As shown in Fig. 1C and G, the number of TH-positive cells in the MPTP-induced PD mouse model decreased significantly compared with the control group, and the number of TH-positive cells decreased further after knocking down TREM2 expression, indicating that the model of MPTP-induced PD mice was successfully established, and the knockdown of TREM2 aggravated the loss of dopaminergic neurons. Here, TREM2 is linked to Parkinson disease.