Increased frequency of cTfh cells in MS patients
Circulating Tfh cells were analyzed by gating CXCR5+PD-1+ cells from CD3+CD4+ T cells. As shown in Fig. 1b(right panel) , d, the average frequency of cTfh cells in MS patients was significantly higher than that observed in HC (7.88±0.42% vs. 5.73±0.48%, p=0.002). The percentage of CD4+ T cells in the PBMC of HC vs. MS patients was not significantly different (Fig. 1b(left panel) , c).
Tfh cells have been categorized into three different subsets based on Th1 (CXCR3) and Th17 (CCR6) related surface markers [25]. Previous work has shown that CXCR3+ Th1 and CCR6+ Th17 cells play essential roles in MS [36]. Here, we explored the expression of CXCR3 and CCR6 markers in Tfh cells to classify and evaluate the frequency of different subsets in MS patients. Our data demonstrate that cTfh17 (CXCR3-CCR6+ Tfh) cells were significantly increased in MS patients compared to HC (50.45±1.36% vs. 45.18±1.44%, p=0.02) (Fig. 2a,d). Recently, CXCR3+CCR6+ T cells have been defined as T helper 1 like Th 17 (Th17.1) cells [37, 38]. We also observed CXCR3+CCR6+ cells among cTfh cells and recognized them as cTfh17.1 cells. Interestingly, the frequency of cTfh17.1 (CXCR3+CCR6+Tfh) cells was significantly higher in MS patients than that in HC (9.66±1.32% vs. 4.58±1.14%, p=0.005) (Fig. 2a,e). In contrast, the frequencies of cTfh1 (CXCR3+CCR6-Tfh) and cTfh2 (CXCR3-CCR6- Tfh) did not show significant difference between HC and MS (Fig. 2a-c).