Figure 7. Treg cell-specific MyD88 signaling activates Stat3 and its deficiency is phenocopied by T_R-cell specific Stat3 deficiency.

A-I. TLR1-2-mediated activation of p65-NF-κB, Stat3 and Stat5 in Myd88^fl/fl and Foxp3^EGFPcreMyd88^Δ/Δ cLP CD4⁺Foxp3⁺Treg cells. A, D, G. Flow cytometric analysis of p-p65-NF-κB (A), pStat3 (D) and pStat5 (G) in cLP CD4⁺Foxp3⁺Treg cells treated with either PBS or the TLR1-2 ligand (TLR1-2-L) Pam3SCK4. (B, E, H) MFI of the respective phosphoprotein. (C, F, I). Chromatin immunoprecipitation (ChIP) assay of NF-κB p65, Stat3 and Stat5 bound to the Foxp3-CNS2 in the respective cLP CD4⁺Foxp3⁺Treg cells treated with either PBS, TLR1-2-L (for p65-NF-kB and Stat3 ChIP) or IL-2 (for Stat5 ChIP). J-O. WT and Foxp3^EGFPcreStat3^Δ/Δ mice were either untreated or received adoptively transferred CD45.1⁺B220⁺IgA⁺ or CD45.1⁺B220⁺IgG⁺ PP B cell derived from CD45.1⁺ WT donor mice. Analysis was carried out 2 weeks following the B cell transfer. J. Frequencies of total B220⁺IgA⁺ in the PP. K. Intestinal lavage fluid IgA and IgG concentrations. L, M. Frequencies of PP Tfr and cLP Treg cells, respectively. N. Frequencies of CD4⁺IL-17⁺ and CD4⁺IFN-γ⁺ T_conv cells. O. Real time PCR analysis of SFB 16S rDNA in the stool. Similar results were obtained in 2 independent experiments. N= 4-7 /group *P<0.05; **P<0.01, ***P<0.001 by One-way ANOVA.