The spatial landscape of glial pathology and T-cell response in Parkinson's disease substantia nigra

Parkinson's Disease (PD) is a progressive neurodegenerative disease that leads to debilitating movement disorders and often dementia. Recent evidence, including identification of specific peripheral T-cell receptor sequences, indicates the adaptive immune response is associated with disease pathogenesis. However, the properties of T-cells in the brain regions where neurons degenerate are uncharacterized. We have analyzed the identities and interactions of T-cells in PD in post-mortem brain tissue using single nucleus RNA sequencing, spatial transcriptomics and T-cell receptor sequencing. We found that T-cells in the substantia nigra of PD brain donors exhibit a CD8+ resident memory phenotype, increased clonal expansion, and altered spatial relationships with astrocytes, myeloid cells, and endothelial cells. We also describe regional differences in astrocytic responses to neurodegeneration. Our findings nominate potential molecular and cellular candidates that allow a deeper understanding of the pathophysiology of neurodegeneration in PD. Together, our work represents a major single nucleus and spatial transcriptional resource for the fields of neurodegeneration and PD. ### Competing Interest Statement The authors have declared no competing interest.