Immunomodulatory effects of mineral fibres in occupationally exposed workers

Our plain-English summary of Immunomodulatory effects of mineral fibres in occupationally exposed workers, by J. Tulinska, E. Jahnova, M. Dusinska, et al (Mutation Research, 2004).

The study

• Authors: J. Tulinska, E. Jahnova, M. Dusinska, M. Kuricova, A. Liskova, S. Ilavska, M. Horvathova, L. Wsolova, S.A. Kyrtopoulos, A. Collins, V. Harrington, L. Fuortes
• Journal: Mutation Research
• Published: 2004;553(1-2):111-24
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In the context of a large-scale molecular epidemiology study, the possible immunomodulatory effects of mineral fibres, in workers occupationally exposed to asbestos, rockwool and glass fibres, were examined. In each plant, 61, 98 and 80 exposed workers and 21, 43 or 36 control clerical subjects, respectively, were recruited. In the case of the asbestos-exposed subjects, an additional town-control group of 49 people was included. Evidence of pulmonary fibrosis was found in 42% of the asbestos-exposed workers, while evidence of pleural fibrosis was found in 24%. The asbestos-exposed cohort had significantly decreased forced vital capacity of lungs as well as forced expiratory volume per first second. Our findings indicate that exposure to all three types of fibres examined modulates to different degrees the immune response. Suppression of T-cell immunity and to a lesser extent, B-cell immunity was found in the case of workers from a former asbestos cement plant, while stimulation of T-cell response was observed in rockwool workers, and stimulation of T- and B-cell response was seen in glass fibre workers. Depression of the percentage of lymphocyte subpopulation of CD 16+56 (natural killer cells) in peripheral blood was found in glass fibre workers. Statistical analysis showed increased levels of proinflammatory cytokines (IL-6 asbestos; IL-8 all three fibres), expression of adhesion molecule L-selectin on granulocytes and monocytes (asbestos), levels of soluble adhesion molecules (SAMs) in sera (ICAM-1 all three fibres; E-selectin glass fibres), increased levels of immunoglobulin E (asbestos and rockwool) and elevated expression of activation markers on eosinophils (CD66b asbestos, glass fibres; CD69 asbestos). Significant correlations were observed between lymphocyte proliferation and markers of DNA damage and repair. Increased levels of proinflammatory cytokines, SAMs, immunoglobulin E and elevated expression of activation markers on eosinophils was found in people with symptoms of hypersensitivity and an elevated inflammatory status.

In plain English

This cross-sectional study examined blood markers of immune function in workers with at least 5 years of exposure at three Slovak plants: a former asbestos cement factory (closed 9 months before the study), a rockwool plant and a glass fibre plant. The authors recruited 61, 98 and 80 exposed workers and 21, 43 and 36 clerical controls from the same plants, plus 49 town controls for the asbestos group. Among asbestos-exposed workers, 42% had evidence of pulmonary fibrosis and 24% of pleural fibrosis, and two lung function measures were significantly reduced. X-rays and spirometry showed no changes in rockwool or glass fibre workers. Asbestos workers' T-cell responses were reduced, while those of rockwool and glass fibre workers were increased. Asbestos workers had higher IL-6, IL-8 and immunoglobulin E levels. IL-8 was raised in all three exposed groups but stayed within normal values. The authors concluded that all three fibre types may modulate immune responses to different degrees. They said the rockwool and glass fibre findings, at very low current exposures, should be interpreted with reservation because of possible confounding.

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: Cross-sectional study comparing exposed workers with control subjects at three industrial plants
• Who was studied: Workers at an asbestos cement plant, a rockwool plant and a glass fibre plant in the Slovak Republic. The authors recruited 61, 98 and 80 exposed workers and 21, 43 and 36 clerical (office-area) controls from the same factories, plus a 49-person town control group for the asbestos plant. Table 1 lists smaller analysed numbers. All exposed workers had at least 5 years of exposure.
• Exposure: Asbestos at an asbestos cement factory that had stopped operating 9 months before the study; the fibre type is not specified. Historical asbestos fibre levels were 2–11 fibres/cm3 in 1978–1990, 1–4 in 1991–1994 and 0.2–1 in 1994–1998, with total dust of 40–60 mg/m3 in 1956–1960. At the time of the study, fibre levels in the production hall were three to five times the Slovak limit. Rockwool (basalt glass) fibres and glass fibres were measured at levels 10–1000 times below Slovak occupational limits.
• Main results:
  • Among asbestos-exposed workers, 42% had evidence of pulmonary fibrosis and 24% had evidence of pleural fibrosis.
  • Nine asbestos-exposed workers (15%) had both interstitial and pleural fibrosis.
  • The asbestos-exposed cohort had significantly decreased forced vital capacity and forced expiratory volume in the first second.
  • X-ray and spirometry showed no changes in rockwool or glass fibre workers.
  • Workers from the former asbestos cement plant had significantly decreased proliferation of lymphocytes stimulated by the T-cell mitogen PHA.
  • T-lymphocyte proliferation was stimulated in rockwool and glass fibre workers.
  • B-lymphocyte proliferation was also increased in glass fibre workers.
  • Asbestos workers had higher levels of soluble ICAM-1, IL-6, IL-8 and immunoglobulin E than controls.
  • Asbestos workers had increased L-selectin (CD62L) on monocytes and granulocytes.
  • Serum IL-8 was significantly elevated in workers exposed to all three types of fibres. The authors noted that these IL-8 levels remained within normal values.
  • Immunoglobulin E was not raised in glass fibre workers compared with their controls.
  • Glass fibre workers had significantly decreased expression of CD16+56 (natural killer cell marker) and increased soluble E-selectin.
  • Neither asbestos cement nor rockwool workers had significant changes in natural killer cell activity or in the percentage of cells with the natural killer phenotype. The natural killer activity assay was not done in glass fibre workers.
  • Asbestos plant workers had increased expression of the activation markers CD69 and CD66b on eosinophils.
  • In asbestos-exposed workers, AlkA-sensitive DNA sites correlated negatively with T- and T-dependent B-lymphocyte proliferation: correlation coefficients of -0.4 (P 0.002) and -0.450 (P less than 0.001), with 59 cases each.
• The authors' conclusion: The authors concluded that exposure to all three fibre types examined may modulate the immune responses to different degrees.
• Limitations the authors state:
  • The authors said the immune changes in workers with current very low exposure to rockwool and glass fibres should be interpreted with reservation, in case they reflect other, confounding factors.
  • The authors suggested that the different T-cell patterns in asbestos versus rockwool and glass fibre workers may reflect differences in exposure duration and underlying health between the groups.

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Pulmonary Fibrosis, Fibrosis, Asbestos-Cement, Cytokine.

Related studies

• Immunological monitoring in workers occupationally exposed to asbestos — S. Ilavská, E. Jahnová, et al. (2005)
• The ability of mineral dusts and fibres to initiate lipid peroxidation. Part I: parameters which determine this ability — M. Gulumian (1999)
• Angiogenic effect induced by mineral fibres — D. Carbonari, A. Campopiano, et al. (2011)
• Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats — J. Topinka, P. Loli, et al. (2006)
• Fibrogenesis by mineral fibres: an in-vitro study of the roles of the macrophage and fibre length — M. Aalto, A.G. Heppleston (1984)
• Inhibition of cytokinesis by asbestos and synthetic fibres — C.G. Jensen, M. Watson (1999)

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