Moore J N, Cook J A, Morris D D, Halushka P V, Wise W C
Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston.
Circ Shock. 1990 Jul;31(3):281-95.
Macrophages release pro-inflammatory substances that may augment intravascular coagulopathy associated with endotoxemia. In the present study, the effect of Salmonella enteritidis endotoxin on expression of procoagulant activity (PCA), eicosanoid metabolism, and production of tumor necrosis factor (TNF) by rat peritoneal macrophages was determined. Endotoxin induced significant dose-dependent increases in the concentrations of immunoreactive (i) thromboxane B2 (TxB2), 6-ketoprostaglandin F1 alpha (i6-keto-PGF1 alpha), and TNF in culture media. Calcium ionophore (A23187; 0.5 microM) induced an approximate two-fold greater increase (P less than 0.05) in iTxB2 and i6-keto-PGF1 alpha than that stimulated by the maximal endotoxin dose. Endotoxin (0.5, 5, and 50 micrograms/ml) induced similar increases in PCA in macrophage lysates which paralleled the production of iTxB2 and i6-keto-PGF1 alpha. In contrast to its marked effect on eicosanoid metabolism, A23187 elicited little increase in PCA. After the responses of peritoneal macrophages from normal animals were characterized, we hypothesized that procedures which alter the in vivo response of rats to endotoxin would similarly alter the in vitro responses of their peritoneal macrophages. In subsequent studies, the effect of altered endotoxin sensitivity on expression of PCA, eicosanoid synthesis, and TNF activity were assessed. Endotoxin tolerance, induced by repeated injection of sublethal doses of endotoxin in vivo, rendered rat peritoneal macrophages refractory to in vitro endotoxin-induced production of iTxB2, i6-keto-PGF1 alpha, PCA, and TNF activity. In contrast, pretreatment of rats with the macrophage stimulant glucan, which enhances endotoxin lethality, augmented the in vitro production of iTxB2, PCA, and TNF by endotoxin-stimulated peritoneal macrophages. These studies demonstrate that endotoxin-induced macrophage arachidonic acid metabolism is associated with expression of PCA and secretion of TNF. Additionally, macrophage synthesis of these pathogenic mediators is reduced under conditions associated with endotoxin resistance (endotoxin tolerance) and is augmented during endotoxin hypersensitivity (glucan stimulation).
巨噬细胞释放促炎物质，可能会加剧与内毒素血症相关的血管内凝血病变。在本研究中，测定了肠炎沙门氏菌内毒素对大鼠腹腔巨噬细胞促凝活性（PCA）表达、类花生酸代谢以及肿瘤坏死因子（TNF）产生的影响。内毒素导致培养基中免疫反应性（i）血栓素B2（TxB2）、6-酮前列腺素F1α（i6-酮-PGF1α）和TNF浓度呈显著的剂量依赖性增加。钙离子载体（A23187；0.5微摩尔）诱导的iTxB2和i6-酮-PGF1α增加幅度比最大内毒素剂量刺激的增加幅度大约两倍（P<0.05）。内毒素（0.5、5和50微克/毫升）诱导巨噬细胞裂解物中PCA出现类似增加，这与iTxB2和i6-酮-PGF1α的产生平行。与对类花生酸代谢的显著影响相反，A23187引起的PCA增加很少。在对正常动物腹腔巨噬细胞的反应进行表征后，我们推测改变大鼠对内毒素体内反应的程序会类似地改变其腹腔巨噬细胞的体外反应。在随后的研究中，评估了内毒素敏感性改变对PCA表达、类花生酸合成和TNF活性的影响。体内重复注射亚致死剂量的内毒素诱导的内毒素耐受，使大鼠腹腔巨噬细胞对体外内毒素诱导的iTxB2、i6-酮-PGF1α、PCA和TNF活性产生耐受。相反，用增强内毒素致死性的巨噬细胞刺激剂葡聚糖预处理大鼠，可增强内毒素刺激的腹腔巨噬细胞体外iTxB2、PCA和TNF的产生。这些研究表明，内毒素诱导的巨噬细胞花生四烯酸代谢与PCA表达和TNF分泌有关。此外，在与内毒素抵抗（内毒素耐受）相关的条件下，这些致病介质的巨噬细胞合成减少，而在内毒素超敏反应（葡聚糖刺激）期间增加。
