Figure 7: Aldh1a2 expression is enriched in neonatal CD301b⁺ DC2s and promotes generation of commensal-specific Treg cells.

(A) Heatmap (top) and Violin Plot (bottom) of Aldh1a2 expression in subpopulations of D10 SDLN migDC. (B) qRT-PCR of Aldh1a2 expression and (C) ALDH enzymatic activity in CD301b⁺ vs. CD301b⁻ migDC2 sorted from SDLN of D10 or adult mice. Each dot is an independent mouse. (D) CD301b⁻ migDC2 were sorted from neonatal SDLN and incubated for 16 with S. epi-ZsGreen. Enzymatic ALDH activity in ZsGreen⁺ vs. ZsGreen⁻ CD301b⁺ DC2. Each dot represents a biological replicate of cells pooled from two mice. Wilcoxon test. (E) Cd11c^creAldh1a2^fl/fl and Aldh1a2^fl/fl littermates were colonized neonatally with S. epi-2w then (F) total number 2w⁺ Treg cells in the SDLN were enumerated on D21. Mann-Whitney test. (G-H) CD301b⁺ or CD301b⁻ migDC2 were sorted from Cd11c^creAldh1a2^fl/fl and Aldh1a2^fl/fl D10 SDLN then incubated overnight with S. epi-OVA before 72h culture with OT-II in the presence of IL-2 and TGF-β. (G) Representative plots (pre-gating: Live CD4⁺TCRβ⁺) and (H) quantification of OT-II Treg cells. One of three representative independent experiments shown. Dots indicate biological replicates from DCs sorted from pooled neonates. Two-way ANOVA unless specified. *p < 0.05, **p < 0.01, ***p < 0.001, ns = not significant.