1. Academic Validation
  2. α-Synuclein-containing erythrocytic extracellular vesicles: essential contributors to hyperactivation of monocytes in Parkinson's disease

α-Synuclein-containing erythrocytic extracellular vesicles: essential contributors to hyperactivation of monocytes in Parkinson's disease

  • J Neuroinflammation. 2022 Feb 22;19(1):53. doi: 10.1186/s12974-022-02413-1.
Zongran Liu 1 Robin Barry Chan 2 Zhijian Cai 3 Xiaodan Liu 1 Yufeng Wu 4 Zhenwei Yu 5 Tao Feng 6 Ying Yang 7 Jing Zhang 8 9
Affiliations

Affiliations

  • 1 Department of Pathology, Peking University Health Science Center, Beijing, 100191, China.
  • 2 AliveX Biotech, Shanghai, 200030, China.
  • 3 School of Basic Medicine, Zhejiang University, Hangzhou, 310002, Zhejiang, China.
  • 4 Department of Laboratory Medicine, Peking University Third Hospital, Peking University Health Science Center, Beijing, China.
  • 5 Beijing Neurosurgical Institute, Capital Medical University, Beijing, 100050, China.
  • 6 Department of Neurology, TianTan Hospital, Capital Medical University, Beijing, 100050, China.
  • 7 Department of Pathology, Peking University Health Science Center, Beijing, 100191, China. rebecca_yang@pku.edu.cn.
  • 8 Department of Pathology, Zhejiang University School of Medicine and First Affiliated Hospital, Hangzhou, 310002, Zhejiang, China. jzhang1989@zju.edu.cn.
  • 9 National Health and Disease Human Brain Tissue Resource Center, Zhejiang University, Hangzhou, 310002, Zhejiang, China. jzhang1989@zju.edu.cn.
Abstract

Background: Immune system dysfunction, including higher levels of peripheral monocytes and inflammatory cytokines, is an important feature of Parkinson's disease (PD) pathogenesis, although the mechanism underlying the process remains to be investigated. In the central nervous system, it is well-known that α-synuclein (α-syn), a key protein involved in PD, activates microglia potently, and it is also reported that α-syn exists in the peripheral system, especially in erythrocytes or red blood cells (RBC) at exceedingly high concentration. The current study focused on the possibility that RBC-derived α-syn mediates the sensitization of peripheral monocytes in PD patients.

Methods: The hyperactivation of monocytes was assessed quantitatively by measuring mRNA levels of typical inflammatory cytokines (including IL-1β, IL-6 and TNF-α) and protein levels of secreted inflammatory cytokines (including pro-inflammatory cytokines: IL-1β, IL-6, TNF-α, IL-8, IFN-γ, IL-2, and IL-12p70 and anti-inflammatory cytokines: IL-4, IL-10, and IL-13). Western blot, nanoparticle tracking analysis and electron microscopy were used to characterize RBC-derived extracellular vesicles (RBC-EVs). Inhibitors of endocytosis and leucine-rich repeat kinase 2 (LRRK2), another key protein involved in PD, were used to investigate how these two factors mediated the process of monocyte sensitization by RBC-EVs.

Results: Increased inflammatory sensitization of monocytes was observed in PD patients and PD model mice. We found that α-syn-containing RBC-EVs isolated from PD model mice or free form oligomeric α-syn induced the inflammatory sensitization of THP-1 cells, and demonstrated that endocytosis was a requirement for this pathophysiological pathway. Furthermore, the hyperactivation of THP-1 cells induced by RBC-EVs was associated with increased LRRK2 production and kinase activity. The phenomenon of inflammatory sensitization of human monocytes and increased LRRK2 were also observed by the treatment of RBC-EVs isolated from PD patients.

Conclusions: Our data provided new insight into how hyperactivation of monocytes occurs in PD patients, and identified the central role played by α-syn-containing RBC-EVs in this process.

Keywords

Extracellular vesicles; LRRK2; Monocytes; Parkinson’s disease; RBC; α-Synuclein.

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