Figure 4: Exosome-carrying MMP1a facilitates Treg generation.

(A,B), naive CD4⁺ T cells and DCs were isolated from the naive mouse spleen, and cultured in the presence of the exosomes and DCs, or TGF-β (20 ng/ml; using as a positive control), for 6 days. The dot plots show the frequency of CD4⁺ Foxp3⁺ Tregs. (C) the Western blots show the MMP1a levels in the exosome extracts. (D) OVA-specific polarized Th2 cells were prepared, and treated in the culture as denoted above each subpanel. The cells are analyzed by flow cytometry. The bars indicate the frequency of CD4⁺ Foxp3⁺ Tregs; the individual dot plots are presented in (E–K). Concentrations of the agents: EE = 2 μg/ml; OVA = 5 μg/ml; anti-MMP1a (aMMP1a) = 1 μg/ml. rMMP1a = 100 ng/ml. Ratio of T cell:DC = 5:1. The data of bars are presented as mean ± SD. *p < 0.01, compared to group (E). The data are representatives of 3 independent experiments.