| 1. |
- Ben-David, Yael, et al.
(författare)
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RIC3, the cholinergic anti-inflammatory pathway, and neuroinflammation
- 2020
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Ingår i: International Immunopharmacology. - : ELSEVIER. - 1567-5769 .- 1878-1705. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels having many functions including inflammation control, as part of the cholinergic anti-inflammatory pathway. Genome wide association studies implicated RIC3, a chaperone of nAChRs, in multiple sclerosis (MS), a neuroinflammatory disease. To understand the involvement of RIC3 in inflammatory diseases we examined its expression, regulation, and function in activated immune cells. Our results show that immune activation leads to dynamic changes in RIC3 expression, in a mouse model of MS and in human lymphocytes and macrophages. We also show similarities in the expression dynamics of RIC3 and CHRNA7, encoding for the alpha 7 nAChR subunit. Homomeric alpha 7 nAChRs were shown to mediate the anti-inflammatory effects of cholinergic agonists. Thus, similarity in expression dynamics between RIC3 and CHRNA7 is suggestive of functional concordance. Indeed, siRNA mediated silencing of RIC3 in a mouse macrophage cell line eliminates the anti-inflammatory effects of cholinergic agonists. Furthermore, we show increased average expression of RIC3 and CHRNA7 in lymphocytes from MS patients, and a strong correlation between expression levels of these two genes in MS patients but not in healthy donors. Together, our results are consistent with a role for RIC3 and for the mechanisms regulating its expression in inflammatory processes and in neuroinflammatory diseases.
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| 2. |
- Beretta, Chiara, et al.
(författare)
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Astrocytes with Alzheimer’s disease pathology provoke lipid droplet mediated cell-to-cell propagation of MHC II complexes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background. Astrocytes are critical for maintaining brain homeostasis, but are also highly involved in neuroinflammation. In the Alzheimer disease (AD) brain, reactive, inflammatory astrocytes are situated closely around amyloid β (Aβ) plaques. We have previously shown that reactive astrocytes ingest large quantities of soluble Aβ aggregates, but are unable to degrade the material, which leads to intracellular Aβ accumulation and severe cellular stress. A common response to cellular stress is the formation of lipid droplets (LDs). Novel data indicate that LDs play an important role in inflammatory processes. However, the involvement of LDs in AD inflammation and progression remains unclear.Methods. The aim of this study was to investigate how astrocytic Aβ pathology affects lipid metabolism and antigen presentation. For this purpose, human induced pluripotent stem cell (iPSC) derived astrocytes were exposed to soluble Aβ42 aggregates and analyzed over time, using a battery of experimental approaches.Results. Our results show that Aβ exposure induces LD accumulation in astrocytes, although the overall lipid composition remains unchanged. Moreover, astrocytes transfer LDs to neighboring cells via tunneling nanotubes (TNTs) and extracellular vesicle (EVs). Interestingly, we found that the antigen presenting protein major histocompatibility complex II (MHCII) is present inside LDs, suggesting an active role of LDs in astrocytic antigen presentation. Immunohistochemical analysis of human brain tissue verified the presence of LD-loaded MHCII+ astrocytes in AD individuals. Moreover, we found infiltrated CD4+ T cells to be in close contact with astrocytes, confirming an astrocyte T cell cross-talk in the AD brainConclusions. Taken together, our data show that Aβ pathology drastically affects lipid storage in astrocytes, which in turn modulates the astrocytic antigen presentation, indicating a role for astrocytic LDs in T cell responses in the AD brain.
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| 3. |
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| 4. |
- Gustafsson, Gabriel, et al.
