A6.2 Purified microbial capsular polysaccharide Galactoxylomannan (GalXM) inhibits the effector T lymphocyte arm and potentiates the regulatory counterpart in rheumatoid arthritis. (31st January 2014)

• Record Type: Journal Article
• Authors: Alunno, Alessia; Pericolini, Eva; Gabrielli, Elena; Bistoni, Onelia; Caterbi, Sara; Bartoloni, Elena; Terenzi, Riccardo; Valentini, Eleonora; La Paglia, Giuliana; Chow, Siu-Kei; Casadevall, Arturo; Vecchiarelli, Anna; Gerli, Roberto
• Is Part Of: Annals of the rheumatic diseases. Volume 73:Supplement 1(2014)
• Page Start: A71
• Page End: A71
• Publication Date: 2014-01-31
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2013-205124.162
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background and Objectives: We previously demonstrated that the purified microbial polysaccharide Galactoxylomannan (GalXM) from the opportunistic fungus Cryptococcus neoformans is able to impair T-cell proliferation and to induce T lymphocyte apoptosis following the interaction with CD45 in normal subjects. Since T lymphocytes are crucially involved in the pathogenesis of rheumatoid arthritis (RA), aim of the present study was to investigate the effects of GalXM on circulatingT-cell subsets in RA and provide the rationale for potential therapeutic application of this compound. Materials and Methods: Sixty RA patients and 40 healthy donors (HD) were included in the study. RA and HD magnetic sorted-CD3 +, CD4 + or CD4 + CD25 high T cells were cultured in presence or absence of GalXM (10 ng/ml), Dex (10nM), MTX (10ng/ml) or FLLL31 (5µM). Lymphocyte apoptosis was performed at different time-points evaluating propidium iodide staining and in selected experiments cleaved caspase 3 staining by flow cytometry. Flow cytometry was also employed for phenotypic analysis of T cell subsets (CD4, CD25, CD127, FoxP3, IL-17, IL-10, IL-17, TGF-β1) and for the analysis of cell proliferation evaluating CFSE dilution. Western blot was employed to assess phospho-STAT3, STAT3, FoxP3 and T-bet expression in cell lysates. Cytokine concentration in culture supernatants (IL-21, IL-22, IL-23, IL-6, IL-17A, IFN-γ, IL-12p70, IL-8, TGF-β1 and IL-10) was assessed with commercial ELISA kits. Results: GalXM selectively reduced proliferation and increased apoptosis rate in RA Th1 and Th17 cells. GalXM was also able to reduce STAT3 phosphorilation eventually leading to decreased IL-17 production in surviving Th17 cells. To note, GalXM strongly up-regulated FoxP3 expression in CD4 + T cells, increased the percentage of non-conventional CD4 + CD25 - FOXP3 + Treg cells and enhanced suppressive activity of both CD4 + CD25 high FOXP3 + and CD4 + CD25 - FOXP3 + Treg cells. All these findings were further supported by a rebalance of effector/regulatory cytokines in culture supernatants. Conclusion: Our results suggest that GalXM represents a powerful compound able to rebalance Treg/T-effector ratio in RA and therefore it is worth to be employed for therapeutic purposes in this disease.