Inhibition of lipopolysaccharide-induced macrophage tumor necrosis factor-alpha synthesis by polymyxin B sulfate.
The antibiotic polymyxin B sulfate is a cationic polypeptide with a unique cyclical configuration and distinct cationic characteristics. In this investigation, polymyxin B was evaluated to determine its ability to prevent synthesis of lactic acid and tumor necrosis factor-alpha (TNF-alpha) by lipopolysaccharide-stimulated strain RAW 264.7 macrophage-like cell populations. In this context, gradient concentrations of polymyxin B were formulated in the presence of fixed concentrations of lipopolysaccharide fractions from Escherichia coli (B4:0111), E coli (J5), Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella minnesota, and S typhimurium (Re). Quantitation of TNF-alpha was established by the application of a tissue culture-based biological assay system, using the WEHI 164 clone 13 indicator cell line. Investigations also included evaluation of the ability of gradient concentrations of lipopolysaccharide fractions from E coli (B4:0111), E coli (J5), K pneumoniae, P aeruginosa, S minnesota, and S typhimurium (Re) to form a complex with polymyxin B. This was established through application of high-performance thin-layer chromatography techniques. On the basis of the known molecular characteristics of lipopolysaccharide, its lipid A-core subfractions, and polymyxin B, these results imply that cytoprotective properties of polymyxin B are attributable to direct interaction and subsequent complex formation. More specifically, the mechanism by which polymyxin B exerts affinity for lipopolysaccharide fractions is proposed to occur through attractive ionic interactions established between the cationic diaminobutyric acid residues of polymyxin B and the mono- or diphosphate group(s) of the lipid A-core moiety. It is highly probable that this molecular phenomenon is accompanied by hydrophobic interactions established between the terminal methyloctanoyl or methylheptanoyl groups of polymyxin B and the saturated carbon chains of the lipid A-core subfraction of lipopolysaccharide fractions.
Coyne
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CP
Department of Clinical Science, College of Veterinary Medicine, Kansas State University, Manhattan 66502.
Fenwick
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BW
D000818:Animals; D002855:Chromatography, Thin Layer / Q000379:methods; D066298:In Vitro Techniques; D007773:Lactates / Q000096:biosynthesis*; D019344:Lactic Acid; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D011112:Polymyxin B / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000187:drug effects*
D007773:Lactates; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D019344:Lactic Acid; D011112:Polymyxin B