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Effects of human apolipoprotein A-I on endotoxin-induced leukocyte adhesion on endothelial cells in vivo and on the growth of Escherichia coli in vitroInterdepartment of Physiology, Graduate School and Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
Department of Medicine, Chulalongkorn University, Bangkok, Thailand
Department of Medicine, Chulalongkorn University, Bangkok, Thailand
Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
Department of Medicine, Faculty of Medicine, Chulalongkorn University, Samakkee Payaban, King Chulalongkorn Memorial Hospital, Patumwan, Bangkok, Thailand , fmedwkv{at}md.chula.ac.th, Weerapan.K{at}chula.ac.th Background: High-density lipoprotein (HDL) has been shown to inhibit leukocyte adhesion to endothelial cells induced by endotoxin in vivo and suppress the growth of bacteria in vitro; however, the components responsible for these effects, either lipids or proteins, are not yet defined. In this study, we examined the effects of apolipoprotein (apo) A-I, the major protein of HDL, on ameliorating the effect of endotoxin and inhibiting the growth of bacteria. Materials and Methods: Apo A-I, purified from normal human HDL, was incubated with endotoxin. Leukocyte adhesion to endothelial cells of rat mesenteric venules was assessed using intravital fluorescence microscopy. Ability of apo A-I to inhibit the growth of Escherichia coli was assessed using a spread plate method. Results: Purified, lipid-free apo A-I could inhibit endotoxin-induced leukocyte adhesion to endothelial cells in vivo in a dose-dependent manner. In addition, apoA-I was able to suppress the growth of Escherichia coli in vitro. Conclusions: These data suggest that apo A-I of HDL can directly interact with endotoxin, ameliorating its effect and that apo A-I may have a direct toxic effect on whole bacteria. Therefore, therapeutic use of apo A-I in septicemia and bacterial infection should be further explored.
Key Words: Apolipoprotein A-I bacteria endothelial cells endotoxin high-density lipoprotein
Journal of Endotoxin Research, Vol. 13, No. 1,
58-64 (2007) |
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