Context: Cinnamon bark is a very popular herb used in traditional medicine to treat various disorders such as chronic gastric symptoms, arthritis, and the common cold.
Objective: The immunomodulatory effect of water extract of cinnamon bark (CWE) on cytokine secretion and involvement of intracellular signaling molecules in activated T cells have been examined.
Materials and methods: Mice were orally administered CWE for 7 days. Serum was obtained 90 min after intravenous injection of anti-CD3 antibody (Ab). Splenocytes were cultured with anti-CD3 Ab and CWE for cytokine expression, cell cycle, apoptotic/necrotic changes, and viability. IκBα, p38, JNK, ERK1/2, STAT4, and STAT6 were analyzed using western blotting.
Results: Administration of CWE decreased systemic levels of IFN-γ, but not the levels of IL-4 or IL-2. In vitro, CWE inhibited anti-CD3 Ab-stimulated IFN-γ and IL-4 at the mRNA and secreted protein levels. Despite its inhibition of IL-2 transcript, CWE enhanced IL-2 secretion. CWE treatment caused a reduction in the sub-G1 phase, accompanied by an increased ratio of apoptotic cells to necrotic cells. The increased IL-2 secretion by CWE was not mediated by its direct effect on CD4 T cells. CWE inhibited the activation of p38, JNK, ERK1/2, and STAT4, but not IκBα degradation or STAT6.
Discussion and conclusions: These observations provided evidence that CWE was able to down-regulate IFN-γ expression in activated T cells without altering IL-2 production, involving inhibition of p38, JNK, ERK1/2, and STAT4. Our results contribute to a better understanding of the immunomodulatory action of cinnamon bark for the application of inflammatory disorders.