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Updated: May 17, 2025
Intravital Imaging of Axonal Interactions with Microglia and Macrophages in a Mouse Dorsal Column Crush Injury
Published on: November 23, 2014
Direct microglia replacement reveals pathologic and therapeutic contributions of brain macrophages to a monogenic
William H Aisenberg1, Carleigh A O'Brien1, Madison Sangster2
1Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Abstract:
Krabbe disease, also named globoid cell (GC) leukodystrophy (GLD) for its distinct lipid-laden macrophages, is a severe leukodystrophy caused by galactosylceramidase (GALC) mutations. Hematopoietic stem cell transplant (HSCT) ameliorates disease and is associated with central nervous system (CNS) engraftment of GALC+ donor macrophages. Yet, the role of macrophages in GLD pathophysiology and HSCT remains unclear. Using single-cell sequencing, we revealed early interferon response signatures that preceded progressively severe macrophage dyshomeostasis and identified a molecular signature of GCs, which we validated in human brain specimens. Genetic depletion and direct microglia replacement by CNS monocyte injection rapidly replaced >80% of endogenous microglia with healthy macrophages in the twitcher (GalcW355∗) mouse model of GLD. Perinatal microglia replacement completely normalized transcriptional signatures, rescued histopathology, and doubled average survival. Overall, we uncovered distinct forms of microglial dysfunction and evidence that direct, CNS-limited microglia replacement improves a monogenic neurodegenerative disease, identifying a promising therapeutic target.
Insights
Krabbe disease (GLD) involves macrophage dysfunction. Replacing microglia in the brain with healthy macrophages in mice significantly improved survival and normalized disease markers, revealing a potential therapy.
Area of Science:
- Neuroscience
- Genetics
- Immunology
Background:
- Krabbe disease (GLD) is a severe leukodystrophy caused by GALC mutations.
- Hematopoietic stem cell transplant (HSCT) shows promise but the role of macrophages in GLD and HSCT is unclear.
Purpose of the Study:
- To investigate the role of macrophages in GLD pathophysiology.
- To explore microglia replacement as a therapeutic strategy for GLD.
Main Methods:
- Single-cell sequencing to analyze macrophage signatures.
- Genetic depletion and direct microglia replacement in the twitcher mouse model.
Main Results:
- Identified early interferon response and macrophage dyshomeostasis in GLD.
- Microglia replacement in mice normalized gene expression, improved histopathology, and doubled survival.
- Validated globoid cell molecular signature in human brain specimens.
Conclusions:
- Uncovered distinct microglial dysfunction in GLD.
- Direct, CNS-limited microglia replacement is a promising therapeutic target for this monogenic neurodegenerative disease.
