Silicon, a Possible Link between Environmental Exposure and Autoimmune Diseases: The Case of Rheumatoid Arthritis

Our plain-English summary of Silicon, a Possible Link between Environmental Exposure and Autoimmune Diseases: The Case of Rheumatoid Arthritis, by C.A. Speck-Hernandez, G. Montoya-Ortiz (Arthritis, 2012).

The study

• Authors: C.A. Speck-Hernandez, G. Montoya-Ortiz
• Journal: Arthritis
• Published: 2012;2012:604187
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Silicon is one of the most common chemicals on earth. Several compounds such as silica, asbestos, silicone or, nanoparticles are built from tetrahedral units with silicon as the central atom. Despite these, structural similarities, they have rarely been analyzed as a group. These compounds generate significant biological alterations that include immune hyperactivation, production of the reactive species of oxygen and tissue injury. These pathological processes may trigger autoimmune responses and lead to the development of rheumatoid arthritis. Populations at risk include those that constantly work in industrial process, mining, and agriculture as well as those that undergo silicone implants. Herein a review on the main features of these compounds and how they may induce autoimmune responses is presented.

In plain English

This article was a review, not a new study. The authors discussed published work on four compounds built around silicon (asbestos, silica, silicone and silica nanoparticles) and how these might trigger autoimmune responses leading to rheumatoid arthritis (RA). For asbestos, the review described laboratory findings that asbestos stimulates inflammation and the production of reactive oxygen species. It summarized a 2006 nested case-control study by Noonan and colleagues of 7,307 residents of Libby, Montana, as reporting a 65% increase in the risk of RA and an odds ratio of 3.23 for the association between asbestos exposure and RA. It also cited a study finding more autoantibodies in the blood of Libby residents, and a study by Salazar and colleagues in which asbestos-exposed rats showed altered antinuclear antibody levels but no correlation with other signs of RA. The authors wrote that the relationship between asbestos and autoimmunity remains unclear and that further research is warranted. Overall, they concluded that these compounds may act, together with genetic background, in the mechanisms leading to autoimmune diseases such as RA.

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: Narrative review of published epidemiological, animal and laboratory studies
• Who was studied: No study population of its own. The review discussed published studies of exposed people, animals and cells, and named as at risk people working in industrial processes, mining and agriculture, and people with silicone implants.
• Exposure: Silicon-derived compounds: asbestos, silica, silicone (mainly breast implants) and silica nanoparticles
• Main results:
  • The review reported that a 2006 nested case-control study by Noonan and colleagues included 7,307 residents of Libby, Montana.
  • According to the review, that Libby study found a 65% increase in the risk of RA and a 54% increase in the risk of other systemic autoimmune diseases in this population.
  • According to the review, the odds ratio for the association between asbestos exposure and RA in the Libby study was 3.23. No confidence interval was given in the review.
  • The review cited Pfau and colleagues as finding a higher frequency of antinuclear and extractable nuclear antigen autoantibodies, and higher serum IgA, in Libby residents than in comparable populations such as Missoula, Montana.
  • The review cited Olsson as showing that miners exposed to asbestos had a higher risk of developing RA.
  • The review reported that Salazar and colleagues found altered antinuclear antibody levels in asbestos-exposed Lewis rats but no correlation with other indicators of RA.
  • The review described laboratory evidence that asbestos stimulates production of reactive oxygen species.
  • For silica, the review's table cited a case-control study (577 RA cases, 659 matched controls) in which silica exposure combined with smoking among men was associated with anti-CCP positive RA.
  • For silicone implants, the review stated that epidemiological studies have not reported an association with autoimmune diseases such as RA.
• The authors' conclusion: The authors concluded that these silicon-derived compounds may act, together with genetic background, in the mechanisms leading to autoimmune diseases such as RA. For asbestos specifically, they wrote that its relationship with autoimmunity remains unclear and that further research is warranted.
• Limitations the authors state:
  • The authors stated that, despite asbestos's toxic effects on the immune system, its relationship with autoimmunity remains unclear.
  • The authors noted discrepancies in the evidence on silicone and autoimmune disease, citing a meta-analysis.

Topics

Medical terms in this study, explained in our Lexicon: Environmental Exposure.

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