Hide I, Toriu N, Nuibe T, Inoue A, Hide M, Yamamoto S, Nakata Y
Department of Pharmacology, Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, Japan.
J Immunol. 1997 Sep 15;159(6):2932-40.
The mast cell plays a pivotal role in initiating allergic inflammation by secreting several cytokines including TNF-alpha, in addition to granule mediators such as histamine. Anti-allergic drugs including azelastine prevent immediate-type hypersensitivity by inhibiting mast cell degranulation, as well as blocking histamine H1 receptors. However, their effects on cytokine release from mast cells remain unknown. In a rat mast RBL-2H3 cell line, azelastine inhibited Ag- and ionomycin-induced TNF-alpha release with IC50 values of 25.7 +/- 3.4 microM and 1.66 +/- 0.45 microM, respectively. These effects were observed at lower concentrations than needed for the inhibition of degranulation. In Ag-stimulated cells, azelastine also inhibited TNF-alpha mRNA expression, TNF-alpha protein synthesis and release, and, possibly related to these effects, Ca2+ influx. In ionomycin-stimulated cells, however, azelastine inhibited TNF-alpha release to a greater extent than mRNA expression/protein synthesis and Ca2+ influx, suggesting that azelastine inhibits the release process more potently than transcription or production of TNF-alpha by interfering with a signal other than Ca2+. Azelastine added 1 h after ionomycin stimulation also immediately blocked subsequent release of TNF-alpha, which had been produced in the cells, without affecting Ca2+ influx. Pretreatment with 1 microM azelastine inhibited ionomycin-induced, but not Ag-induced, protein kinase C translocation to the membranes. These results suggest that the release process of TNF-alpha in mast cells is regulated by a mechanism distinct from that of degranulation, and that in Ca2+-ionophore-stimulated cells, it is also different from that of transcription/production, and possibly involves protein kinase C activation.
肥大细胞在引发过敏性炎症中起关键作用，它除了分泌组胺等颗粒介质外，还分泌包括肿瘤坏死因子-α（TNF-α）在内的多种细胞因子。包括氮卓斯汀在内的抗过敏药物通过抑制肥大细胞脱颗粒以及阻断组胺H1受体来预防速发型超敏反应。然而，它们对肥大细胞释放细胞因子的影响尚不清楚。在大鼠肥大RBL-2H3细胞系中，氮卓斯汀抑制抗原和离子霉素诱导的TNF-α释放，其半数抑制浓度（IC50）值分别为25.7±3.4微摩尔/升和1.66±0.45微摩尔/升。这些作用在低于抑制脱颗粒所需的浓度下即可观察到。在抗原刺激的细胞中，氮卓斯汀还抑制TNF-α信使核糖核酸（mRNA）表达、TNF-α蛋白质合成和释放，并且可能与这些作用相关的是，抑制钙离子内流。然而，在离子霉素刺激的细胞中，氮卓斯汀对TNF-α释放的抑制作用比对mRNA表达/蛋白质合成和钙离子内流的抑制作用更大，这表明氮卓斯汀通过干扰钙离子以外的信号，比TNF-α的转录或产生更有效地抑制释放过程。在离子霉素刺激1小时后添加氮卓斯汀也能立即阻断细胞内已产生的TNF-α的后续释放，而不影响钙离子内流。用1微摩尔/升氮卓斯汀预处理可抑制离子霉素诱导的而非抗原诱导的蛋白激酶C转位至细胞膜。这些结果表明，肥大细胞中TNF-α的释放过程受一种不同于脱颗粒的机制调节，并且在钙离子载体刺激的细胞中，它也不同于转录/产生过程，可能涉及蛋白激酶C激活。
