Th218 - Longitudinal Single-cell RNA Sequencing and T Cell Receptor Analysis of Paired Central and Peripheral Immune Cells in Familial and Sporadic ALS Patients

William Orent, PhD; Ryan Hobson, MS – Columbia University; Vilas Menon, PhD – Columbia University; Neil Shneider, MD, PhD; Wassim Elyaman, PhD – Columbia University

Abstract Text: Amyotrophic Lateral Sclerosis (ALS) is a multisystem neurodegenerative disorder characterized by the loss of motor neurons in the motor cortex and spinal cord. In the US over 5,000 people are diagnosed with ALS each year. Mutations in the FUS gene can lead to a more aggressive, heritable ALS (fusALS) when compared to other sporadic ALS (sALS). While microglial activation and Treg dysfunction have been observed in both disease states, we lack a comprehensive understanding of how the central and peripheral immune system change throughout disease progression and differ between disease classification. We attempt to address this knowledge gap by following fusALS (n = 15) and sALS (n = 8) patients over their disease course, collecting blood and cerebrospinal fluid (CSF) at multiple timepoints and cortex samples posthumously. Biofluids were subjected to 5’ single cell RNA and T cell receptor sequencing. Notably, we observed different proportions of CD4 Th17 and gamma-delta cells between fusALS blood and CSF samples while sALS patients displayed an enriched TEMRA-like population in the CSF. These cell type proportional differences were sustained throughout disease progression. High levels of clonal expansion were captured in all samples. In sALS patients, hyperexpanded clonotypes were localized to MAIT and TEMRA-like populations in the blood and CSF. Additionally, flow cytometry analysis of sALS autopsy samples revealed T cells infiltrating into the motor cortex and spinal cord. This work adds to the growing body of evidence implicating immune involvement in ALS and reveals several specific immune system states unique to fusALS and sALS.