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MiR-155 KO in human dendritic cells

ABSTRACT: In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor / interleukin-1 (TLR/IL-1) inflammatory pathway as a general target of miR-155. We further demonstrate that miR-155 directly controls the level of important signal transduction molecules. Our observations suggest, therefore, that in mature human DCs, miR-155 is part of a negative feedback loop, which down-modulates inflammatory cytokine production in response to microbial stimuli.

ORGANISM(S): Homo sapiens

PROVIDER: GSE13296 | GEO | 2009/03/04

SECONDARY ACCESSION(S): PRJNA109507

REPOSITORIES: GEO

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Project description:Toll-like receptor (TLR)-induced maturation of dendritic cells (DCs) leads to the production of proinflammatory cytokines as well as the upregulation of various molecules involved in T cell activation. These are believed to be the critical events that account for the induction of the adaptive immune response. Here, we have examined the role of micro-RNA-155 (miR-155) in DC function and the induction of immunity. Using a model where the transfer of self-antigen-pulsed, TLR-matured DCs can induce a functional CD8 T cell response and autoimmunity, we find that DCs lacking miR-155 have an impaired ability to break immune tolerance. Importantly, transfer of self- antigen-pulsed DCs overexpressing miR-155 was sufficient to break tolerance in the absence of TLR stimuli. Although these unstimulated DCs induced T cell function in vivo, there was no evidence for the upregulation of costimulatory ligands or cytokine secretion. Further analysis showed that miR-155 influenced the level of the phosphatase SHIP1 in DCs, and that the lack of SHIP1 in DCs was sufficient to break T cell tolerance in vivo, again in the absence of TLR induced DC maturation. Our study demonstrates that the overexpression of miR-155 in DCs is a critical event that is alone sufficient to break self tolerance and promote a CD8-mediated autoimmune response in vivo. This process is independent of the induction of conventional DC maturation markers, indicating that miR-155 regulation of SHIP represents a unique axis that regulates DC function in vivo. Dendritic cell culture: Bone marrow was flushed from tibias and femurs of mice with HBSS. Bone marrow cells were cultured at 2x106 cells/ml in 10 ml non-tissue culture treated dishes in RPMI 1640 containing 10% LPS-free FBS, Penicillin:streptomycin glutamine 2-mercaptoethanol (cRPMI), with 40ng/ml murine GM-CSF (Peprotech). On day 3 of cultures 10ml of fresh media was added also containing 40ng/ml GM-CSF. On days 6 and 8, 10ml of media was removed and centrifuged to collect cells, which were resuspended in 10ml fresh media containing GM-CSF and were added back to dishes. Non-adherent cells were isolated on day 9. DCs were plated in 24-well plates at 2x106 cells/ml in 1ml of cRPMI with or without the class B CpG ODN1826 (ACGT DNA Technologies corporation, Toronto, ON, Canada) at 10?M final concentration overnight. Array analysis of mi-RNA expression: BMDCs from WT mice were either stimulated with CpG or left in media alone overnight. Whole RNA was isolated using mirVana miRNA isolation kit following the manufacturers instructions. RNA samples were labeled and hybridized to Agilent mouse miRNA 8x15K arrays (Agilent). Data was generated from 8 individual samples (4 unstimulated and 4 CpG-treated).

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MiR-155 KO in human dendritic cells

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