Microglia in Rasmussen Encephalitis

Introduction

Rasmussen encephalitis is a rare, progressive, and severe inflammatory disease of the brain that typically affects one cerebral hemisphere, predominantly in children. Microglia play a central role in the immunopathogenesis of this condition, mediating both the inflammatory response and the cytotoxic mechanisms that lead to progressive neuronal loss and cortical atrophy^{1Rasmussen encephalitis2014 · The Lancet Neurology · PMID 24988961Open reference}.

Microglia are the resident immune cells of the central nervous system and serve as the primary mediators of neuroinflammation in Rasmussen encephalitis. Their activation and interactions with T-cells drive the characteristic progressive neurological decline seen in this condition^{2Pathogenesis, diagnosis and treatment of Rasmussen encephalitis2002 · Expert Opinion on Therapeutic Targets · PMID 15934827Open reference}.

Overview

flowchart TD
    MICROGLIA["MICROGLIA"] -->|"expressed in"| TREM2["TREM2"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| NEUROINFLAMMATION["NEUROINFLAMMATION"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| NEURON["NEURON"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| TNF["TNF"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| SNCA["SNCA"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| TAU["TAU"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| TREM2["TREM2"]
    MICROGLIA["MICROGLIA"] -->|"activates"| TREM2["TREM2"]
    MICROGLIA["MICROGLIA"] -->|"associated with"| NEURODEGENERATION["NEURODEGENERATION"]
    MICROGLIA["MICROGLIA"] -->|"regulates"| Alzheimer["Alzheimer"]
    MICROGLIA["MICROGLIA"] -->|"regulates"| Als["Als"]
    MICROGLIA["MICROGLIA"] -->|"regulates"| Neurodegeneration["Neurodegeneration"]
    MICROGLIA["MICROGLIA"] -->|"activates"| NEUROINFLAMMATION["NEUROINFLAMMATION"]
    MICROGLIA["MICROGLIA"] -->|"activates"| Parkinson["Parkinson"]
    style microglia fill:#4fc3f7,stroke:#333,color:#000

Multi-Taxonomy Classification

Taxonomy Database Cross-References

Morphology & Electrophysiology

• Morphology: microglial cell (source: Cell Ontology)

  • Morphology can be inferred from Cell Ontology classification

PanglaoDB Marker Cross-References

• Unknown (PanglaoDB):

External Database Links

• Cell Ontology (CL:0000129)

• OBO Foundry (CL:0000129)

• Allen Brain Cell Atlas

• CellxGene Census

• Human Cell Atlas

• PanglaoDB

Taxonomy & Classification

PanglaoDB Marker Cross-References

• Unknown (PanglaoDB):

External Database Links

• Cell Ontology (CL:0000129)

• OBO Foundry (CL:0000129)

• Allen Brain Cell Atlas

• CellxGene Census

• PanglaoDB

Microglia Function

• Immune Surveillance: Brain monitoring

• Antigen Presentation: T-cell activation

• Cytotoxicity: Direct killing

Role in Rasmussen Encephalitis

Immune Pathogenesis

Rasmussen encephalitis is an immune-mediated disease characterized by a focal inflammatory process that progressively destroys one cerebral hemisphere. The pathogenesis involves a complex interplay between microglia, CD8+ cytotoxic T-cells, and neurons^{3Rasmussen's encephalitis2003 · Brain and Development · PMID 12883473Open reference}.

CD8+ T-cell mediated cytotoxicity:

• CD8+ T-cells recognize neuronal antigens presented on MHC-I molecules

• Cytotoxic T-cells release granzyme and perforin leading to apoptotic neuronal death

• The attack predominantly targets pyramidal neurons in the affected cortex

• Microglia serve as antigen-presenting cells that activate the T-cell response

Microglial activation:

• Activated microglia express increased levels of MHC-I and MHC-II

• Microglia produce pro-inflammatory cytokines including IL-1β, TNF-α, and IL-6

• Chronically activated microglia create a self-perpetuating inflammatory cycle

• Microglial proliferation correlates with disease progression^{4Microglial activation in Rasmussen encephalitis2004 · Indian Journal of Pediatrics}

Neuroimaging Correlates

• PET imaging shows increased microglial activation in the affected hemisphere

• ** TSPO binding** is elevated in active inflammatory regions

• Longitudinal PET demonstrates progressive involvement correlating with clinical decline^{5Longitudinal PET imaging in Rasmussen encephalitis2012 · Journal of Nuclear Medicine · PMID 22523310Open reference}

Clinical Features

Treatment Approaches

• Immunotherapy: Corticosteroids, IVIG, cyclophosphamide may slow progression

• Anti-epileptic drugs: Control seizures but do not halt disease progression

• Hemispherectomy: Surgical disconnection of affected hemisphere (only curative option)

• Emerging therapies: T-cell targeted treatments under investigation^{6Surgical outcome and biomarkers in Rasmussen encephalitis2020 · Epilepsia · PMID 32875612Open reference}

See Also

• Microglia Neuroinflammation

• TREM2

• Neuroinflammation

• Epilepsy

• Seizures