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Updated: May 12, 2026
Development and Functional Characterization of Murine Tolerogenic Dendritic Cells
Published on: May 18, 2018
Mature dendritic cell suppression by IL-1 receptor antagonist on retinal pigment epithelium cells
Sunao Sugita1, Yuko Kawazoe, Ayano Imai
1Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University Graduate School of Medicine and Dental Sciences, Tokyo, Japan. sunaoph@cdb.riken.jp
Purpose:
To determine whether retinal pigment epithelial (RPE) cells can inhibit mature dendritic cells (mDCs).
Methods:
Cultured RPE cells were established from C57BL/6 mice. DCs were established from bone marrow cells of normal mice, and mDCc were induced by culture in medium containing granulocyte macrophage-colony-stimulating factor (GM-CSF) and IL-4 in the presence of lipopolysaccharide and TNF-α. Activation of mDCs was assessed by a proliferation assay and ELISA to measure the production of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-12p40). Expression of major histocompatibility complex (MHC) class II, CD11c, and costimulatory molecules such as CD80, CD86, programmed cell death 1 ligand 1 (PD-L1), and PD-L2 on mDCs or RPE-exposed mDCs was evaluated by immune staining and flow cytometry. Production of IL-1 receptor antagonist (IL-1Ra) by RPE cells was evaluated by oligonucleotide microarray or ELISA. Anti-IL-1Ra neutralizing antibodies or RPE cells from IL-1Ra knockout donors were used for the assay.
Results:
Cultured RPE cells greatly suppressed the activation of mDCs, especially the production of pro-inflammatory cytokines, and the expression of cell-surface molecules. Moreover, RPE cells significantly suppressed mixed lymphocyte reactions by mDCs. In an examination of immunoregulatory candidate molecules, RPE cells expressed much higher levels of IL-1Ra as compared with control cells, and RPE cells pretreated with recombinant TNF-α and/or IL-1β produced high levels of IL-1Ra. RPE cells in the presence of anti-IL-1Ra antibodies, but not other candidate factors, failed to suppress activation by mDCs. In addition, RPE cells from IL-1Ra null donors failed to suppress mDC activation.
Conclusions:
Our results suggest that ocular resident cells can produce pro-inflammatory cytokine antagonist that suppresses antigen-presenting cell activation.
Insights
Retinal pigment epithelial (RPE) cells inhibit mature dendritic cells (mDCs) by producing interleukin-1 receptor antagonist (IL-1Ra). This finding suggests ocular cells can suppress antigen-presenting cell activation, crucial for immune regulation in the eye.
Area of Science:
- Immunology
- Ophthalmology
- Cell Biology
Background:
- Dendritic cells (DCs) are key antigen-presenting cells initiating immune responses.
- Retinal pigment epithelial (RPE) cells play a critical role in maintaining ocular immune privilege.
- The interaction between RPE cells and mature DCs (mDCs) is not fully understood.
Purpose of the Study:
- To investigate the inhibitory effect of RPE cells on the activation and function of mDCs.
- To identify the specific mechanisms and molecules involved in RPE-mediated suppression of mDCs.
Main Methods:
- RPE cells were cultured from C57BL/6 mice.
- mDCs were generated from mouse bone marrow and stimulated.
- mDC activation was assessed via proliferation assays, cytokine production (ELISA), and surface marker expression (flow cytometry).
- The role of IL-1 receptor antagonist (IL-1Ra) was evaluated using neutralizing antibodies and IL-1Ra knockout RPE cells.
Main Results:
- RPE cells significantly suppressed mDC activation, including pro-inflammatory cytokine production and surface molecule expression.
- RPE cells markedly reduced the ability of mDCs to stimulate mixed lymphocyte reactions.
- High levels of IL-1Ra were expressed by RPE cells, and its blockade or absence abrogated the suppressive effect on mDCs.
Conclusions:
- RPE cells possess potent inhibitory capabilities against mDC activation.
- Interleukin-1 receptor antagonist (IL-1Ra) is a key mediator of RPE-induced suppression of mDCs.
- Ocular resident cells can produce antagonists to suppress antigen-presenting cell activation, contributing to ocular immune homeostasis.
