Moschetta A, vanBerge-Henegouwen G P, Portincasa P, Palasciano G, Groen A K, van Erpecum K J
Gastrointestinal Research Unit, Departments of Gastroenterology and Surgery, University Medical Center Utrecht, The Netherlands.
J Lipid Res. 2000 Jun;41(6):916-24.
Inclusion of phosphatidylcholine within bile salt micelles protects against bile salt-induced cytotoxicity. In addition to phosphatidylcholine, bile may contain significant amounts of sphingomyelin, particularly under cholestatic conditions. We compared protective effects of egg yolk phosphatidylcholine (similar to phosphatidylcholine in bile), egg yolk sphingomyelin (mainly 16:0 acyl chains) and dipalmitoyl phosphatidylcholine against taurocholate in complementary in vitro studies. Upon addition of taurocholate-containing micelles to sonicated egg yolk phosphatidylcholine vesicles, subsequent micellization of the vesicular bilayer proved to be retarded when phospholipids had also been included in these micelles in the rank order: egg yolk phosphatidylcholine < dipalmitoyl phosphatidylcholine < sphingomyelin. Hemolysis of erythrocytes and LDH release by CaCo-2 cells after addition of taurocholate micelles were strongly reduced by including small amounts of sphingomyelin or dipalmitoyl phosphatidylcholine in these micelles (PL/(PL + BS) >/= 0.1), whereas egg yolk phosphatidylcholine provided less protection. Amounts of non-phospholipid-associated bile salts (thought to be responsible for cytotoxicity) in egg yolk phosphatidylcholine-containing micelles were significantly higher than in corresponding sphingomyelin- or dipalmitoyl phosphatidylcholine-containing micelles (tested at PL/(PL + BS) ratios 0.1, 0.15, and 0.2). LDH release upon incubation of CaCo-2 cells with taurocholate simple micelles at these so-called "intermixed micellar-vesicular" concentrations was identical to LDH release upon incubation with corresponding taurocholate-phospholipid mixed micelles. In conclusion, we found greatly enhanced protective effects of sphingomyelin and dipalmitoyl phosphatidylcholine compared to egg yolk phosphatidylcholine against bile salt-induced cytotoxicity, related to different amounts of non-phospholipid-associated bile salts. These findings may be relevant for protection against bile salt-induced cytotoxicity in vivo.
胆汁盐微团中包含磷脂酰胆碱可防止胆汁盐诱导的细胞毒性。除磷脂酰胆碱外，胆汁可能含有大量鞘磷脂，特别是在胆汁淤积的情况下。我们在互补的体外研究中比较了蛋黄磷脂酰胆碱（类似于胆汁中的磷脂酰胆碱）、蛋黄鞘磷脂（主要是16:0酰基链）和二棕榈酰磷脂酰胆碱对牛磺胆酸盐的保护作用。将含牛磺胆酸盐的微团添加到超声处理的蛋黄磷脂酰胆碱囊泡中后，当磷脂也按以下顺序包含在这些微团中时，囊泡双层随后的微团化被证明受到阻碍：蛋黄磷脂酰胆碱<二棕榈酰磷脂酰胆碱<鞘磷脂。在这些微团中加入少量鞘磷脂或二棕榈酰磷脂酰胆碱（PL/(PL + BS)≥0.1）后，加入牛磺胆酸盐微团后红细胞的溶血和CaCo-2细胞的LDH释放显著降低，而蛋黄磷脂酰胆碱提供的保护较少。含蛋黄磷脂酰胆碱的微团中与非磷脂相关的胆汁盐（被认为是细胞毒性的原因）的量显著高于相应的含鞘磷脂或二棕榈酰磷脂酰胆碱的微团（在PL/(PL + BS)比率为0.1、0.15和0.2时测试）。在这些所谓的“混合微团 - 囊泡”浓度下，用牛磺胆酸盐简单微团孵育CaCo-2细胞时的LDH释放与用相应的牛磺胆酸盐 - 磷脂混合微团孵育时的LDH释放相同。总之，我们发现与蛋黄磷脂酰胆碱相比，鞘磷脂和二棕榈酰磷脂酰胆碱对胆汁盐诱导的细胞毒性的保护作用大大增强，这与不同量的非磷脂相关胆汁盐有关。这些发现可能与体内防止胆汁盐诱导的细胞毒性有关。
