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Functional improvement of regulatory T cells from rheumatoid arthritis subjects induced by capsular polysaccharide glucuronoxylomannogalactan.

Pericolini E, Gabrielli E, Alunno A, Bartoloni Bocci E, Perito S, Chow SK, Cenci E, Casadevall A, Gerli R, Vecchiarelli A - PLoS ONE (2014)

Bottom Line: GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production.These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients.It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.

View Article: PubMed Central - PubMed

Affiliation: Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy.

ABSTRACT

Objective: Regulatory T cells (Treg) play a critical role in the prevention of autoimmunity, and the suppressive activity of these cells is impaired in rheumatoid arthritis (RA). The aim of the present study was to investigate function and properties of Treg of RA patients in response to purified polysaccharide glucuronoxylomannogalactan (GXMGal).

Methods: Flow cytometry and western blot analysis were used to investigate the frequency, function and properties of Treg cells.

Results: GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production.

Conclusion: These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients. It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.

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Schematic representation of GXMGal effects on Treg (A) and on Treg/Th17 balance (B).
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pone-0111163-g007: Schematic representation of GXMGal effects on Treg (A) and on Treg/Th17 balance (B).

Mentions: FOXP3 is thought to be the main marker of Treg, since it plays a critical role in their development and maturation [37]. Compelling evidence show that FOXP3-deficient mice develop autoimmune disease [38], [39]. The role of Treg in RA has been partially elucidated and different results have been reported. In particular, a decreased number of Treg in the blood of RA patients has been observed [12]; however, other reports show high levels of circulating conventional CD4+CD25+FOXP3+ Treg cells in RA [13], [14], while additional studies reported an unaltered number [40]. Because of these controversial results about the number of circulating Treg cells, the interpretation of the data is problematic. Nevertheless, compelling evidence has emerged about the impaired function of these cells in RA patients [6]. Recent investigations revealed that a potentiation of Treg cells is beneficial in RA [40], [41]. In this study we report that the treatment with GXMGal induces strong and long-lasting increase of FOXP3 expression in RA Treg cells still evident 18 h after stimulation. This was accompanied by early and transient enhancement of TGF-β1 production and long-lasting production of IL-10. The major source of early production of TGF-β1 appeared to be the CD4+CD25−FOXP3+ T cell subset. On the contrary, the early production of IL-10 seems to be due to both CD4+CD25+FOXP3+ and CD4+CD25−FOXP3+ cells, although only CD4+CD25+FOXP3+ cells seemed to be responsible of its long-lasting production. We previously demonstrated that GXMGal inhibits pro-inflammatory cytokine secretion. Since the suppressive activity of Treg cells could be counteracted by inflammatory mediators [42], [43], particularly by TNF-α [44], it is possible that the increased activity of Treg cells induced by GXMGal could also include the previously described inhibition of TNF-α [1]. Accordingly, the treatment of RA subjects with an anti-TNF-α specific antibody was shown to restore Treg cell function via increased expression of FOXP3 phosphorylation [45]. Similarly, GXMGal could retain beneficial effects similar to those of anti-TNF-α treatment by influencing Treg cell activity. GXMGal did not modulate the percentage of CD4+CD25+FOXP3+ cells, while atypical CD4+CD25−FOXP3+ cells appeared to be numerically increased after GXMGal addition. The percentage of both cells was calculated on CD4+ T cells gated on PBMC, suggesting that the small and not statistically significant decline of CD4+CD25+FOXP3+, observed after GXMGal treatment, could at least in part account for the increased number of CD4+CD25−FOXP3+; however it is likely that besides the shift of CD4+CD25+FOXP3+ into CD4+CD25−FOXP3+, there is also an increase of the CD4+CD25−FOXP3+ cell number per se. Moreover, the significant increased expression of FOXP3 observed in conventional RA Treg cells after 18 h of GXMGal treatment clearly demonstrated that the associated increase of suppressive activity of all Treg is ascribed to CD4+CD25+FOXP3+ cells. GXMGal effects on different Treg subsets have been summarized in Figure 7.


