Hörkkö S, Bird D A, Miller E, Itabe H, Leitinger N, Subbanagounder G, Berliner J A, Friedman P, Dennis E A, Curtiss L K, Palinski W, Witztum J L
Department of Medicine, University of California, San Diego, La Jolla, California 92093-0682,
J Clin Invest. 1999 Jan;103(1):117-28. doi: 10.1172/JCI4533.
We recently cloned monoclonal IgM autoantibodies which bind to epitopes of oxidized low-density lipoprotein (OxLDL) from apoE-deficient mice (EO- autoantibodies). We now demonstrate that those EO- autoantibodies that were originally selected for binding to copper-oxidized low-density lipoproteins (CuOx-LDL), also bound both to the oxidized protein and to the oxidized lipid moieties of CuOx-LDL. The same EO- autoantibodies showed specific binding to products of oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine (OxPAPC) and to the specific oxidized phospholipid, 1-palmitoyl-2-(5-oxovaleroyl)-phosphatidyl-choline (POVPC), whereas oxidation of fatty acids (linoleic or arachidonic acid) or cholesteryl esters (cholesteryl-oleate or cholesteryl-linoleate) did not yield any binding activity. Those EO- autoantibodies that bound to oxidized phospholipids (e.g., EO6) inhibited the binding and degradation of CuOx-LDL by mouse peritoneal macrophages up to 91%, whereas other IgM EO- autoantibodies, selected for binding to malondialdehyde (MDA)-LDL, had no influence on binding of either CuOx-LDL or MDA-LDL by macrophages. F(ab')2 fragments of EO6 were equally effective as the intact EO6 in preventing the binding of CuOx-LDL by macrophages. The molar ratios of IgM to LDL needed to maximally inhibit the binding varied from approximately 8 to 25 with different CuOx-LDL preparations. Finally, a POVPC-bovine serum albumin (BSA) adduct also inhibited CuOx-LDL uptake by macrophages. These data suggest that oxidized phospholipid epitopes, present either as lipids or as lipid-protein adducts, represent one class of ligands involved in the recognition of OxLDL by macrophages, and that apoE-deficient mice have IgM autoantibodies that can bind to these neoepitopes and inhibit OxLDL uptake.
我们最近克隆了单克隆IgM自身抗体，其可与载脂蛋白E缺陷小鼠的氧化低密度脂蛋白（OxLDL）表位结合（EO-自身抗体）。我们现在证明，那些最初因能结合铜氧化低密度脂蛋白（CuOx-LDL）而被筛选出来的EO-自身抗体，也能与CuOx-LDL的氧化蛋白部分及氧化脂质部分结合。同样的EO-自身抗体显示出与氧化1-棕榈酰-2-花生四烯酰磷脂酰胆碱（OxPAPC）的产物以及特定氧化磷脂1-棕榈酰-2-（5-氧代戊酰基）-磷脂酰胆碱（POVPC）有特异性结合，而脂肪酸（亚油酸或花生四烯酸）或胆固醇酯（胆固醇油酸酯或胆固醇亚油酸酯）的氧化未产生任何结合活性。那些与氧化磷脂结合的EO-自身抗体（如EO6）可抑制小鼠腹腔巨噬细胞对CuOx-LDL的结合和降解达91%，而其他因能结合丙二醛（MDA）-LDL而被筛选出来的IgM EO-自身抗体对巨噬细胞结合CuOx-LDL或MDA-LDL均无影响。EO6的F(ab')2片段在阻止巨噬细胞结合CuOx-LDL方面与完整的EO6同样有效。对于不同的CuOx-LDL制剂，最大程度抑制结合所需的IgM与LDL的摩尔比约为8至25。最后，POVPC-牛血清白蛋白（BSA）加合物也抑制巨噬细胞对CuOx-LDL的摄取。这些数据表明，以脂质或脂蛋白加合物形式存在的氧化磷脂表位代表了一类参与巨噬细胞识别OxLDL的配体，并且载脂蛋白E缺陷小鼠具有能与这些新表位结合并抑制OxLDL摄取的IgM自身抗体。
