Background It is now realized that Parkinson’s disease(PD)pathology extends beyond the substantia nigra,affecting both central and peripheral nervous systems,and exhibits a variety of non-motor symptoms often precedi...Background It is now realized that Parkinson’s disease(PD)pathology extends beyond the substantia nigra,affecting both central and peripheral nervous systems,and exhibits a variety of non-motor symptoms often preceding motor features.Neuroinflammation induced by activated microglia and astrocytes is thought to underlie these manifestations.α-Synuclein aggregation has been linked with sustained neuroinflammation in PD,aggravating neuronal degeneration;however,there is still a lack of critical information about the structural identity of theα-synuclein conformers that activate microglia and/or astrocytes and the molecular pathways involved.Methods To investigate the role ofα-synuclein conformers in the development and maintenance of neuroinflammation,we used primary quiescent microglia and astrocytes,post-mortem brain tissues from PD patients and A53Tα-synuclein transgenic mice that recapitulate key features of PD-related inflammatory responses in the absence of cell death,i.e.,increased levels of pro-inflammatory cytokines and complement proteins.Biochemical and-omics techniques including RNAseq and secretomic analyses,combined with 3D reconstruction of individual astrocytes and live calcium imaging,were used to uncover the molecular mechanisms underlying glial responses in the presence ofα-synuclein oligomers in vivo and in vitro.Results We found that the presence of SDS-resistant hyper-phosphorylatedα-synuclein oligomers,but not monomers,was correlated with sustained inflammatory responses,such as elevated levels of endogenous antibodies and cytokines and microglial activation.Similar oligomericα-synuclein species were found in post-mortem human brain samples of PD patients but not control individuals.Detailed analysis revealed a decrease in Iba1^(Low)/CD68^(Low) microglia and robust alterations in astrocyte number and morphology including process retraction.Our data indicated an activation of the p38/ATF2 signaling pathway mostly in microglia and a sustained induction of the NF-κB pathway in astrocytes of A53T mice.The sustained NF-κB activity triggered the upregulation of astrocytic T-type Ca_(v)3.2 Ca^(2+)channels,altering the astrocytic secretome and promoting the secretion of IGFBPL1,an IGF-1 binding protein with anti-inflammatory and neuroprotective potential.Conclusions Our work supports a causative link between the neuron-producedα-synuclein oligomers and sustained neuroinflammation in vivo and maps the signaling pathways that are stimulated in microglia and astrocytes.It also highlights the recruitment of astrocytic Ca_(v)3.2 channels as a potential neuroprotective mediator against theα-synuclein-induced neuroinflammation.展开更多
基金funded by a Michael J.Fox Foundation grant,Target Advancement Program 2018 and a Hellenic Foundation for Research and Innovation(HFRI)Grant(581)to EE.Partial financial support was received from Special Account for Research Grants of NKUA(18638)to EE and a PhD scholarship grant to D.A.(2022-050-0502-52576)from the Greek State Scholarships Foundation(I.K.Y.)through the action“Scholarships Programs for post-graduate studies”in the framework of the Operational Program“Human Resources Development Program,Education and Lifelong Learning”of the National Strategic Reference Framework(NSRF 2014–2020).
文摘Background It is now realized that Parkinson’s disease(PD)pathology extends beyond the substantia nigra,affecting both central and peripheral nervous systems,and exhibits a variety of non-motor symptoms often preceding motor features.Neuroinflammation induced by activated microglia and astrocytes is thought to underlie these manifestations.α-Synuclein aggregation has been linked with sustained neuroinflammation in PD,aggravating neuronal degeneration;however,there is still a lack of critical information about the structural identity of theα-synuclein conformers that activate microglia and/or astrocytes and the molecular pathways involved.Methods To investigate the role ofα-synuclein conformers in the development and maintenance of neuroinflammation,we used primary quiescent microglia and astrocytes,post-mortem brain tissues from PD patients and A53Tα-synuclein transgenic mice that recapitulate key features of PD-related inflammatory responses in the absence of cell death,i.e.,increased levels of pro-inflammatory cytokines and complement proteins.Biochemical and-omics techniques including RNAseq and secretomic analyses,combined with 3D reconstruction of individual astrocytes and live calcium imaging,were used to uncover the molecular mechanisms underlying glial responses in the presence ofα-synuclein oligomers in vivo and in vitro.Results We found that the presence of SDS-resistant hyper-phosphorylatedα-synuclein oligomers,but not monomers,was correlated with sustained inflammatory responses,such as elevated levels of endogenous antibodies and cytokines and microglial activation.Similar oligomericα-synuclein species were found in post-mortem human brain samples of PD patients but not control individuals.Detailed analysis revealed a decrease in Iba1^(Low)/CD68^(Low) microglia and robust alterations in astrocyte number and morphology including process retraction.Our data indicated an activation of the p38/ATF2 signaling pathway mostly in microglia and a sustained induction of the NF-κB pathway in astrocytes of A53T mice.The sustained NF-κB activity triggered the upregulation of astrocytic T-type Ca_(v)3.2 Ca^(2+)channels,altering the astrocytic secretome and promoting the secretion of IGFBPL1,an IGF-1 binding protein with anti-inflammatory and neuroprotective potential.Conclusions Our work supports a causative link between the neuron-producedα-synuclein oligomers and sustained neuroinflammation in vivo and maps the signaling pathways that are stimulated in microglia and astrocytes.It also highlights the recruitment of astrocytic Ca_(v)3.2 channels as a potential neuroprotective mediator against theα-synuclein-induced neuroinflammation.