(författare)
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Alpha-synuclein oligomer-selective antibodies reduce intracellular accumulation and mitochondrial impairment in alpha-synuclein exposed astrocytes
- 2017
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Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Due to its neurotoxic properties, oligomeric alpha-synuclein (α-syn) has been suggested as an attractive target for passive immunization against Parkinson’s disease (PD). In mouse models of PD, antibody treatment has been shown to lower the levels of pathogenic α-syn species, including oligomers, although the mechanisms of action remain unknown. We have previously shown that astrocytes rapidly engulf α-syn oligomers that are intracellularly stored, rather than degraded, resulting in impaired mitochondria.Methods: The aim of the present study was to investigate if the accumulation of α-syn in astrocytes can be affected by α-syn oligomer-selective antibodies. Co-cultures of astrocytes, neurons, and oligodendrocytes were derived from embryonic mouse cortex and exposed to α-syn oligomers or oligomers pre-incubated with oligomer-selective antibodies.Results: In the presence of antibodies, the astrocytes displayed an increased clearance of the exogenously added α-syn, and consequently, the α-syn accumulation in the culture was markedly reduced. Moreover, the addition of antibodies rescued the astrocytes from the oligomer-induced mitochondrial impairment.Conclusions: Our results demonstrate that oligomer-selective antibodies can prevent α-syn accumulation and mitochondrial dysfunction in cultured astrocytes.
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| 5. |
- Lekholm, Emilia, et al.
(författare)
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Putative Membrane-Bound Transporters MFSD14A and MFSD14B Are Neuronal and Affected by Nutrient Availability
- 2017
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Characterization of orphan transporters is of importance due to their involvement in cellular homeostasis but also in pharmacokinetics and pharmacodynamics. The tissue and cellular localization, as well as function, is still unknown for many of the solute carriers belonging to the major facilitator superfamily (MFS) Pfam clan. Here, we have characterized two putative novel transporters MFSD14A (HIAT1) and MFSD14B (HIATL1) in the mouse central nervous system and found protein staining throughout the adult mouse brain. Both transporters localized to neurons and MFSD14A co-localized with the Golgi marker Giantin in primary embryonic cortex cultures, while MFSD14B staining co-localized with an endoplasmic retention marker, KDEL. Based on phylogenetic clustering analyses, we predict both to have organic substrate profiles, and possible involvement in energy homeostasis. Therefore, we monitored gene regulation changes in mouse embryonic primary cultures after amino acid starvations and found both transporters to be upregulated after 3 h of starvation. Interestingly, in mice subjected to 24 h of food starvation, both transporters were downregulated in the hypothalamus, while Mfsdl4a was also downregulated in the brainstem. In addition, in mice fed a high fat diet (HFD), upregulation of both transporters was seen in the striatum. Both MFSD14A and MFSD14B were intracellular neuronal membrane bound proteins, expressed in the Golgi and Endoplasmic reticulum, affected by both starvation and HFD to varying degree in the mouse brain.
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| 6. |
- Mothes, Tobias, et al.
(författare)
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APOEε2 drives tau processing and tau-mediated inflammation in human iPSC derived astrocytes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Alzheimer’s disease (AD) and progressive supra-nuclear palsy (PSP) are both proteinopathies, characterized by accumulation of tau aggregates. APOEε4 is the greatest genetic risk factor for developing AD, while APOEε2 constitutes a decreased risk. On the contrary, APOEε2 is a significant risk factor for developing PSP. In the brain, astrocytes are the predominant producer of ApoE, but they are also important for synapse function, inflammation and overall brain homeostasis. Although, tau inclusions appear frequently in astrocytes in both AD and PSP brains, their connection to ApoE remains unclear. Methods: The aim of this study was to investigate how the APOEε-genotype influences astrocytes’ accumulation, processing and spreading of pathogenic tau aggregates, as well as their inflammatory status and neuronal support. For this purpose, we exposed isogenic hiPSC-derived APOE 2/2 and APOE 4/4 astrocytes to synthetic tau fibrils (Tau-F). Intracellular tau processing was analysed with immunocytochemistry and western blot, while secreted tau was analysed with ELISA. Cytokine levels in astrocyte conditioned medium (ACM) were measured with MesoScale analysis and seeding efficiency was examined using the Tau RD P301S FRET Biosensor and a close-culture chamber. Lastly, we exposed iPSC derived neurons to ACM from tau exposed astrocytes of both genotypes to assess potential neurotoxic effects.Results: Exposure to Tau-F resulted in more and larger intracellular tau-deposits in APOE 2/2 astrocytes, compared to APOE 4/4 astrocytes, while the tau levels in ACM remained similar. Western blot analysis demonstrated that the processing of internalized tau was clearly different between the genotypes. Moreover, APOE 2/2 was the dominant driver of inflammation with higher secreted levels of IL-8, CXCL10 and CCL2. The ApoE genotype did not influence neuronal health or direct seeding capacity of excreted tau. However, Tau-F had a 3-fold higher seeding efficiency when diluted in ACM from APOE 2/2 astrocytes, compared to APOE 4/4 astrocytes. Conclusions: Our results show that APOE 2/2 astrocytes accumulate, process and spread pathogenic tau aggregates more efficiently than APOE 4/4 astrocytes, highlighting a role of ApoE in astrocyte-mediated tau pathology. Moreover, the APOE 2/2 astrocytes display a more robust inflammatory response, which could be of relevance for the disease course.
