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Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Exosome-mediated microglia-astrocyte interactions drive neuroinflammation in Parkinson's disease with Peli1 as a
Min Guo1, Ao Guan1, Minjie Zhang2
1Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China.
Abstract:
Neuroinflammation is a key feature of Parkinson's disease (PD), characterized by activated microglia and the conversion of astrocytes into the neurotoxic phenotype, exacerbating the neuroinflammation. In PD, microglia critically drive neurotoxic reactive astrocytes (A1, A1-like, or neuroinflammatory reactive astrocytes)-though the underlying mechanisms remain elusive. Given the established role of exosomes as critical intercellular messengers, we investigated whether microglia-derived exosomes contribute to neurotoxic astrocyte transformation. Our findings demonstrate that microglial depletion via PLX3397 significantly attenuated α-synuclein pre-formed fibrils (α-syn PFF)-induced neurotoxic reactive astrocytes. Crucially, purified microglial exosomes alone proved sufficient to drive astrocyte polarization toward the neurotoxic phenotype in mice. Complementary approaches-exosome depletion from microglial supernatants and GW4869-mediated exosome secretion blockade-convergently alleviated neurotoxic astrocytic phenotype conversion, verifying exosome-dependent mechanisms. Mechanistically, PFF-activated microglial exosomes carried proinflammatory factors and toxic α-syn oligomers. These cargo components exacerbated neuroinflammation through induction of the neurotoxic astrocyte phenotype and direct mediation of neuronal damage. Critically, upon intrastriatal injection, these exosomes were internalized by astrocytes in the striatum and substantia nigra, triggering concurrent astrocyte proliferation and neurotoxic phenotypic conversion. Additionally, we identify Peli1, an E3 ubiquitin ligase selectively enriched in microglia, as a key regulator of microglia activation and exosome release. Peli1 inhibition alleviates microglia activation and neurotoxic astrocyte conversion. Moreover, our findings reveal a feedback loop between neurotoxic astrocytes and microglia, wherein neurotoxic astrocytes upregulate Peli1 expression in microglia, further promoting neuroinflammation. This study highlights microglial exosomes in regulating neurotoxic astrocyte activation and identifies Peli1 as a novel target for PD intervention.
Insights
Microglia-derived exosomes drive neuroinflammation in Parkinson's disease by transforming astrocytes into a toxic state. Inhibiting exosome release or targeting Peli1 shows therapeutic potential for Parkinson's disease.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Neuroinflammation, involving activated microglia and reactive astrocytes, is central to Parkinson's disease (PD).
- The precise mechanisms by which microglia induce neurotoxic astrocyte phenotypes in PD remain unclear.
- Exosomes are recognized as key mediators of intercellular communication.
Purpose of the Study:
- To investigate the role of microglia-derived exosomes in the transformation of astrocytes into a neurotoxic phenotype in Parkinson's disease.
- To elucidate the molecular mechanisms underlying exosome-mediated neuroinflammation in PD.
- To identify potential therapeutic targets for PD intervention.
Main Methods:
- Microglial depletion using PLX3397 to assess its effect on α-synuclein pre-formed fibrils (α-syn PFF)-induced neurotoxic astrocytes.
- Administration of purified microglial exosomes to mice to evaluate their impact on astrocyte phenotype.
- Exosome depletion and secretion blockade (GW4869) to confirm exosome-dependent mechanisms.
- Analysis of exosome cargo, including proinflammatory factors and α-syn oligomers.
- Intrastriatal injection of exosomes to observe astrocyte internalization and phenotypic changes in vivo.
- Investigation of the role of Peli1 (E3 ubiquitin ligase) in microglia activation and exosome release.
Main Results:
- Microglial depletion significantly reduced α-syn PFF-induced neurotoxic reactive astrocytes.
- Microglia-derived exosomes alone were sufficient to induce a neurotoxic astrocyte phenotype in mice.
- Exosome-dependent mechanisms were confirmed by exosome depletion and secretion blockade.
- PFF-activated microglial exosomes contained proinflammatory factors and toxic α-syn oligomers, exacerbating neuroinflammation and neuronal damage.
- Injected exosomes were internalized by astrocytes, leading to proliferation and neurotoxic conversion.
- Peli1 was identified as a key regulator of microglia activation and exosome release, with its inhibition alleviating neuroinflammation.
- A feedback loop was observed where neurotoxic astrocytes upregulate Peli1 in microglia, further promoting neuroinflammation.
Conclusions:
- Microglia-derived exosomes play a critical role in mediating neuroinflammation by inducing neurotoxic astrocyte activation in Parkinson's disease.
- Peli1 is a novel regulator of microglia activation and exosome release, representing a potential therapeutic target for PD.
- Targeting microglial exosome pathways offers a promising strategy for intervening in PD pathogenesis.
