Figure 2. The DEL-1 EGF-like repeats (DEL-1[E1–E3]) are sufficient to upregulate the Treg/Th17 cell ratio.

(A–D) Groups of Del1^KO mice were subjected to ligature-induced periodontitis (LIP) for 10 days and ligatures were removed on day 10 to facilitate inflammation resolution. The mice were locally microinjected daily with DEL-1–Fc, DEL-1-[E1–E3]–Fc, or Fc control from day 10 to day 14 for a total of 5 doses. FACS plots of Tregs (top) and Th17 cells (bottom) in gingival tissues (A) and cLNs (C) of microinjected Del1^KO mice on day 15 and bar graphs showing the percentages and absolute numbers of Tregs (top left and middle) and Th17 cells (bottom left and middle) in CD4⁺ T cells, Treg/Th17 cell ratio (top right) from gingival tissues (B) and cLNs (D) (n = 6–7 mice/group). Data are means ± SD and are pooled from 2 independent experiments. **P < 0.01, ***P < 0.001, ****P < 0.0001 vs. Fc treatment group by 1-way ANOVA with Dunnett’s multiple-comparisons test for comparison with Fc control treatment.