The effect of phospholipids and fatty acids on tight-junction permeability and bacterial translocation
The effect of phospholipids and fatty acids on tight-junction permeability and bacterial translocation
复制标题
磷脂和脂肪酸对紧密连接通透性和细菌易位的影响
DOI：
10.1007/s003830100592
复制
发表时间：
2001
影响因子：
1.8
通讯作者：
C. Harmon
中科院分区：
文献类型：
--
作者：
T. Sawai;R. Drongowski;R. Lampman;A. Coran;C. Harmon
摘要炎症性肠病（IBD）患者肠上皮细胞中磷脂酶A2（PLA 2）活性升高。 我们最近报道，PLA 2介导的水解磷脂酰胆碱（PC）溶血磷脂酰胆碱（L-PC）时，都被施加到培养的EC单层的顶端表面，导致增加细菌易位（BT）和降低跨上皮电阻（TEER）。游离脂肪酸（FFA）是该反应的其他产物，然而，它们对Caco-2细胞渗透性的影响尚未报道。除PC外，其他管腔磷脂也存在于肠上皮细胞表面。PLA 2还可以介导除PC以外的管腔磷脂的水解。本研究的目的是研究磷脂以外的PC和普通FFA对肠上皮通透性和BT的影响。人Caco-2肠细胞在双室细胞培养系统的顶室中的多孔过滤器上生长至汇合。单层完整性和紧密连接渗透性测量为TEER。首先，使用薄层色谱法（TLC）测定PC水解释放的常见FFA。在单独的实验中，用磷脂酰乙醇胺（PE）、溶血磷脂酰乙醇胺（L-PE）或溶解在PC溶液中的棕榈油酸、油酸、亚油酸和花生四烯酸处理单层。BT的大小确定2小时后，通过添加土方ichiacoli C25的顶室，然后通过定量培养基底室样品处理。统计学分析采用Kurosaki-Wallis检验。在Caco-2单层顶面与PLA 2孵育的PC样品的TLC显示产生了棕榈油酸、油酸、亚油酸和花生四烯酸。与对照组相比，L-PE显著降低TEER，但程度低于单独的L-PC。L-PE对BT无影响。棕榈油酸和油酸同样显着降低TEER相比，控制，但小于L-PC。所有检测的FFA对BT均无影响。应用于肠细胞顶面的磷脂，如体内粘液中发现的磷脂，可被酶PLA 2水解，产生溶血磷脂和FFA物质，可改变肠细胞单层通透性。然而，FFA和L-PL，而不是L-PC，似乎没有刺激BT的效果。这一观察结果可能对IBD患者的发病机制和治疗策略具有临床意义，其中肠上皮细胞PLA 2活性已被证明升高。
Abstract The activity of phospholipase A2 (PLA2) is elevated in the intestinal epithelia of patients with inflammatory bowel disease (IBD). We recently reported that PLA2 mediates hydrolysis of phosphatidylcholine (PC) to lysophosphatidylcholine (L-PC) when both are applied to the apical surface of cultured EC monolayers, resulting in increased bacterial translocation (BT) and decreased transepithelial electrical resistance (TEER). Free fatty acids (FFA) are the other products of this reaction, however, their effect on Caco-2 cell permeability has not been reported. In addition to PC, other luminal phospholipids are present at the surface of the enterocyte. PLA2 may also mediate the hydrolysis of luminal phospholipids other than PC. The aim of this study was to examine the effects of phospholipids other than PC and common FFA on intestinal epithelial permeability and BT. Human Caco-2 enterocytes were grown to confluence on porous filters in the apical chamber of a two-chamber cell-culture system. Monolayer integrity and tight-junction permeability were measured as TEER. First, common FFA released by PC hydrolysis were determined using thin-layer chromatography (TLC). In separate experiments, monolayers were treated with phosphatidylethanolamine (PE), lysophosphatidylethanolamine (L-PE), or palmitoleic acid, oleic acids, linoleic acids, and arachidonic acid solubilized in solution with PC. The magnitude of BT was determined 2 h after treatment by adding Escherichiacoli C25 to the apical chamber followed by quantitatively culturing basal-chamber samples. Statistical analysis was by the Kurosaki-Wallis test. TLC of PC samples incubated with PLA2 on the apical surface of Caco-2 monolayers demonstrated the production of palmitoleic acid, oleic acids, linoleic acids, and arachidonic acid. L-PE significantly decreased TEER compared to controls, but to a lesser degree than L-PC alone. L-PE had no effects on BT. Palmitoleic acid and oleic acid likewise significantly decreased TEER compared to controls, however, less than L-PC. All FFA tested had no effect on BT. Phospholipids applied to the apical surface of enterocytes, such as those found in vivo in mucus, can be hydrolyzed by the enzyme PLA2 resulting in lysophospholipid and FFA species that can alter enterocyte monolayer permeability. However, FFA and L-PL, other than L-PC, appear to have no effect to stimulate BT. This observation may have clinical implications in the pathogenesis and treatment strategies for IBD patients in whom enterocyte PLA2 activity has been shown to be elevated.