Cinnamon extract inhibits degranulation and de novo synthesis of inflammatory mediators in mast cells

Background Mast cells ( MC ) are main effector cells of allergic and other inflammatory reactions; however, only a few anti‐ MC agents are available for therapy. It has been reported that cinnamon extract ( CE ) attenuates allergic symptoms by affecting immune cells; however, its influence on MC was not studied so far. Here, we analyzed the effects of CE on human and rodent MC in vitro and in vivo . Methods Expression of MC ‐specific proteases was examined in vivo in duodenum of mice following oral administration of CE . Release of mediators and phosphorylation of signaling molecules were analyzed in vitro in human MC isolated from intestinal tissue (hi MC ) or RBL ‐2H3 cells challenged with CE prior to stimulation by Fcε RI cross‐linking. Results Following oral treatment with CE , expression of the mast cell proteases MCP 6 and MC ‐ CPA was significantly decreased in mice. In hi MC , CE also caused a reduced expression of tryptase. Moreover, in hi MC stimulated by IgE cross‐linking, the release of β‐hexosaminidase was reduced to about 20% by CE . The de novo synthesis of cysteinyl leukotrienes, TNF α, CXCL 8, CCL 2, CCL 3, and CCL 4, was almost completely inhibited by CE . The attenuation of mast cell mediators by CE seems to be related to particular signaling pathways, because we found that activation of the MAP kinases ERK , JNK , and p38 as well as of Akt was strongly reduced by CE . Conclusion CE decreases expression of mast cell–specific mediators in vitro and in vivo and thus is a new plant‐originated candidate for anti‐allergic therapy.