Brazilian propolis inhibits the differentiation of Th17 cells by inhibition of interleukin-6-induced phosphorylation of signal transducer and activator of transcription 3

Abstract

Propolis is a resinous substance collected by honeybees from leaf buds and cracks in the bark of various plants. It has been reported to show immunomodulatory activity. Previously, we reported the protective effect of Brazilian propolis ethanolic extract against the pathogenesis of collagen-induced arthritis (CIA), an experimental animal model of rheumatoid arthritis (RA). Moreover, we found that the protective effect against CIA was involved in suppression of the production of interleukin-17 (IL-17) in CIA mice. In the present study, we demonstrated for the first time that propolis inhibited IL-6 plus transforming growth factor-β induced Th17 differentiation in vitro. Propolis also suppressed the IL-6-induced phosphorylation of signal transducer and activator of transcription 3 (STAT3), a cytokine-activated essential transcription factor in Th17 development, concomitantly with the enhanced suppressor of cytokine signaling 3 expression involved in the downregulation of STAT3 phosphorylation. These data suggest that the suppressive effect of propolis on Th17 differentiation might be useful for controlling unbalanced cytokine networks in autoimmune diseases.

Keywords::

• Propolis
• interleukin-17
• signal transducer and activator of transcription 3
• supressors of cytokine signaling 3
• Th17 cell

Acknowledgments

The authors wish to thank Yamada Apiculture Center, Inc., Okayama Japan, for their generous provision of the propolis extracts.

Declaration of interest

Part of this work was supported by the Yamada Bee Farm Grant for Honeybee Research.