A Blood-Derived Factor Rescues ALS: Platelet Factor 4 Activates OPTN-Dependent Autophagy to Clear SOD1 Aggregates Independently of PINK1

Here, by integrating population-scale epidemiology with mechanistic dissection, we identify platelet factor 4 (PF4) as the central driver of a circulating neuroprotective axis that restores proteostasis and rescues ALS. In a prospective cohort of >500,000 UK Biobank participants, platelet indices were strongly associated with ALS risk, and serum PF4 levels were significantly reduced in ALS patients.

Systemic administration of recombinant PF4 in hSOD1G93A mice produced dramatic therapeutic effects: extended survival, preserved motor function, attenuated neuroinflammation, and reduced neuromuscular junction denervation. Remarkably, this efficacy appears pathology-selective--robust in SOD1-driven models but shows no observable effect in TDP-43 or C9orf72 ALS models. Mechanistically, PF4 achieves what few molecules can: it engages the cell surface receptor LRP1 to activate the TBK1-OPTN signaling axis, restoring impaired autophagic flux through a PINK1/Parkin-independent pathway requiring ATG7, establishing a previously unrecognized peripheral platelet-autophagy-neuron axis that facilitates the co-clearance of pathological SOD1 aggregates and damaged mitochondria.