FOXP3 and systemic lupus erythematosus: The in vitro restimulation assay substantiated that the increased FoxP3+ Tregs in lupus mice treated with Dex-NPs were induced in an antigen-specific manner and this Treg expansion was probably impelled by DCs since the direct in vitro interaction between the BM-cDCs pretreated with Dex-NPs and Treg led to substantial Treg expansion (Figure 7A).