In vitro, wild-type α-synuclein directly binds to TLRs−1 and −2 in a Myd88-dependent manner (Daniele et al., 2015) and human PD subjects display elevated expression of TLR2 and TLR4 in peripheral monocytes and brain tissue (Watson et al., 2012; Drouin-Ouellet et al., 2015). Here, TLR2 is linked to Parkinson disease.