The suppression of IL-17 production from T cells by gallate-type procyanidin is mediated by selectively inhibiting cytokine production from dendritic cells

Abnormal T helper 17 (Th17) responses promote inflammation and cause inflammatory diseases. Natural components that modulate Th17 functions can be effective for the amelioration of inflammatory diseases. Procyanidin B2 3,3 ''-di-O-gallate (PCB2DG) contained in grape seeds markedly suppressed interleukin (IL)-17 production from spleen cells but not CD4(+) T cells. The aim of this study was to elucidate the mechanisms by which PCB2DG suppresses IL-17. Our results showed that PCB2DG suppressed the production of IL-17, tumor necrosis factor (TNF)-alpha, IL-1 beta, and IL-6 with the suppression of transcription factors expression. In addition, we revealed that TNF-alpha and IL-1 beta were required to induce IL-17 production in this experimental condition, and PCB2DG suppressed these cytokines from dendritic cells (DCs). Furthermore, CD4-DC co-culture experiments showed that the production of IL-17, TNF-alpha, and IL-1 beta was markedly inhibited in co-cultures of PCB2DG-pretreated CD4+ T cells and DCs. These results suggested that PCB2DG first modulated TNF-alpha production by CD4(+) T cells and then suppressed IL-1 beta secretion from DCs, resulting in decreased IL-17 production. Thus, PCB2DG can control the cytokine network associated with Th17 cells, providing a novel mechanism underlying the immunosuppressive effects of polyphenols.

Automated summary

PCB2DG from grape seeds suppresses the production of IL-17, TNF-alpha, IL-1 beta, and IL-6 by modulating transcription factors expression and cytokine secretion, providing a novel mechanism for the immunosuppressive effects of polyphenols.