Microglial heterogeneity in chronic pain.

Area of Science:

• Neuroscience
• Immunology
• Genetics

Background:

• Microglia, the primary immune cells of the central nervous system (CNS), play crucial roles in brain health and disease.
• Recent transcriptomic analyses have significantly advanced the characterization of disease-associated microglia (DAM) in both mice and humans.
• Sex and CNS compartment influence microglia functions in health, with peripheral nerve injury inducing specific microglial gene expression patterns.

Purpose of the Study:

• To review preclinical evidence on how the CNS compartment and sex affect microglia functions in health.
• To explore the potential for unique microglia transcriptional profiles associated with chronic pain conditions.
• To discuss the role of microglial activation in neuropathic pain models and its relevance to chronic pain patients.

Main Methods:

• Review of existing preclinical evidence on microglia function.
• Analysis of transcriptomic data characterizing disease-associated microglia.
• Examination of gene expression in microglia following peripheral nerve injury.
• Correlation of findings with neuroimaging studies in chronic pain patients.

Main Results:

• Sex and CNS compartment significantly influence microglia functions.
• Peripheral nerve injury induces a specific subset of gene expression in spinal cord microglia.
• Microglial activation is observed in pain-related brain areas in neuropathic pain models, consistent with human neuroimaging data.

Conclusions:

• Future research should investigate unique microglia transcriptional profiles in chronic pain.
• Novel approaches like scRNA-seq, spatial transcriptomics, CYTOF, and electron microscopy are essential for a comprehensive characterization of microglia in chronic pain.
• Understanding neuroimmune interactions, particularly microglia's role, is critical for advancing chronic pain research.