Aggregated alpha-synuclein activates microglia: a process leading to disease progression in Parkinson's disease.
A growing body of evidence indicates that an inflammatory process in the substantia nigra, characterized by activation of resident microglia, likely either initiates or aggravates nigral neurodegeneration in Parkinson's disease (PD). To study the mechanisms by which nigral microglia are activated in PD, the potential role of alpha-synuclein (a major component of Lewy bodies that can cause neurodegeneration when aggregated) in microglial activation was investigated. The results demonstrated that in a primary mesencephalic neuron-glia culture system, extracellular aggregated human alpha-synuclein indeed activated microglia; microglial activation enhanced dopaminergic neurodegeneration induced by aggregated alpha-synuclein. Furthermore, microglial enhancement of alpha-synuclein-mediated neurotoxicity depended on phagocytosis of alpha-synuclein and activation of NADPH oxidase with production of reactive oxygen species. These results suggest that nigral neuronal damage, regardless of etiology, may release aggregated alpha-synuclein into substantia nigra, which activates microglia with production of proinflammatory mediators, thereby leading to persistent and progressive nigral neurodegeneration in PD. Finally, NADPH oxidase could be an ideal target for potential pharmaceutical intervention, given that it plays a critical role in alpha-synuclein-mediated microglial activation and associated neurotoxicity.
Zhang
Wei
W
Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina, USA.
Wang
Tongguang
T
Pei
Zhong
Z
Miller
David S
DS
Wu
Xuefei
X
Block
Michelle L
ML
Wilson
Belinda
B
Zhang
Wanqin
W
Zhou
Yong
Y
Hong
Jau-Shyong
JS
Zhang
Jing
J
D000818:Animals; D001253:Astrocytes / Q000502:physiology; D001921:Brain; D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism; D004298:Dopamine / Q000502:physiology; D004622:Embryo, Mammalian; D004789:Enzyme Activation; D006801:Humans; D007150:Immunohistochemistry; D008636:Mesencephalon; D051379:Mice; D018345:Mice, Knockout; D017628:Microglia / Q000187:drug effects* / Q000502:physiology*; D019255:NADPH Oxidases / Q000172:deficiency / Q000502:physiology; D009410:Nerve Degeneration / Q000139:chemically induced; D009457:Neuroglia / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000032:analysis; D018384:Oxidative Stress; D010300:Parkinson Disease / Q000209:etiology*; D010587:Phagocytosis; D011108:Polymers / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins; D013378:Substantia Nigra / Q000378:metabolism*; D014316:Tritium; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis; D051844:alpha-Synuclein / Q000737:chemistry* / Q000494:pharmacology* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D009573:Nitrites; D011108:Polymers; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D051844:alpha-Synuclein; D014316:Tritium; D009569:Nitric Oxide; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase; D019255:NADPH Oxidases; D015232:Dinoprostone; D004298:Dopamine