Fingolimod, an antagonist of sphingosine 1-phosphate, ameliorates Sjögren's syndrome by reducing the number of STAT3-induced germinal center B cells and increasing the number of Breg cells.

BACKGROUND

Sjögren's syndrome (SS) is an autoimmune disease caused by infiltrating lymphocytes. FTY720 affects the S1P signaling pathway, which plays a role in T and B cell migration from secondary lymphoid tissues to target organs. In this study, we investigate the regulatory mechanism of FTY720 in the context of SS.

METHOD

FTY720 was given orally every day to NOD mice. The salivary flow rate (SFR) and blood glucose level were assayed every 3 weeks. Histopathological features were investigated at the end of the study. In vitro, FTY720 was added to mouse splenocytes, and changes in the lymphocyte subsets were assessed.

RESULTS

In vivo, FTY720 increased the SFR and reduced the blood glucose level. The salivary gland histological score and infiltration of the salivary glands by B and T cells were dramatically decreased. Furthermore, STAT expression in the salivary gland was decreased. In vitro, FTY720 inhibited Th17 cells, while increasing regulatory T (Treg) cells, respectively. Also, FTY720 decreased and increased the numbers of germinal center (GC) B cells and regulatory B cells (Breg cells), respectively. FTY720 decreased the IgG level in culture supernatants. Also, STAT3 activation was decreased by FTY720.

CONCLUSION

Our results show the therapeutic potential of FTY720 in the context of SS; FTY720 prevents lymphocyte migration from secondary lymphoid organs to target organs.