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Toxicity to endothelial cells mediated by cotton bract tannin. Potential contribution to the pathogenesis of byssinosis.

Johnson CM; Hanson MN; Rohrbach MS
Am J Pathol 1986 Mar; 122(3):399-409
The toxic effects of cotton bract tannin on porcine aortic and pulmonary artery endothelial cells were studied using the release of radiolabeled chromium (Cr) from cells in tissue culture as an index of cell membrane damage. Porcine endothelial cells from the thoracic aorta or pulmonary artery were dissociated with collagenase and established as secondary cultures showing endothelial morphology with no evident smooth muscle contamination. Porcine skin fibroblasts were isolated from explants. Both cell types were passaged and frozen prior to use. Lyophilized cotton bract tannin concentrates were dissolved in serum free culture medium. Fourth passage endothelial cells and third passage skin fibroblasts were grown to confluence and loaded with Cr-51. Replicate cultures were incubated with tannin or control serum free medium and the percent released Cr-51 calculated. Cells were also exposed to endotoxin from Enterobacter-agglomerans. Cell morphology changes were observed by phase contrast light, scanning and transmission electron microscopy. Tannin resulted in the release of Cr-51 from endothelial cells after about 3 hours which increased with increasing time and concentration. This occurred to a lesser extent in fibroblasts. Release of Cr-51 reached a maximum which was less than that available for release by detergent. This effect of tannin was greater on aortic than on pulmonary endothelial cells. Exposure to tannin also produced characteristic changes in endothelial cell morphology within minutes. These included an increase in the prominence of intercellular junctions and the formation of folds and microvilli. Prolonged exposure for 6 hours or more produced pyknotic nuclei and multiple membrane folds correlated with the release of Cr-51 in the supernatant. Brief exposure (1 to 30 minutes) to cytotoxic tannin doses produced smaller releases of Cr- 51 into the medium 6 hours later. Morphology changes were somewhat different from those following long exposure and included cell retraction and detachment from the culture dish and vacuolization. Cells exposed to endotoxin in high concentrations lost some Cr-51 but showed no morphology changes. The authors conclude that severe cytotoxicity and morphology changes were produced by tannin in-vitro with concentrations achievable in-vivo, and that they could contribute to the byssinosis syndrome.
NIOSH-Publication; NIOSH-Grant; Laboratory-animals; In-vitro-studies; Cell-damage; Cell-morphology; Cotton-dust; Cytotoxic-effects; Cytotoxicity; Cell-wall-permeability; Cellular-reactions; Cellular-structures; Cytotoxins
Christopher M. Johnson, MD, Section of Hematology Research, Mayo Clinic/Foundation, Rochester, MN 55905
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The American Journal of Pathology
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Mayo Foundation, Rochester, Minnesota
Page last reviewed: October 22, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division