In-air micro-particle induced X-ray emission analysis of asbestos and metals in lung tissue

Our plain-English summary of In-air micro-particle induced X-ray emission analysis of asbestos and metals in lung tissue, by Y. Shimizu, K. Dobashi, T. Kusakbe, et al (International Journal of Immunopathology and Pharmacology, 2008).

The study

• Authors: Y. Shimizu, K. Dobashi, T. Kusakbe, T. Nagamine, M. Oikawa, T. Satoh, J. Haga, Y. Ishii, T. Ohkubo, T. Kamiya, K. Arakawa, T. Sano, S. Tanaka, K. Shimizu, S. Matsuzaki, M. Utsugi, M. Mori
• Journal: International Journal of Immunopathology and Pharmacology
• Published: 2008;21(3):567-76
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Inhalation of asbestos increases the risk of lung cancer and pulmonary fibrosis. It is difficult to directly assess the distribution and content of inhaled particles in lung tissue sections. The purpose of this study is to employ an in-air micro particle induced X-ray emission (in-air micro-PIXE) system for assessment of the spatial distribution and content of asbestos and other metals in lung tissue. A proton ion-microbeam from this system was applied to irradiate lung tissue of patients with or without asbestosis, tumor tissue from both groups, and asbestos fibers (in vitro). The content of each element composing asbestos and those of other metals were calculated and their distribution was assessed from the characteristic X-ray pattern for each element obtained after irradiation. This in-air micro-PIXE system could identify the location of asbestos bodies composed of Si, Mg, and Fe in lung tissue sections. Macrophage and lymphocytes accumulated in that area. This new system also revealed deposits of titanium, nickel, and cobalt in the lung tissues, in addition to asbestos bodies. The Si and Fe content were higher in lungs with asbestosis than in lungs without asbestosis or in tumor tissue. Analysis of asbestos fibers composed of chrysotile, crocidolite, and amosite showed that the ratios of Si, Fe, and Mg corresponded with those for the chemical structures. In-air micro-PIXE analysis is useful for assessing the distribution and quantities of asbestos bodies and also other metals in lung tissue comparing to immune-related cell localizations, and is also useful for analysis of standard asbestos fibers.

In plain English

This Japanese methods study tested whether in-air micro-PIXE, which reads X-rays given off when a proton beam strikes tissue, could map asbestos and other metals in lung tissue. The authors examined surgically removed lung and tumor tissue from four men with lung adenocarcinoma. Two had asbestosis: a plumber and a builder with 15 and 30 years of asbestos exposure. The other two, desk workers, had no history of asbestos exposure. They also analysed standard chrysotile, crocidolite and amosite fibers. Silicon was significantly higher in asbestosis lungs than control lungs. In small areas of asbestosis lung, silicon, iron and magnesium lay together, with macrophages and lymphocytes gathered there. One asbestosis patient had extremely high titanium, nickel and cobalt, not overlapping with silicon. In standard fibers, the iron-to-silicon ratio was significantly higher in crocidolite and amosite than in chrysotile, and the magnesium-to-silicon ratio was significantly higher in chrysotile than in crocidolite or amosite. The authors concluded the method can show where asbestos bodies and other metals lie in lung tissue. They named the small patient number as the main limitation.

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 testing a technique (in-air micro-PIXE) on lung tissue from four patients, plus in vitro analysis of standard asbestos fibers
• Who was studied: Four men who had surgery for lung adenocarcinoma (none had mesothelioma), studied at Gunma University, Japan. Two had asbestosis (aged 68±2.8 years). Two were control patients with no history of asbestos exposure (aged 71±2.8 years). Both non-tumor lung tissue and tumor tissue from each patient were analysed.
• Exposure: The asbestosis patients had occupational asbestos exposure: a plumber with 15 years and a builder with 30 years, per Table I (the OCR prints '15' as 'IS'). Both were smokers. The control patients were desk workers whom the authors describe as not exposed to asbestos and as having no history of exposure. One control was a former smoker and one had never smoked. The fiber type in the patients' lungs was not determined. Standard chrysotile, crocidolite and amosite fibers were analysed separately in vitro.
• Main results:
  • In large-area analysis, silicon (Si) content was significantly higher in asbestos lung than in control lung.
  • In large-area analysis, Si was also higher in tumors from asbestos lungs than in tumors from control lungs.
  • In large-area analysis, iron (Fe) and cobalt (Co) did not differ statistically between the four tissue types.
  • In large-area analysis, titanium (Ti) was higher in asbestos lung than in control lung. Magnesium (Mg), nickel (Ni) and aluminum (Al) did not differ between asbestosis and control tissues.
  • In small-area analysis of asbestosis lung, Si, Fe and Mg were co-localized, and macrophages and lymphocytes accumulated in these areas.
  • In small-area analysis, measured relative to sulphur, Fe, Ni, Al and Co were significantly higher in asbestos lungs than in control lungs, tumors from control lungs, and tumors from asbestos lungs.
  • Measured relative to Si, Fe, Ti, Ni and Co were significantly higher in asbestos lungs than in control lungs or tumors. Mg tended to be higher in asbestos lungs than in control lungs, but the difference was not statistically significant.
  • The metal findings came mainly from one patient. Asbestosis patient 2 had extremely high Ti, Ni and Co, which did not overlap with Si. Asbestosis patient 1 had levels the same as the background levels in control patients.
  • Lung tumors had lower metal content than non-tumor tissue from both asbestosis and control patients.
  • In the in vitro analysis of standard fibers (n=4), the Fe-to-Si ratio was significantly higher in crocidolite and amosite than in chrysotile. The Mg-to-Si ratio was significantly higher in chrysotile than in crocidolite or amosite.
• The authors' conclusion: The authors concluded that in-air micro-PIXE can identify the spatial distribution and quantities of asbestos bodies and other metals in lung tissue sections, and can also be used to assess asbestos fibers in vitro. They added that it appears useful for predicting the kind of asbestos from the ratios of Si, Fe and Mg.
• Limitations the authors state:
  • The main limitation was the small patient population. The authors said the study's purpose was to test the technique, not to examine how common asbestosis or metal accumulation is.
  • Inhaled fibers are often coated with iron-containing hemosiderin, and asbestos is not a pure substance. The authors said this made it difficult to determine the kind of asbestos in the lungs when it did not contain Fe.
  • Environmental exposure to silicon could not be excluded in the control patients.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Pulmonary Fibrosis, Asbestos Bodies, Macrophage, Chrysotile, Crocidolite, Amosite.

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