Glial state changes and neuroinflammatory RIPK1 signaling are a key feature of ALS pathogenesis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that causes motor neuron loss in the brain and spinal cord. Neuroinflammation driven by activated microglia and astrocytes is prominent in ALS, but an understanding of cell state dynamics and which pathways contribute to the disease remains unclear. Single nucleus RNA sequencing of ALS spinal cords demonstrated striking changes in glial cell states, including increased expression of inflammatory and glial activation markers. Many of these signals converged on RIPK1 and the necroptotic cell death pathway. Activation of the necroptosis pathway in ALS spinal cords was confirmed in a large bulk RNA sequencing dataset and at the protein level. Blocking RIPK1 kinase activity delayed symptom onset and motor impairment and modulated glial responses in SOD1G93A mice. We used a human iPSC-derived motor neuron, astrocyte, and microglia tri-culture system to identify potential biomarkers secreted upon RIPK1 activation, inhibited pharmacologically in vitro, and modulated in the CSF of people with ALS treated with a RIPK1 inhibitor. These data reveal ALS-enriched glial populations associated with inflammation and suggest a deleterious role for neuroinflammatory signaling in ALS pathogenesis.

Matija Zelic1, Anna Blazier1, Fabrizio Pontarelli1, Michael LaMorte1, Jeremy Huang2, Ozge E. Tasdemir-Yilmaz1, Yi Ren1, Sean K. Ryan1, Pavithra Krishnaswami2, Mikhail Levit2, Disha Sood1, Yao Chen2, Joseph Gans2, Xinyan Tang3, Jennifer Hsiao-Nakamoto3, Fen Huang3, Bailin Zhang2, Giorgio Gaglia2, Dimitry Ofengeim1, Timothy R. Hammond1

1Sanofi, Rare and Neurologic Diseases, Cambridge, MA, USA
2Sanofi, Precision Medicine and Computational Biology, Cambridge, MA, USA
3Denali Therapeutics, Inc., South San Francisco, CA, USA