PMID: 8944708Nov 1, 1996Paper

Endocytosis and Ca2+ are required for endotoxin-stimulated TNF-alpha release by rat Kupffer cells

The American Journal of Physiology
S N LichtmanJ J Lemasters

Abstract

Endotoxin [lipopolysaccharide (LPS)] is a cell wall polymer derived from Gram-negative bacteria that stimulates macrophages to produce a variety of inflammatory mediators. In these studies, we examined LPS-stimulated formation of tumor necrosis factor-alpha (TNF-alpha) by cultured rat Kupffer cells. Cytochalasin B and methylpalmitate, blockers of endocytosis, decreased LPS-stimulated TNF-alpha release by > 92%. Bafilomycin A, monensin, and chloroquine, which prevent endosomal acidification, also blocked LPS-stimulated release of TNF-alpha by > 90%. Cytochalasin B and bafilomycin A decreased TNF-alpha mRNA levels by > 90% after LPS stimulation. Consistent with the requirement for LPS uptake and processing was the observation that Kupffer cells required 30 min of contact with LPS for maximal TNF-alpha release. LPS-stimulated TNF-alpha release was unaltered by incubation in Ca(2+)-free ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid medium, and A-23187, a Ca2+ ionophore, failed to stimulate TNF-alpha release in the absence of LPS. However, nisoldipine, a Ca2+ channel blocker, suppressed LPS-stimulated TNF-alpha release in cells cultured both in Ca(2+)-containing and Ca(2+)-free media. Although thapsigargin di...Continue Reading

Citations

Aug 16, 2002·American Journal of Physiology. Gastrointestinal and Liver Physiology·Grace L SuStewart C Wang
May 12, 2004·American Journal of Physiology. Lung Cellular and Molecular Physiology·Frank AntonicelliWilliam MacNee
Jul 18, 2002·American Journal of Physiology. Gastrointestinal and Liver Physiology·Grace L Su

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