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General Commentary ARTICLE

Front. Immunol., 15 November 2018 | https://doi.org/10.3389/fimmu.2018.02659

Commentary: Soluble CD83 Alleviates Experimental Autoimmune Uveitis by Inhibiting Filamentous Actin-Dependent Calcium Release in Dendritic Cells

Mariana Pereira Pinho and José Alexandre Marzagão Barbuto*
  • Tumor Immunology Laboratory, Immunology Department, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil

A Commentary on
Soluble CD83 Alleviates Experimental Autoimmune Uveitis by Inhibiting Filamentous Actin-Dependent Calcium Release in Dendritic Cells

by Lin, W., Buscher, K., Wang, B., Fan, Z., Song, N., Li, P., et al. (2018). Front. Immunol. 9:1567. doi: 10.3389/fimmu.2018.01567

CD83 is a molecule known as an activation marker of dendritic cells (DC), that exists in two different forms—membrane-bound and soluble—which have antagonistic immunomodulatory functions (1). The soluble form (sCD83) consist of the extracellular domain of membrane CD83 (mCD83), and has immunosuppressive functions (2, 3). Its potential to be used in the treatment of autoimmune disease has been frequently assessed (4, 5). In the recent issue of Frontiers in Immunology, Lin et al. (6) consistently showed the positive effect of the use of sCD83 to treat experimental autoimmune uveitis.

The authors went one step further and described the mechanism of action by which the soluble form of CD83 was able to protect against the uveitis in mice. They showed that sCD83-treated DC, as well as T cells co-cultured with these cells, had lower intracellular calcium signaling, an effect that was dose-dependent. This is the second report showing that CD83 molecules can interfere with calcium signaling. We had previously shown that the membrane form of CD83, present in the surface of mature DC, was important to induce higher calcium signaling on the T cells (7). Thus, both studies elegantly support the opposed functions of soluble and membrane-bound CD83, with lower, in the presence of sCD83, vs. higher calcium signaling induced by mCD83.

The elevation of intracellular calcium usually requires two steps. The first starts with the activation of phospholipase C (PLCγ) that produces inositol 1,4,5-trisphosphate (IP3) which, in turn, binds to its receptor in the membrane of the endoplasmic reticulum (ER), causing the release of calcium stored in the ER. The second step is the amplification phase, where the depletion of ER calcium stores is sensed by STIM1, leading to the opening of CRAC (calcium release–activated calcium) channels, composed of ORAI subunits, in the plasma membrane of the cell. This causes a sustained elevation of the intracellular calcium concentration that will lead to cell activation (8). The article showed that sCD83 treatment prevents the co-localization of ORAI1 and mitochondria, two important pieces to sustain the calcium signaling (9), in the immunological synapsis of DC and T cells. Thus, sCD83 would act interfering with the calcium influx, the second step in the calcium signaling. On the other hand, our study suggests that mCD83 acts in the first phase of calcium signaling. We showed that, in the absence of extracellular calcium, blockage of mCD83 seemed to abrogate the residual increase in the intracellular calcium concentration, indicating that mCD83 was important to generate the initial release of calcium from the ER.

These data seem to be contradictory, but can be explained by the last piece of evidence showed by Lin and co-authors. They showed that sCD83 interferes with F-actin accumulation in the immunological synapsis, which was responsible for the aberrant localization of ORAI1 in sCD83-treated DC. The ability of sCD83 to modulate DC cytoskeleton had already been reported before (10). In our work, we hypothesized that CD83 was responsible for bringing the complex comprising both LAT and PLCγ closer to the TCR, thus boosting the first phase of calcium signaling. Although not fully established, this co-localization seems to require cytoskeletal rearrangement (11). Thus, by interfering with actin localization, mCD83 molecules could boost both the first and second step of calcium signaling. If CD83-induced actin-relocation is dependent of its interaction with a ligand, sCD83, when binding to CD83 ligand, would prevent this signaling, similarly to the effect of a blocking antibody, leading to diminished calcium signaling.

Altogether, these findings help to elucidate the mechanism by which CD83 molecules exert their immunomodulatory functions, generating relevant information that can be used to improve and refine the strategies aiming to interfere with this axis.

Author Contributions

All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.

Funding

The authors are supported by grants from the Sao Paulo Research Foundation—FAPESP (#2014/25988-1), the Coordination for the Improvement of Higher Education Personnel—CAPES, and from National Council for Scientific and Technological Development—CNPq (409825/2016-6, 308053/2017-6).

