Treg cells are upregulated by the PGE2–EP4 signaling pathway in bone marrow after ischemic stroke. (A) Flow cytometry analysis of Treg cells in bone marrow (BM) from mice treated with vehicle, indomethacin, or L-161,982. (B) Quantification showed that indomethacin and L-161,982 significantly reduced the percent of Treg cells compared to that in the control group. (C) Flow cytometry analysis of IDO production in CD11C+ cells from mice that underwent ischemic stroke. (D) Quantification showed that IDO level was significantly increased in CD11C+ dendritic cells at 6 h after stroke and remained high for 3 days. This effect was abolished by treatment with indomethacin. *P<0.05 vs. corresponding sham group, n=6 per group; #P<0.05 vs. 3-day PBS group, n=6 per group.