Single-cell transcriptomic and functional studies identify glial state changes and a role for inflammatory RIPK1...

Area of Science:

• Neuroscience
• Immunology
• Genetics

Background:

• Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease marked by motor neuron loss.
• Neuroinflammation, driven by microglia and astrocytes, is a key feature of ALS, yet its precise mechanisms are not fully understood.

Purpose of the Study:

• To investigate glial cell state dynamics and molecular pathways contributing to ALS pathogenesis.
• To explore the role of receptor-interacting protein kinase 1 (RIPK1) and necroptosis in ALS.
• To identify potential biomarkers for ALS and RIPK1 activity.

Main Methods:

• Single-nucleus RNA sequencing of spinal cord tissue from ALS patients.
• In vivo studies using SOD1^G93A mouse models of ALS.
• In vitro studies with human induced pluripotent stem cell (iPSC)-derived motor neuron, astrocyte, and microglia tri-cultures.
• Analysis of cerebrospinal fluid (CSF) from ALS patients.

Main Results:

• Identification of distinct glial cell states in ALS, characterized by increased inflammatory and activation markers.
• Convergence of inflammatory signals on the RIPK1 pathway and necroptosis.
• Pharmacological inhibition of RIPK1 kinase activity in SOD1^G93A mice delayed disease onset and motor impairment, and modulated glial responses.
• Identification of secreted biomarkers associated with RIPK1 activation in vitro and modulated by RIPK1 inhibition in human ALS CSF.

Conclusions:

• ALS involves specific glial populations associated with heightened inflammation.
• Neuroinflammatory signaling, particularly involving RIPK1 and necroptosis, plays a detrimental role in ALS pathogenesis.
• Targeting RIPK1 may offer a therapeutic strategy for ALS.