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Augmentation of host defense against bacterial infection pretreated intraperitoneally with an alpha-glucan RBS in
1Department of Immunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
Abstract:
Protection against Listeria monocytogenes and Escherichia coli in mice was enhanced by an intraperitoneal (i.p.) administration of polysaccharide "RBS". Peritoneal macrophages from mice administered i.p. with 30 mg/kg doses of RBS 4 days earlier exhibited increased scavenger functions as assessed by in vivo phagocytosis, in vitro intracellular killing and generation of superoxide anion. When cytokine production of the macrophages was assessed by biological assay and Northern blotting analysis, interleukin (IL)-1 production and IL-1 alpha gene expression were significantly increased in macrophages from RBS-treated mice. On the other hand, tumor necrosis factor (TNF) alpha gene was expressed in macrophages from RBS-treated mice at a much reduced level as compared with those in mice treated i.p. with Corynebacterium parvum on 4 days earlier. In correlation with expression of TNF gene in the macrophages, RBS-treated mice were less susceptible to the lethal toxicity of LPS than C.parvum-treated mice. In RBS-treated mice, in vivo elimination of bacteria was enhanced at the early phase of infection with L.monocytogenes or E.coli, resulting in augmentation of host defense against these bacterial infection. These results suggest that adequately enhanced activities of macrophages acting as scavenger phagocytes play important roles in the enhanced resistance against bacteria in mice treated i.p. with RBS.
Insights
Polysaccharide RBS enhances protection against bacterial infections in mice by boosting macrophage scavenger functions. This immune enhancement improves resistance to Listeria monocytogenes and Escherichia coli.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Bacterial infections pose significant health risks.
- Enhancing host immune responses is crucial for combating pathogens.
- Macrophages play a key role in innate immunity against bacterial infections.
Purpose of the Study:
- To investigate the immunomodulatory effects of polysaccharide RBS.
- To assess the impact of RBS on macrophage function and host defense.
- To evaluate protection against Listeria monocytogenes and Escherichia coli infections.
Main Methods:
- Administration of polysaccharide RBS intraperitoneally in mice.
- Assessment of peritoneal macrophage scavenger functions (phagocytosis, intracellular killing, superoxide anion generation).
- Analysis of cytokine production (IL-1, TNF-alpha) using biological assays and Northern blotting.
Main Results:
- RBS treatment significantly increased macrophage scavenger functions.
- Interleukin-1 production and IL-1 alpha gene expression were elevated.
- Tumor necrosis factor-alpha gene expression was reduced compared to Corynebacterium parvum.
- RBS-treated mice showed enhanced elimination of L. monocytogenes and E. coli.
- RBS-treated mice exhibited reduced susceptibility to LPS toxicity.
Conclusions:
- Polysaccharide RBS enhances host defense against bacterial infections.
- Improved macrophage scavenger activity is a key mechanism of RBS action.
- RBS demonstrates potential as an immunomodulatory agent for infectious diseases.