PDF(Pubmed)
Abstract：
Dietary sphingomyelin (SM) has been reported to favorably modulate postprandial lipemia. Mechanisms underlying these beneficial effects on cardiovascular risk markers are not fully elucidated. Rodent studies showed that tritiated SM was hydrolyzed in the intestinal lumen into ceramides (Cer) and further to sphingosine (SPH) and fatty acids (FA) that were absorbed by the intestine. Our objective was to investigate the uptake and metabolism of SPH and/or tricosanoic acid (C23:0), the main FA of milk SM, as well as lipid secretion in Caco-2/TC7 cells cultured on semipermeable inserts. Mixed micelles (MM) consisting of different digested lipids and taurocholate were prepared without or with SPH, SPH and C23:0 (SPH+C23:0), or C23:0. Triglycerides (TG) were quantified in the basolateral medium, and sphingolipids were analyzed by tandem mass spectrometry. TG secretion increased 11-fold in all MM-incubated cells compared with lipid-free medium. Apical supply of SPH-enriched MM led to increased concentrations of total Cer in cells, and coaddition of C23:0 in SPH-enriched MM led to a preferential increase of C23:0 Cer and C23:0 SM. Complementary experiments using deuterated SPH demonstrated that SPH-d9 was partly converted to sphingosine-1-phosphate-d9, Cer-d9, and SM-d9 within cells incubated with SPH-enriched MM. A few Cer-d9 (2% of added SPH-d9) was recovered in the basolateral medium of (MM+SPH)-incubated cells, especially C23:0 Cer-d9 in (MM+SPH+C23:0)-enriched cells. In conclusion, present results indicate that MM enriched with (SPH+C23:0), such as found in postprandial micelles formed after milk SM ingestion, directly impacts sphingolipid endogenous metabolism in enterocytes, resulting in the secretion of TG-rich particles enriched with C23:0 Cer.
摘要：
据报道，膳食鞘磷脂（SM）可有利地调节餐后血脂。这些对心血管风险标志物有益作用的潜在机制尚未完全阐明。啮齿动物研究表明，tri化的SM在肠腔中水解为神经酰胺（Cer），以及进一步由肠吸收的鞘氨醇(SPH)和脂肪酸(FA)。我们的目的是研究在半透性插入物上培养的Caco-2/TC7细胞中SPH和/或C23：0的摄取和代谢，以及脂质分泌。制备由不同消化脂质和牛磺胆酸盐组成的混合胶束（MM），SPH和C23:0(SPH+C23:0)或C23:0。在基底外侧培养基中定量甘油三酯(TG),并通过串联质谱法分析鞘脂。与无脂培养基相比，所有MM孵育细胞的TG分泌增加了11倍。富含SPH的MM的顶部供应导致细胞中总Cer的浓度增加，并且在富含SPH的MM中共同添加C23：0导致C23：0Cer和C23：0SM的优先增加。使用氘代SPH的补充实验表明，在与富含SPH的MM孵育的细胞内，SPH-d9部分转化为鞘氨醇-1-磷酸-d9，Cer-d9和SM-d9。在(MM+SPH)孵育细胞的基底外侧培养基中回收了一些Cer-d9(添加的SPH-d9的2%),尤其是(MM+SPH+C23:0)富集细胞中的C23:0Cer-d9。总之,目前的结果表明，MM富含(SPH+C23:0)，例如在牛奶SM摄入后形成的餐后胶束中发现的，直接影响肠细胞中的鞘脂内源性代谢，导致分泌富含C23:0Cer的富含TG的颗粒。
