Production of reactive oxygen species by phagocytic cells after exposure to glass wool and stone wool fibres - effect of fibre preincubation in aqueous solution

Our plain-English summary of Production of reactive oxygen species by phagocytic cells after exposure to glass wool and stone wool fibres - effect of fibre preincubation in aqueous solution, by T. Zoller, W.J. Zeller (Toxicology Letters, 2000).

The study

• Authors: T. Zoller, W.J. Zeller
• Journal: Toxicology Letters
• Published: 2000;114(1-3):1-9
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The potential of four man-made vitreous fibres (MMVFs) (glass wool Code A, stone wool Code G, HT-N and MMVF 21) and of two natural mineral fibres (crocidolite, erionite) to induce production of reactive oxygen species (ROS) by differentiated HL-60 cells (HL-60-M cells) was investigated by determination of luminol-enhanced chemiluminescence (CL). Quartz served as positive control. The same system was used to uncover possible influences of fibre preincubation in aqueous solutions on the ROS-generating potential. Following preincubation in unbuffered saline over about 4 weeks, Code A and G fibres showed decreased ROS-generating potential as compared to freshly suspended fibres. On the other hand, MMVF 21 and HT-N fibres as well as crocidolite and erionite showed no decreased CL after incubation in aqueous solutions. The observed decrease of the ROS-generating potential of Code A and G fibres after preincubation may be an expression of fibre surface alterations (leaching, initiation of dissolution) that influences the response of exposed phagocytic cells. After incubation of both fibres in buffered solutions at different pH values (5.0, 7.4) a reduced ROS-generating potential was still discernible as compared to freshly suspended fibres.

In plain English

This was a laboratory study using a human cell line, not a study of people. The authors, at the German Cancer Research Center in Heidelberg, turned HL-60 cells into macrophage-like cells. They exposed them to four man-made vitreous fibres (glass wool Code A and the stone wools Code G, HT-N and MMVF 21), to two natural mineral fibres (crocidolite and erionite), and to quartz as a positive control. They measured how much reactive oxygen species the cells released by recording light given off (chemiluminescence). The fibres were either freshly suspended or soaked for about 4 weeks in salt solution. Code A and Code G were also soaked in buffered solutions at pH 5.0 and 7.4. Quartz produced the highest peak. After soaking in unbuffered saline, Code A and Code G caused significantly less reactive oxygen production than fresh fibres, and a reduction was still seen after the buffered soaks. MMVF 21, HT-N, crocidolite and erionite instead caused somewhat more after soaking. The authors concluded that soaking may significantly change the fibres' ability to trigger reactive oxygen release. They noted that 4-week results do not allow direct conclusions about how long fibres persist in the body.

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 using a differentiated human cell line (cell culture study)
• Who was studied: The human promyelocytic cell line HL-60, differentiated with vitamin D3 into macrophage-like cells (called HL-60-M cells), studied at the German Cancer Research Center, Heidelberg, Germany. Each experiment was repeated at least three times.
• Exposure: Four man-made vitreous fibres (glass wool Code A, stone wool Code G, HT-N and MMVF 21) and two natural mineral fibres (crocidolite, erionite), with quartz as positive control. The dusts were either freshly suspended or preincubated for about 3 to 6 (usually 4) weeks in physiological saline or in Sörensen phosphate buffer at pH 5.0 or pH 7.4.
• Main results:
  • In all experiments, quartz produced the highest chemiluminescence peak.
  • After preincubation in aqueous solution, the ability of Code A (glass wool) and Code G (stone wool) fibres to stimulate HL-60-M cells was significantly decreased compared with freshly suspended fibres.
  • In one representative experiment, freshly prepared Code A and Code G fibres gave a peak of about 2×10^6 cpm. After 4 weeks of incubation in unbuffered physiological saline, the peak dropped below 0.5×10^6 cpm.
  • MMVF 21 and HT-N stone wool fibres showed rather increased chemiluminescence after preincubation compared with freshly suspended fibres.
  • Crocidolite and erionite likewise induced slightly increased chemiluminescence when preincubated compared with freshly suspended fibres. Crocidolite caused low chemiluminescence intensity overall.
  • During 4 weeks in unbuffered saline, Code A and Code G fibres raised the pH from 7.2 to 9.7 and 9.3 respectively. MMVF 21 and HT-N fibres lowered it to 5.5 and 6.3 respectively.
  • When Code A and Code G fibres were preincubated in buffered solution at pH 5.0, their ability to induce reactive oxygen production was also reduced. A decrease was also seen after preincubation at pH 7.4.
  • At the concentrations used, neither freshly suspended nor preincubated fibres affected the viability of the HL-60-M cells. The authors did not present these data.
• The authors' conclusion: The authors concluded that preincubation of man-made vitreous fibres in aqueous solutions may be followed by significant changes in their potential to generate reactive oxygen species. For Code A and Code G, preincubation resulted in a distinct reduction.
• Limitations the authors state:
  • Because of limited supply, MMVF 21 and HT-N fibres were not tested in buffered solutions.
  • Results after short-term (about 4 weeks) incubation do not allow direct conclusions about biopersistence.
  • Successive cultures of HL-60-M cells varied in their capacity to produce reactive oxygen species, so most results were expressed as a percentage of the quartz control.

Topics

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

Medical terms in this study, explained in our Lexicon: Reactive Oxygen Species (ROS), Vitreous, Crocidolite, erionite.

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