Exploring the Role of Microglial Cells in the Gut-Brain Axis Communication: A Systematic Review

Area of Science:

• Neuroscience
• Immunology
• Microbiology

Background:

• The gut-brain axis (GBA) is a bidirectional communication pathway critical for neurological health.
• Microglia, the brain's immune cells, regulate neuroinflammation and synaptic plasticity.
• Gut microbiota's influence on microglial activity is implicated in various neurological disorders, but mechanisms are unclear.

Purpose of the Study:

• To systematically review preclinical studies on microbiota-microglia interactions.
• To synthesize evidence on how gut microbiota alterations affect microglial function and neuroinflammation.
• To explore the therapeutic potential of microbiota-based interventions for brain health.

Main Methods:

• Systematic literature search of 4481 studies across PubMed, Science Direct, and Google Scholar.
• In-depth review of 20 preclinical studies meeting inclusion criteria.
• Analysis of experimental models including fecal microbiota transplantation, dietary changes, and bacterial supplementation.

Main Results:

• Gut dysbiosis is linked to microglial overactivation and neuroinflammation via microbial metabolites (e.g., SCFAs) and signaling pathways (e.g., TLR4/NF-κB).
• Microbiota-targeted interventions demonstrated potential in reducing neuroinflammation and improving cognitive function.
• Inconsistencies in methodologies and microbiota analysis across studies pose challenges for clinical translation.

Conclusions:

• Gut microbiota significantly impacts microglial states and neuroinflammatory signatures.
• Targeting the gut microbiota presents a promising therapeutic avenue for neuroinflammatory diseases.
• Further standardization of research methods is needed to advance clinical applications.