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Takeo Mukai
Tokyo Daigaku Ikagaku Kenkyujo
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6648-1271
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Background: Microglia are the immune cells in the central nervous system constantly surveying their environment and reacting to various injuries. Activated microglia may cause impaired synaptic plasticity, therefore modulating and restoring them to more neutral phenotype is crucial to counteract a pro-inflammatory, neurotoxic state. In this study, we focused on elucidating whether human umbilical cord (UC) tissue-derived mesenchymal stromal cells (MSCs) can exert immunomodulatory effect and change the phenotype of activated microglia.
Methods: Primary culture of microglia was activated by lipopolysaccharide (LPS) and was co-cultured with three lots of MSCs. We investigated immunomodulation, actin dynamics and phagocytic capacity of activated microglia, and examined change of Rho GTPase in microglia as the mechanism.
Results: MSCs suppressed the expression of IL-1β and pNFκB in LPS-activated microglia, and conversely elevated the expression of IL-1β in resting-surveying microglia with lot-to-lot variation. Morphological and phagocytotic analyses revealed that LPS stimulation significantly increased active Rho GTPase, Rac1, and Cdc42 levels in the microglia, and their morphology changed to amoeboid in which F-actin spread with ruffle formation. The F-actin spreading persisted after removal of LPS stimulation and reduced phagocytosis. On the other hand, MSC co-culture induced bimodal increase in active Rac1 and Cdc42 levels in LPS-activated microglia. Moreover, extended ruffles of F-actin shrinked and concentrated to form an actin ring, thereby restoring phagocytosis. We confirmed that inhibition of the PI3K/Akt pathway attenuated F-actin dynamics and phagocytosis restored by MSCs.
Conclusions: Overall, we demonstrated that MSCs immunomodulated microglia with lot-to-lot variation, and changed the phenotype of LPS-activated microglia, thereby restoring actin dynamics and phagocytosis by increase of active Rho GTPase. Modulation of the phenotype of activated microglia by MSCs can be a novel therapeutic strategy for the treatment of neurological disorders accompanied by inflammation.
Keywords
Mesenchymal stromal cells, Umbilical cord, Microglia, Phagocytosis, Immunomodulation, RhoGTPase, Lot-to-lot variation
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A new preprint design is coming!
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research
Takeo Mukai
Tokyo Daigaku Ikagaku Kenkyujo
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6648-1271
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
View the published article at Cell Death Discovery.
Version 1
Posted 16 Jun, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Oncology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at Cell Death Discovery.
Background: Microglia are the immune cells in the central nervous system constantly surveying their environment and reacting to various injuries. Activated microglia may cause impaired synaptic plasticity, therefore modulating and restoring them to more neutral phenotype is crucial to counteract a pro-inflammatory, neurotoxic state. In this study, we focused on elucidating whether human umbilical cord (UC) tissue-derived mesenchymal stromal cells (MSCs) can exert immunomodulatory effect and change the phenotype of activated microglia.
Methods: Primary culture of microglia was activated by lipopolysaccharide (LPS) and was co-cultured with three lots of MSCs. We investigated immunomodulation, actin dynamics and phagocytic capacity of activated microglia, and examined change of Rho GTPase in microglia as the mechanism.
Results: MSCs suppressed the expression of IL-1β and pNFκB in LPS-activated microglia, and conversely elevated the expression of IL-1β in resting-surveying microglia with lot-to-lot variation. Morphological and phagocytotic analyses revealed that LPS stimulation significantly increased active Rho GTPase, Rac1, and Cdc42 levels in the microglia, and their morphology changed to amoeboid in which F-actin spread with ruffle formation. The F-actin spreading persisted after removal of LPS stimulation and reduced phagocytosis. On the other hand, MSC co-culture induced bimodal increase in active Rac1 and Cdc42 levels in LPS-activated microglia. Moreover, extended ruffles of F-actin shrinked and concentrated to form an actin ring, thereby restoring phagocytosis. We confirmed that inhibition of the PI3K/Akt pathway attenuated F-actin dynamics and phagocytosis restored by MSCs.
Conclusions: Overall, we demonstrated that MSCs immunomodulated microglia with lot-to-lot variation, and changed the phenotype of LPS-activated microglia, thereby restoring actin dynamics and phagocytosis by increase of active Rho GTPase. Modulation of the phenotype of activated microglia by MSCs can be a novel therapeutic strategy for the treatment of neurological disorders accompanied by inflammation.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
This is a list of supplementary files associated with this preprint. Click to download.
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