The microbiota-microglia axis in central nervous system disorders
Omar Mossad1,2, Daniel Erny1
1Institute of Neuropathology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Abstract:
The innate immune system in the central nervous system (CNS) is mainly represented by specialized tissue-resident macrophages, called microglia. In the past years, various species-, host- and tissue-specific as well as environmental factors were recognized that essentially affect microglial properties and functions in the healthy and diseased brain. Host microbiota are mostly residing in the gut and contribute to microglial activation states, for example, via short-chain fatty acids (SCFAs) or aryl hydrocarbon receptor (AhR) ligands. Thereby, the gut microorganisms are deemed to influence numerous CNS diseases mediated by microglia. In this review, we summarize recent findings of the interaction between the host microbiota and the CNS in health and disease, where we specifically highlight the resident gut microbiota as a crucial environmental factor for microglial function as what we coin "the microbiota-microglia axis."
Insights
The gut microbiota influences central nervous system (CNS) health by modulating microglia, the brain's immune cells. This review explores the microbiota-microglia axis, highlighting gut microbes' role in CNS diseases.
Area of Science:
- Neuroimmunology
- Microbiology
- Central Nervous System (CNS) Research
Background:
- Microglia are the primary immune cells in the CNS, crucial for brain health and disease.
- Microglial function is influenced by various factors, including host and environmental elements.
- The gut microbiota, residing in the digestive system, significantly impacts host physiology.
Purpose of the Study:
- To review the intricate relationship between the host microbiota and the CNS.
- To highlight the role of gut microbiota in modulating microglial function in both health and disease.
- To introduce and define the concept of the "microbiota-microglia axis."
Main Methods:
- Literature review of recent findings on microbiota-CNS interactions.
- Analysis of studies investigating microglial responses to microbial metabolites like short-chain fatty acids (SCFAs) and aryl hydrocarbon receptor (AhR) ligands.
- Synthesis of evidence linking gut microbial composition to CNS conditions.
Main Results:
- Gut microbiota composition and metabolites (e.g., SCFAs, AhR ligands) directly influence microglial activation states and functions.
- The gut microbiota acts as a critical environmental factor shaping microglial properties in the CNS.
- Dysbiosis or alterations in gut microbiota are implicated in the pathogenesis of various CNS diseases.
Conclusions:
- The gut microbiota plays a pivotal role in regulating microglial function, establishing the "microbiota-microglia axis."
- Understanding this axis is crucial for developing novel therapeutic strategies for CNS disorders.
- Targeting the gut microbiota may offer a promising avenue for managing neuroinflammatory and neurodegenerative diseases.
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