TLR4 and Parkinson disease: Another study of PD mouse model induced with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) revealed that FMT is capable of reducing expression of alpha-synuclein, inhibiting microglia activation and blocking TLR4/P13K/AKT/NF-KB signaling in the SN (52).