In ALS, microglia—brain immune cells—express abnormally high levels of receptors that recognize a "eat me" signal on cell surfaces, causing them to phagocytose stressed but viable motor neurons rather than genuinely dying cells. Blocking these receptors delays disease onset but extends survival, suggesting that immune cell misidentification of living neurons contributes to neurodegeneration.
Key Points
- Microglia TAM receptors (AXL, MER) elevated 16-fold in ALS spinal cord
- Most neurons displaying apoptotic signals remain alive, not undergoing programmed death
- Removing AXL and MER receptors extends survival despite earlier symptom onset
Longevity Analysis
This research reframes a cardinal problem in neurodegeneration: the immune system's inability to accurately distinguish living from dying cells. Rather than neurons passively deteriorating, microglia actively consume viable neurons based on corrupted recognition signals. The survival advantage from blocking TAM signaling suggests that therapeutic approaches focused on restoring accurate immune interpretation—rather than solely supporting neuron survival—may preserve motor function longer in ALS and potentially other neurodegenerative conditions where immune surveillance becomes dysregulated.
Original published by LifeSpan.io, by Arkadi Mazin.