Gustafson-Svärd C, Lilja I, Sjödahl R, Tagesson C
Dept. of Occupational and Environmental Medicine, Linköping University, Faculty of Health Sciences, Sweden.
Scand J Gastroenterol. 1995 Oct;30(10):1000-7. doi: 10.3109/00365529509096345.
We have recently reported that tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine that has been suggested to play a role in the pathogenesis of inflammatory bowel disease, potentiates phospholipase A2 (PLA2)-stimulated arachidonic acid (AA) release and prostaglandin E2 (PGE2) formation in cultured intestinal epithelial cells (INT 407). The aim of the present study was to investigate which particular isoforms of PLA2 and cyclooxygenase (COX) are involved in these processes.
Cells were labeled with 14C-AA or 14C-oleic acid, and the amounts of released fatty acid and PGE2 were analyzed by thin-layer chromatography. mRNA was analyzed by reverse transcription and polymerase chain reaction.
The cells contained mainly mRNA for cytosolic PLA2 (cPLA2) and only trace amounts of mRNA for group I and II PLA2. TNF-alpha potentiated the release of 14C-AA but not of 14C-oleic acid. The TNF-alpha-potentiated PGE2 release was reduced after inhibition of cellular COX activity or mRNA synthesis. TNF-alpha increased the amounts of mRNA for COX-2 but not for COX-1.
The results point to the possibility that TNF-alpha may modulate the intestinal mucosal content of biologically active AA metabolites by priming cPLA2- and COX-2-mediated processes in the epithelial cells.
我们最近报道，肿瘤坏死因子-α（TNF-α）是一种促炎细胞因子，已被认为在炎症性肠病的发病机制中起作用，它能增强磷脂酶A2（PLA2）刺激的花生四烯酸（AA）释放以及培养的肠上皮细胞（INT 407）中前列腺素E2（PGE2）的形成。本研究的目的是调查PLA2和环氧化酶（COX）的哪些特定亚型参与了这些过程。
用14C-AA或14C-油酸标记细胞，通过薄层色谱法分析释放的脂肪酸和PGE2的量。通过逆转录和聚合酶链反应分析mRNA。
细胞主要含有胞质型PLA2（cPLA2）的mRNA，而I型和II型PLA2的mRNA仅含微量。TNF-α增强了14C-AA的释放，但未增强14C-油酸的释放。抑制细胞COX活性或mRNA合成后，TNF-α增强的PGE2释放减少。TNF-α增加了COX-2的mRNA量，但未增加COX-1的mRNA量。
结果表明，TNF-α可能通过启动上皮细胞中cPLA2和COX-2介导的过程来调节生物活性AA代谢产物的肠黏膜含量。
