Oxalate deposition on asbestos bodies

Our plain-English summary of Oxalate deposition on asbestos bodies, by A.J. Ghio, V.L. Roggli, J.H. Richards, et al (Human Pathology, 2003).

The study

• Authors: A.J. Ghio, V.L. Roggli, J.H. Richards, K.M. Crissman, J.D. Stonehuerner, C.A. Piantadosi
• Journal: Human Pathology
• Published: 2003;34(8):737-42
• Type of article: Case report
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We report on a deposition of oxalate crystals on ferruginous bodies after occupational exposure to asbestos demonstrated in 3 patients. We investigated the mechanism and possible significance of this deposition by testing the hypothesis that oxalate generated through nonenzymatic oxidation of ascorbate by asbestos-associated iron accounts for the deposition of the crystal on a ferruginous body. Crocidolite asbestos (1000 microg/mL) was incubated with 500 micromol H(2)O(2) and 500 micromol ascorbate for 24 hours at 22 degrees C. The dependence of oxalate generation on iron-catalyzed oxidant production was tested with the both the metal chelator deferoxamine and the radical scavenger dimethylthiourea. Incubation of crocidolite, H(2)O(2), and ascorbate in vitro generated approximately 42 nmol of oxalate in 24 hours. Oxalate generation was diminished significantly by the inclusion of either deferoxamine or dimethylthiourea in the reaction mixture. Incubation of asbestos bodies and uncoated fibers isolated from human lung with 500 micromol H(2)O(2) and 500 micromol ascorbate for 24 hours at 22 degrees C resulted in the generation of numerous oxalate crystals. We conclude that iron-catalyzed production of oxalate from ascorbate can account for the deposition of this crystal on ferruginous bodies.

In plain English

This article combined case reports of three patients with laboratory experiments. The authors described three men with occupational asbestos exposure who had crystals on asbestos bodies in their lungs. One was a 61-year-old former shipyard pipe insulator with asbestosis who died of respiratory failure. One was a 60-year-old with a 15-year history of asbestos exposure and a cavitary lung mass. One was a 53-year-old pipe insulator found at autopsy to have a biphasic pleural mesothelioma. The crystals were described as consistent with calcium oxalate. In the laboratory, crocidolite incubated with hydrogen peroxide and ascorbate (vitamin C) for 24 hours generated approximately 42 nmol of oxalate, significantly more than without the fiber. Adding the metal chelator deferoxamine or the radical scavenger dimethylthiourea significantly decreased this oxalate generation. When asbestos bodies and uncoated fibers from a human lung were incubated with ascorbate and hydrogen peroxide, many crystals consistent with oxalate formed in Hanks balanced salt solution, but none in calcium-free saline. The authors concluded that iron-catalyzed production of oxalate from ascorbate can account for the deposition of this crystal on ferruginous bodies.

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: Case reports of 3 patients combined with in vitro laboratory experiments
• Who was studied: 3 patients with calcium oxalate crystals on ferruginous bodies in the lung after asbestos exposure: a 61-year-old former shipyard pipe insulator with asbestosis, a 60-year-old black man with a 15-year history of asbestos exposure, and a 53-year-old white man who had worked as a pipe insulator for at least 20 years. The laboratory work used crocidolite, plus asbestos bodies and uncoated fibers taken from a human lung at autopsy. No place or dates of the cases are given.
• Exposure: The patients had occupational asbestos exposure: shipyard pipe insulation work for patient 1, pipe insulation for at least 20 years for patient 3, and 15 years of unspecified asbestos exposure for patient 2. Fiber types in the patients are not stated. In the laboratory, crocidolite (1000 micrograms per mL) was incubated with 500 micromol hydrogen peroxide and 500 micromol ascorbate for 24 hours at 22 degrees C.
• Main results:
  • Patient 1: colorless crystals seen in the sputum were all attached to or covering asbestos bodies. At autopsy, many crystals were bipyramidal, consistent with calcium oxalate dihydrate.
  • Patient 2: the lung removed at surgery showed the typical histopathology of asbestosis, and crystals were located on asbestos bodies.
  • Patient 3: autopsy found a biphasic mesothelioma involving 2/3 of the pleural cavity, and 974,000 asbestos bodies per gram of tissue. Many of these bodies were associated with crystals containing calcium only, consistent with calcium oxalate.
  • In vitro, crocidolite with hydrogen peroxide and ascorbate generated approximately 42 nmol of oxalate in 24 hours. Compared with incubation without the fiber, crocidolite significantly increased oxalate production.
  • As oxalate rose in the crocidolite incubations, ascorbate concentrations fell.
  • Compared with incubations containing crocidolite, adding deferoxamine (a metal chelator) or dimethylthiourea (an oxidant scavenger) significantly decreased oxalate generation. Both also reduced ascorbate consumption.
  • Asbestos bodies and uncoated fibers from human lung, incubated with ascorbate and hydrogen peroxide, produced no crystals in calcium-free saline.
  • The same incubation with ascorbate and hydrogen peroxide, done in Hanks balanced salt solution, produced a large number of crystals. Many abutted fibers and many others were separate. Electron microscopy with energy dispersive X-ray spectroscopy found their structure and composition consistent with oxalate.
• The authors' conclusion: The authors concluded that iron-catalyzed production of oxalate from ascorbate can account for the deposition of calcium oxalate crystals on ferruginous bodies. They also stated that this mechanism could account for accelerated ascorbate depletion in lung diseases associated with redox-active iron.

Topics

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

Medical terms in this study, explained in our Lexicon: Deposition, Asbestos Bodies, Ferruginous Bodies, Occupational Exposure, Ferruginous body, Crocidolite.

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• Using in vitro iron deposition on asbestos to model asbestos bodies formed in human lung — Z. Shen, D. Bosbach, et al. (2000)
• Role of iron in inactivation of epidermal growth factor receptor after asbestos treatment of human lung and pleural target cells — A. Baldys, A.E. Aust (2005)
• Prevention of asbestos-induced cell death in rat lung fibroblasts and alveolar macrophages by scavengers of active oxygen species — M.A. Shatos, J.M. Doherty, et al. (1987)
• Pulmonary fibrosis and ferruginous bodies associated with exposure to synthetic fibers — A.J. Ghio, W. Funkhouser, et al. (2006)

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