As described previously29 (link), CD4+ T cells were isolated from the spleens of WT and GPR43−/− mice by using anti-mouse CD4-magnetic beads (BD Biosciences). To polarize Th17 cells, CD4+ T cells were cultured with 10 ng/ml TGF-β1, 30 ng/ml IL-6, 10 µg/ml anti-IFN-γ, and 10 µg/ml anti-IL-4 and activated with anti-CD3 and anti-CD28 for 5 d.