Table 1.
Summary of literatures assessing exosomes as biomarkers in PD
| Exosomal source | Target | Patients | Findings | Author, year | Ref |
|---|---|---|---|---|---|
| Plasma | αsyn | 267 PD, 215 control | Exosomal αsyn and exo/total ratio are higher in PD compared to controls (P < 0.0001) | Shi et al. 2014 | [53] |
| Tau | 91 PD, 106 control | Exosomal tau is higher in PD than in control (P = 0.038) | Shi et al. 2016 | [55] | |
| CSF | αsyn | 76 PD, 58 control | Exosomal αsyn is lower in the PD (P < 0.05) | Stuendl et al. 2016 | [54] |
| LRRK2 | – | LRRK2-positive exosomes circulate in CSF | Fraser et al. 2013 | [58] | |
| miR-1, miR-19b-3p, miR-153, miR-409-3p, miR-10a-5p, let-7g-3p | 47 PD, 27 control | Sixteen exosomal miRNAs (including miR-153, miR-409-3p, miR-10a-5p, and let-7g-3p are validated) are up-regulated and 11 miRNAs (including miR-1 and miR-19b-3p are validated) are down-regulated in PD (relative fold > 2, P < 0.05). | Gui et al. 2015 | [62] | |
| Urine | LRRK2 | 20 PD, 15 control | LRRK2 levels are overall comparable but highly variable in urinary exosomes derived from PD | Fraser et al. 2013 | [58] |
| PD (14 males, 12 females), control (10 males, 11 females) | Levels of LRRK2 are lower in females, whereas the DJ-1 level is the opposite. | Ho et al. 2014 | [59] | ||
| DJ-1 | 14 PD, 10 control | In males, DJ-1 level in exosomes is higher (1.7-fold) in PD than in control | Ho et al. 2014 | [59] | |
| Ser(P)-1292 LRRK2 | 79 PD, 79 control | Ser(P)-1292 LRRK2 levels are higher in males than in females (P < 0.0001) and elevated in PD patients when compared with controls (P = 0.0014). | Fraser et al. 2016 | [60] | |
| Ser(P)-1292/total LRRK2 | 14 males (7 LRRK2+/PD+; 4 LRRK2−/PD+; 3 LRRK2−/PD−) 62 males (16 LRRK2−/PD−; 16 LRRK2+/PD−; 14 LRRK2+/PD+; 16 LRRK2−/PD+) | LRRK2+/PD+ have a higher Ser(P)-1292 LRRK2-to-total ratio than LRRK2−/PD− (4.8-fold, P < 0.001) and LRRK2−/PD+ (4.6-fold, P < 0.001). Among mutation carriers, those with PD have a higher Ser(P)-1292 LRRK2-to-total ratio than those without PD (2.2-fold, P < 0.001). | Fraser et al. 2016 | [61] |
PD: parkinson’s disease, αsyn: α-synuclein, exo/total ratio: exosomal αsyn/total αsyn ratio, CSF: cerebrospinal fluid, LRRK2: leucine-rich repeat kinase 2, Ser(P)-1292 LRRK2: phosphorylated Ser-1292 LRRK2.