Distribution of Foxp3+ T-regulatory cells in experimental autoimmune neuritis rats

T-regulatory cells expressing the forkhead box transcription factor 3 (Foxp3) play essential roles in immune homeostasis. Experimental autoimmune neuritis (EAN) is an autoantigen-specific T-cell-mediated disease model for human demyelinating inflammatory disease of the peripheral nervous system. We investigated the distribution of Foxp3+ cells in sciatic nerves, spleen and lymph nodes of EAN rats, and the influence of FTY720 on the localization of Foxp3+ cells in EAN rats. In sciatic nerves of EAN rats, accumulation of Foxp3+ cells was not seen during the pre-symptomatic phase (until Day 9) or during early or peak disease activity. In contrast, Foxp3+ cell accumulation was regularly seen in the recovery from neurologic disease, suggesting a contribution of Foxp3+ cells to the resolution of EAN. FTY720 was given at onset of EAN (Day 10) until Day 18. Following FTY720 administration, percentages of Foxp3+ cells in EAN rats were increased in circulating blood, but reduced in lymph nodes compared to the PBS control. FTY720 treatment suppressed total numbers but increased percentages of Foxp3+ cells in sciatic nerves of EAN rats. These data not only suggests a protective role of Foxp3+ cells in EAN but also provides a potential way to alter localization of Foxp3+ cells in vivo.