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Lookup NU author(s): Dr Emily Mavin, Dr Lindsay Nicholson, Dr Kile GreenORCiD, Professor Anne Dickinson, Dr Xiao WangORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Mesenchymal stromal cells (MSCs) are potent regulators of immune responses largely through paracrine signaling. MSC secreted extracellular vesicles (MSC-EVs) are increasingly recognized as the key paracrine factors responsible for the biological and therapeutic function of MSCs. We report the first comprehensive study demonstrating the immunomodulatory effect of MSC-EVs on dendritic cell (DC) maturation and function. MSC-EVs were isolated from MSC conditioned media using differential ultracentrifugation. Human monocyte-derived DCs were generated in the absence or presence of MSC-EVs (20 ug/ml) then subjected to phenotypic and functional analysis in vitro. MSC-EV treatment impaired antigen uptake by immature DCs and halted DC maturation resulting in reduced expression of the maturation and activation markers CD83, CD38, and CD80, decreased secretion of pro‐inflammatory cytokines IL‐6 and IL‐12p70 and increased production of anti‐inflammatory cytokine TGF‐β. MSC‐EV treated DCs also demonstrated a diminished CCR 7 expression after LPS stimulation, coupled with a significantly reduced ability to migrate towards the CCR7-ligand CCL21, although they were still able to stimulate allogeneic T cell proliferation in vitro. Through microRNA profiling we have identified 49 microRNAs, which were significantly enriched in MSC-EVs compared to their parent MSCs. MicroRNAs with known effect on DC maturation and functions, including miR-21-5p, miR-142-3p, miR-223-3p and miR-126-3p, were detected within the top 10 most enriched miRNAs in MSC-EVs, with MiR-21-5p as the third highest expressed miRNA in MSC-EVs. In silico analysis revealed that miR-21-5p targets the CCR7 gene for degradation. To verify these observations, DCs were transfected with miR-21-5p mimics and analyzed for their ability to migrate towards the CCR7-ligand CCL21 in vitro. MiR-21-5p mimic transfected DCs showed a clear trend of reduced CCR7 expression and a significantly decreased migratory ability towards the CCL21. Our findings suggest that MSC-EVs are able to recapitulate MSC mediated DC modulation and MSC-EV enclosed microRNAs may represent a novel mechanism through which MSCs modulate DC functions. As MSCs are currently used in clinical trials to treat numerous diseases associated with immune dysregulation such as graft-versus-host disease and inflammatory bowel disease, our data provide novel evidence to inform potential future application of MSC-EVs as a cell-free therapeutic agent.
Author(s): Reis M, Mavin E, Nicholson L, Green K, Dickinson A, Wang X
Publication type: Article
Publication status: Published
Journal: Frontiers in Immunology
Year: 2018
Volume: 9
Online publication date: 09/11/2018
Acceptance date: 15/10/2018
Date deposited: 16/10/2018
ISSN (electronic): 1664-3224
Publisher: Frontiers Research Foundation
URL: https://doi.org/10.3389/fimmu.2018.02538
DOI: 10.3389/fimmu.2018.02538
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