T cell - DAM feedback loop drives CNS inflammation and neurodegenration in SPG15 at an early age [CD45+]

The immune system is an emerging cause of neuroinflammation and is suspected to be involved in neurodegeneration. The role of microglia, the macrophages of the Central Nervous System (CNS), was extensively researched in CNS neuropathologies. However, we only start to understand the role of T cells in diseases like Alzheimer’s Disease (AD) and Huntington’s Disease (HD) and how microglial – T cell crosstalk contributes to these pathologies. Here we tackle these topics in a rare and less investigated disease called Spastic Paraplegia 15 (SPG15) using a Zfyve26-/- mouse model. We were able to show, that CD8+ T cells and microglia potentiate a pro-inflammatory response through bidirectional communication in SPG15 KO and not WT mouse brains. The increase of CD8+ T cells in SPG15 KO animals also required a TCR dependent component. These findings are in line with previous reports on neurodegenerative disease which hints at cross-condition mechanisms involved in CD8+T cell responses in CNS, when encountering accumulation of non-degradable material in the brain. Immune cells from old (15 months) and Zfyve26-/- (KO) or Zfyve26+/- (WT) mouse brains were isolated using Fluorescence-activated cell sorting (FACS). All animals were of B57BL/6 𝐶𝑋𝐶𝑅4;𝐶𝑟𝑒𝐸𝑅(𝑇2)−𝐼𝑅𝐸𝑆−𝐺𝐹𝑃;𝑅26𝐶𝐴𝐺−𝐿𝑆𝐿−𝑡𝑑𝑇 background and treated with tamoxifen at the age of 4-6 weeks. 3' counting scRNAseq was performed on CD45+ cells using SeqWell ^s3. These cells were stained with CITE-seq antibodies (ADTs and HTOs). Full length scRNAseq libraries were generated via SmartSeq2. To that purpose, CD3+ cells were sorted into 384 well plates.