Antagonizing Neuronal Toll-like Receptor 2 Prevents Synucleinopathy by Activating Autophagy

Impaired autophagy has been implicated in many neurodegenerative diseases, such as Parkinson's disease (PD), and might be responsible for deposition of aggregated proteins in neurons. However, little is known about how neuronal autophagy and clearance of aggregated proteins are regulated. Here, we show a role for Toll-like receptor 2 (TLR2), a pathogen-recognizing receptor in innate immunity, in regulation of neuronal autophagy and clearance of alpha-synuclein, a protein aggregated in synucleinopathies, including in PD. Activation of TLR2 resulted in the accumulation of alpha-synuclein aggregates in neurons as a result of inhibition of autophagic activity through regulation of the AKT/mTOR pathway. In contrast, inactivation of TLR2 resulted in autophagy activation and increased clearance of neuronal alpha-synuclein, and hence reduced neurodegeneration, in transgenic mice and in in vitro models. These results uncover roles of TLR2 in regulating neuronal autophagy and suggest that the TLR2 pathway may be targeted for autophagy activation strategies in treating neurodegenerative disorders.