Departments of Cellular and Molecular Medicine, Lerner Research Institute (J.A.D., Y.H., K.A., G.G., V.G., P.L.F., W.H.W.T., J.D.S., S.L.H.), Cardiovascular Medicine, Heart, and Vascular Institute (W.H.W.T., J.D.S., S.L.H.), and Molecular Cardiology, Lerner Research Institute (E.F.P.), Cleveland Clinic, Cleveland, OH; Department of Medicine, New York University, New York, NY (O.E.-O., E.A.F.); and Departments of Chemistry (G.G., V.G., S.L.H.) and Mathematics (Y.W.), Cleveland State University, Cleveland, OH.
Circulation. 2013 Oct 8;128(15):1644-55. doi: 10.1161/CIRCULATIONAHA.113.002624. Epub 2013 Aug 22.
Prior studies show that apolipoprotein A1 (apoA1) recovered from human atherosclerotic lesions is highly oxidized. Ex vivo oxidation of apoA1 or high-density lipoprotein (HDL) cross-links apoA1 and impairs lipid binding, cholesterol efflux, and lecithin-cholesterol acyltransferase activities of the lipoprotein. Remarkably, no studies to date directly quantify either the function or HDL particle distribution of apoA1 recovered from the human artery wall.
A monoclonal antibody (10G1.5) was developed that equally recognizes lipid-free and HDL-associated apoA1 in both native and oxidized forms. Examination of homogenates of atherosclerotic plaque-laden aorta showed >100-fold enrichment of apoA1 compared with normal aorta (P<0.001). Surprisingly, buoyant density fractionation revealed that only a minority (<3% of total) of apoA1 recovered from either lesions or normal aorta resides within an HDL-like particle (1.063≤d≤1.21). In contrast, the majority (>90%) of apoA1 within aortic tissue (normal and lesions) was recovered within the lipoprotein-depleted fraction (d>1.21). Moreover, both lesion and normal artery wall apoA1 are highly cross-linked (50% to 70% of total), and functional characterization of apoA1 quantitatively recovered from aorta with the use of monoclonal antibody 10G1.5 showed ≈80% lower cholesterol efflux activity and ≈90% lower lecithin-cholesterol acyltransferase activity relative to circulating apoA1.
The function and distribution of apoA1 in human aorta are quite distinct from those found in plasma. The lipoprotein is markedly enriched within atherosclerotic plaque, predominantly lipid-poor, not associated with HDL, extensively oxidatively cross-linked, and functionally impaired.
先前的研究表明，从人动脉粥样硬化病变中回收的载脂蛋白 A1（apoA1）高度氧化。apoA1 或高密度脂蛋白（HDL）的体外氧化交联 apoA1 并损害脂蛋白的脂质结合、胆固醇流出和卵磷脂胆固醇酰基转移酶活性。值得注意的是，迄今为止，没有研究直接定量测定从人动脉壁中回收的 apoA1 的功能或 HDL 颗粒分布。
开发了一种单克隆抗体（10G1.5），该抗体平等地识别天然和氧化形式的无脂和与 HDL 相关的 apoA1。对富含动脉粥样硬化斑块的主动脉匀浆的检查显示，与正常主动脉相比，apoA1 的富集度超过 100 倍（P<0.001）。令人惊讶的是，浮密度分级分离显示，从病变或正常主动脉中回收的 apoA1 中只有少数（<总 apoA1 的 3%）位于类似 HDL 的颗粒（1.063≤d≤1.21）内。相比之下，主动脉组织（正常和病变）中超过 90%的 apoA1 位于脂蛋白耗尽部分（d>1.21）内。此外，病变和正常动脉壁 apoA1 均高度交联（总交联的 50%至 70%），并且使用单克隆抗体 10G1.5 从主动脉定量回收的 apoA1 的功能特征显示，胆固醇流出活性约低 80%，卵磷脂胆固醇酰基转移酶活性约低 90%，与循环 apoA1 相比。
人主动脉中的 apoA1 的功能和分布与血浆中的截然不同。脂蛋白在动脉粥样硬化斑块中明显富集，主要是脂质缺乏，不与 HDL 相关，广泛氧化交联，并且功能受损。
