Bidirectional effects of hepatic ischemia/reperfusion on E. coli-induced TNF-alpha gene expression.
Bidirectional effects of hepatic ischemia/reperfusion on E. coli-induced TNF-alpha gene expression.
复制标题
肝缺血/再灌注对大肠杆菌诱导的 TNF-α 基因表达的双向影响。
DOI：
10.1152/ajpregu.1996.270.1.r289
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Matuschak,GM
中科院分区：
文献类型：
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作者：
Epperly,NA;Lechner,AJ;Johanns,CA;Webster,RO;Matuschak,GM
我们测试了这样的假设：革兰氏阴性菌血症 (GNB) 和低流量缺血导致的肝 O2 供应短暂（30 分钟）减少，由于环氧合酶与补体 (C) 途径的序列特异性激活，差异调节肿瘤坏死因子-α (TNF-α) 基因表达。在 t = 0 时，在门静脉内 10(9) 活大肠杆菌血清型 055:B5 (EC) 或 0.9% NaCl (NS) 后，对缓冲液灌注的 Sprague-Dawley 大鼠肝脏 (n = 82) 进行了 180 分钟的研究。与接受恒流灌注的 EC 和 NS 对照相比，在 EC + 30 I/R 中研究了序贯 GNB 和缺血/再灌注 (I/R) NS + 30 I/R 肝脏，其中 EC 或 NS 后 0.5 小时开始 30 分钟缺血 (I)，随后进行 120 分钟再灌注 (R)。在 30 I/R + EC 组和 30 I/R + NS 组中，该顺序相反。对细菌清除率、生物活性和抗原性 TNF-α、前列腺素 E2 (PGE2) 以及肝 O2 摄取和性能进行了连续评估。 EC 对照中的静脉 TNF-α 增加，180 分钟后达到峰值 155 +/- 29 U/ml（与 NS 对照相比，P < 0.001），肝 TNF-α mRNA 也是如此。尽管库普弗细胞对 EC 的清除率相当，但 EC + 30 I/R 中 TNF-α 转录物和蛋白质水平均显着减弱（相对于 EC，P < 0.001）。 Indomethacin (10(-5) M) 减少I/R 诱导的PGE2 分泌并使TNF-α 恢复至对照水平。相反，30 I/R + EC 灌注液中的 TNF-α 水平超过 EC + 30 I/R 肝脏的水平 (P < 0.05)，并且与 EC 对照没有区别。别嘌呤醇预处理可抑制 30 个 I/R + EC 器官中 TNF-α 的产生，但 C 热灭活或可溶性人补体受体 1 型输注则不受此影响。这些结果确定了一种新的序列依赖性相互作用，即GNB后的肝O2剥夺通过环加氧酶代谢物的产生下调TNF-α，而GNB之前的缺血通过反应性O2物种而不是C激活增加细胞因子表达。
We tested the hypothesis that gram-negative bacteremia (GNB) and brief (30 min) reductions in the hepatic O2 supply by low-flow ischemia differentially modulate tumor necrosis factor-alpha (TNF-alpha) gene expression owing to sequence-specific activation of cyclooxygenase vs. complement (C) pathways. Buffer-perfused Sprague-Dawley rat livers (n = 82) were studied over 180 min after intraportal 10(9) live E. coli serotype 055:B5 (EC) or 0.9% NaCl (NS) at t = 0. Compared with EC and NS controls receiving constant-flow perfusion, sequential GNB and ischemia/reperfusion (I/R) were studied in EC + 30 I/R and NS + 30 I/R livers, in which 30 min of ischemia (I) beginning 0.5 h after EC or NS was followed by 120 min of reperfusion (R). This sequence was reversed in 30 I/R + EC and 30 I/R + NS groups. Bacterial clearance, bioactive and antigenic TNF-alpha, prostaglandin E2 (PGE2), and hepatic O2 uptake and performance were serially assessed. Venous TNF-alpha increased in EC controls to peak at 155 +/- 29 U/ml after 180 min (P < 0.001 vs. NS controls) as did hepatic TNF-alpha mRNA. Both TNF-alpha transcripts and protein levels were markedly attenuated in EC + 30 I/R (P < 0.001 vs. EC) despite equivalent EC clearance by Kupffer cells. Indomethacin (10(-5) M) decreased I/R-induced PGE2 secretion and restored TNF-alpha to control levels. In contrast, TNF-alpha levels in 30 I/R + EC perfusates exceeded those of EC + 30 I/R livers (P < 0.05) and were indistinguishable from EC controls. Allopurinol pretreatment but not heat inactivation of C or infusion of soluble human complement receptor type 1 inhibited TNF-alpha production in 30 I/R + EC organs. These results identify a novel sequence-dependent interaction whereby hepatic O2 deprivation after GNB downregulates TNF-alpha via generation of cyclooxygenase metabolites, whereas ischemia preceding GNB increases cytokine expression via reactive O2 species but not C activation.