Oxidized lipoprotein induces the macrophage ascorbate transporter (SVCT2): protection by intracellular ascorbate against oxidant stress and apoptosis.
To assess whether ascorbic acid decreases the cytotoxicity of oxidized human low density lipoprotein (oxLDL) in cells involved in atherosclerosis, its interaction with oxLDL was studied in murine RAW264.7 macrophages. Macrophages took up ascorbate to millimolar intracellular concentrations and retained it with little loss over 18h in culture. Culture of the macrophages with oxLDL enhanced ascorbate uptake. This was associated with increased expression of the ascorbate transporter (SVCT2), which was prevented by ascorbate and by inhibiting the NF-kappaB pathway. Culture of RAW264.7 macrophages with oxLDL increased intracellular dihydrofluorescein oxidation and lipid peroxidation, both of which were decreased by intracellular ascorbate. Ascorbate also protected the cells against oxLDL-induced cytotoxicity and apoptosis, but it did not affect macrophage accumulation of lipid from oxLDL or oxLDL-induced increases in macrophage cytokine secretion. These results suggest that ascorbate protects macrophages against oxLDL-induced oxidant stress and subsequent apoptotic death without impairing their function.
Chi
Xiumei
X
Department of Medicine, Vanderbilt University School of Medicine, 7465 Medical Research Building IV, Nashville, TN 37232-6303, USA.
May
James M
JM
D000818:Animals; D017209:Apoptosis; D001205:Ascorbic Acid / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D008077:Lipoproteins, LDL / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D029363:Organic Anion Transporters, Sodium-Dependent / Q000378:metabolism*; D018384:Oxidative Stress; D020133:Reverse Transcriptase Polymerase Chain Reaction; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters / Q000378:metabolism*
D017931:DNA Primers; D008077:Lipoproteins, LDL; D016328:NF-kappa B; D029363:Organic Anion Transporters, Sodium-Dependent; C555163:SLC23A2 protein, human; C555165:Slc23a2 protein, mouse; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters; C099252:oxidized low density lipoprotein; D001205:Ascorbic Acid