Panel A shows flow cytometry plots of CD4-positive Foxp3-positive, CD4-positive Foxp3-negative, and CD8-positive cell populations with CD137 and forward scatter measurements. Panel B shows a bar plot with x-axis Experimental group and y-axis Soluble CD137 concentration (picograms per milliliter). Panel C shows a bar plot with x-axis Experimental group and y-axis Serum CD137 concentration (picograms per milliliter). Panel D shows line graphs with x-axis Weeks and y-axis Percent diabetic for female and male mice. Panel E shows bar plots with x-axis Experimental group and y-axis Percentage of CD8 T cells or CD4 T cells among CD45-positive cells. Panel F shows bar plots with x-axis Experimental group and y-axis Percentages of CD44-high CD127-low cells, CD44-high CD127-high cells, CD44-low cells, CXCR6-positive cells, or TIM3-positive CXCR6-positive cells among CD8 T cells. Panel G shows bar plots with x-axis Experimental group and y-axis Percentages of CD44-high CD127-low cells, CD44-high CD127-high cells, CD44-low cells, or CXCR6-positive cells among Foxp3-negative CD4 T cells. Panel H shows bar plots with x-axis Experimental group and y-axis Percentage of Ki67-positive cells among CD44-high CD127-low or CD44-high CD127-high CD8 T cells. Panel I shows bar plots with x-axis Experimental group and y-axis Percentage of Ki67-positive cells among CD44-high CD127-low or CD44-high CD127-high Foxp3-negative CD4 T cells.
Foxp3 + Tregs mediate T1D suppression through soluble CD137. (A) CD137 expression in splenic Foxp3+ and Foxp3− CD4 T cells and CD8 T cells of Cre+-Tnfrsf9+/+ and Cre+-Tnfrsf9E7fl/fl mice. NOD.Tnfrsf9−/− cells were used as the negative control. Representative flow cytometry profiles of three mice per genotype are shown. (B) Soluble CD137 produced by cultured Cre+-Tnfrsf9+/+ and Cre+-Tnfrsf9E7fl/fl splenic Foxp3+ Tregs (n = 7). ns: not significant. (C) Circulating soluble CD137 in 7- to 9-wk-old Cre+-Tnfrsf9+/+, Cre+-Tnfrsf9E7fl/fl, and Cre+-Tnfrsf9fl/fl males. ****P < 0.0001 by an unpaired t test. (D) T1D incidence study of Cre+-Tnfrsf9fl/fl mice and Cre+-Tnfrsf9+/+, Cre+-Tnfrsf9E7fl/fl, and Cre−-Tnfrsf9E7fl/fl female (left) and male (right) littermates. *P < 0.05; **P < 0.005; ***P < 0.0005; ****P < 0.0001 by a log-rank test. (E) Frequencies of islet-infiltrating CD4 and CD8 T cells in 8- to 10-wk-old prediabetic Cre+-Tnfrsf9+/+, Cre+-Tnfrsf9E7fl/fl, and Cre+-Tnfrsf9fl/fl females. (F and G) Frequencies of CD8 (F) and Foxp3− CD4 (G) T cell subsets in islets of 8- to 10-wk-old prediabetic Cre+-Tnfrsf9+/+, Cre+-Tnfrsf9E7fl/fl, and Cre+-Tnfrsf9fl/fl females. (H and I) Frequencies of Ki67+ cells in CD8 (H) and Foxp3− CD4 (I) T cell subsets in islets of 8- to 10-wk-old prediabetic Cre+-Tnfrsf9+/+, Cre+-Tnfrsf9E7fl/fl, and Cre+-Tnfrsf9fl/fl females. *P < 0.05; **P < 0.005; ***P < 0.0005 by an unpaired t test. ns: not significant. Results shown for E–I are summarized from five to seven experiments.