Figure 8:

CCR6 expression is required for T_H17 cells to promote learned-helplessness. Male and female mice received T_H17 cells transduced with either a scrambled siRNA (siSCR) or siRNA targeting CCR6 (siCCR6) and 48 h later were subjected to the reduced paradigm of learned-helplessness. (A) Before transfer, T_H17 cells transduced with either a scrambled siRNA (47.4% CD4 are T_H17 cells) or siRNA targeting CCR6 (43.5% CD4 are T_H17 cells) were stained for CCR6, IL-17A and CD4 for analysis by flow cytometry. Mean ± SEM, Mann-Whitney, U=0, *p<0.05 (n=3-4). (B) The number of escape failures was recorded. Each symbol represents an individual mouse. Mean ± SEM, t-test, t(20)=2.132, *p<0.05 (n=11). Immediately after the last foot shocks, mice were perfused and hippocampi were collected. Dissociated cells were stained for IL-17A and CD4 (C), CD4 (C), Foxp3 and CD4 (E), F4/80 and CD45 (F), F4/80 and CD45 (G), CD11c and CD45 (H) and gated on CD4⁺ cells (C-E). Data represent mean±SEM, (n=5). (I) Mice received T_H17 cells differentiated from wild-type CD4 cells (WT, 33% CD4 are T_H17 cells) or CCR6-deficient CD4 cells (CCR6 KO, 28% CD4 are T_H17 cells) and 48 h later were subjected to the reduced paradigm of learned-helplessness. The number of escape failures was recorded. Each symbol represents an individual mouse. Mean ± SEM, Mann-Whitney, *p<0.05 (n=10). Immediately after the last foot shocks, mice were perfused and hippocampi were collected. Dissociated cells were stained for IL-17A and CD4, and gated on CD4⁺ cells (J) or stained for PD-1, IL-17A, and CD4 and gated on IL-17A⁺ CD4⁺ cells (K). Data represent mean±SEM, Mann-Whitney U=21 (I) and Wilcoxon test, W=−19 (K), *p<0.05 (n=9).