Activation of Naive CD4(+)CD25(+)FOXP3(+)Treg by Specific Autoantigen and Th2 Cytokines IL-4 and IL-5 Induces Autoantigen Specific Treg That Inhibit EAE

CD4+CD25+FOXP3+Treg (tTreg) protect against induction of autoimmunity, but fresh naïve or ex vivo expanded tTreg have limited ability to control established autoimmunity. We have examined pathways of naïve tTreg activation by antigen and Th2 cytokines IL-4 and IL-5. First, IL-4 and antigen induce Ts2 cells that express IL-5Ralpha. In a second step, IL-5, not IL-4, and antigen induce Ts2 cells to Th2-like Treg. EAE was induced in Lewis rats by immunization with myelin basic protein (MBP) in Freund’s complete adjuvant. Naïve CD4+CD25+Treg cultured with MBP and IL-4 for 4d produced Ts2 cells. To produce Th2-like Treg, Ts2 cells were cultured with IL-5 and MBP for 4d. Cells were assessed by FACS, RT-PCR and ability to suppress EAE. 5×106 Ts2 or 1×106 Th2-like Treg were given ivi 9d post-immunization. Ts2 cells activated by MBP, but not those activated by renal tubular antigen, suppressed EAE between 11 and 16d post-immunization. Clinical score: 0.1±0.5(n=6) in treated vs 1.5±2.7(n=13) in controls at 12d (p<0.01); 1.3±0.7 vs 2.5±0.8 at 13d (p<0.001). Onset of EAE was delayed, peak disease score reduced, as was weight loss. Naïve tTreg had no effect on EAE. Th2-like Treg had no effect on the onset until 14d when there was rapid recovery with no weakness from 15–21d. Controls did not recover until 22d. The Ts2 and Th2-like Treg were 99% CD4+, 98% CD25+ and 70–80% FOXP3+. Naïve tTreg expressed no il5ra whereas Ts2 and Th2-like Treg expressed Il5ra. Th2-like Treg had higher Foxp3, irf4 and gata3. Ex vivo culture of naïve tTreg with IL-4 and autoantigen induces antigen-specific Treg that can control established autoimmune responses. These Ts2 cells further activated by culture with IL-5 and MBP also control autoimmunity. Both cells may have therapeutic potential.