W179 - A Comprehensive Analysis of T Cell Dynamics and Clonality in the Blood and CNS Across Sporadic and Familial ALS

Ryan Hobson – Columbia University; Ryan Talcoff – Columbia University; Maedot Yidenk – Columbia University; Benjamin Hoover – Columbia University; Neil Shneider, MD – Columbia University; Wassim Elyaman – Columbia University

Abstract Text: Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder characterized by the rapid loss of motor neurons. While 90% of ALS cases are sporadic, the remaining 10% have a family history usually characterized by mutations in several ALS-associated genes including aggressive Fused in Sarcoma (FUS) mutations. Although reactive microglia in the central nervous system (CNS) and regulatory T-cell dysfunction have been observed across ALS, we lack a comprehensive understanding of how the immune response is mounted and whether it differs between sporadic and familial ALS. Here we built a groundbreaking pipeline leveraging multi-tissue single-cell RNA and TCR-sequencing to perform phenotypic analysis and lineage tracing to identify the spatiotemporal trajectory of clonal T-cells in ALS and their phenotypes across tissues. Our cohort included >80 paired CSF and PBMC samples from pre-symptomatic/symptomatic FUS-ALS, sporadic ALS, and postmortem motor cortex and brain border tissues from ALS patients, alongside paired PBMC/CSF samples from multiple sclerosis patients and healthy control subjects. We identified shared expanded T-cell clones across FUS-ALS patients and peripheral and central compartments, exhibiting high levels of granzymes and other cytotoxic genes. Microglia-like cells and gamma-delta T-cells are enriched in FUS-ALS CSF, and high levels of MAIT cells showed elevated LIGHT signaling, which has been implicated in motor neuron killing. Enhanced CCL5-CCR4 signaling, generated by natural killer and CD8 effector memory T-cells, received by regulatory T-cells, was observed exclusively in FUS-ALS CSF. These findings highlight a unique FUS-ALS immune environment in the CNS offering potential for immunotherapy strategies to modulate neuroinflammation.