Macrophage scavenger receptor CD36 is the major receptor for LDL modified by monocyte-generated reactive nitrogen species
Eugene A. Podrez, … , Henry F. Hoff, Stanley L. Hazen
Eugene A. Podrez, … , Henry F. Hoff, Stanley L. Hazen
Published April 15, 2000
Citation Information: J Clin Invest. 2000;105(8):1095-1108. https://doi.org/10.1172/JCI8574.
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Article

Macrophage scavenger receptor CD36 is the major receptor for LDL modified by monocyte-generated reactive nitrogen species

Abstract

The oxidative conversion of LDL into an atherogenic form is considered a pivotal event in the development of cardiovascular disease. Recent studies have identified reactive nitrogen species generated by monocytes by way of the myeloperoxidase-hydrogen peroxide-nitrite (MPO-H2O2-NO2–) system as a novel mechanism for converting LDL into a high-uptake form (NO2-LDL) for macrophages. We now identify the scavenger receptor CD36 as the major receptor responsible for high-affinity and saturable cellular recognition of NO2-LDL by murine and human macrophages. Using cells stably transfected with CD36, CD36-specific blocking mAbs, and CD36-null macrophages, we demonstrated CD36-dependent binding, cholesterol loading, and macrophage foam cell formation after exposure to NO2-LDL. Modification of LDL by the MPO-H2O2-NO2– system in the presence of up to 80% lipoprotein-deficient serum (LPDS) still resulted in the conversion of the lipoprotein into a high-uptake form for macrophages, whereas addition of less than 5% LPDS totally blocked Cu2+-catalyzed LDL oxidation and conversion into a ligand for CD36. Competition studies demonstrated that lipid oxidation products derived from 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine can serve as essential moieties on NO2-LDL recognized by CD36. Collectively, these results suggest that MPO-dependent conversion of LDL into a ligand for CD36 is a likely pathway for generating foam cells in vivo. MPO secreted from activated phagocytes may also tag phospholipid-containing targets for removal by CD36-positive cells.

Authors

Eugene A. Podrez, Maria Febbraio, Nader Sheibani, David Schmitt, Roy L. Silverstein, David P. Hajjar, Peter A. Cohen, William A. Frazier, Henry F. Hoff, Stanley L. Hazen

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Figure 2

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Binding of [125I]LDL by CD36-transfected cells after modification by MPO...
Binding of [125I]LDL by CD36-transfected cells after modification by MPO-generated nitrating intermediates. (a) [125I]LDL was incubated with isolated human MPO (30 nM), glucose (100 μg/mL), glucose oxidase (20 ng/mL), and NO2– (0.5 mM) in sodium phosphate buffer supplemented with DTPA (100 μM) for 8 hours at 37°C (complete system, NO2-LDL) as described in Methods. Reactions were stopped by addition of BHT (40 μM) and catalase (300 nM), and then lipoproteins (5 μg/mL) were incubated with CD36- or vector-transfected 293 cells at 4°C for 3 hours in the appropriate media containing additional catalase (300 nM) and BHT (20 μM). LDL modified by dialysis against copper for 5 hours (Cu2+ oxLDL, 5 μg/mL) was used as a positive control. Cellular binding of lipoproteins was subsequently determined as described in Methods. AP < 0.001 for comparison versus LDL modified in the presence of MPO- and a H2O2-generating system (MPO/GGOx/LDL). (b and inset) [125I]LDL (0.2 mg/mL) was incubated with isolated human MPO (30 nM), glucose (100 μM), glucose oxidase (20 nM), and the indicated concentrations of NO2– in sodium phosphate buffer supplemented with DTPA (100 μM) and NaCl (100 mM) overnight at 37°C. Cellular binding of lipoproteins (10 μg/mL) was subsequently determined as described in Methods. Data represent the mean ± SD of triplicate determinations of a representative experiment performed 3 times.