Saito H, Okuhira K, Tsuchimoto N, Vertut-Doi A, Matsumoto C, Tanimoto T, Okada S, Handa T
National Institute of Health Sciences, Osaka , Japan.
Lipids. 2001 Jan;36(1):27-33. doi: 10.1007/s11745-001-0664-1.
Cholesteryl ester, along with triglyceride (TG), is the major core component of plasma lipoproteins. We investigated the effect of core composition on the physical state and metabolic behavior of lipid emulsions, as model particles of lipoproteins. Fluorescence studies using 1,6-diphenylhexatriene analogs showed that although cholesteryl oleate (CO) significantly decreased core mobility, the surface rigidity of phosphatidylcholine (PC) monolayers was independent of core composition. When intravenously injected into rats, the increased amount of core CO tended to retard TG emulsion removal from plasma, and the initial clearance rate was correlated with the amount of apolipoprotein E (apoE) bound from plasma. In addition, PC liposomes with a similar emulsion particle size showed negligible binding of apoE and were cleared at a slower rate compared to all emulsions. Furthermore, the effect of CO on the binding behavior of apoE to the emulsion surface and the emulsion uptake by hepatocytes was assessed in vitro. Replacing core TG with CO was found to decrease the apoE binding capacity to emulsions markedly without changing the binding affinity and thereby to reduce the cell uptake of emulsion particles by HepG2 cells. These results indicate that the physical state of core lipids, which can be modulated by CO content, plays a role in emulsion metabolism through the alteration in apoE binding.
胆固醇酯与甘油三酯（TG）一样，是血浆脂蛋白的主要核心成分。我们研究了核心组成对脂质乳剂（作为脂蛋白的模型颗粒）的物理状态和代谢行为的影响。使用1,6 - 二苯基己三烯类似物的荧光研究表明，尽管油酸胆固醇酯（CO）显著降低了核心流动性，但磷脂酰胆碱（PC）单层的表面刚性与核心组成无关。当静脉注射到大鼠体内时，核心CO含量的增加倾向于延缓TG乳剂从血浆中的清除，并且初始清除率与从血浆中结合的载脂蛋白E（apoE）的量相关。此外，具有相似乳剂粒径的PC脂质体显示出可忽略不计的apoE结合，并且与所有乳剂相比清除速率较慢。此外，在体外评估了CO对apoE与乳剂表面结合行为以及肝细胞对乳剂摄取的影响。发现用CO替代核心TG可显著降低apoE与乳剂的结合能力，而不改变结合亲和力，从而降低HepG2细胞对乳剂颗粒的细胞摄取。这些结果表明，可通过CO含量调节的核心脂质的物理状态通过改变apoE结合在乳剂代谢中起作用。
