TLR4 and Parkinson disease: (6) additional factors contributing to PD neuroinflammation involve the pKr-2 protein, which can facilitate neuroinflammation and PD progression in rodent models by upregulating microglial TLR4 (Shin et al., 2015); mPGES-1, which is upregulated in the SN of 6-OHDA-induced PD models and could lead to neurotoxicity (Uematsu et al., 2002; Engblom et al., 2003; Kamei et al., 2004; Morales-Garcia et al., 2011, 2015, 2017; Kim et al., 2016; Ikeda-Matsuo et al., 2019); and type-I IFN, which aggravates PD by inducing neuroinflammation in the early stages of this disease (Main et al., 2016).