Studies using lectins to determine mineral interactions with cellular membranes

Our plain-English summary of Studies using lectins to determine mineral interactions with cellular membranes, by B.T. Mossman, L. Jean, J.M. Landesman (Environmental Health Perspectives, 1983).

The study

• Authors: B.T. Mossman, L. Jean, J.M. Landesman
• Journal: Environmental Health Perspectives
• Published: 1983;51:23-5
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Chrysotile asbestos interacts with mucin-secreting cells of tracheal organ cultures, causing an increase in secretion of mucin into the culture medium. This response occurs in the absence of obvious morphologic damage to tracheal epithelial cells. We speculated that asbestos-induced hypersecretion was regulated by the interaction of fibers with specific carbohydrate residues on the cell surface. To test this hypothesis, lectins, i.e., proteins with a high affinity for mono- and oligosaccharides on the plasma membrane, were added to tissues 30 min before addition of chrysotile. Secretion of mucin into the medium was then determined over a 2-hr period by using incorporation of 3H-glucosamine. Blocking of alpha-D-mannose and alpha-D-glucose residues inhibited chrysotile-induced hypersecretion (p less than 0.05), whereas lectins blocking residues of alpha-D-N-acetylgalactosamine, beta-D-N-acetylglucosamine, alpha-L-fucose and sialic acids were ineffective. Preincubation of cultures with carboxypeptidase A or phospholipase A2, but not with neuraminidase, diminished mucin secretion caused by chrysotile. To determine if the positive surface charge of chrysotile was important in interaction with mucin cells, we examined comparatively the effects of various polycations (cationic ferritin, polylysine, DEAE-dextran) and chrysotile after leaching of fibers to remove Mg2+. Although use of polycations enhanced secretion of mucin, effects were not as striking as those observed with chrysotile. In contrast, leached chrysotile failed to elicit a hypersecretory response. These results suggest the interaction of a positively charged component (presumably Mg2+) of chrysotile with glycolipids and glycoproteins containing terminal residues of alpha-D-mannose or alpha-D-glucose.

In plain English

This was a laboratory study using windpipe (tracheal) tissue from young male Fischer rats, kept alive in culture dishes. The authors tested which parts of the cell surface take part when chrysotile asbestos makes mucus-producing cells release more mucin. They pretreated the tissue with lectins (proteins that bind particular sugars on cell surfaces) or with enzymes, then added UICC reference chrysotile for two hours. Chrysotile alone raised mucin release to 168% of untreated cultures. After pretreatment with the lectin Con A, which binds alpha-D-mannose and alpha-D-glucose, it was 130% (p less than 0.05). Four other lectins did not lower the response. The higher dose of each of two enzymes, carboxypeptidase A and phospholipase A2, reduced chrysotile's effect. The enzyme neuraminidase did not. Chrysotile soaked in acid to remove magnesium caused no increase. Several positively charged substances raised secretion, but none as strikingly as chrysotile. The authors suggested that the increased secretion occurs when a positively charged component of chrysotile, presumably magnesium, interacts with the surface of mucin-secreting cells.

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: Laboratory (in vitro) experiment on animal tissue in organ culture, using lectins and enzymes to block cell-surface sites before chrysotile exposure
• Who was studied: Tracheal explants (pieces of windpipe tissue) from male pathogen-free 6-week-old Fischer rats, four explants per dish, with 5 to 30 dishes per test group
• Exposure: UICC reference chrysotile asbestos at 0.4 mg/mL for a 2-hour period. Comparisons were chrysotile leached for 1 week in 1 N hydrochloric acid to remove magnesium, and positively charged substances (DEAE-dextran, polylysine, cationic ferritin).
• Main results:
  • Chrysotile alone raised mucin secretion to 168% of the amount in untreated cultures (30 dishes)
  • With the lectin Con A (binds alpha-D-mannose and alpha-D-glucose) added before chrysotile, mucin secretion was 130% of untreated cultures (25 dishes). This was statistically different from chrysotile alone (p less than 0.05).
  • Lectins blocking alpha-D-N-acetylgalactosamine, beta-D-N-acetylglucosamine, alpha-L-fucose and sialic acids did not reduce chrysotile-induced secretion. Values were 165% to 198% of untreated cultures.
  • In the enzyme experiments (5 dishes per group), chrysotile alone gave 405 ± 36% of untreated cultures. With the higher dose of carboxypeptidase A before chrysotile, the value was 281 ± 20%, which was statistically different (p less than 0.05).
  • With the higher dose of phospholipase A2 before chrysotile, mucin secretion was 300 ± 12% of untreated cultures. This was statistically different from chrysotile alone (p less than 0.05).
  • Neuraminidase before chrysotile did not lower mucin secretion (400 ± 15% of untreated cultures)
  • Chrysotile leached with acid did not increase mucin secretion (84 ± 9% of untreated cultures, compared with 383 ± 44% for unleached UICC chrysotile; 5 dishes per group)
  • Positively charged substances raised mucin secretion to between 119% and 289% of untreated cultures, depending on substance and dose. None produced as striking an effect as chrysotile.
• The authors' conclusion: The authors suggested that increased mucin secretion occurs when a positively charged component of chrysotile (presumably magnesium) interacts with the surface of mucin-secreting cells. They added that the lectin results indicate interaction with a surface receptor of alpha-D-mannose or alpha-D-glucose.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Ferritin, Glycoprotein.

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• Sialic acid mediates the initial binding of positively charged inorganic particles to alveolar macrophage membranes — J.E. Gallagher, G. George, et al. (1987)
• Effects of cigarette smoke on epithelial uptake of non-asbestos mineral particles in tracheal organ culture — B. Keeling, J. Hobson, et al. (1993)
• Ozone enhances the uptake of mineral particles by tracheobronchial epithelial cells in organ culture — A. Churg, M. Brauer, et al. (1996)

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