title: Lipopolysaccharide-induced hemolysis: Evidence for direct membrane interactions.
abstract: While hemolysis in patients with sepsis is associated with increased mortality its mechanisms are unknown and Toll-like receptor (TLR)-4 mediated effects, complement-mediated hemolysis, or direct cell membrane effects are all conceivable mechanisms. In this study, we tested the hypotheses that toxic lipopolysaccharide (LPS) as well as non-toxic RS-LPS evokes hemolysis (1) by direct membrane effects, and (2) independent of the complement system and TLR-4 activation. We found, that incubation with LPS resulted in a marked time and concentration dependent increase of free hemoglobin concentration and LDH activity in whole blood and washed red cells. Red cell integrity was diminished as shown by decreased osmotic resistance, formation of schistocytes and rolls, and a decrease in red cell membrane stiffness. Non-toxic RS-LPS inhibited the LPS-evoked increase in TNF-α concentration demonstrating its TLR-4 antagonism, but augmented LPS-induced increase in supernatant hemoglobin concentration and membrane disturbances. Removal of plasma components in washed red cell assays failed to attenuate hemolysis. In summary, this study demonstrates direct physicochemical interactions of LPS with red cell membranes resulting in hemolysis under in vitro conditions. It might thus be hypothesized, that not all effects of LPS are mediated by TLR and may explain LPS toxicity in cells missing TLR.
authors.affiliation: Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.|Institut für Physiologische Chemie, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Brauckmann
authors.affiliation: Institut für Physiologische Chemie, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Effenberger-Neidnicht
authors.affiliation: Institut für Physiologische Chemie, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: de Groot
authors.affiliation: Institut für Physikalische Chemie, Universität Duisburg-Essen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nagel
authors.affiliation: Institut für Physikalische Chemie, Universität Duisburg-Essen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Mayer
authors.affiliation: Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Peters
authors.affiliation: Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hartmann
mesh_terms: D000743:Anemia, Hemolytic / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D018805:Sepsis / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D006454:Hemoglobins; D008070:Lipopolysaccharides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D003165:Complement System Proteins; D007770:L-Lactate Dehydrogenase