Siegel G, Abletshauser C, Malmsten M, Klüssendorf D
Institute of Physiology, Biophysical Research Group, The Free University of Berlin, Arnimallee 22, DE-14195, Berlin, Germany.
Biosens Bioelectron. 2003 May;18(5-6):635-47. doi: 10.1016/s0956-5663(03)00034-4.
Proteoheparan sulfate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques. Low-density lipoprotein (LDL) was found to deposit strongly at the proteoheparan sulfate-coated surface, particularly in the presence of Ca(2+), apparently through complex formation 'proteoglycan-LDL-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. HDL bound to heparan sulfate proteoglycan protected against LDL deposition and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL was able to decelerate the ternary complex deposition and to disrupt newly formed nanoplaques. Therefore, HDL attached to its proteoglycan receptor sites is thought to raise a multidomain barrier, selection and control motif for transmembrane and paracellular lipoprotein uptake into the arterial wall. The molecular arteriosclerosis model was tested on its reliability in a biosensor application in order to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The very low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL)/LDL and VLDL/IDL/LDL/HDL plasma fractions from a high-risk patient with dyslipoproteinemia and type 2 diabetes mellitus showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca(2+) concentration, with a strong increase at higher Ca(2+) concentrations. Nanoplaque formation and size of the HDL-containing lipid fraction remained well below that of the LDL-containing lipid fraction. Fluvastatin, whether applied acutely to the patient (one single 80 mg slow release matrix tablet) or in a 2-months medication regimen, markedly slowed down this process of ternary aggregational nanoplaque build-up and substantially inhibited nanoplaque size development at all Ca(2+) concentrations used. The acute action resulted without any significant change in lipid concentrations of the patient. Furthermore, after nanoplaque generation, fluvastatin, similar to HDL, was able to reduce nanoplaque formation and size. These immediate effects of fluvastatin have to be taken into consideration while interpreting the clinical outcome of long-term studies.
硫酸乙酰肝素蛋白聚糖可通过其跨膜疏水蛋白核心结构域以单分子层形式吸附到甲基化硅胶表面。由于静电排斥作用，其阴离子糖胺聚糖侧链伸展到血液替代溶液中，从而形成一个受体位点，可通过载脂蛋白内富含碱性氨基酸的残基与特定脂蛋白结合。采用椭偏技术研究了结合过程。发现低密度脂蛋白（LDL）在硫酸乙酰肝素蛋白聚糖包被的表面大量沉积，尤其是在存在Ca(2+)的情况下，显然是通过形成“蛋白聚糖-LDL-钙”复合物。这种三元复合物的形成可被解释为在分子水平上形成动脉粥样硬化纳米斑块，这是动脉粥样硬化原发性病变的原因。结合到硫酸乙酰肝素蛋白聚糖上的高密度脂蛋白（HDL）可防止LDL沉积，并完全抑制蛋白聚糖-脂蛋白复合物的钙化。此外，HDL能够减缓三元复合物的沉积并破坏新形成的纳米斑块。因此，附着在其蛋白聚糖受体位点上的HDL被认为可形成一个多结构域屏障，作为跨膜和细胞旁脂蛋白摄取进入动脉壁的选择和控制基序。在生物传感器应用中测试了分子动脉粥样硬化模型的可靠性，以揭示降脂药物氟伐他汀可能的急性多效性作用。来自一名患有血脂异常和2型糖尿病的高危患者的极低密度脂蛋白（VLDL）/中间密度脂蛋白（IDL）/LDL和VLDL/IDL/LDL/HDL血浆组分在正常血Ca(2+)浓度下就已开始形成动脉粥样硬化纳米斑块，在较高Ca(2+)浓度下显著增加。含HDL的脂质组分的纳米斑块形成和大小仍远低于含LDL的脂质组分。氟伐他汀，无论是急性给予患者（一片80mg缓释基质片）还是采用2个月的用药方案，在所有使用的Ca(2+)浓度下均显著减缓了三元聚集纳米斑块形成的过程，并大幅抑制了纳米斑块大小的发展。急性给药后患者的脂质浓度没有任何显著变化。此外，在纳米斑块形成后，氟伐他汀与HDL类似，能够减少纳米斑块的形成和大小。在解释长期研究的临床结果时，必须考虑氟伐他汀的这些即时作用。
