The neuroinvasive propensity of SARS-CoV-2 is probably facilitated by high expression levels of ACE2 and TMPRSS2 in neurons, astrocytes, and oligodendrocytes that, together with TLR4 activation, can predispose patients to α-SYN aggregation, neurodegeneration, and PD pathogenesis [144]. Here, TLR4 is linked to Parkinson disease.