Abstract
Heme-catalyzed oxidation of low-density lipoprotein (LDL) is one of the relevant mechanisms involved in LDL modification. We previously revealed a substantial oxidation of plasma hemoglobin to methemoglobin and a subsequent heme-catalyzed LDL oxidation generating moieties toxic to endothelium in heme oxygenase-1 (HO-1)-deficiency in human. Drawing upon our previous observation we posited a pathway for oxidation of plasma hemoglobin in the HO-1-deficient child involving LDL-associated lipid hydroperoxide. In support, LDL-associated lipid hydroperoxide oxidized ferrohemoglobin to methemoglobin - known to readily release its heme moieties - in a dose-dependent manner. Repeated heme exposure of the child's LDL further increased its lipid hydroperoxide content within min leading to additional cytotoxic effect on endothelium. Both cytotoxicity and HO-1 inducing ability of the oxidized LDL were strongly dependent on its lipid hydroperoxide content. We wondered if cells of the HO-1-deficient patient were prone to oxidative damage arising from heme-mediated oxidation of LDL. Indeed, we found elevated cytotoxicity induced by heme-catalyzed oxidation of LDL in lymphoblastoid cells derived from the HO-1-deficient patient. We conclude that oxidation of hemoglobin to methemoglobin by LDL-associated lipid hydroperoxide and increased sensitivity of cells of the HO-1-deficient child to stress of oxidized LDL might contribute to the vascular disorders reported earlier.
Original language | English (US) |
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Pages (from-to) | 377-385 |
Number of pages | 9 |
Journal | Cellular and Molecular Biology |
Volume | 51 |
Issue number | 4 |
DOIs | |
State | Published - Sep 30 2005 |
Keywords
- Heme
- Heme oxygenase-1 (HO-1) deficiency
- Hemoglobin
- Lipid hydroperoxide
- Oxidized LDL