IL4-driven microglia modulate stress resilience through BDNF-dependent neurogenesis

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Adult neurogenesis in the hippocampus is crucial for stress response.
• The precise role of microglia in hippocampal neurogenesis and stress resilience is not fully understood.

Purpose of the Study:

• To investigate the function of specific microglia phenotypes in regulating hippocampal neurogenesis and stress resilience.
• To explore the therapeutic potential of modulating microglial activity for mood disorders.

Main Methods:

• Identification of interleukin 4 (IL4)-driven microglia expressing Arg1.
• Manipulation of Arg1+ microglia levels in the hippocampus via IL4 receptor (IL4R) knockdown or enhancement.
• Assessment of hippocampal neurogenesis and behavioral responses to stress.
• Investigation of the role of brain-derived neurotrophic factor (BDNF).

Main Results:

• IL4-driven microglia expressing Arg1 are critical for maintaining hippocampal neurogenesis and stress resistance.
• Reducing Arg1+ microglia suppressed neurogenesis and increased stress vulnerability.
• Enhancing IL4 signaling and Arg1+ microglia restored neurogenesis and stress resilience.
• BDNF was essential for the pro-neurogenic effects of IL4-driven microglia.

Conclusions:

• IL4-driven microglia promote BDNF-dependent hippocampal neurogenesis in response to chronic stress, conferring resilience to depressive-like symptoms.
• Targeting this specific microglial phenotype presents a novel therapeutic avenue for mood disorders.