To better understand the role of advanced glycation end products (AGEs) in atherogenesis,
we developed specific antibodies against different immunological epitopes of AGE structures,
including Nepsilon-(carboxymethyl)lysine-protein adduct (CML) and a structure(s) other
than CML (nonCML), and demonstrated the immunohistochemical localization of CML- and
nonCML-epitopes in atherosclerotic lesions of human aorta, which were obtained at
autopsy from 20 nondiabetic patients (12 males and eight females; mean age, 60.8+/-16.7
years). Monoclonal anti-CML antibody (6D12) recognized not only AGE-modified proteins,
but also CML-modified proteins. On the other hand, polyclonal anti-nonCML antibody
reacted to AGE-modified proteins, but not to CML-modified proteins. Both antibodies
were unreactive to the early-stage products of glycation, including fructose-modified
butyloxycarbonyl-lysine and fructose-epsilon-aminocaproic acid. Atherosclerotic lesions
included diffuse intimal thickening (DIT), fatty streaks (FS), atherosclerotic plaques
(AP) and complicated lesions. An immunohistochemical analysis showed both CML- and
nonCML-epitopes to be found along the collagen fibers in DIT in subjects more than
40 years old, but not in subjects less than 40 years old. CML-epitopes accumulated
mainly in the cytoplasm of macrophage/foam cells, while nonCML-epitopes accumulated
exclusively in the extracellular spaces in FS. APs showed the CML-epitope stored macrophage/foam
cells, and the accumulation of both CML- and nonCML-epitopes in the lipid-rich fibrous
area. An immunohistochemical analysis with a monoclonal antibody against oxidized
low density lipoprotein (FOH1a/DLH3) showed the presence of this antigen within the
cytoplasm of the macrophage/foam cells in atherosclerotic lesions, which were also
positive for the CML-epitopes. These findings thus suggest that the heterogeneous
localization of AGEs in atherosclerotic lesions depends on their different epitopes,
and that a close link, therefore, exists between the peroxidation of LDL and the formation
of AGEs in atherosclerotic lesions.