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| 7. |
- Mothes, Tobias, et al.
(författare)
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Astrocytic uptake of neuronal corpses promotes cell-to-cell spreading of tau pathology
- 2023
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Ingår i: Acta neuropathologica communications. - : BioMed Central (BMC). - 2051-5960. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Tau deposits in astrocytes are frequently found in Alzheimer's disease (AD) and other tauopathies. Since astrocytes do not express tau, the inclusions have been suggested to be of neuronal origin. However, the mechanisms behind their appearance and their relevance for disease progression remain unknown. Here we demonstrate, using a battery of experimental techniques that human astrocytes serve as an intermediator, promoting cell-to-cell spreading of pathological tau. Human astrocytes engulf and process, but fail to fully degrade dead neurons with tau pathology, as well as synthetic tau fibrils and tau aggregates isolated from AD brain tissue. Instead, the pathogenic tau is spread to nearby cells via secretion and tunneling nanotube mediated transfer. By performing co-culture experiments we could show that tau-containing astrocytes induce tau pathology in healthy human neurons directly. Furthermore, our results from a FRET based seeding assay, demonstrated that the tau proteoforms secreted by astrocytes have an exceptional seeding capacity, compared to the original tau species engulfed by the cells. Taken together, our study establishes a central role for astrocytes in mediating tau pathology, which could be of relevance for identifying novel treatment targets for AD and other tauopathies.
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| 8. |
- Rostami, Jinar, et al.
(författare)
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Astrocytes have the capacity to act as antigen-presenting cells in the Parkinson's disease brain
- 2020
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Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMany lines of evidence suggest that accumulation of aggregated alpha-synuclein (αSYN) in the Parkinson’s disease (PD) brain causes infiltration of T cells. However, in which ways the stationary brain cells interact with the T cells remain elusive. Here, we identify astrocytes as potential antigen-presenting cells capable of activating T cells in the PD brain. Astrocytes are a major component of the nervous system, and accumulating data indicate that astrocytes can play a central role during PD progression.MethodsTo investigate the role of astrocytes in antigen presentation and T-cell activation in the PD brain, we analyzed post mortem brain tissue from PD patients and controls. Moreover, we studied the capacity of cultured human astrocytes and adult human microglia to act as professional antigen-presenting cells following exposure to preformed αSYN fibrils.ResultsOur analysis of post mortem brain tissue demonstrated that PD patients express high levels of MHC-II, which correlated with the load of pathological, phosphorylated αSYN. Interestingly, a very high proportion of the MHC-II co-localized with astrocytic markers. Importantly, we found both perivascular and infiltrated CD4+ T cells to be surrounded by MHC-II expressing astrocytes, confirming an astrocyte T cell cross-talk in the PD brain. Moreover, we showed that αSYN accumulation in cultured human astrocytes triggered surface expression of co-stimulatory molecules critical for T-cell activation, while cultured human microglia displayed very poor antigen presentation capacity. Notably, intercellular transfer of αSYN/MHC-II deposits occurred between astrocytes via tunneling nanotubes, indicating spreading of inflammation in addition to toxic protein aggregates.ConclusionsIn conclusion, our data from histology and cell culture studies suggest an important role for astrocytes in antigen presentation and T-cell activation in the PD brain, highlighting astrocytes as a promising therapeutic target in the context of chronic inflammation.
