Imiquimod’s In Vitro effect on a clinically effective DCs based therapy against melanoma and its effect on the immunogenicity of melanoma cell lines.
Iván
E.
Flores Colmann1, 2, 3,
Felipe
E.
Falcón Beas1, 2, 3,
Jimena
P.
Gatica Arenas1, 2, 3,
Fabián
I.
Tempio Sepúlveda1, 2, 3,
Daniel
A.
Rojas-Sepúlveda1, 2, 3,
Cristián
A.
Falcón Beas1, 2, 3,
Flavio
A.
Salazar Onfray1, 2, 3 and
Mercedes
N.
Lopez1, 2, 3, 4*
-
1
Faculty of Medicine, Universidad de Chile, Chile
-
2
Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Chile
-
3
Millennium Institute on Immunology and Immunotherapy, Universidad de Chile, Chile
-
4
Clinical Hospital, Universidad de chile, Chile
Introduction: Malignant melanoma (MM) is the most lethal skin cancer worldwide. We have developed a clinically successful immunotherapy against MM based on dendritic cells (DCs) stimulated with a melanoma cell lysate (TRIMEL) which induces their maturation and allows them to present tumor antigens called TAPCells, that stands for tumor antigen presenting cells. Previously, we reported that the antitumor effect of TAPCells were partially caused by the presence of TLR4 ligands in TRIMEL. TLR7/8 agonists have shown TH1 polarizing effects on the immune response. Moreover, the combination of TLR4 and TLR7 activity produces a synergistic effect on antitumoral DCs in murine models, mainly because of an increase of IL-12 production and, when cultured with CD4+ T cells, of the ratio TH1/TH2. Imiquimod, a TLR 7 agonist, has shown efficacy against various types of skin cancer including malignant melanoma. On a murine model, topical imiquimod’s treatment on B16 melanoma tumors showed tumoral regression, though the immunological bases are not completely understood. Accordingly, we propose that the use of Imiquimod may improve the capability of TAPCells as tumor antigen presenting cells to differentiate pro inflammatory T cells and its use in melanoma cell lines may increase their immunogenic properties.
Material and Methods: We differentiated PBMC from healthy donors into DCs. Later, some were left without stimulus in an immature state (iDCs) as controls, or stimulated with TRIMEL (TAPCells) with or without Imiquimod. CD86, CD83, CD80 and PD-L1 expression was measured by flow cytometry after stimulation on DCs. Then, DCs from different treatments were cultured with CD3+ T-cells for 3 days and IL-4, IFN-γ and IL-17 producing cells were analyzed by flow cytometry. On the other hand, melanoma cell lines were treated with Imiquimod for 48 hrs, and MHC-I, MICA/B, CD1d expression was analyzed by flow cytometry. Cytotoxic assays between effector cells (CD8+ T cell clones and NK cells) and melanoma cell lines loaded with radioactive chromium were performed.
Results: We found an increased expression of CD86, and a decreased expression of PD-L1 molecules on TAPCells treated with imiquimod, also showing a higher induction of TH17 profile on T cells cultured with these DCs, with an increased population of IFN-γ and IL-17 double positive T cells. Imiquimod treatment on melanoma cell lines induced the molecular expression of MHC I, MICA/B and CD1d. In the cytotoxic assay, CD8+ T cell clones and NK cells exhibit greater cytotoxic capacity against melanoma lines, when Imiquimod was added.
Discussion: Here we evidenced that Imiquimod treated TAPcells have a higher maturation state than TAPCells alone, which translates into higher levels of IL-17 producing T cells. Furthermore, we proved an interesting effect of Imiquimod on melanoma cell lines, which produced higher cytotoxicity by both CD8 T cell clones and NK cells. This study is the first approach to a modification of TAPCells therapy that could increase the immunotherapy response. Also, here we showed an increase on MHC-I and MICA/B in melanoma cell lines when treated with imiquimod that makes them more susceptible to CD8+ T cells and NK cells cytotoxicity, which could be an interesting modulation of the tumoral microenviroment towards breaking its tolerance, though future studies are required.
Acknowledgements
Funded by grants FONDEF-D11I1036; FONDECYT-1130324; IMII P09/016-F.
Keywords:
Immunotherapy,
Melanoma,
Dendritic Cells,
imiquimod,
T lymphocytes
Conference:
IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015.
Presentation Type:
Poster Presentation
Topic:
Immunotherapy
Citation:
Flores Colmann
IE,
Falcón Beas
FE,
Gatica Arenas
JP,
Tempio Sepúlveda
FI,
Rojas-Sepúlveda
DA,
Falcón Beas
CA,
Salazar Onfray
FA and
Lopez
MN
(2015). Imiquimod’s In Vitro effect on a clinically effective DCs based therapy against melanoma and its effect on the immunogenicity of melanoma cell lines..
Front. Immunol.
Conference Abstract:
IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología.
doi: 10.3389/conf.fimmu.2015.05.00085
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
15 May 2015;
Published Online:
14 Sep 2015.
*
Correspondence:
MD, PhD. Mercedes N Lopez, Faculty of Medicine, Universidad de Chile, Santiago, Chile, melopez@me.com