Fig. 8.

Combination anti-IL-6R and Xiap^−/− Treg cells rescue mice from infection-induced inflammation. a, b Xiap^−/− iTreg cells plus anti-IL-6R rescue Xiap^−/− mice from C. albicans infection. Male Xiap^−/− mice (KO) were intravenously administered with C. albicans and Xiap^−/− iTreg cells (1 × 10⁶) or anti-IL-6R antibody (500 μg) at day 2, or both, as indicated. Survival of mice is presented as a Kaplan–Meier survival curve (a). n = 11 for KO, n = 10 for KO + KO iTreg, n = 6 for KO + Ab, n = 9 for KO + KO iTreg + Ab. ***P < 0.001 for Log-rank (Mantel–Cox) Test (a). n.s., not significant. The serum level of IL-6 was determined on day 14 after infection (b). *P < 0.05 for unpaired t-test (b). c, d Anti-IL-6R prevents the conversion of the transferred Xiap^−/− Treg cells. CD45.1⁺ Xiap^−/− iTreg cells were transferred into CD45.2⁺ Xiap^−/− mice infected with C. albicans as in (a). CD45.1⁺ T cells were recovered at day 10 post-infection, and the expression of Foxp3 and IFN-γ was determined (c). The Foxp3⁺IFN-γ⁺ fractions in the CD45.1⁺ Treg cells were quantitated (d), n = 5. **P < 0.01 for unpaired t-test (d). e, f Anti-IL-6R reduces kidney neutrophil infiltration and fungal load in C. albicans-infected Xiap^−/− mice with KO iTreg cells transfer. Male Xiap^−/− mice were infected with C. albicans, as described in (a). Kidneys were isolated 14 days post-infection and neutrophils (e) and C. albicans titres (f) were quantitated. *P < 0.05, **P < 0.01 for unpaired t-test. n.s., not significant. g Anti-IL-6R does not affect IL-17 production. Male CD45.1⁺ Xiap^−/− mice were infected with C. albicans and treated with anti-IL-6R and anti-IL-6R plus CD45.2⁺ KO iTreg cells. Spleen T cells and B cells were isolated 7 days after treatments. CD45.2⁺ iTreg cells were depleted. T cells were incubated with B cells and heat-killed C. albicans (HKCA) for 4 days, and the production of IL-17A after stimulation with TPA/A23187 (10/100 ng ml⁻¹) was determined by ELISA^{47, 48}. Values are mean ± SD of triplicate samples in an experiment. Experiments were independently repeated three times with similar results