The neuronal-like behaviour of macrophages

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• Tissue-resident macrophages (TRMs) are plastic immune cells involved in organ physiology and pathology.
• Macrophages communicate with nervous system and tissue-resident cells, exhibiting diverse molecular and functional roles.
• Recent findings reveal macrophages near muscle spindles, sensory neurons that detect muscle length.

Purpose of the Study:

• To discuss potential roles of muscle spindle macrophages in muscle contraction and locomotion.
• To explore their functions during homeostasis and in disease states.
• To debate the broader implications of neurotransmitter use by myeloid cells in cell communication, neural development, and repair.

Main Methods:

• This study is a discussion and debate based on existing literature and recent findings.
• It involves analyzing gene expression signatures and functional roles of specific macrophage populations.
• The discussion focuses on cell-to-cell communication mechanisms involving neurotransmitters.

Main Results:

• Muscle spindle macrophages display neuron-like gene expression signatures.
• These macrophages release glutamate, a neurotransmitter, to support muscle contraction.
• This function deviates from classical immune cell roles, resembling neuronal activity.

Conclusions:

• Muscle spindle macrophages play a unique role in muscle function through neurotransmitter release.
• The use of neurotransmitters by myeloid cells may be a common mechanism for optimizing cell communication.
• This highlights a potential paradigm shift in understanding immune cell interactions with the nervous system for tissue homeostasis and repair.