Cinnamon extract suppresses experimental colitis through modulation of antigen-presenting cells

Figure 1 Treatment of cinnamon extract inhibits maturation of macrophage cell line. Murine Raw 264.7 macrophages were stimulated with PMA/ionomycin in the absence or presence of 0.2 mg/mL cinnamon extract. Expression levels of cytokines (A) and co-stimulatory molecules (B) were measured by quantitative real-time PCR. To mimic in vivo stimulation, cells were treated with lipopolysaccharide alone or in combination with 0.2 mg/mL cinnamon extract. Expression level of cytokines (C), co-stimulatory molecules (D) and cyclooxygenase (COX)-2 (E) was measured by quantitative real-time PCR. Error bars indicated SD. ^aP < 0.05, ^bP < 0.005, ^cP < 0.001. Data are representative of three individual experiments.

Figure 2 Treatment with cinnamon extract inhibits maturation of MHCII⁺ APCs. MHCII⁺ APCs were stimulated with lipopolysaccharide (LPS) alone or in combination with cinnamon extract (0.1, 0.3 and 0.5 mg/mL). Expression levels of cytokines (A) and co-stimulatory molecules (C) were measured by quantitative real-time PCR. B: Intracellular expression levels of interleukin (IL)-10 and tumor necrosis factor (TNF)-α proteins were analyzed by flow cytometry. Effect of cinnamon extract treatment on cyclooxygenase (COX)-2 expression at the mRNA (D) and protein (E) level was measured by quantitative real-time PCR and immunoblotting, respectively. Error bars indicated SD. ^aP < 0.05, ^bP < 0.005, ^cP < 0.001. Data are representative of three individual experiments. IFN: Interferon.

Figure 3 Treatment of cinnamon extract inhibits maturation of CD11⁺ dendritic cells. CD11⁺ dendritic cells (DCs) were stimulated in the absence or presence of cinnamon extract (CE) and expression levels of cytokines [interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-12, interferon (IFN)-γ, tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β] (A) and co-stimulatory molecules (B7.1, B7.2, ICOS ligand, B7-DC and MHCII) (B) were measured by quantitative real-time PCR. Effect of cinnamon extract (CE) treatment on cyclooxygenase (COX)-2 expression at the RNA (C) and protein (D) level was measured by quantitative real-time PCR and immunoblotting, respectively. Error bars indicated SD. ^aP < 0.05, ^bP < 0.005, ^cP < 0.001. Data are representative of three independent experiments.

Figure 4 Treatment with cinnamon extract inhibits APC-dependent T-cell proliferation. APC-dependent T-cell proliferation was measured. MHCII⁺ APCs (A) and CD11c⁺ dendritic cells (DCs) (B) were pre-pulsed in the absence or presence of cinnamon extract for 24 h. Then, they were co-cultured with CD4⁺ T cells isolated from Do11.10 mice in the presence of Ova peptide. After 72 h co-culture, T-cell proliferation was measured by [H³]-thymidine incorporation assay. Error bars indicated SD. ^aP < 0.05, ^bP < 0.005, ^cP < 0.001. Data are representative of three independent experiments.

Figure 5 Cinnamon-extract-treated dendritic cells inhibit Th1 polarization. CD11c⁺ dendritic cells (DCs) were pre-pulsed with lipopolysaccharide (LPS) alone or in combination with cinnamon extract (CE) (0.2 mg/mL) for 24 h. Then, they were co-cultured with CD4⁺ T cells isolated from Do11.10 mice. A: After 72 h co-culture, CD4⁺ T cells were re-isolated from each treatment group and relative expression levels of cytokine mRNA were measured by quantitative real-time PCR; B: Intracellular protein levels of interleukin (IL)-10 and interferon (IFN)-γ in CD4⁺ T cells in each treatment group was analyzed by flow cytometry. Error bars indicated SD. ^aP < 0.05, ^bP < 0.005, ^cP < 0.001. Data are representative of three independent experiments.

Figure 6 Oral administration of cinnamon extract ameliorates experimental colitis. Mice were orally fed with PBS or cinnamon extract (CE) (50 μg/g per day) for 20 d, and intestinal colitis was induced by intrarectal injection of TNBS (50 μg/g in 50% ethanol). A: A change in body weight was monitored for 5 d; B: Gross intestinal changes were analyzed with a magnifying glass 3 d after colitis induction; C: After HE staining, histological analysis was performed by comparing colon sections of treatment groups; D: After induction of inflammatory bowel disease, cyclooxygenase (COX)-2 expression in mesenteric lymph nodes was compared by quantitative real-time PCR and immunoblotting; E: Expression levels of cytokines in mesenteric lymphocytes were measured by quantitative real-time PCR; F: Intracellular protein levels of interleukin (IL)-10 and tumor necrosis factor (TNF)-α were measured by flow cytometry. Error bars indicated SD. ^bP < 0.005, ^cP < 0.001. Data are representative of three independent experiments. IFN: Interferon.