Bergstraesser L M, Bates S R
Biochim Biophys Acta. 1985 Oct 2;836(3):296-305. doi: 10.1016/0005-2760(85)90133-x.
Macrophage-conditioned medium containing very-low-density lipoproteins (VLDL) and its effects on smooth muscle cell triacylglycerol metabolism was investigated. Macrophages exposed to VLDL from normolipemic rats accumulated high levels of intracellular triacylglycerol, while similarly treated smooth muscle cells showed only slight changes. Medium, initially composed of VLDL and albumin, contained substantial levels of free fatty acids after exposure to macrophages. In the presence of albumin, the loss of VLDL triacylglycerol from the medium and the appearance of medium free fatty acids was consistent with a precursor-product relationship. The extent of medium fatty acid accumulation was dependent on the length of time of incubation with macrophages and was proportional to the concentration of VLDL and albumin added to the culture dish. This macrophage-conditioned medium, when given to smooth muscle cells, promoted a 6-12-fold increase in smooth muscle cell triacylglycerol levels over that produced by fresh VLDL and albumin. Similar increases in cell triacylglycerol levels could be produced using fresh medium approximating the oleate concentration and the fatty acid to albumin molar ratios found in macrophage-conditioned medium. In macrophage-conditioned medium with VLDL but without albumin, little free fatty acid was found. Other factors produced by macrophages did not seem to affect the metabolism of VLDL by smooth muscle cells since, in the absence of albumin, media with VLDL caused comparable responses in smooth muscle cell triacylglycerol accumulation whether or not the medium was previously exposed to macrophages. Thus, the minor changes in triacylglycerol content in smooth muscle cells promoted by medium containing VLDL and albumin were substantially enhanced by a prior exposure of the medium to macrophages, primarily due to the free fatty acids present in the macrophage-conditioned medium.
研究了含有极低密度脂蛋白（VLDL）的巨噬细胞条件培养基及其对平滑肌细胞三酰甘油代谢的影响。暴露于正常血脂大鼠的VLDL的巨噬细胞积累了高水平的细胞内三酰甘油，而同样处理的平滑肌细胞仅表现出轻微变化。最初由VLDL和白蛋白组成的培养基在暴露于巨噬细胞后含有大量游离脂肪酸。在白蛋白存在下，培养基中VLDL三酰甘油的损失和培养基游离脂肪酸的出现与前体-产物关系一致。培养基脂肪酸积累的程度取决于与巨噬细胞孵育的时间长度，并与添加到培养皿中的VLDL和白蛋白的浓度成正比。这种巨噬细胞条件培养基给予平滑肌细胞时，使其三酰甘油水平比新鲜VLDL和白蛋白产生的水平提高了6至12倍。使用接近巨噬细胞条件培养基中发现的油酸浓度和脂肪酸与白蛋白摩尔比的新鲜培养基，也可产生类似的细胞三酰甘油水平升高。在含有VLDL但不含白蛋白的巨噬细胞条件培养基中，几乎没有发现游离脂肪酸。巨噬细胞产生的其他因素似乎不影响平滑肌细胞对VLDL的代谢，因为在没有白蛋白的情况下，含有VLDL的培养基无论是否先前暴露于巨噬细胞，在平滑肌细胞三酰甘油积累方面都引起了相当的反应。因此，含有VLDL和白蛋白的培养基促进的平滑肌细胞三酰甘油含量的微小变化，在培养基预先暴露于巨噬细胞后会显著增强，主要是由于巨噬细胞条件培养基中存在的游离脂肪酸。
