SNCA and multiple system atrophy: Specifically, TLR4 has been shown to play an important role in the clearance of different forms of alpha-synuclein by microglia, thus providing a neuroprotective effect, as demonstrated in a mouse model of MSA and in in vitro settings (Stefanova et al., 2011; Fellner et al., 2013; Venezia et al., 2017).