Identification of 4-hydroxy-2-nonenal–histidine adducts that serve as ligands for human lectin-like oxidized LDL receptor-1

Abstract

LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) is an endothelial scavenger receptor that is important for the uptake of OxLDL (oxidized low-density lipoprotein) and contributes to the pathogenesis of atherosclerosis. However, the precise structural motifs of OxLDL that are recognized by LOX-1 are unknown. In the present study, we have identified products of lipid peroxidation of OxLDL that serve as ligands for LOX-1. We used CHO (Chinese-hamster ovary) cells that stably express LOX-1 to evaluate the ability of BSA modified by lipid peroxidation to compete with AcLDL (acetylated low-density lipoprotein). We found that HNE (4-hydroxy-2-nonenal)-modified proteins most potently inhibited the uptake of AcLDL. On the basis of the findings that HNE-modified BSA and oxidation of LDL resulted in the formation of HNE-histidine Michael adducts, we examined whether the HNE-histidine adducts could serve as ligands for LOX-1. The authentic HNE-histidine adduct inhibited the uptake of AcLDL in a dose-dependent manner. Furthermore, we found the interaction of LOX-1 with the HNE-histidine adduct to have a dissociation constant of 1.22×10(-8) M using a surface plasmon resonance assay. Finally, we showed that the HNE-histidine adduct stimulated the formation of reactive oxygen species and activated extracellular-signal-regulated kinase 1/2 and NF-κB (nuclear factor κB) in HAECs (human aortic endothelial cells); these signals initiate endothelial dysfunction and lead to atherosclerosis. The present study provides intriguing insights into the molecular details of LOX-1 recognition of OxLDL.

Malondialdehyde epitopes as mediators of sterile inflammation

“…Interestingly, LOX-1 is a scavenger receptor that was originally identified as the major receptor for OxLDL [99], while later studies demonstrated that it binds to many different ligands including apoptotic cells, platelets, bacteria as well as to other lipid peroxidation products such as 4-HNE [100], [101]. Given that MDA epitopes are generated virtually in any tissue one can speculate that even more MDA receptors may exist, also in light of the fact that other OSEs have been found to bind to PRRs such as CD36, CD68, MARCO or TLRs.…”

Role of 4-Hydroxynonenal-Protein Adducts in Human Diseases

“…Experimental ischemia or ischemia/reperfusion was shown to induce early generation of HNE and HNE-dependent protein modifications in the lung (43) The complexity of this process was illustrated by the report that HNE-histidine adducts bound to Lectin-like oxidized LDL receptor-1 (LOX-1), a class-E scavenger, multiligand receptor also implicated in atherosclerotic plaque formation (100,121). Apparently, local spectrin aggregation might lead to membrane surface area extrusion and loss, by freeing the lipid bilayer from the underlying cytoskeleton (9).…”

LOX-1 Ligands Containing Apolipoprotein B and Carotid Intima-media Thickness in Middle-aged Community-dwelling US Caucasian and Japanese Men

“…[8] In contrast, amongst the apo B-containing lipoproteins, various types of modified LDL, such as malondialdehyde-LDL, 4-hydroxy-2-nonenal (HNE)-LDL [8], and 4-oxo-2-nonenal (ONE)-LDL [9] and carbamylated LDL [10] are ligands for LOX-1. Accordingly, measuring total LOX-1 ligands would better reflect the biological activities of apo Bcontaining lipoproteins than measuring one specific antigenic determinant of modified LDL.…”

“…[7] Initially, LOX-1 was identified as a receptor to recognize LDL with cupric ionmediated oxidization or acetylated; until now, it has been clarified that LOX-1 recognized many types of modified LDL. [8][9][10][11] Recently, an assay to measure the biological activity of apolipoprotein B (ApoB)-containing lipoprotein based on binding to LOX-1 was developed [12], which might reflect atherogenicity of whole modified LDL better than one specific antigenic determinant of oxidized LDL. [13,14] However, to our knowledge, no previous reports have examined the impact of serum levels of LAB on the intima-media thickness (IMT) of carotid artery.…”