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Schromm AB, Brandenburg K, Loppnow H, Zähringer U, Rietschel ET, Carroll SF, Koch MHJ, Kusumoto S, Seydel U. The Charge of Endotoxin Molecules Influences Their Conformation and IL-6-Inducing Capacity. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.10.5464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The activation of cells by endotoxin (LPS) is one of the early host responses to infections with Gram-negative bacteria. The lipid A part of LPS molecules is known to represent the endotoxic principle; however, the specific requirements for the expression of biologic activity are still not fully understood. We previously found that a specific molecular conformation (endotoxic conformation) is a prerequisite for lipid A to be biologically active. In this study, we have investigated the interdependence of molecular charge and conformation of natural and chemically modified LPS and lipid A and its transport and intercalation into phospholipid membranes mediated by human LPS-binding protein, as well as IL-6 production after stimulation of whole blood or PBMCs. We found that the number, nature, and location of negative charges strongly modulate the molecular conformation of endotoxin. In addition, the LPS-binding protein-mediated transport of LPS into phospholipid membranes depends on the presence of net negative charge, yet charge is only a necessary, but not a sufficient, prerequisite for transport and intercalation. The biologic activity is determined mainly by the molecular conformation: only conical molecules are highly biologically active, whereas cylindrical ones are largely inactive. We could demonstrate that the net negative charge of the lipid A component and its distribution within the hydrophilic headgroup strongly influence the molecular conformation and, therefore, also the biologic activity.
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Affiliation(s)
- Andra B. Schromm
- *Research Center Borstel, Center for Medicine and Biosciences, Department of Immunochemistry and Biochemical Microbiology, Borstel, Germany
| | - Klaus Brandenburg
- *Research Center Borstel, Center for Medicine and Biosciences, Department of Immunochemistry and Biochemical Microbiology, Borstel, Germany
| | - Harald Loppnow
- †Martin-Luther-Universität Halle-Wittenberg, Kardiologische Intensivmedizin, Forschungslabor, Halle (Saale), Germany
| | - Ulrich Zähringer
- *Research Center Borstel, Center for Medicine and Biosciences, Department of Immunochemistry and Biochemical Microbiology, Borstel, Germany
| | - Ernst Th. Rietschel
- *Research Center Borstel, Center for Medicine and Biosciences, Department of Immunochemistry and Biochemical Microbiology, Borstel, Germany
| | | | - Michel H. J. Koch
- §European Molecular Biology Laboratory c/o DESY, Hamburg, Germany; and
| | - Shoichi Kusumoto
- ¶Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Ulrich Seydel
- *Research Center Borstel, Center for Medicine and Biosciences, Department of Immunochemistry and Biochemical Microbiology, Borstel, Germany
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