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Updated: Sep 16, 2025
High-throughput Assay to Phenotype Salmonella enterica Typhimurium Association, Invasion, and Replication in Macrophages
Published on: August 11, 2014
Characterize febrile temperature dependency of anti-infection pathways in Salmonella-infected mouse macrophages
Zhaojun Xu1, Yefei Zhan1, Qifa Song2
1Department of Intensive Care Unit, Ningbo No. 2 Hospital, Ningbo, Zhejiang Province, China.
Abstract:
The influence of fever on the initiation phase of anti-infection immune responses, which involve mainly macrophages, has not been well studied. RAW264.7 macrophages were inoculated with Salmonella Typhimurium (STm), which was subsequently stained with carboxyfluorescein succinimidyl ester. Upon culture at various febrile temperatures, RNA sequencing identified 18 temperature-independent pathways that were activated at 37-40 °C and responsible for cell death, PAMP receptors, and the synthesis of effector proteins, as well as eight high temperature-dependent pathways that were activated only at 38-40 °C and responsible for endocytosis, cell killing, and cell interactions. The FCM analysis indicated that when weighed against potentially much more severe side effects from 40 to 41 °C, reasonably high bactericidal activity was achieved at 38-39 °C in macrophages. Our findings provide essential knowledge about fever control treatment in terms of basic immune and metabolic pathways.
Insights
Fever enhances macrophage anti-infection responses by activating specific immune pathways. Temperatures between 38-39°C show significant bacterial killing activity in macrophages without severe side effects.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- The role of fever in initiating anti-infection immune responses, particularly in macrophages, remains under-investigated.
- Fever is a common physiological response to infection, but its precise impact on cellular immunity requires further elucidation.
Purpose of the Study:
- To investigate the influence of febrile temperatures on macrophage anti-infection immune responses.
- To identify temperature-dependent and independent pathways activated in macrophages during Salmonella Typhimurium infection.
Main Methods:
- RAW264.7 macrophages were infected with Salmonella Typhimurium (STm).
- RNA sequencing was performed on macrophages cultured at various temperatures (37-40°C).
- Flow cytometry analysis (FCM) assessed bactericidal activity at different temperatures.
Main Results:
- 18 temperature-independent pathways (37-40°C) involved in cell death, PAMP receptors, and effector protein synthesis were identified.
- Eight high temperature-dependent pathways (38-40°C) related to endocytosis, cell killing, and cell interactions were activated.
- Optimal bactericidal activity against STm in macrophages was observed at 38-39°C, with fewer side effects compared to higher temperatures.
Conclusions:
- Febrile temperatures modulate macrophage immune responses through distinct temperature-dependent and independent pathways.
- Moderate fever (38-39°C) enhances macrophage bactericidal activity against Salmonella Typhimurium.
- Findings offer insights into fever control strategies by highlighting the impact on innate immune pathways.
