Ferritin adsorption on amosite fibers: possible implications in the formation and toxicity of asbestos bodies

Our plain-English summary of Ferritin adsorption on amosite fibers: possible implications in the formation and toxicity of asbestos bodies, by B. Fubini, F. Barceló, C. Otero Areán (Journal of Toxicology and Environmental Health, 1997).

The study

• Authors: B. Fubini, F. Barceló, C. Otero Areán
• Journal: Journal of Toxicology and Environmental Health
• Published: 1997;52(4):343-52
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In order to investigate how endogenous iron can be deposited in vivo on inhaled mineral fibers during early stages of formation of asbestos bodies, in vitro experiments were performed on the adsorption of ferritin onto amosite asbestos. The mineral dust was found to adsorb the protein from an aqueous solution containing 0.3 mg/ml horse spleen ferritin. In order to simulate physiological conditions the aqueous solution was adjusted with 150 mM saline. Polyacrylamide-SDS gel electrophoresis of the desorbed protein showed subunits of approximately 13 and 15 kD, aside from the 20-kD subunit present in the native protein. This suggests that as a result of interactions between ferritin molecules and the solid surface of the mineral fibers, the protein iron core may be released or partially exposed. Data indicate these interactions may have implications in the observed mineral fiber toxicities.

In plain English

This laboratory experiment studied how body iron might collect on inhaled asbestos fibers to form "asbestos bodies". The authors mixed amosite asbestos powder with a saltwater solution of ferritin, an iron-storage protein taken from horse spleen, for 12 hours at 25°C. The brown solution lost all its color, and only 2% of the protein was left in the liquid; the rest had stuck to the fibers. The protein could not be washed off with distilled water, only with a detergent. When the recovered protein was analysed, it showed two smaller fragments, at about 15 and 13 kilodaltons, besides the normal 20-kilodalton ferritin unit. These fragments were absent from a control ferritin solution put through the same steps without amosite. In a preliminary test, ferritin did not stick to fiberglass. The authors concluded that binding to amosite breaks up part of the protein, which should expose its iron core. They suggested this may matter for how asbestos bodies form and for amosite's toxicity. They noted that horse ferritin may behave like human ferritin, but this still had to be checked.

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: in vitro laboratory experiment (protein adsorption onto mineral fibers)
• Who was studied: No people or animals were studied. The materials were amosite asbestos powder from the Union Internationale Contre le Cancer (UICC) and horse spleen ferritin from Sigma Chemical Co.
• Exposure: Amosite fibers were incubated with a 0.3 mg/ml horse spleen ferritin solution in 150 mM salt for 12 hours at 25°C, at a protein-to-mineral ratio of 1:50 by weight. The control was a ferritin solution processed the same way but without incubation with the mineral.
• Main results:
  • After incubation with amosite, only 2% of the initial amount of ferritin remained in solution; the rest had adsorbed to the fibers.
  • Protein recovered from the amosite showed two bands at about 15 and 13 kD. These were not present in the control experiment (ferritin processed the same way without amosite), which showed only the 20-kD subunit.
  • The adsorbed ferritin could not be removed by washing with distilled water; it was recovered only with the detergent SDS.
  • In a preliminary test under the same conditions, ferritin did not adsorb onto fiberglass.
  • The amosite fibers were about 0.2 micrometres in diameter. Most were 20 to 70 micrometres long, based on 300 counted fibers.
• The authors' conclusion: The authors concluded that adsorption onto amosite cleaves some ferritin subunits, which should expose the iron core. They considered this likely to have implications for the formation of ferruginous (asbestos) bodies and for the toxicity of inhaled amosite. They proposed, without testing it in this study, that the exposed iron could drive reactions linked to radical damage to DNA.
• Limitations the authors state:
  • The experiments used horse spleen ferritin. The authors said the results may also apply to human ferritin, but that further research was in progress to verify this.

Topics

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

Medical terms in this study, explained in our Lexicon: Ferritin, Amosite, Asbestos Bodies, Mineral Fiber.

Related studies

• Adsorption isotherms of albumin and ferritin on Rhodesian chrysotile: effects of magnesium depletion — F. Valerio, M. Veggi, et al. (1980)
• Ascorbic acid modifies the surface of asbestos: possible implications in the molecular mechanisms of toxicity — G. Martra, M. Tomatis, et al. (2003)
• Long and short fiber amosite asbestos alters at a different extent the redox metabolism in human lung epithelial cells — C. Riganti, E. Aldieri, et al. (2003)
• An assessment of asbestos body formation in extrapulmonary sites: liver and spleen — M.G. Williams, R.F. Dodson, et al. (2001)
• Ferruginous bodies: implications in the mechanism of fiber and particle toxicity — A.J. Ghio, A. Churg, et al. (2004)
• High aspect ratio materials: role of surface chemistry vs. length in the historical "long and short amosite asbestos fibers" — M. Tomatis, F. Turci, et al. (2010)

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