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LBP, CD14, TLR4 and the murine innate immune response to a peritoneal Salmonella infection
M Bernheiden1, J M Heinrich, G Minigo
1Institut für Immunologie und Transfusionsmedizin, Universität Greifswald, Germany.
Abstract:
In mice, defense against an intraperitoneal Salmonella infection depends on a vigorous innate immune response. Mutations which lead to an inadequate early response to the pathogen thus identify genes involved in innate immunity. The best studied host resistance factor, NRAMP-1, is an endosomal membrane protein whose loss leads to an inability of the animals to hold the infection in check. However, innate defense against Salmonella is not restricted to mechanisms which directly attack the pathogen within macrophages. Here we have examined the contribution of the LBP, CD14 and TLR4 gene products to innate defense against Salmonella. To this end, we have generated mice which carry a wild-type allele of NRAMP-1, but which are deficient for the LBP, CD14 or TLR4 genes. Loss of any of these genes leads to a susceptibility to Salmonella as dramatic as that seen in animals lacking functional NRAMP-1 protein. This indicates that LBP, CD14 and TLR4 are all critical elements required in the proper induction of this innate defense system.
Insights
Mice lacking LBP, CD14, or TLR4 genes show severe susceptibility to Salmonella infection. These genes are crucial for the innate immune response, highlighting their importance in controlling bacterial infections.
Area of Science:
- Immunology
- Microbiology
- Genetics
Background:
- Innate immunity is vital for controlling Salmonella infections in mice.
- NRAMP-1 is a known host resistance factor, but other mechanisms contribute to defense.
- The roles of LBP, CD14, and TLR4 in Salmonella defense require further investigation.
Purpose of the Study:
- To investigate the contribution of LBP, CD14, and TLR4 gene products to innate defense against Salmonella.
- To determine if deficiencies in LBP, CD14, or TLR4 impact Salmonella susceptibility.
Main Methods:
- Generated mice deficient in LBP, CD14, or TLR4, while maintaining a wild-type NRAMP-1 allele.
- Assessed Salmonella infection susceptibility in these genetically modified mice.
Main Results:
- Mice lacking LBP, CD14, or TLR4 exhibited dramatic susceptibility to Salmonella.
- This susceptibility was comparable to that observed in mice lacking functional NRAMP-1.
- Loss of any of these genes critically impairs the innate immune response to Salmonella.
Conclusions:
- LBP, CD14, and TLR4 are essential components for inducing effective innate defense against Salmonella.
- These genes play a critical role in controlling intraperitoneal Salmonella infections in mice.