Fingolimod modulates peripheral effector and regulatory T cells in MS patients

Abstract

Multiple sclerosis (MS) is a complex neurological disease where, in genetically predisposed individuals, the unbalanced interplay between pathogenic and regulatory T cells will result in the progression of the autoimmune assault to neural antigens. Fingolimod (FTY720), an oral sphingosine 1-phosphate modulator recently approved for the treatment of MS, inhibits the egress of T cells from lymph nodes acting specifically on naïve and memory T cells and sparing effector T cells. Here we characterized IL-17 and IFNγ producing effector CD4 and CD8 positive T cells as well as CD4 positive CD25(high)CD127(low) regulatory T cells in MS patients before and 1 month after treatment was started. We observed that fingolimod did not significantly affect the percentage of CCR6 and CD161 positive T cells in both CD4 and CD8 compartments. In contrast, it significantly reduced the levels of both CD4+ CCR6+ CD161+ and CD8+ CCR6+ CD161+ producing IFNγ alone or in combination with IL-17. The percentage of IL-17 secreting cells in both subsets was affected by the treatment to a lesser extent. Finally, we observed that CD4+ CD25(high)CD127(low) regulatory T cells were decreased in MS patients compared to healthy controls and fingolimod significantly increased their frequencies. All together these findings demonstrate that fingolimod functionally modulates the ability of potentially pathogenic effector cells to produce relevant pro-inflammatory cytokines and increases the number of circulating regulatory T cells possibly contributing in restoring a balance between these populations.

Fig. 1

Frequencies of CCR6- and CD161-positive cells in circulating and TCR-activated CD4+ and CD8+ T lymphocytes. Ex vivo evaluation of CCR6- and CD161-positive fraction in CD4 (Panels a–b) and in CD8+ T cells (Panels c–d) derived from PBMC of ten controls (HD) and ten MS patients at baseline (MS t0) and after FTY720 administration (MS t1). Percentage analysis of CCR6+ (Panel e) and CD161+ (Panel f) CD4+ T cells, CCR6+ (Panel g) and CD161+ (Panel h) CD8+ T cells in short-term TCR-activated peripheral lymphocytes derived from ten MS patients at baseline (t0) and after FTY720 administration (t1)

Fig. 2

Cytokine analysis of TCR-activated CD4+ T lymphocytes in MS patients at baseline (t0) and after FTY720 administration (t1). Comparison of the frequencies of IFNγ-, IL-17-single and IFNγ and IL-17-double producing cells in TCR-expanded CD4+ T subset (Panels a–b–c), in CCR6+ (Panels d–e–f) and in CD161+ (Panels g–h–i) TCR-expanded CD4+ T cell populations derived from ten MS patients at baseline (t0) and after FTY720 administration (t1)

Fig. 3

Cytokine analysis of TCR-activated CD8+ T lymphocytes in MS patients at baseline (t0) and after FTY720 administration (t1). Comparison of the frequencies of IFNγ-, IL-17-single and IFNγ and IL-17-double producing cells in TCR-activated CD8+ T subset (Panels a–b–c), in CCR6+ (Panels d–e–f), CD161+ (Panels g–h–i) and CD161^bright (Panels j–k–l) of short-term TCR-activated CD8+ T cell populations derived from ten MS patients at baseline (t0) and after FTY720 administration (t1)

Fig. 4

Analysis of Treg frequencies in the peripheral blood of MS and healthy individuals. Comparison of the frequency of CD4+ CD25^highCD127- (Panel a) and CD39+ CD25^highCD127^low CD4+ circulating Treg cells from ten healthy donors and ten MS patients at baseline and after FTY720 therapy