Fig. 7

CRA promoted IL-21 release from T cells by upregulating STAT3/BCL6/cMaf pathway. Panel A. Tumor-infiltrating T cells expressed IL-21. CT26.CL25 tumor-bearing mice were orally administrated with 25, 50, or 100 mg/kg of CRA every day for 33 days. Co-localization between T cells (CD3, red) and IL-21 (green) in tumors were assessed by IHC (magnification, 400 ×). Panel B. CRA induced B cell differentiation in an in vitro co-cultural system of T and B cells. T and B cells at 1:2 ratio were co-cultured with 3 to 12 μg/mL of CRA for 72 h. The proportion of plasma cells was determined. Splenocytes were used as positive cell control. Panel C. CRA induced IL-21 release from T cells in vitro. After treating with CRA, the concentration of IL-21 in cell culture media of splenic T cells was determined by ELISA. The effects of CRA on Panel D. E. and F. Stat3, cMaf, and Bcl6 expression in splenic T cells. Splenic T cells were treated with different doses of CRA for 24 h. The mRNA expression of Stat3, cMaf, and Bcl6 was determined by qPCR. Panel G. Stattic suppressed CRA-induced IL-21 expression. Splenic T cells were pre-treated with different concentration (0.13 to 0.5 μg/mL) of Stattic for 1 h and then treated with CRA for 24 h. The mRNA expression of IL-21 was determined by qPCR