Tannic acid, a higher galloylated pentagalloylglucose, suppresses antigen-specific IgE production by inhibiting ɛ germline transcription induced by STAT6 activation

Interleukin (IL)-4 is a critical stimulator that induces e{open} germline transcripts (e{open}GT) for switch recombination to initiate immunoglobulin (Ig) E and is important in allergic disease pathogenesis. We found pentagalloylglucose (PGG) inhibited IL-4-induced e{open}GT expression. PGG exerted its inhibitory function by suppressing IL-4-induced activation of IL-4Rα, JAK3 and STAT6. Furthermore, tannic acid, a higher galloylated PGG, attenuated ovalbumin-induced IgE production in vivo by inhibiting IL-4-induced e{open}GT expression and the IL-4 signaling pathway. In conclusion, our results suggest that tannic acid may attenuate allergic diseases by suppressing IgE production by inhibiting IL-4-induced signaling.