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Molecular Characterization of Lipopolysaccharide Binding to Human α-1-Acid Glycoprotein.

Huang JX, Azad MA, Yuriev E, Baker MA, Nation RL, Li J, Cooper MA, Velkov T - J Lipids (2012)

Bottom Line: The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules.In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants.The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP.

View Article: PubMed Central - PubMed

Affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia.

ABSTRACT
The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules. Here, for the first time we have characterized human AGP binding characteristics of the LPS from a number of pathogenic Gram-negative bacteria: Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Pseudomonas aeruginosa, and Serratia marcescens. The binding affinity and structure activity relationships (SAR) of the AGP-LPS interactions were characterized by surface plasma resonance (SPR). In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants. The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP. Together, these data are consistent with the role of AGP in the binding and transport of LPS in plasma during acute-phase inflammatory responses to invading Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus

The protective effect of AGP against LPS-induced cytotoxicity in HEK293 cell culture. (a) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O127:B8 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O127:B8 LPS, in the presence and absence of AGP. (b) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O111:B4 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O111:B4 LPS, in the presence and absence of AGP. The inset table documents the IC50 values for LPS in the presence of increasing AGP levels.
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fig5: The protective effect of AGP against LPS-induced cytotoxicity in HEK293 cell culture. (a) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O127:B8 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O127:B8 LPS, in the presence and absence of AGP. (b) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O111:B4 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O111:B4 LPS, in the presence and absence of AGP. The inset table documents the IC50 values for LPS in the presence of increasing AGP levels.

Mentions: In order to investigate the protective effect of AGP on mammalian cells in the present of LPS, we performed a cell viability assay using HEK293 cells. The exposure of HEK293 cells to 100 μg/mL E. coli O111:B4 LPS induced more than 80% cell death with an IC50 value of 89.7 μg/mL (Figure 5). Similar results were observed with E. coli O127:B8 LPS which elicited an IC50 value of 71.4 μg/mL (Figure 5). The cytotoxic effect of LPS could be ameliorated in a concentration-dependent manner by AGP (Figure 5). In the presence of 1 mg/mL AGP, which is approximately equivalent to the human plasma concentration of AGP in healthy individuals (20 μM) [14, 49, 50], 80% of the HEK293 cells retained viability after a 24 hr incubation with 100 μg/mL E. coli O111:B4 LPS (Figure 5). The IC50 values for both LPS samples decreased in the presence of 1 mg/mL AGP, indicative of a protective effect (Figure 5, insets).


Molecular Characterization of Lipopolysaccharide Binding to Human α-1-Acid Glycoprotein.

Huang JX, Azad MA, Yuriev E, Baker MA, Nation RL, Li J, Cooper MA, Velkov T - J Lipids (2012)

The protective effect of AGP against LPS-induced cytotoxicity in HEK293 cell culture. (a) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O127:B8 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O127:B8 LPS, in the presence and absence of AGP. (b) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O111:B4 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O111:B4 LPS, in the presence and absence of AGP. The inset table documents the IC50 values for LPS in the presence of increasing AGP levels.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig5: The protective effect of AGP against LPS-induced cytotoxicity in HEK293 cell culture. (a) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O127:B8 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O127:B8 LPS, in the presence and absence of AGP. (b) Top panel. The percentage of cell growth in the presence of increasing concentrations of E. coli O111:B4 LPS. (○) 0 mg/mL AGP; (■) 0.2 mg/mL AGP; (▲) 1 mg/mL AGP. Bottom panel. The percentage of cell viability upon exposure to 100 μg/mL E. coli O111:B4 LPS, in the presence and absence of AGP. The inset table documents the IC50 values for LPS in the presence of increasing AGP levels.
Mentions: In order to investigate the protective effect of AGP on mammalian cells in the present of LPS, we performed a cell viability assay using HEK293 cells. The exposure of HEK293 cells to 100 μg/mL E. coli O111:B4 LPS induced more than 80% cell death with an IC50 value of 89.7 μg/mL (Figure 5). Similar results were observed with E. coli O127:B8 LPS which elicited an IC50 value of 71.4 μg/mL (Figure 5). The cytotoxic effect of LPS could be ameliorated in a concentration-dependent manner by AGP (Figure 5). In the presence of 1 mg/mL AGP, which is approximately equivalent to the human plasma concentration of AGP in healthy individuals (20 μM) [14, 49, 50], 80% of the HEK293 cells retained viability after a 24 hr incubation with 100 μg/mL E. coli O111:B4 LPS (Figure 5). The IC50 values for both LPS samples decreased in the presence of 1 mg/mL AGP, indicative of a protective effect (Figure 5, insets).

Bottom Line: The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules.In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants.The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP.

View Article: PubMed Central - PubMed

Affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia.

ABSTRACT
The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules. Here, for the first time we have characterized human AGP binding characteristics of the LPS from a number of pathogenic Gram-negative bacteria: Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Pseudomonas aeruginosa, and Serratia marcescens. The binding affinity and structure activity relationships (SAR) of the AGP-LPS interactions were characterized by surface plasma resonance (SPR). In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants. The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP. Together, these data are consistent with the role of AGP in the binding and transport of LPS in plasma during acute-phase inflammatory responses to invading Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus