Exploring transcriptome-wide changes in the brain-localized immune cells in a mouse model of Parkinson's Disease

In this study we identify the gene expression changes that occur in the brain-localized immune cells in a mouse model of Parkinson's Disease. A mouse model of Parkinson's Disease was created as previously described by stereotacticaly injecting an AAV-expressing the human A53T_mutated form of a-Synuclein into the Substantia Nigra of adult mice, while control mice were injected with empty vector (EV). These mice exhibit neurodegeneration in the Substantia Nigra and Parkinson-like behaviour phenotypes. Sixteen weeks after the injection, the Substantia Nigra and Srtiatum were micro-dissected and a Percoll gradient was used to enrich for the immune cells present in these tissues. The immune cells were also isolated from the Substantia Nigra and Striatum of same-age WT uninjected mice (WT). RNA was isolated from these cells and single-end 75nt high throughput sequencing were performed on libraries prepared from the RNA. We identified over 400 genes that were differentially expressed between control and Parkinson's mice with a log2 fold-change > |0.75|. These genes were enriched for terms related to immune activation such as: cytokine processing, leukocyte activation, and antigen presentation. The genes associated with these GO terms tended to be up-regulated in the Parkinson's mice suggesting that brain-localized immune cells are more activated in Parkinson's disease. We sequenced tissues from five mice per condition at ~35 million reads/sample in single-end mode with 75 nt read length on the NextSeq 500 platform (Illumina) with the High Output Kit v2.5