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Updated: May 21, 2025
Rat Model of Widespread Cerebral Cortical Demyelination Induced by an Intracerebral Injection of Pro-Inflammatory Cytokines
Published on: September 21, 2021
Dicer deficiency affects microglial function during demyelination and impairs remyelination
Ajai Tripathi1, Nagendra Kumar Rai1, Aaron Perles1
1Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA.
Abstract:
Microglia are essential regulators of central nervous system (CNS) homeostasis, playing key roles in demyelination and remyelination. Dysregulated microglial activity contributes to pathological inflammation and impaired repair processes in demyelinating diseases. Here, we investigate the role of Dicer1, a critical enzyme in microRNA biogenesis, in affecting microglial function, demyelination, and remyelination. Loss of Dicer1 in microglia resulted in amplified inflammatory responses, defective myelin debris clearance, and disruption of metabolic homeostasis, leading to exacerbated demyelination and delayed remyelination. Transcriptomic analysis revealed significant upregulation of inflammatory pathways, including interferon signaling and JAK/STAT activation, alongside a loss of homeostatic microglial gene expression. Protein-level validation confirmed sustained secretion of pro-inflammatory cytokines such as IFN-γ, IL-16, and CXCL12, creating a chronic inflammatory environment that impaired remyelination. Furthermore, Dicer1-deficient microglia failed to support oligodendrocyte progenitor cells (OPCs) differentiation/maturation, with increased apoptosis of mature oligodendrocytes (OLs), contributing to remyelination failure. These findings identify Dicer1 as a critical regulator of microglial homeostasis and inflammation resolution, highlighting its potential as a therapeutic target to mitigate inflammation and promote repair in demyelinating diseases.
Insights
Loss of Dicer1 in microglia amplifies inflammation and impairs myelin repair in demyelinating diseases. This highlights Dicer1 as a potential therapeutic target for promoting central nervous system repair.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Microglia are crucial for central nervous system (CNS) homeostasis and repair in demyelinating diseases.
- Dysregulated microglial function exacerbates inflammation and hinders repair in conditions like multiple sclerosis.
Purpose of the Study:
- To investigate the role of Dicer1, essential for microRNA biogenesis, in microglial function during demyelination and remyelination.
- To understand how Dicer1 deficiency impacts inflammatory responses, debris clearance, and oligodendrocyte support.
Main Methods:
- Utilized Dicer1-deficient microglia models.
- Performed transcriptomic analysis to identify affected pathways.
- Validated protein secretion and cellular interactions.
- Assessed effects on oligodendrocyte progenitor cell (OPC) differentiation and oligodendrocyte (OL) survival.
Main Results:
- Dicer1 deficiency in microglia led to heightened inflammation, impaired myelin debris clearance, and disrupted metabolic homeostasis.
- Transcriptomics revealed upregulated inflammatory pathways (interferon signaling, JAK/STAT) and reduced homeostatic gene expression.
- Dicer1-deficient microglia secreted increased pro-inflammatory cytokines (IFN-γ, IL-16, CXCL12), hindering remyelination.
- Failure to support OPC differentiation and increased mature OL apoptosis contributed to remyelination failure.
Conclusions:
- Dicer1 is a critical regulator of microglial homeostasis and inflammation resolution in the CNS.
- Dicer1 deficiency exacerbates demyelination and delays remyelination by promoting chronic inflammation and impairing oligodendrocyte support.
- Targeting Dicer1 in microglia offers a potential therapeutic strategy for demyelinating diseases.
