The flavonoid phloretin suppresses stimulated expression of endothelial adhesion molecules and reduces activation of human platelets
2005
Stangl, V. | Lorenz, M. | Ludwig, A. | Grimbo, N. | Guether, C. | Sanad, W. | Ziemer, S. | Martus, P. | Baumann, G. | Stangl, K.
Atherosclerosis is a chronic inflammatory disease accompanied by the expression of endothelial adhesion molecules. Phloretin is a plant-derived phytochemical that is mainly present in apples. Because phloretin is reported to promote antioxidative activities, we investigated the effects of phloretin on cytokine-induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule-1 (E-selectin) in human umbilical vein endothelial cells (HUVECs). Phloretin prevented TNF-[alpha]-stimulated upregulation of VCAM-1, ICAM-1, and E-selectin expression in a concentration-dependent manner. To the same extent as for TNF-[alpha], phloretin also inhibited IL-1{szligbeta}-induced upregulation in expression of all 3 adhesion molecules. Inhibition of cytokine-induced adhesion molecule expression for VCAM-1, ICAM-1, and E-selectin was detected already at the level of mRNA. Preincubation with phloretin dose-dependently attenuated TNF-[alpha]-stimulated adhesion of monocytic THP-1 cells to HUVECs and human aortic endothelial cells. Phloretin did not affect TNF-[alpha]-stimulated activation of nuclear factor [kappa]B (NF-[kappa]B) but inhibited activation of interferon regulatory factor 1, a transcription factor involved in the regulation of endothelial cell adhesion molecule expression. In human platelets, phloretin diminished adenosine diphosphate (ADP) and thrombin receptor-activating peptide-stimulated expression of the activated form of the GPIIb/IIIa complex and reduced platelet aggregation stimulated by ADP. Thus phloretin may have beneficial effects in the onset and progression of cardiovascular diseases.
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