The association of phagocytosed asbestos dust with lysosome enzymes

Our plain-English summary of The association of phagocytosed asbestos dust with lysosome enzymes, by B.A. Smith, J.M. Davis (The Journal of Pathology, 1971).

The study

• Authors: B.A. Smith, J.M. Davis
• Journal: The Journal of Pathology
• Published: 1971;105(3):153-7
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The occurrence of acid phosphatase in guinea-pig granulomas produced by the intrapleural injection of asbestos dust was investigated by histochemical staining combined with electron microscopy. It was found that the acid phosphatase reaction was confined to the lysosome series of organelles, but that not all of these structures gave a positive reaction. In dust-containing macrophages and giant cells, often fewer than 50 per cent of primary lysosomes and as few as 10 per cent. of dust-containing phagosomes showed evidence of acid phosphatase. There was no increase in enzyme activity between 2 and 4 wk. When fibroblasts were present in the granulomas these usually contained small amounts of chrysotile dust. In these cells, however, both primary lysosomes and dust-containing phagosomes were positive for acid phosphatase in the majority of cases. The implication of these findings on the toxicity of chrysotile asbestos dust is discussed.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

In this animal experiment, the authors injected 25 mg of chrysotile asbestos dust into the chest (pleural) cavity of guinea-pigs. This produced lumps of inflammatory tissue called granulomas. Animals were killed 2 and 4 weeks later. The authors then used a staining method with electron microscopy to locate acid phosphatase, a digestive enzyme found in lysosomes, the cell compartments that break down material. The number of animals was not reported. The staining reaction was found almost entirely within lysosomes and the compartments holding swallowed dust. In the scavenger cells (macrophages and giant cells), often fewer than 50 per cent of primary lysosomes, and as few as 10 per cent of dust-containing compartments, gave a positive staining reaction for the enzyme. Enzyme activity did not increase between 2 and 4 weeks. In fibroblasts, which held little dust, most primary lysosomes and dust-containing compartments stained positive for the enzyme. The study found no satisfactory evidence that dust compartments burst and released enzymes into the cell. The authors concluded that cell death (necrosis) was probably rare because only a very small proportion of dust-containing compartments also contained enzymes.

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: Animal experiment: histochemical staining for acid phosphatase combined with electron microscopy of guinea-pig pleural granulomas
• Who was studied: Guinea-pigs at the Department of Pathology, Cambridge University, killed 2 and 4 weeks after dust injection. The number of animals was not stated.
• Exposure: A single intrapleural injection of 25 mg of chrysotile asbestos dust into the right lower thoracic cavity. The dust was almost entirely fibrous chrysotile, mostly in bundles less than 5 micrometres long and 0.1 to 1 micrometre in diameter.
• Main results:
  • The acid phosphatase reaction deposits were almost entirely limited to lysosomes, phagosomes and phagosome residual bodies.
  • In dust-containing macrophages and giant cells, often fewer than 50 per cent of primary lysosomes showed evidence of acid phosphatase (a positive staining reaction).
  • In dust-containing macrophages and giant cells, as few as 10 per cent of dust-containing phagosomes showed evidence of acid phosphatase.
  • There was no increase in enzyme activity between 2 and 4 weeks.
  • In fibroblasts, which usually contained small amounts of chrysotile, most primary lysosomes and dust-containing phagosomes were positive for acid phosphatase.
  • Even by 4 weeks, little dust had escaped into the cell cytoplasm. Almost all of it remained in phagosome residual bodies.
  • No satisfactory evidence was found of phagosome rupture releasing lysosome enzymes into the cytoplasm.
• The authors' conclusion: The authors concluded that lysosome enzymes are deposited in some dust-containing phagosomes and remain active for several weeks. They considered that necrosis is probably rare because only a very small proportion of dust-containing phagosomes also contain enzymes.
• Limitations the authors state:
  • The few lead phosphate deposits seen outside lysosomes came from badly preserved areas. The authors judged that these deposits did not correctly show where the enzymes were in living cells.
  • The authors stated that the fibroblast findings did not settle whether there are distinct families of lysosomes or whether lysosome enzyme activity develops slowly.

Topics

Medical terms in this study, explained in our Lexicon: Granuloma, Macrophage, Fibroblast, Chrysotile.

Related studies

• The long term fibrogenic effects of chrysotile and crocidolite asbestos dust injected into the pleural cavity of experimental animals — J.M. Davis (1970)
• Non-thermal plasma induces a stress response in mesothelioma cells resulting in increased endocytosis, lysosome biogenesis and autophagy — L. Shi, F. Ito, et al. (2017)
• Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages — E. Bey, J.S. Harington (1971)
• Lysosomal enzyme secretion by macrophages during intracellular storage of particles — R.T. Dean, W. Hylton, et al. (1979)
• Spontaneous lysosomal enzyme secretion by a murine macrophage-like cell line — W. Jessup, R.T. Dean (1980)
• Effects of chrysotile on a lysosomal enzyme preparation and on the hydrolytic enzyme activity of cultured alveolar macrophages — R. Desai, R.J. Richards (1983)

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