BDNF insufficiency exacerbates ALS progression.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with progressive loss of motor neurons. Insufficiency of neurotrophic factors is suspected to underlie the disease, but direct evidence remains scarce. In this study, we discover that brain-derived neurotrophic factor (BDNF) val/met mutation, which results in a decrease in BDNF secretion, reduces survival time of ALS patients in two separate cohorts. Using a knockin mouse model of the ALS causal gene FUSR521C, we demonstrate that BDNF haploinsufficiency leads to shortened lifespan, accelerated motor dysfunctions, and exacerbated motor neuron death. Importantly, activation of the BDNF receptor TrkB by an agonistic antibody effectively rescues these ALS-associated phenotypes. In additional ALS mouse models, TrkB activation antibody also shows superior therapeutic effects compared to current ALS medication riluzole. Our data indicate that insufficient BDNF could be a crucial contributing factor for ALS progression, and activation of BDNF-TrkB pathway may represent a promising therapeutic strategy against ALS.