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Updated: Nov 24, 2025
Assessing Microglial Phagocytosis of Myelin Debris in vitro Under Repeated Magnetic Stimulation
Published on: June 17, 2025
Microglia facilitate repair of demyelinated lesions via post-squalene sterol synthesis
Stefan A Berghoff1, Lena Spieth1, Ting Sun1,2
1Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
Abstract:
The repair of inflamed, demyelinated lesions as in multiple sclerosis (MS) necessitates the clearance of cholesterol-rich myelin debris by microglia/macrophages and the switch from a pro-inflammatory to an anti-inflammatory lesion environment. Subsequently, oligodendrocytes increase cholesterol levels as a prerequisite for synthesizing new myelin membranes. We hypothesized that lesion resolution is regulated by the fate of cholesterol from damaged myelin and oligodendroglial sterol synthesis. By integrating gene expression profiling, genetics and comprehensive phenotyping, we found that, paradoxically, sterol synthesis in myelin-phagocytosing microglia/macrophages determines the repair of acutely demyelinated lesions. Rather than producing cholesterol, microglia/macrophages synthesized desmosterol, the immediate cholesterol precursor. Desmosterol activated liver X receptor (LXR) signaling to resolve inflammation, creating a permissive environment for oligodendrocyte differentiation. Moreover, LXR target gene products facilitated the efflux of lipid and cholesterol from lipid-laden microglia/macrophages to support remyelination by oligodendrocytes. Consequently, pharmacological stimulation of sterol synthesis boosted the repair of demyelinated lesions, suggesting novel therapeutic strategies for myelin repair in MS.
Insights
Microglia/macrophages synthesize desmosterol, a cholesterol precursor, to resolve inflammation and promote myelin repair in multiple sclerosis (MS). This finding suggests new therapeutic strategies for demyelinating diseases.
Area of Science:
- Neuroscience
- Immunology
- Biochemistry
Background:
- Multiple sclerosis (MS) involves inflamed, demyelinated lesions requiring debris clearance and a shift to an anti-inflammatory state.
- Oligodendrocytes need increased cholesterol for new myelin synthesis, but the regulation of this process in lesions is unclear.
Purpose of the Study:
- To investigate the role of cholesterol metabolism and sterol synthesis in the resolution of demyelinated lesions.
- To determine how microglia/macrophage cholesterol processing impacts oligodendrocyte differentiation and remyelination.
Main Methods:
- Gene expression profiling
- Genetic analysis
- Comprehensive phenotyping of demyelinated lesions
- Pharmacological manipulation of sterol synthesis
Main Results:
- Microglia/macrophages phagocytosing myelin debris synthesized desmosterol, not cholesterol.
- Desmosterol activated liver X receptor (LXR) signaling, reducing inflammation and promoting oligodendrocyte differentiation.
- LXR target genes facilitated lipid and cholesterol efflux from microglia/macrophages, supporting remyelination.
Conclusions:
- Microglial/macrophage sterol synthesis is a critical, paradoxical regulator of demyelinated lesion repair.
- Desmosterol-mediated LXR activation is key to resolving inflammation and enabling remyelination.
- Targeting sterol synthesis offers a potential therapeutic avenue for promoting myelin repair in MS.
