Table 1.
Summaries of studies exploring the roles of exosomes in Parkinson’s disease (PD)-associated inflammation
| Authors | Country | Study subjects | Main conclusions |
|---|---|---|---|
| Han et al., 2019 | China | 20 Sporadic mild-late-stage PD patients without any α-synuclein genetic variants and 20 controls (sex-and age-matched) | (1) Significant increases in TNF-α and IL-1β levels were detected in PD patient serum exosomes. (2) PD patient serum exosomes contained a higher density of oligomeric and monomeric α-synuclein than those from controls. (3) When PD exosomes were injected into the striatum of mice, the levels of IL-1β, α-synuclein, p-synuclein, and P62 increased. (4) Mice injected with PD exosomes in the striatum showed ipsilateral rotation, and mice injected with PD exosomes by intravenous injection showed obvious motor deficits. |
| Calvani et al., 2020 | Italy | 20 PD patients and 30 age-matched controls | Higher levels of IL-8 and MIP-1β and lower levels of IL-9 and MIP-1α were detected in PD patients. |
| Picca et al., 2020 | Italy | 20 older adult PD patients and 12 age- and sex-matched controls | (1) PD patients had more circulating exosomes than the control group, and the cell flux level of MQC was severely impaired. (2) CD9, CD63, ATP5A, NDUFS3, and SDHB levels were lower in PD patients. |
| Sarkar et al., 2019 | USA | Microglial cells were primed with LPS for 3 hours and then treated with Mn for a further 24 hours and compared with unstimulated or LPS-primed microglial cells | (1) ASC loaded in the exosome can stimulate the activation of inflammatory bodies in adjacent cells. (2) Exosomes isolated from welder serum-stimulated the expression of NLRP3 and pro-IL-1β, further validating the role of exosomes in modulating inflammasome propagation. |
| Tsutsumi et al., 2019 | Japan | Rat midbrain | Exosomes were involved in the effects of microglial activation on dopaminergic neurodegeneration. |
| Harischandra et al., 2018 | USA | MN9D-SynGFP cell line and MN9D-EVGFP cell line (300 mM MnCl2 exposure for 24 h) | (1) The miRNA released by the PD cell model involves a variety of biological processes, such as mitochondrial function, inflammation, autophagy, and protein aggregation. (2) MiR-125b (known pro-inflammatory miRNA) increases significantly. |
| Picca et al., 2019 | Italy | 20 PD patients and 20 sex- and age-matched controls | Isolated sEVs were used to identify the mitochondrial components, in particular respiratory chain complex subunits and mtDNA and MQC factors. |
ASC: The NLRP3 inflammasome oligomeric complex is composed of an adapter protein ASC (apoptosis-associated speck-like protein containing a CARD); ATP5A: adenosine triphosphate 5A; IL-8: interleukin-8; IL-9: interleukin-9; LPS: lipopolysaccharide; MIP-1α: macrophage inflammatory protein 1-α; MIP-1β: macrophage inflammatory protein 1-β; MN9D-EVGFP: vector control of MN9D dopaminergic cell; MN9D-SynGFP: GFP-positive α-synuclein-expressing MN9D dopaminergic cell; MQC: mitochondrial quality control; NDUFS3: NADH ubiquinone oxidoreductase subunit S3; NLRP3: nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3; SDHB: succinate dehydrogenase complex iron-sulfur subunit B; TNF-α: tumor necrosis factor-α.