Functional improvement of regulatory T cells from rheumatoid arthritis subjects induced by capsular polysaccharide glucuronoxylomannogalactan.

Pericolini E, Gabrielli E, Alunno A, Bartoloni Bocci E, Perito S, Chow SK, Cenci E, Casadevall A, Gerli R, Vecchiarelli A - PLoS ONE (2014)

Schematic representation of GXMGal effects on Treg (A) and on Treg/Th17 balance (B).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206502&req=5

pone-0111163-g007: Schematic representation of GXMGal effects on Treg (A) and on Treg/Th17 balance (B).
Mentions: FOXP3 is thought to be the main marker of Treg, since it plays a critical role in their development and maturation [37]. Compelling evidence show that FOXP3-deficient mice develop autoimmune disease [38], [39]. The role of Treg in RA has been partially elucidated and different results have been reported. In particular, a decreased number of Treg in the blood of RA patients has been observed [12]; however, other reports show high levels of circulating conventional CD4+CD25+FOXP3+ Treg cells in RA [13], [14], while additional studies reported an unaltered number [40]. Because of these controversial results about the number of circulating Treg cells, the interpretation of the data is problematic. Nevertheless, compelling evidence has emerged about the impaired function of these cells in RA patients [6]. Recent investigations revealed that a potentiation of Treg cells is beneficial in RA [40], [41]. In this study we report that the treatment with GXMGal induces strong and long-lasting increase of FOXP3 expression in RA Treg cells still evident 18 h after stimulation. This was accompanied by early and transient enhancement of TGF-β1 production and long-lasting production of IL-10. The major source of early production of TGF-β1 appeared to be the CD4+CD25−FOXP3+ T cell subset. On the contrary, the early production of IL-10 seems to be due to both CD4+CD25+FOXP3+ and CD4+CD25−FOXP3+ cells, although only CD4+CD25+FOXP3+ cells seemed to be responsible of its long-lasting production. We previously demonstrated that GXMGal inhibits pro-inflammatory cytokine secretion. Since the suppressive activity of Treg cells could be counteracted by inflammatory mediators [42], [43], particularly by TNF-α [44], it is possible that the increased activity of Treg cells induced by GXMGal could also include the previously described inhibition of TNF-α [1]. Accordingly, the treatment of RA subjects with an anti-TNF-α specific antibody was shown to restore Treg cell function via increased expression of FOXP3 phosphorylation [45]. Similarly, GXMGal could retain beneficial effects similar to those of anti-TNF-α treatment by influencing Treg cell activity. GXMGal did not modulate the percentage of CD4+CD25+FOXP3+ cells, while atypical CD4+CD25−FOXP3+ cells appeared to be numerically increased after GXMGal addition. The percentage of both cells was calculated on CD4+ T cells gated on PBMC, suggesting that the small and not statistically significant decline of CD4+CD25+FOXP3+, observed after GXMGal treatment, could at least in part account for the increased number of CD4+CD25−FOXP3+; however it is likely that besides the shift of CD4+CD25+FOXP3+ into CD4+CD25−FOXP3+, there is also an increase of the CD4+CD25−FOXP3+ cell number per se. Moreover, the significant increased expression of FOXP3 observed in conventional RA Treg cells after 18 h of GXMGal treatment clearly demonstrated that the associated increase of suppressive activity of all Treg is ascribed to CD4+CD25+FOXP3+ cells. GXMGal effects on different Treg subsets have been summarized in Figure 7.

Bottom Line: GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production.These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients.It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.

View Article: PubMed Central - PubMed

Affiliation: Microbiology Section, Department of Experimental Medicine, University of Perugia, Perugia, Italy.

ABSTRACT

Objective: Regulatory T cells (Treg) play a critical role in the prevention of autoimmunity, and the suppressive activity of these cells is impaired in rheumatoid arthritis (RA). The aim of the present study was to investigate function and properties of Treg of RA patients in response to purified polysaccharide glucuronoxylomannogalactan (GXMGal).

Methods: Flow cytometry and western blot analysis were used to investigate the frequency, function and properties of Treg cells.

Results: GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production.

Conclusion: These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients. It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.

Show MeSH
Related in: MedlinePlus