Distinct forebrain regions define a dichotomous astrocytic profile in multiple system atrophy

Area of Science:

• Neuroscience
• Cell Biology
• Pathology

Background:

• Astrocytes play a complex role in neurodegeneration, with distinct subtypes potentially contributing differently to disease.
• Multiple System Atrophy (MSA) is a rare Parkinsonian disease marked by significant astrocyte reactivity, but subtype-specific roles are unclear.

Purpose of the Study:

• To investigate the distinct regional and functional roles of astrocyte subtypes in the neuropathology of Multiple System Atrophy (MSA).

Main Methods:

• Profiling glial fibrillary acidic protein (GFAP) in human post-mortem brain tissues (motor cortex, putamen, substantia nigra) from MSA patients.
• Analyzing astrocyte phenotypes in a transgenic MSA mouse model, including transcriptomic profiling of isolated striatal and cortical astrocytes using magnetic-activated cell sorting.

Main Results:

• A profound astrocytic response was observed in both human MSA brains and the mouse model.
• MSA mice showed decreased expression of glutamate transporters (GLT-1 and GLAST) in the basal ganglia.
• Transcriptomic analysis revealed distinct astrocyte signatures: anti-inflammatory and pro-myelinogenic in the motor cortex, versus pro-inflammatory and dysregulated metabolic functions in the striatum.

Conclusions:

• Astrocytes exhibit a region-dependent, dichotomous response in MSA, with potentially beneficial roles in the cortex and detrimental roles in the striatum.
• These findings highlight differential astrocytic contributions to neurodegeneration in MSA, suggesting targeted therapeutic strategies may be region-specific.