Exploring [11C]CPPC as a CSF1R-targeted PET imaging marker for early Parkinson's disease severity

Area of Science:

• Neuroscience
• Immunology
• Radiochemistry

Background:

• Microglia-mediated immune changes are implicated in Parkinson's disease (PD) pathogenesis.
• Current positron emission tomography (PET) ligands for imaging microglia lack specificity in the nervous system.
• Colony stimulating factor 1 receptor (CSF1R) is explored as a potential microglial-sensitive marker for innate immunity.

Purpose of the Study:

• To develop and validate imaging of CSF1R as a marker of brain immune activity in Parkinson's disease.
• To assess the correlation between CSF1R imaging, disease severity, and cognitive function in PD patients.

Main Methods:

• Immunohistochemistry of human brain samples (PD vs. controls) to assess CSF1R colocalization with Iba-1.
• Autoradiography using a CSF1R ligand on postmortem brain tissue to quantify binding potential (Bmax).
• Positron emission tomography (PET) imaging with a CSF1R radioligand in PD patients and controls, correlating binding with clinical measures.

Main Results:

• CSF1R expression was significantly increased in the brains of PD patients compared to controls, co-localizing with Iba-1.
• Autoradiography showed elevated CSF1R ligand binding in the inferior parietal cortex of PD patients.
• [11C]CPPC PET revealed higher CSF1R binding in moderate PD, correlating with motor disability and reduced verbal fluency.

Conclusions:

• CSF1R imaging shows promise as a biomarker for assessing brain immune function in Parkinson's disease.
• Increased CSF1R binding is associated with both cognitive and motor aspects of PD severity.
• This imaging approach may offer new insights into PD neuroinflammation and disease progression.