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Published on: February 22, 2017
Modulatory effects of Salmonella LAP-LPS on murine macrophages
1Department of Microbiology, Punjab University, Chandigarh - 160 014, India.
Purpose:
To study the modulatory effects of Salmonella lipid associated protein - lipopolysaccharides (LAP-LPS) on murine macrophages as the intracellular survival within the host macrophages is an important feature for a number of gram-negative pathogens like S. typhi.
Methods:
Macrophage functions were studied in two groups of mice immunized with either LPS or LAP-LPS.
Results:
Comparison of protective efficacy of mice preimmunized with LPS based preparations, against challenge infectious doses, showed higher protection in LAP-LPS complex immunized mice group as compared to the mice group immunized with LPS alone. Aggregation of S. typhi cells was lesser with intestinal mucus extracted from LAP-LPS immunized mice as compared to LPS immunized challenged group. A significant increase in the number of macrophages in LAP-LPS immunized mice was also observed in comparison to control and LPS immunized mice groups. Nitric oxide (NO) and superoxide dismutase (SOD) production were also more in macrophages derived from LAP-LPS immunized mice group. Phagocytic uptake studies showed that there was enhanced uptake of bacteria in the LAP-LPS immunized animals in comparison to LPS immunized and controls. Similar trend was observed in intracellular killing of bacteria by the macrophages.
Conclusions:
The results indicated the involvement of protein moiety in LAP on modulation of effects of LPS on macrophages.
Insights
Salmonella lipid associated protein-lipopolysaccharides (LAP-LPS) enhance macrophage immune responses, including nitric oxide and superoxide dismutase production. This improved macrophage function offers greater protection against S. typhi infections compared to LPS alone.
Area of Science:
- Immunology
- Microbiology
- Bacteriology
Background:
- Intracellular survival of gram-negative pathogens like Salmonella typhi within host macrophages is a critical virulence factor.
- Lipopolysaccharides (LPS) are key components of the outer membrane of gram-negative bacteria, known to modulate immune responses.
- Salmonella lipid associated protein-lipopolysaccharides (LAP-LPS) represent a complex structure with potential immunomodulatory properties.
Purpose of the Study:
- To investigate the modulatory effects of Salmonella LAP-LPS on murine macrophage functions.
- To assess the role of the protein moiety within LAP-LPS in influencing LPS-mediated macrophage responses.
- To evaluate the protective efficacy of LAP-LPS immunization against S. typhi challenge.
Main Methods:
- Murine macrophages were studied in mice immunized with either LPS or LAP-LPS.
- Macrophage functions assessed included nitric oxide (NO) and superoxide dismutase (SOD) production, phagocytic uptake, and intracellular bacterial killing.
- Bacterial aggregation in intestinal mucus and overall protective efficacy against infectious challenge were compared between immunization groups.
Main Results:
- LAP-LPS immunization conferred higher protection against S. typhi challenge compared to LPS immunization alone.
- Macrophages from LAP-LPS immunized mice exhibited increased NO and SOD production, enhanced phagocytic uptake, and improved intracellular bacterial killing.
- LAP-LPS immunization led to a significant increase in macrophage numbers and reduced bacterial aggregation in intestinal mucus.
Conclusions:
- The protein component of LAP-LPS plays a significant role in modulating LPS effects on macrophages.
- LAP-LPS demonstrates superior immunomodulatory and protective capabilities compared to LPS alone.
- These findings highlight the potential of LAP-LPS as a vaccine candidate against Salmonella infections.
