Palinski W, Koschinsky T, Butler S W, Miller E, Vlassara H, Cerami A, Witztum J L
Department of Medicine, University of California, San Diego, La Jolla 92093, USA.
Arterioscler Thromb Vasc Biol. 1995 May;15(5):571-82. doi: 10.1161/01.atv.15.5.571.
Atherosclerosis is known to be accelerated in diabetic patients, but the mechanisms of this acceleration are poorly understood. Nonenzymatic glycosylation of long-lived proteins results in the formation of advanced glycosylation end products (AGEs), which are extensively cross-linked and could contribute to atherogenesis. Oxidative modification of LDL is also an important process in atherogenesis. In vitro evidence suggests that hyperglycemia may enhance lipid peroxidation, and conversely, that increased lipid peroxidation may enhance AGE formation. If such interactions occur in vivo, we hypothesized that AGE should be found in atherosclerotic lesions of euglycemic LDL receptor-deficient rabbits in areas rich in lipids and oxidized lipoproteins. To demonstrate the presence of AGEs, we developed antisera against a specific "model" compound of AGE, 2-furoyl-4(5)-(2-furanyl)-1H-imidazole (FFI) by using FFI-hexanoic acid (FFI-HA)-protein adducts as the antigen and against AGEs in general by using AGE-albumin as the antigen. Antisera generated with FFI-HA-protein adducts recognized FFI-HA alone as well as FFI-protein adducts. Native proteins or proteins conjugated with aldehydes formed during lipid peroxidation in vitro were not recognized by these antisera. Immunocytochemistry with both FFI-specific and AGE-specific antisera revealed the presence of these epitopes in atherosclerotic lesions of euglycemic LDL receptor-deficient rabbits but not in normal aortic tissues. AGE epitopes within atherosclerotic lesions were predominantly found in similar locations as epitopes generated during modification of the lipoproteins by oxidation, consistent with the hypothesized interactions between oxidation and glycosylation. Indirect evidence in support of the in vivo presence of FFI-like structures was also obtained by the observation that both diabetic and euglycemic human subjects contained autoantibodies that recognize FFI-protein adducts. Taken together, these data provide immunological evidence for the in vivo presence of FFI-like structures and other AGE-protein adducts in atherosclerotic lesions, even in euglycemic conditions.
已知糖尿病患者的动脉粥样硬化进程会加速，但其加速机制尚不清楚。长寿蛋白质的非酶糖基化会导致晚期糖基化终产物（AGEs）的形成，这些产物广泛交联，可能促进动脉粥样硬化的发生。低密度脂蛋白（LDL）的氧化修饰也是动脉粥样硬化发生过程中的一个重要环节。体外实验证据表明，高血糖可能会增强脂质过氧化，反之，脂质过氧化增加可能会促进AGEs的形成。如果这种相互作用发生在体内，我们推测在血糖正常的低密度脂蛋白受体缺陷型兔的动脉粥样硬化病变中，富含脂质和氧化脂蛋白的区域应该能找到AGEs。为了证明AGEs的存在，我们通过使用FFI-己酸（FFI-HA）-蛋白质加合物作为抗原，制备了针对AGE的一种特定“模型”化合物2-呋喃甲酰基-4(5)-(2-呋喃基)-1H-咪唑（FFI）的抗血清，并通过使用AGE-白蛋白作为抗原制备了针对一般AGEs的抗血清。用FFI-HA-蛋白质加合物产生的抗血清能识别单独的FFI-HA以及FFI-蛋白质加合物。这些抗血清不能识别天然蛋白质或体外脂质过氧化过程中形成的与醛结合的蛋白质。使用针对FFI特异性和AGE特异性的抗血清进行免疫细胞化学检测发现，在血糖正常的低密度脂蛋白受体缺陷型兔的动脉粥样硬化病变中存在这些表位，而在正常主动脉组织中则不存在。动脉粥样硬化病变中的AGE表位主要位于与脂蛋白氧化修饰过程中产生的表位相似的位置，这与氧化和糖基化之间的推测相互作用一致。通过观察发现糖尿病患者和血糖正常的人类受试者都含有能识别FFI-蛋白质加合物的自身抗体，这也为体内存在类似FFI的结构提供了间接证据。综上所述，这些数据为动脉粥样硬化病变中即使在血糖正常的情况下也存在类似FFI的结构和其他AGE-蛋白质加合物提供了免疫学证据。
