Antisera and monoclonal antibodies specific for epitopes generated during oxidative modification of low density lipoprotein.

Abstract

Increasing evidence indicates that low density lipoprotein (LDL) has to be modified to Induce foam cell formation. One such modification, oxidation of LDL, generates a number of highly reactive short chain-length aldehydlc fragments of oxidized fatty acids capable of conjugating with lyslne residues of apoprotein B. By Immunizing animals with homologous malondlaldehyde-modlfled LDL (MDA-LDL), 4-hydroxynonenal-LDL (4-HNE-LDL), and Cu ++ -oxldlzed LDL, we developed polyvalent and monoclonal antibodies against three epitopes found In oxldatively modified LDL The present article characterizes an antiserum and monoclonal antibody (MAL-2 and MDA2, respectively) specific for MDA-lyslne, and an antiserum and monoclonal antibody (HNE-6 and NA59, respectively) specific for 4-HNE-lyslne. In addition, a monoclonal antibody (OLF4-3C10) was developed against an as yet undefined epltope generated during Cu ++ oxldatJon of LDL With these antibodies, we demonstrated that MDA-lyslne and 4-HNE-lyslne adducts develop on apo-llpoproteln B during copper-Induced oxidation of LDL in vitro. The application of these antibodies for immunocytochemlcal demonstration of oxidized lipoprotelns In atherosclerotic lesions of progressive severity Is described in the companion article. These antibodies should prove useful In studying the role of oxldatively modified lipoprotelns as well as other oxldatively modified proteins In atherogenesls.

Atherogenesis and the humoral immune response to modified lipoproteins

“…The results of these studies were rather disappointing, because the results were often conflicting and failed to produce a clear cut indication of the clinical value of modified lipoprotein antibody assays as biomarkers for the development and/or progression of atherosclerosis. While some groups reported a positive correlation between the levels of oxLDL antibodies and different endpoints considered as evidence of atherosclerotic vascular disease, such as progression of carotid atherosclerosis or risk for the future development of myocardial infarction [21][22][23][24][25][26][27], others failed to show such correlation or showed an inverse correlation [28][29][30][31][32][33][34][35][36][37][38].…”

“…The precise nature of the epitopes that elicit autoimmune responses has yet to be defined, but in vitro modified human LDL, e.g. copper oxidized, MDA modified, and AGE modified, are immunogenic in laboratory animals and are also recognized by spontaneously formed human autoantibodies [4][5][6][7]. Human autoantibodies reactive with oxLDL were the first to be purified and characterized [8][9][10] and human AGE-LDL antibodies have also been isolated and characterized [11].…”

Lipotoxicity: the obese and endurance-trained paradox

“…51 We have recently shown that obese subjects have an increased skeletal muscle content of 4-Hydroxynonenal (4-HNE), a by-product of lipid peroxidation, 52 as compared with lean and ETr subjects. 9 The production of lipid peroxidation by-products, such as 4-Hydroxynonenal (4-HNE) and malondialdehyde (MDA), may reduce insulin sensitivity by increasing paracrine factors, such as TNFa.…”

Distribution of IgM and IgG antibodies to oxidized LDL in immune complexes isolated from patients with type 1 diabetes and its relationship with nephropathy

“…The investigation of the possible pathogenic role of circulating oxLDL antibodies has produced conflicting data. While some groups reported a positive correlation between the levels of free oxLDL antibodies and different endpoints considered as evidence of atherosclerotic vascular disease, progression of carotid atherosclerosis, or risk for the future development of myocardial infarction, (13)(14)(15)(16)(17)(18)(19) others failed to show such correlation or showed an inverse correlation. (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) On the other hand, there is a significant body of evidence supporting a pathogenic role for immune complexes formed by oxLDL and their corresponding antibodies (oxLDL IC), both in what concerns atherosclerosis and macrovascular disease (5;9;30-34) and nephropathy.…”