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Abstract

Background Ceylon cinnamon has been shown to possess anti-inflammatory properties in many diseases including allergic inflammation. Objective The aim of this study was to analyse in more detail the effects of cinnamon extract (CE) and its major compounds p-cymene and trans-cinnamaldehyde (CA) on allergen-specific immune responses in vitro and in vivo. Methods Therefore, monocyte-derived mature dendritic cells (DC) from grass or birch pollen allergic donors were pulsed with the respective allergen in the presence or absence of CE, p-cymene, CA or the solvent ethanol and co-cultured with autologous CD4⁺ T cells. Furthermore, basophil activation test was performed with or without CE or ethanol treatment. For the in vivo experiments, BALB/c mice were immunized with ovalbumin (OVA) and orally treated with CE or ethanol. Results Addition of CE, p-cymene or CA, but not ethanol significantly inhibited DC maturation and subsequent allergen-specific T cell proliferation as well as Th1 and Th2 cytokine production. Sulphidoleukotriene release and CD63 expression by basophils were also significantly diminished after addition of CE. In vivo, treatment of OVA-sensitized mice with CE led to a significant shift from OVA-specific IgE towards IgG2a production and to a strong inhibition of OVA-specific proliferation. Moreover, airway inflammation as well as anaphylaxis after intranasal or systemic allergen challenge was significantly reduced in CE-treated mice. Furthermore, topical application of CE prevented calcipotriol-induced atopic dermatitis-like inflammation in these mice. Conclusions and Clinical Relevance Taken together, our data indicate that the anti-inflammatory effect of cinnamon might be exploited for treatment of allergic inflammation, which needs to be further investigated.