Ignatowski T A, Gallant S, Spengler R N
Dept. of Pathology, S.U.N.Y. at Buffalo, School of Medicine and Biomedical Sciences 14214, USA.
J Neuroimmunol. 1996 Apr;65(2):107-17. doi: 10.1016/0165-5728(96)00004-5.
Macrophage (M phi) responsiveness can be regulated by various mediators, including those which emanate from, and mimic, the sympathetic nervous system. Whereas beta-adrenergic agonists suppress, alpha 2-adrenergic agonists augment lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF) production and gene expressed. The susceptibility of M phi s to regulation of LPS-induced TNF production and mRNA accumulation was examined following beta-adrenergic and alpha 2-adrenergic receptor activation at specific time points post-LPS challenge. Complete Freund's adjuvant-elicited murine M phi s were incubated with LPS (30 ng/ml) in the presence or absence of adrenergic agonists or antagonists. We assessed the susceptibility of immunologically-activated M phi s to adrenergic receptor regulation: a) during the 1 h delay in the production of TNF after LPS-stimulation, and b) during the rapid increase in TNF production which follows. Disparate responsiveness of M phi s to adrenergic drugs was observed during this time course of TNF production and TNF mRNA accumulation. In particular, while the concomitant addition of an alpha 2-adrenergic antagonist and LPS resulted in 45% suppression of TNF production, this selective blockade of alpha 2-adrenergic receptors on M phi s was equally effective throughout the first 45 min post-LPS challenge. After this initial period, the alpha 2-adrenergic receptor became progressively less responsive as demonstrated by the delayed addition of yohimbine (10(-5) M) post-LPS challenge. The addition of the selective alpha 2-adrenergic agonist UK-14304 (10(-7) M) to LPS-activated M phi s augmented TNF mRNA accumulation. However, this augmentation was even greater when the addition of the alpha 2-adrenergic agonist was delayed post-LPS challenge. It was also shown that the beta-adrenergic agonist isoproterenol (10(-6) M) produced maximum suppression of TNF production within the first 1.5 h post-LPS challenge. Suppression by isoproterenol (10(-6) M) of TNF mRNA accumulation occurred throughout the 2-h period assessed post-LPS stimulation of M phi s. The decline in isoproterenol-induced regulation was accompanied by an elevation in beta 2-adrenergic receptor mRNA accumulation. Furthermore, suppression of TNF production induced by a maximum concentration of isoproterenol was observed at various LPS concentrations (0.001-1000 ng/ml), although this was not as pronounced a suppression as demonstrated for dibutyrl cAMP. These results demonstrate that the susceptibility of M phi s to adrenergic receptor regulation changes throughout the time period necessary for gene activation and ultimate release of TNF. Thus, the production of TNF during LPS-dependent disease states may be regulated by adrenergic mediators throughout different temporal windows, better explaining the role played by the nervous system.
巨噬细胞（M phi）的反应性可受多种介质调节，包括那些源自交感神经系统并与之类似的介质。β-肾上腺素能激动剂具有抑制作用，而α2-肾上腺素能激动剂则可增强脂多糖（LPS）刺激的肿瘤坏死因子（TNF）生成及基因表达。在LPS刺激后的特定时间点，分别激活β-肾上腺素能受体和α2-肾上腺素能受体后，检测了M phi对LPS诱导的TNF生成及mRNA积累调节的敏感性。将完全弗氏佐剂诱导的小鼠M phi与LPS（30 ng/ml）共同孵育，同时加入或不加入肾上腺素能激动剂或拮抗剂。我们评估了免疫激活的M phi对肾上腺素能受体调节的敏感性：a）在LPS刺激后TNF生成延迟的1小时内，以及b）在随后TNF生成快速增加的阶段。在TNF生成及TNF mRNA积累的这一过程中，观察到M phi对肾上腺素能药物的反应性存在差异。具体而言，同时加入α2-肾上腺素能拮抗剂和LPS可导致TNF生成受到45%的抑制，这种对M phi上α2-肾上腺素能受体的选择性阻断在LPS刺激后的最初45分钟内同样有效。在这一初始阶段之后，如在LPS刺激后延迟加入育亨宾（10(-5) M）所显示的，α2-肾上腺素能受体的反应性逐渐降低。向LPS激活的M phi中加入选择性α2-肾上腺素能激动剂UK-14304（10(-7) M）可增强TNF mRNA积累。然而，当在LPS刺激后延迟加入α2-肾上腺素能激动剂时，这种增强作用更为明显。还表明，β-肾上腺素能激动剂异丙肾上腺素（10(-6) M）在LPS刺激后的最初1.5小时内对TNF生成产生最大抑制作用。在评估的LPS刺激M phi后的2小时内，异丙肾上腺素（10(-6) M）对TNF mRNA积累均有抑制作用。异丙肾上腺素诱导的调节作用减弱伴随着β2-肾上腺素能受体mRNA积累的增加。此外，在不同LPS浓度（0.001 - 1000 ng/ml）下均观察到最大浓度异丙肾上腺素对TNF生成的抑制作用，尽管其抑制作用不如二丁酰环磷腺苷明显。这些结果表明，M phi对肾上腺素能受体调节的敏感性在基因激活及TNF最终释放所需的整个时间段内都会发生变化。因此，在LPS依赖性疾病状态下TNF的生成可能在不同的时间窗内受到肾上腺素能介质的调节，这更好地解释了神经系统所起的作用。