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

1. Prechtel AT, Steinkasserer A. CD83: an update on functions and prospects of the maturation marker of dendritic cells. Arch Dermatol Res. (2007) 299:59–69. doi: 10.1007/s00403-007-0743-z

PubMed Abstract | CrossRef Full Text | Google Scholar

2. Lechmann M, Krooshoop DJ, Dudziak D, Kremmer E, Kuhnt C, Figdor CG, et al. The extracellular domain of CD83 inhibits dendritic cell-mediated T cell stimulation and binds to a ligand on dendritic cells. J Exp Med. (2001) 194:1813–21. doi: 10.1084/jem.194.12.1813

PubMed Abstract | CrossRef Full Text | Google Scholar

3. Senechal B, Boruchov AM, Reagan JL, Hart DNJ, Young JW. Infection of mature monocyte-derived dendritic cells with human cytomegalovirus inhibits stimulation of T-cell proliferation via the release of soluble CD83. Blood (2004) 103:4207–15. doi: 10.1182/blood-2003-12-4350

PubMed Abstract | CrossRef Full Text | Google Scholar

4. Zinser E, Lechmann M, Golka A, Lutz MB, Steinkasserer A. prevention and treatment of experimental autoimmune encephalomyelitis by soluble CD83. J Exp Med. (2004) 200:345–51. doi: 10.1084/jem.20030973

PubMed Abstract | CrossRef Full Text | Google Scholar

5. Eckhardt J, Kreiser S, Döbbeler M, Nicolette C, DeBenedette MA, Tcherepanova IY, et al. Soluble CD83 ameliorates experimental colitis in mice. Mucosal Immunol. (2014) 7:1006–18. doi: 10.1038/mi.2013.119

PubMed Abstract | CrossRef Full Text | Google Scholar

6. Lin W, Buscher K, Wang B, Fan Z, Song N, Li P, et al. Soluble CD83 alleviates experimental autoimmune uveitis by inhibiting filamentous actin-dependent calcium release in dendritic cells. Front Immunol. (2018) 9:1567. doi: 10.3389/fimmu.2018.01567

PubMed Abstract | CrossRef Full Text | Google Scholar

7. Pinho MP, Migliori IK, Flatow EA, Barbuto JAM. Dendritic cell membrane CD83 enhances immune responses by boosting intracellular calcium release in T lymphocytes. J Leukoc Biol. (2014) 95:1–8. doi: 10.1189/jlb.0413239

PubMed Abstract | CrossRef Full Text | Google Scholar

8. Hogan PG, Lewis RS, Rao A. Molecular basis of calcium signaling in lymphocytes: STIM and ORAI. Annu Rev Immunol. (2010) 28:491–533. doi: 10.1146/annurev.immunol.021908.132550

PubMed Abstract | CrossRef Full Text | Google Scholar

9. Quintana A, Pasche M, Junker C, Al-Ansary D, Rieger H, Kummerow C, et al. Calcium microdomains at the immunological synapse: how ORAI channels, mitochondria and calcium pumps generate local calcium signals for efficient T-cell activation. EMBO J. (2011) 30:3895–912. doi: 10.1038/emboj.2011.289

PubMed Abstract | CrossRef Full Text | Google Scholar

10. Kotzor N, Lechmann M, Zinser E, Steinkasserer A. The soluble form of CD83 dramatically changes the cytoskeleton of dendritic cells. Immunobiology (2004) 209:129–40. doi: 10.1016/j.imbio.2004.04.003

PubMed Abstract | CrossRef Full Text | Google Scholar

11. Beemiller P, Krummel MF. Regulation of T-cell receptor signaling by the actin cytoskeleton and poroelastic cytoplasm. Immunol Rev. (2013) 256:148–59. doi: 10.1111/imr.12120

PubMed Abstract | CrossRef Full Text | Google Scholar

Keywords: CD83, calcium signaling, dendritic cells, T lymphocytes, T cell activation

Citation: Pinho MP and Barbuto JAM (2018) Commentary: Soluble CD83 Alleviates Experimental Autoimmune Uveitis by Inhibiting Filamentous Actin-Dependent Calcium Release in Dendritic Cells. Front. Immunol. 9:2659. doi: 10.3389/fimmu.2018.02659

Received: 16 August 2018; Accepted: 29 October 2018;
Published: 15 November 2018.

Edited by:

Jan Fric, International Clinical Research Center (FNUSA-ICRC), Czechia

Reviewed by:

Luuk Hilbrands, Radboud University Nijmegen, Netherlands

Copyright © 2018 Pinho and Barbuto. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: José Alexandre Marzagão Barbuto, jbarbuto@icb.usp.br