Abstract
Caffeic acid phenethyl ester (CAPE), which is derived from the propolis of honeybee hives, has been shown to reveal anti-inflammatory properties. Since T-cells play a key role in the onset of several inflammatory diseases, we have evaluated the immunosuppressive activity of CAPE in human T-cells, discovering that this phenolic compound is a potent inhibitor of early and late events in T-cell receptor-mediated T-cell activation. Moreover, we found that CAPE specifically inhibited both interleukin (IL)-2 gene transcription and IL-2 synthesis in stimulated T-cells. To further characterize the inhibitory mechanisms of CAPE at the transcriptional level, we examined the DNA binding and transcriptional activities of nuclear factor (NF)-κB, nuclear factor of activated cells (NFAT), and activator protein-1 (AP-1) transcription factors in Jurkat cells. We found that CAPE inhibited NF-κB-dependent transcriptional activity without affecting the degradation of the cytoplasmic NF-κB inhibitory protein, IκBα. However, both NF-κB binding to DNA and transcriptional activity of a Gal4-p65 hybrid protein were clearly prevented in CAPE-treated Jurkat cells. Moreover, CAPE inhibited both the DNA-binding and transcriptional activity of NFAT, a result that correlated with its ability to inhibit phorbol 12-myristate 13-acetate plus ionomycin-induced NFAT1 dephosphorylation. These findings provide new insights into the molecular mechanisms involved in the immunomodulatory and anti-inflammatory activities of this natural compound.
Footnotes
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This work was supported by Ministerio de Ciencia y Tecnología Grant SAF2001-0037-C04-02 (to E.M.) and European Union Grant QLK3-CT-2000-00463 (to E.M. and B.F.). A.M. was supported by Ministerio de Ciencia y Tecnología Grant SAF2002-01157.
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DOI: 10.1124/jpet.103.060673.
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ABBREVIATIONS: CAPE, caffeic acid phenethyl ester; AP-1, activator protein-1; EMSA, electrophoretic mobility shift assay; IκB, κB inhibitor; NFAT, nuclear factor of activated cells; NF-κB, nuclear factor-κB; PBMC, peripheral blood mononuclear cells; TCR, T-cell receptor; IL, interleukin; mAb, monoclonal antibody; ICAM-1, intercellular adhesion molecule-1; SEB, staphylococcal enterotoxin B; PHA, phytohemagglutinin; PBS, phosphate-buffered saline; Sp-1, specificity protein 1; DTT, dithiothreitol; RLU, relative light units; PMA, phorbol 12-myristate 13-acetate; COX-2, cyclooxygenase-2; PE, phycoerythrin.
- Received September 30, 2003.
- Accepted November 10, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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