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Tumor necrosis factor-inducing activities of lipid A preparations from Pseudomonas diminuta and Pseudomonas
S Arata1, K Nakaya, H Furuhashi
1Department of Microbial Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo.
Abstract:
Tumor necrosis factor (TNF)-inducing activities of lipid A preparations from P. diminuta and P. vesicularis, which contain mainly 2 mol of 2,3-diamino-2,3-dideoxy-D-glucose and 1 mol of nonglycosidic phosphate as the backbone component and have partly different fatty acid compositions, were examined. TNF was induced by injecting various lipid A fractions into mice that had previously been sensitized with Mycobacterium bovis BCG vaccine. A major component of lipid A of both strains, referred to as A3 fraction, exhibited stronger TNF-inducing activity than A2 fraction having incomplete acyl residues. The removal of ester-linked fatty acyl groups by mild hydrazinolysis of the P. diminuta lipid A results in a marked decrease of the activity. These results suggest that the structure of the hydrophobic part, including the amide-linked acyloxyacyl group(s), of the lipid A molecule play an important role in inducing TNF in the sera of mice.
Insights
Lipid A structure significantly influences tumor necrosis factor (TNF) induction. Specific fatty acid components, particularly the hydrophobic part, are crucial for potent TNF-inducing activity in mice.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Lipid A is a key component of lipopolysaccharides in Gram-negative bacteria.
- Lipid A structure varies among bacterial species and influences biological activities.
- Tumor necrosis factor (TNF) is a critical cytokine involved in inflammation and immune responses.
Purpose of the Study:
- To investigate the TNF-inducing activities of lipid A from P. diminuta and P. vesicularis.
- To determine the role of lipid A's fatty acid composition in TNF induction.
- To compare the TNF-inducing potential of different lipid A fractions.
Main Methods:
- Lipid A preparations from P. diminuta and P. vesicularis were analyzed.
- Fractions were injected into Mycobacterium bovis BCG-sensitized mice to induce TNF.
- Mild hydrazinolysis was used to remove ester-linked fatty acyl groups.
Main Results:
- The A3 fraction of lipid A, a major component, showed stronger TNF induction than the A2 fraction.
- Removal of ester-linked fatty acyl groups from P. diminuta lipid A significantly reduced its TNF-inducing activity.
- Variations in fatty acid composition impacted TNF induction efficacy.
Conclusions:
- The hydrophobic portion of lipid A, including acyloxyacyl groups, is vital for TNF induction.
- Specific structural features of lipid A dictate its immunomodulatory properties.
- Understanding lipid A structure-activity relationships is important for immune response modulation.