Microglial dysregulation and spatiotemporal dynamics of inflammation in multiple sclerosis white matter: an
Keqiang Ma1, Qing Zhang1, Hong Du1
1Laboratory of Molecular and Statistical Genetics and Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, China.
Objective:
White matter damage in Multiple Sclerosis (MS) exhibits significant heterogeneity. The cellular and molecular underpinnings of this heterogeneity are not fully understood. This study investigated cell-specific changes and spatial heterogeneity in MS white matter by integrating single-cell and spatial transcriptomics (ST) to guide potential clinical interventions.
Methods:
Single-nucleus RNA sequencing (snRNA-seq) identified key cell types, regulons, and cellular functional heterogeneity using Gene Regulatory Network (GRN) analysis, cell communication, subpopulation classification, functional enrichment, and pseudotime analysis. ST explored functional heterogeneity and cell type distribution in MS white matter niches via correlation, enrichment analysis, and deconvolution.
Results:
snRNA-seq analysis identified module M3, showing transcription factor dysregulation in MS white matter compared to controls. These genes were predominantly expressed in microglia and enriched in inflammation related signaling pathways; IKAROS Family Zinc Finger 1 (IKZF1) was identified as a candidate transcriptional regulator connected to these changes. Microglia exhibited heterogeneity, existing in dynamic regulation from homeostatic to pro-inflammatory phenotypes, the latter showing Disease-associated Microglia (DAM) characteristics. Spatial transcriptomic analysis revealed strong heterogeneity within MS white matter with distinct niche functions. The Lesion Rim (LR), a transition zone, correlated strongly with microglia and was highly enriched with DAM characteristics. The LR was identified as an inflammatory hotspot enriched for DAM and altered IKZF1 regulon activity, supporting snRNA-seq findings.
Conclusion:
IKZF1 regulon inactivation in microglia coincides with altered white matter lesions in MS and dysregulated inflammatory pathways. Microglial heterogeneity in MS, including DAM phenotypes, extends beyond traditional polarization models. MS white matter displays significant spatial heterogeneity. Hindered remyelination in the LR may reflect inflammation from sustained microglial activation.
Insights
Single-cell and spatial transcriptomics reveal significant white matter heterogeneity in Multiple Sclerosis (MS). Microglia exhibit diverse phenotypes, with inflammation hotspots like the Lesion Rim (LR) showing altered IKZF1 activity, impacting disease progression.
Area of Science:
- Neuroimmunology
- Transcriptomics
- Cellular Biology
Background:
- Multiple Sclerosis (MS) involves white matter damage with poorly understood heterogeneity.
- Cellular and molecular drivers of MS white matter pathology require further investigation.
Purpose of the Study:
- To investigate cell-specific changes and spatial heterogeneity in MS white matter.
- To integrate single-cell and spatial transcriptomics for potential clinical interventions.
Main Methods:
- Single-nucleus RNA sequencing (snRNA-seq) for cell type identification and functional analysis.
- Gene Regulatory Network (GRN) analysis to identify transcriptional regulators.
- Spatial transcriptomics (ST) to map cell distribution and niche functions.
Main Results:
- snRNA-seq identified dysregulated transcription factors in MS white matter, particularly in microglia (Module M3).
- IKAROS Family Zinc Finger 1 (IKZF1) identified as a key regulator linked to inflammation.
- Spatial transcriptomics revealed distinct white matter niches, with the Lesion Rim (LR) as an inflammatory hotspot enriched for Disease-associated Microglia (DAM) and altered IKZF1 activity.
Conclusions:
- IKZF1 inactivation in microglia correlates with MS white matter lesions and inflammation.
- Microglial heterogeneity, including DAM phenotypes, is complex and extends beyond simple polarization.
- Spatial heterogeneity in MS white matter, particularly the LR, may impede remyelination due to sustained microglial activation.
