DYNAMIC CHANGES IN CHONDROITIN SULFATE AND DERMATAN SULFATE PROTEOGLYCANS IN A VENOUS ENDOTHELIUM INDUCED BY VERY LOW DENSITY LIPOPROTEIN

Chondroitin sulfate/dermatan sulfate proteoglycans (CS/DS-PGs) are components of the vascular extracellular matrix. Although CS/DS-PGs have been characterized biochemically in atherosclerotic arteries, little is known regarding their characteristics in the venous endothelium. The aim of this work was to analyze the expression and the chemical structure of CS/DS-PGs in human umbilical vein endothelial cells in presence of increasing levels of VLDL (0, 75 and 100 mcg/mL). After treatment, CS/DS-PGs were characterized through: 1) PG core protein secretion, specifically decorin, biglycan, and versican analysis by immunoblot; 2) glycosaminoglycan chain structural analysis by HPLC; and 3) the levels of chondroitin N-acetylgalactosaminyltransferase-2 (ChGn-2), chondroitin-4-O-sulfotransferase-1 (C4ST-1), glucuronyl C-5 epimerase (DS-epi1/2) and dermatan 4-O-sulfotransferase-1 (D4ST-1) mRNA by RT-PCR. A significant increase in decorin and versican was detected at 75 mcg/mL (p<0.05, n=3), whereas a significant decrease in biglycan was observed at 100 mcg/mL VLDL compare with the control (p<0.001, n=3). A significant increase in CS and DS chains was detected at both levels of VLDL (38.5±15.0; 388.0±20.0 and 82.5±50.0 ng/mL; 0, 75 and 100 mcg/mL VLDL, p<0.05, n=3), accompanied by an increase in the sulfation ratio 4S/0S (4.88±0.13; 13.97±1.8; 14.53±1.46; 0, 75 y 100 mcg/mL, n=3). A significant increase in ChGn-2 and C4ST-1 was only observed at 100 mcg/mL VLDL (p<0.05 and p<0.0001, n=3), whereas no differences were observed in DS-epi1/2 and D4ST-1. VLDL are able to induce a differential endothelial CS/DS-PG remodeling depending on their levels. At physiological levels, VLDL induced a CS/DS-PG secretion pattern that may contribute to the atheroprotective properties of this endothelial phenotype; such characteristics were lost in the presence of higher levels of the lipoprotein. Our results highlight the importance of CS/DS-PGs as new players in the atherosclerosis development.