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Alterations in human red blood cell membrane properties induced by the lipopolysaccharide from Proteus mirabilis

Krzysztof Gwozdzinski1, Anna Pieniazek, Beata Sudak

  • 1Department of Molecular Biophysics, University of Lódz, Banacha 12, 90-237 Lodz, Poland. kgwozdz@biol.uni.lodz.pl

Chemico-Biological Interactions
|August 7, 2003
PubMed

Insights

Lipopolysaccharide (LPS) endotoxin from Proteus mirabilis alters red blood cell (RBC) membranes, increasing fluidity and protein mobility. This leads to increased osmotic fragility and loss of membrane integrity in RBCs.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Membrane Biophysics

Background:

  • Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria.
  • Bacterial endotoxins like LPS can induce significant physiological responses in host organisms.
  • Red blood cells (RBCs) are crucial for oxygen transport and their membrane integrity is vital.

Purpose of the Study:

  • To investigate the effects of lipopolysaccharide (LPS) from Proteus mirabilis on red blood cell (RBC) membrane properties.
  • To examine alterations in lipid membrane fluidity, protein conformation, and osmotic fragility upon LPS exposure.
  • To compare the impact of LPS on both intact RBCs and isolated RBC membranes.

Main Methods:

  • Electron paramagnetic resonance (EPR) spectroscopy using spin-labeled fatty acids (5-, 12-, 16-DS) to assess lipid membrane fluidity.
  • EPR spectroscopy with covalently bound spin labels (ISL) to evaluate membrane protein conformational changes.
  • Spectrophotometric methods to determine the osmotic fragility of RBCs.

Main Results:

  • LPS S1959 significantly increased RBC membrane fluidity, particularly in the deeper lipid bilayer regions (indicated by 12-DS).
  • LPS exposure led to decreased rotational correlation time of membrane proteins (ISL), suggesting increased mobility, especially in the spectrin-actin complex.
  • A significant increase in RBC osmotic fragility was observed at higher LPS concentrations.
  • The effects of LPS were more pronounced on isolated membranes compared to intact RBCs.

Conclusions:

  • LPS from Proteus mirabilis induces significant alterations in RBC membrane lipid and protein dynamics.
  • These LPS-induced changes compromise the structural integrity of the RBC membrane, leading to increased fragility.
  • The findings highlight the potential of bacterial endotoxins to disrupt cellular membrane functions.

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