Astrocyte-neuron communication through the complement C3-C3aR pathway in Parkinson's disease

Area of Science:

• Neuroimmunology
• Neurodegeneration
• Molecular Neuroscience

Background:

• Neuroinflammation and autoimmunity are key in neurodegenerative diseases.
• The astrocyte-neuron C3/C3aR pathway's role in alpha-synuclein (α-syn) pathology is not fully understood.
• Alpha-synuclein pathology is a hallmark of Parkinson's disease (PD).

Purpose of the Study:

• To investigate the role of complement C3 in α-syn pathology and neurodegeneration.
• To elucidate the mechanisms of astrocyte-neuron communication via the C3/C3aR pathway in PD pathogenesis.

Main Methods:

• Detected complement C3 levels in plasma and substantia nigra of mouse models.
• Utilized α-syn preformed fibril (PFF) injection and A53T transgenic mice.
• Investigated the effects of complement C3 overexpression and downregulation.
• Examined the impact of Toll-like receptor 2 (TLR2) and NF-κB inhibition on C3 expression.
• Assessed neuronal apoptosis and α-syn pathology.

Main Results:

• Elevated complement C3 levels were found in PD mouse models.
• Complement C3 overexpression worsened motor deficits, dopaminergic neuron loss, and α-syn pathology.
• Downregulation of complement C3 conferred protection against α-syn PFF-induced pathology.
• Inhibition of TLR2 or NF-κB reduced astrocyte C3 expression after α-syn PFF treatment.
• Astrocyte-neuron C3/C3aR signaling influenced neuronal apoptosis and α-syn pathology, potentially via GSK3β.

Conclusions:

• Astrocyte-neuron communication through the C3/C3aR pathway is critical in Parkinson's disease pathogenesis.
• The C3/C3aR pathway represents a potential therapeutic target for Parkinson's disease.