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Immunohistochemical expression of microtubule-associated protein 5 (MAP5) in glial cells in multiple system atrophy

N Arai1, M Nishimura, M Oda

  • 1Department of Clinical Neuropathology, Tokyo Metropolitan Institute for Neurosciences, Japan.

Insights

This study identifies microtubule-associated protein 5 (MAP5) in glial cytoplasmic inclusions (GCIs) in multiple system atrophy (MSA). These findings suggest MAP5-positive glial cells in MSA are reactive microglia and oligodendroglia.

Area of Science:

  • Neuroscience
  • Immunohistochemistry
  • Cell Biology

Background:

  • Multiple system atrophy (MSA) is a neurodegenerative disorder characterized by varying degrees of olivopontocerebellar atrophy and striatonigral degeneration.
  • Glial cytoplasmic inclusions (GCIs) are a hallmark pathological feature in MSA, but their cellular origin remains debated.
  • Microtubule-associated protein 5 (MAP5) is typically found in developing brain tissue.

Purpose of the Study:

  • To investigate the cellular composition of GCIs in MSA using immunohistochemical markers.
  • To determine the presence and significance of MAP5 in glial cells within MSA brains.
  • To elucidate the potential role of microglia and oligodendroglia in MSA pathogenesis.

Main Methods:

  • Immunohistochemistry was performed on brain tissue from 5 MSA cases using antibodies against MAP1, MAP2, MAP5, transferrin, leukocyte common antigen (LCA), and glial fibrillary acidic protein (GFAP).
  • Quantification of MAP5-positive glial cells (MAP5-Gs) was conducted in various brain regions and compared to control samples.
  • Co-localization studies were performed to identify markers present in MAP5-Gs.

Main Results:

  • MAP5 was strongly detected in GCIs in all 5 MSA cases.
  • MAP5-Gs were significantly increased in regions affected by GCIs, including the putamen, substantia nigra, cerebellar white matter, and internal capsule.
  • LCA (microglia marker) and transferrin (oligodendroglia marker) were detected in some MAP5-Gs, while GFAP (astrocyte marker) was absent.

Conclusions:

  • MAP5-positive glial cells in MSA likely represent reactive microglia and oligodendroglia.
  • This study provides the first immunohistochemical evidence of MAP5 expression in glial pathological changes associated with MSA.
  • The findings contribute to understanding the cellular mechanisms underlying GCI formation and MSA pathology.

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