Epigallocatechin-3-gallate Reduces Scavenger Receptor A Expression and Foam Cell Formation in Human Macrophages

Foam cells are formed when macrophages imbibe low-density lipoprotein (LDL) through scavenger receptors. Here we examined how epigallocatechin-3-gallate (EGCG) influences foam cell formation. We found that EGCG dose dependently reduced oxidized LDL (oxLDL) uptake in THP-1 (10 mu M, 20.0 +/- 0.50, p < 0.05) and primary macrophages (134.6 +/- 15.6,p < 0.05) and reduced intracellular cholesterol content in these cells, respectively (10 mu M, 32.6 +/- 0.14, p < 0.05; 31.7 1.26, p < 0.05). EGCG treatment decreased scavenger receptor A expression, but not the expression of CD36 or of reverse cholesterol transporters. Moreover, EGCG stimulated translocation of the p50 and p65 subunits of NF-kappa B and enhanced NF-kappa B DNA-binding activity, thus suppressing SR-A promoter activity. EGCG's suppression of SR-A expression was blocked by the NF-kappa B inhibitor Bay. The present findings suggest that EGCG regulates NF-kappa B activity and thus suppresses SR-A expression, oxLDL uptake, and foam cell formation.