Exopolysaccharides from Cyanobacterium aponinum from the Blue Lagoon in Iceland increase IL-10 secretion by human dendritic cells and their ability to reduce the IL-17+RORγt+/IL-10+FoxP3+ ratio in CD4+ T cells.

Authors: Gudmundsdottir AB (1,2,3) , Omarsdottir S (2) , Brynjólfsdóttir A (4) , Paulsen BS (5) , Olafsdottir ES (2) , Freysdottir J (1,3,6)
(1) Centre for Rheumatology Research, Landspitali - The National University Hospital of Iceland (2) Faculty of Pharmaceutical Sciences, University of Iceland (3) Department of Immunology, Landspitali - The National University Hospital of Iceland (4) Blue Lagoon Ltd. (5) Department of Pharmaceutical Chemistry, University of Oslo (6) Faculty of Medicine, School of Health Sciences, Biomedical Center, University of Iceland
Source: Immunol Lett. 2015 Feb;163(2):157-62
DOI: 10.1016/j.imlet.2014.11.008 Publication date: 2015 Feb E-Publication date: Dec. 9, 2014 Availability: abstract Copyright: © 2014 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.
Language: English Countries: Iceland Location: Blue Lagoon Correspondence address: jonaf@landspitali.is


Article abstract

Regular bathing in the Blue Lagoon in Iceland has beneficial effects on psoriasis. Cyanobacterium aponinum is a dominating member of the Blue Lagoon's microbial ecosystem. The aim of the study was to determine whether exopolysaccharides (EPSs) secreted by C. aponinum (EPS-Ca) had immunomodulatory effects in vitro. Human monocyte-derived dendritic cells (DCs) were matured in the absence or presence of EPS-Ca and the effects were determined by measuring the secretion of cytokines by ELISA and the expression of surface molecules by flow cytometry. DCs matured with EPS-Ca at 100 μg/ml secreted higher levels of IL-10 than untreated DCs. Subsequently, DCs matured in the presence or absence of EPS-Ca were co-cultured with allogeneic CD4(+) T cells and their effects on T cell activation analysed by measuring expression of intracellular and surface molecules and cytokine secretion. Supernatant from allogeneic T cells co-cultured with EPS-Ca-exposed DCs had raised levels of IL-10 compared with control. A reduced frequency of IL-17(+)RORγt(+) T cells was observed when co-cultured with EPS-Ca-exposed DCs and a tendency towards increased frequency of FoxP3(+)IL-10(+) T cells, resulting in a lower IL-17(+)RORγt(+)/FoxP3(+)IL-10(+) ratio. The study shows that EPSs secreted by C. aponinum stimulate DCs to produce vast amounts of the immunosuppressive cytokine IL-10. These DCs induce differentiation of allogeneic CD4(+) T cells with an increased Treg but decreased Th17 phenotype. These data suggest that EPSs from C. aponinum may play a role in the beneficial clinical effect on psoriasis following bathing in the Blue Lagoon.

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