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| 9. |
- Rostami, Jinar, et al.
(författare)
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Crosstalk between astrocytes and microglia results in increased degradation of α-synuclein and amyloid-β aggregates
- 2021
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Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundAlzheimer’s disease (AD) and Parkinson’s disease (PD) are characterized by brain accumulation of aggregated amyloid-beta (Aβ) and alpha-synuclein (αSYN), respectively. In order to develop effective therapies, it is crucial to understand how the Aβ/αSYN aggregates can be cleared. Compelling data indicate that neuroinflammatory cells, including astrocytes and microglia, play a central role in the pathogenesis of AD and PD. However, how the interplay between the two cell types affects their clearing capacity and consequently the disease progression remains unclear.MethodsThe aim of the present study was to investigate in which way glial crosstalk influences αSYN and Aβ pathology, focusing on accumulation and degradation. For this purpose, human-induced pluripotent cell (hiPSC)-derived astrocytes and microglia were exposed to sonicated fibrils of αSYN or Aβ and analyzed over time. The capacity of the two cell types to clear extracellular and intracellular protein aggregates when either cultured separately or in co-culture was studied using immunocytochemistry and ELISA. Moreover, the capacity of cells to interact with and process protein aggregates was tracked using time-lapse microscopy and a customized “close-culture” chamber, in which the apical surfaces of astrocyte and microglia monocultures were separated by a <1 mm space.ResultsOur data show that intracellular deposits of αSYN and Aβ are significantly reduced in co-cultures of astrocytes and microglia, compared to monocultures of either cell type. Analysis of conditioned medium and imaging data from the “close-culture” chamber experiments indicate that astrocytes secrete a high proportion of their internalized protein aggregates, while microglia do not. Moreover, co-cultured astrocytes and microglia are in constant contact with each other via tunneling nanotubes and other membrane structures. Notably, our live cell imaging data demonstrate that microglia, when attached to the cell membrane of an astrocyte, can attract and clear intracellular protein deposits from the astrocyte.ConclusionsTaken together, our data demonstrate the importance of astrocyte and microglia interactions in Aβ/αSYN clearance, highlighting the relevance of glial cellular crosstalk in the progression of AD- and PD-related brain pathology.
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| 10. |
- Rostami, Jinar, et al.
(författare)
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Human astrocytes transfer aggregated alpha-synuclein via tunneling nanotubes
- 2017
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Ingår i: The Journal of Neuroscience. - : SOC NEUROSCIENCE. - 0270-6474 .- 1529-2401. ; 37:49, s. 11835-11853
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Tidskriftsartikel (refereegranskat)abstract
- Many lines of evidence suggest that the Parkinson’s disease (PD)-related protein α-synuclein (α-SYN) can propagate from cell to cell in a prion-like manner. However, the cellular mechanisms behind the spreading remain elusive. Here, we show that human astrocytes derived from embryonic stem cells actively transfer aggregated α-SYN to nearby astrocytes via direct contact and tunneling nanotubes (TNTs). Failure in the astrocytes’ lysosomal digestion of excess α-SYN oligomers results in α-SYN deposits in the trans-Golgi network followed by endoplasmic reticulum swelling and mitochondrial disturbances. The stressed astrocytes respond by conspicuously sending out TNTs, enabling intercellular transfer of α-SYN to healthy astrocytes, which in return deliver mitochondria, indicating a TNT-mediated rescue mechanism. Using a pharmacological approach to inhibit TNT formation, we abolished the transfer of both α-SYN and mitochondria. Together, our results highlight the role of astrocytes in α-SYN cell-to-cell transfer, identifying possible pathophysiological events in the PD brain that could be of therapeutic relevance.
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