Cellular iron deposition patterns predict clinical subtypes of multiple system atrophy

Area of Science:

• Neuroscience
• Neuropathology
• Iron Metabolism

Background:

• Multiple system atrophy (MSA) is a neurodegenerative disease linked to iron accumulation in the brain.
• The precise role of iron dysregulation in MSA pathogenesis and its relation to alpha-synuclein pathology remain unclear.
• Understanding iron dysregulation at a cellular level is crucial for deciphering MSA.

Purpose of the Study:

• To map iron burden in subcortical and brainstem regions in human MSA brains.
• To conduct the first cell type-specific evaluation of pathological iron deposition in MSA.
• To compare iron deposition patterns between MSA subtypes (MSA-P and MSA-C).

Main Methods:

• Histological mapping of iron burden in post-mortem brains from MSA patients.
• Cell type-specific iron evaluation using iron staining and immunolabelling in key brain regions.
• Analysis of gene expression for iron- and oxygen-homeostatic genes in MSA cases.

Main Results:

• Distinct regional iron burden patterns were observed between MSA-P and MSA-C subtypes.
• Subcortical microglia predominantly accumulated iron, particularly in MSA-P; astroglia showed more heterogeneous accumulation in MSA-C.
• Cellular iron burden was associated with oligodendroglial, not neuronal, alpha-synuclein pathology; gene expression revealed oxygen homeostasis dysregulation.

Conclusions:

• Distinct regional and cellular iron distribution patterns were identified in MSA-P and MSA-C.
• Cellular vulnerability to iron deposition serves as a novel neuropathological characteristic predicting MSA clinical subtypes.
• Findings suggest distinct iron-related pathomechanisms in MSA subtypes, informing targeted iron chelation therapies.