The autophagy activator Spermidine reduces neuroinflammation and soluble amyloid beta in an Alzheimer’s disease mouse model

Deposition of amyloid beta (Aβ) along with glia cell-mediated neuroinflammation are prominent pathogenic hallmarks of Alzheimer’s disease (AD). In recent years, impairment of autophagy has been found to be another important feature, contributing to AD progression and aging. Therefore, we assessed the effect of the autophagy activator Spermidine, a small body-endogenous polyamine often used as dietary supplement and known to promote longevity, on glia cell-mediated neuroinflammation. Spermidine reduced TLR3- and TLR4- mediated inflammatory processes in microglia and astrocytes by decreasing cytotoxicity, inflammasome activity and NF-κB signaling. In line with these anti-inflammatory effects, oral treatment of the amyloid prone AD-like APPPS1 mice with Spermidine reduced neuroinflammation and neurotoxic soluble Aβ. Mechanistically, single nuclei sequencing revealed microglia as one of the main targets of Spermidine treatment, with increased expression of genes implicated in cell motility and phagocytosis. Thus, Spermidine provides a promising therapeutic potential to target glia cells in AD progression.