Phase specific suppression of neutrophil function in hibernating Syrian hamster

Area of Science:

• Immunology
• Physiology
• Hibernation Biology

Background:

• Hibernation involves cycles of torpor and arousal, with reduced innate immune function during hibernation.
• Mechanisms underlying suppressed immune function during hibernation remain unclear.

Purpose of the Study:

• To investigate neutrophil functionality during hibernation in Syrian hamsters.
• To understand how hibernation affects the innate immune response to endotoxemia.

Main Methods:

• Studied neutrophil function in Syrian hamsters during hibernation and arousal.
• Assessed inflammatory response to lipopolysaccharide (LPS)-induced endotoxemia.
• Analyzed neutrophil pathogen binding, phagocytosis, and oxidative burst.
• Investigated the role of plasma factors in modulating neutrophil activity.

Main Results:

• The inflammatory response to LPS was inhibited during hibernation, partly due to reduced interleukin-6 (IL-6) production during early arousal.
• Neutrophil pathogen binding, phagocytosis, and oxidative burst were significantly reduced in early arousal.
• Neutrophil function was repressed in plasma from early arousal but restored by summer euthermic plasma, indicating an inhibitory plasma factor.

Conclusions:

• A plasma factor present during early arousal inhibits toll-like receptor (TLR) recognition and neutrophil function.
• Identifying this factor could lead to new therapeutic strategies for inflammatory and autoimmune diseases.