also showed crocidolite.
  • In an extracted asbestos body, iron content was much higher in the coating than in the uncoated fibre.
  • In the same extracted body, comparable amounts of magnesium were found in the fibre and in the coating.
  • In lung tissue, silicon (marking the fibre) was almost absent at the two ends of an asbestos body, where iron content was very high.
  • In lung tissue, magnesium also appeared accumulated on its own in areas near asbestos and other ferruginous bodies.
  • Iron did not appear in these magnesium-rich tissue areas next to the body.
  • Magnesium, iron and oxygen were found in the same places, which the authors read as magnesium and iron being present as oxygen-containing compounds.
  • The authors stated that similar results came from tissue samples of two other patients, but did not show these data.
• The authors' conclusion: The authors concluded that magnesium should be considered an active participant in building the coating that isolates asbestos fibres from surrounding tissue, rather than a constituent of the fibres themselves.
• Limitations the authors state:
  • The extracted asbestos bodies were isolated from tissue by chemical procedures that might have altered their composition.
  • The electron microscopy (EDX) peak intensities could only be compared relative to each other.
  • No quantitative analyses were performed when the authors compared how abundant the elements were in asbestos bodies in tissue sections versus extracted bodies.
  • The study could not explain the mechanisms behind magnesium accumulation.
  • The authors called for more analyses using samples from patients with different exposure histories.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Body Formation, Environmental Exposure, Parenchyma, Asbestos Bodies, Deposition, Ferruginous body, Ferruginous Bodies.

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