Vega Antonio, Chacón Pedro, Alba Gonzalo, El Bekay Rajaa, Martín-Nieto José, Sobrino Francisco
Departamento de Bioquímica Médica y Biología, Universidad de Sevilla, E-41009 Sevilla, Spain.
J Leukoc Biol. 2006 Jul;80(1):152-63. doi: 10.1189/jlb.0705411. Epub 2006 Apr 19.
Cyclooxygenase (COX) is a key enzyme in prostaglandin (PG) synthesis. Up-regulation of its COX-2 isoform is responsible for the increased PG release, taking place under inflammatory conditions, and also, is thought to be involved in allergic and inflammatory diseases. In the present work, we demonstrate that COX-2 expression becomes highly induced by anti-immunoglobulin E (IgE) antibodies and by antigens in human neutrophils from allergic patients. This induction was detected at mRNA and protein levels and was accompanied by a concomitant PGE(2) and thromboxane A(2) release. We also show evidence that inhibitors of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, such as 4-(2-aminoethyl)benzenesulphonyl fluoride and 4-hydroxy-3-methoxyaceto-phenone, completely cancelled anti-IgE-induced COX-2 protein up-regulation, suggesting that this process is mediated by reactive oxygen species (ROS) derived from NADPH oxidase activity. Moreover, the mitogen-activated protein kinases (MAPKs), p38 and extracellular signal-regulated kinase, and also, the transcription factor, nuclear factor (NF)-kappaB, are involved in the up-regulation of COX-2 expression, as specific chemical inhibitors of these two kinases, such as SB203580 and PD098059, and of the NF-kappaB pathway, such as N(alpha)-benzyloxycarbonyl-l-leucyl-l-leucyl-l-leucinal, abolished IgE-dependent COX-2 induction. Evidence is also presented, using Fe(2)(+)/Cu(2)(+) ions, that hydroxyl radicals generated from hydrogen peroxide through Fenton reactions could constitute candidate modulators able to directly trigger anti-IgE-elicited COX-2 expression through MAPK and NF-kappaB pathways. Present results underscore a new role for ROS as second messengers in the modulation of COX-2 expression by human neutrophils in allergic conditions.
环氧化酶（COX）是前列腺素（PG）合成中的关键酶。其COX-2亚型的上调导致炎症条件下PG释放增加，并且被认为与过敏性和炎症性疾病有关。在本研究中，我们证明COX-2表达在过敏性患者的人中性粒细胞中被抗免疫球蛋白E（IgE）抗体和抗原高度诱导。这种诱导在mRNA和蛋白质水平上均被检测到，并且伴随着PGE(2)和血栓素A(2)的释放。我们还表明，还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶抑制剂，如4-(2-氨基乙基)苯磺酰氟和4-羟基-3-甲氧基苯乙酮，完全消除了抗IgE诱导的COX-2蛋白上调，这表明该过程由NADPH氧化酶活性产生的活性氧（ROS）介导。此外，丝裂原活化蛋白激酶（MAPK）、p38和细胞外信号调节激酶，以及转录因子核因子（NF）-κB，均参与COX-2表达的上调，因为这两种激酶的特异性化学抑制剂，如SB203580和PD098059，以及NF-κB途径的抑制剂，如N(α)-苄氧羰基-L-亮氨酰-L-亮氨酰-L-亮氨酸，消除了IgE依赖性COX-2诱导。使用Fe(2)(+)/Cu(2)(+)离子也证明，通过芬顿反应由过氧化氢产生的羟基自由基可能是能够通过MAPK和NF-κB途径直接触发抗IgE诱导的COX-2表达的候选调节剂。目前的结果强调了ROS作为第二信使在过敏性条件下人中性粒细胞调节COX-2表达中的新作用。
