Partially opened triple helix is the biologically active conformation of 1-->3-B-glucans that induces pulmonary inflammation in rats.
Young-S; Robinson-V; Barger-M; Frazer-D; Castranova-V; Jacobs-R
J Toxicol Environ Health, A 2003 Jun; 66(6):551-563
1-->3-beta-Glucans produce pulmonary inflammation in rats and are commonly found in indoor air dust samples. Conformation is an important factor determining the biological activity of 1-->3-beta-glucans. The partially opened triple-helix conformation induced by NaOH treatment and the annealed triple-helix conformation have been identified by fluorescence resonance energy transfer spectroscopy in our previous study. The objective of this study was to examine the role of these conformations of 1-->3-beta-glucans in the induction of pulmonary inflammation in rats. A partially opened triple-helix conformation of the known inflammatory 1-->3-beta-glucan zymosan was prepared by treating zymosan with NaOH followed by neutralization and dialysis. The annealed triple-helix conformation was prepared by allowing the partially opened triple-helix conformation to anneal for 9 d at room temperature. Rats were exposed to fresh or annealed NaOH-treated zymosan via intratracheal instillation. The results show that the zymosan-induced pulmonary inflammatory responses were significantly reduced after the 9-d annealing period, which suggests that this inflammatory response was dependent on the conformation of zymosan. Freezing NaOH-treated zymosan (for 7 d) inhibited the annealing process. Exposure of rats to thawed preparations of zymosan resulted in the same inflammatory responses as the freshly prepared partially opened triple-helix zymosan. In contrast, the potency of untreated zymosan did not change significantly following a 7-d annealing period, indicating that annealing occurs only after the conformation has been modified by NaOH treatment. This study indicates that the partially opened triple helix of 1-->3-beta-glucans is more active than the closed conformation in inducing pulmonary inflammation in rats.
Dust-exposure; Dust-inhalation; Yeasts; Fungi; Breathing; Pulmonary-system-disorders; Waste-disposal; Sewage-treatment; Paper-mills; Microorganisms; Indoor-air-pollution; Indoor-environmental-quality
Shih-Houng Young, PhD, MB Research Lab, 1765 Wentz Road, PO Box 178, Spinnerstown, PA 18968
Journal of Toxicology and Environmental Health, Part A: Current Issues