Granulocyte-colony stimulating factor attenuates oligomeric amyloid β neurotoxicity by activation of neprilysin.

Soluble oligomeric amyloid β (oAβ) causes synaptic dysfunction and neuronal cell death, which are involved in the pathogenesis of Alzheimer's disease (AD). The hematopoietic growth factor granulocyte-colony stimulating factor (G-CSF) is expressed in the central nervous system (CNS) and drives neurogenesis. Here we show that G-CSF attenuated oAβ neurotoxicity through the enhancement of the enzymatic activity of Aβ-degrading enzyme neprilysin (NEP) in neurons, while the NEP inhibitor thiorphan abolished the neuroprotection. Inhibition of MEK5/ERK5, a major downstream effector of G-CSF signaling, also ablated neuroprotective effect of G-CSF. Furthermore, intracerebroventricular administration of G-CSF enhanced NEP enzymatic activity and clearance of Aβ in APP/PS1 transgenic mice. Thus, we propose that G-CSF may be a possible therapeutic strategy against AD.