Thivierge M, Doty M, Johnson J, Stanková J, Rola-Pleszczynski M
Department of Pediatrics, Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Canada.
J Immunol. 2000 Nov 1;165(9):5221-6. doi: 10.4049/jimmunol.165.9.5221.
The cysteinyl leukotrienes, leukotriene (LT) C(4), LTD(4), and LTE(4), are lipid mediators that have been implicated in the pathogenesis of several inflammatory processes, including asthma. The human LTD(4) receptor, CysLT(1)R, was recently cloned and characterized. We had previously shown that HL-60 cells differentiated toward the eosinophilic lineage (HL-60/eos) developed specific functional LTD(4) receptors. The present work was undertaken to study the potential modulation of CysLT(1)R expression in HL-60/eos by IL-5, an important regulator of eosinophil function. Here, we report that IL-5 rapidly up-regulates CysLT(1)R mRNA expression, with consequently enhanced CysLT(1)R protein expression and function in HL-60/eos. CysLT(1)R mRNA expression was augmented 2- to 15-fold following treatment with IL-5 (1-20 ng/ml). The effect was seen after 2 h, was maximal by 4 h, and maintained at 8 h. Although CysLT(1)R mRNA was constitutively expressed in undifferentiated HL-60 cells, its expression was not modulated by IL-5 in the absence of differentiation. Differentiated HL-60/eos cells pretreated with IL-5 (10 ng/ml) for 24 h showed enhanced CysLT(1)R expression on the cell surface, as assessed by flow cytometry using a polyclonal anti-CysLT(1)R Ab. They also showed enhanced responsiveness to LTD(4), but not to LTB(4) or platelet-activating factor, in terms of Ca(2+) mobilization, and augmented the chemotactic response to LTD(4). Our findings suggest a possible mechanism by which IL-5 can modulate eosinophil functions and particularly their responsiveness to LTD(4), and thus contribute to the pathogenesis of asthma and allergic diseases.
半胱氨酰白三烯，即白三烯（LT）C4、LTD4和LTE4，是脂质介质，与包括哮喘在内的多种炎症过程的发病机制有关。人LTD4受体CysLT1R最近已被克隆并鉴定。我们之前已经表明，向嗜酸性粒细胞谱系分化的HL-60细胞（HL-60/eos）会产生特异性功能性LTD4受体。目前的工作旨在研究嗜酸性粒细胞功能的重要调节因子白细胞介素-5（IL-5）对HL-60/eos中CysLT1R表达的潜在调节作用。在此，我们报告IL-5能迅速上调CysLT1R mRNA的表达，从而增强HL-60/eos中CysLT1R蛋白的表达及功能。用IL-5（1 - 20 ng/ml）处理后，CysLT1R mRNA的表达增加了2至15倍。该效应在2小时后出现，4小时时达到最大值，并在8小时时维持。虽然CysLT1R mRNA在未分化的HL-60细胞中组成性表达，但在未分化状态下其表达不受IL-5的调节。用IL-5（10 ng/ml）预处理24小时的分化HL-60/eos细胞，通过使用多克隆抗CysLT1R抗体的流式细胞术评估，显示细胞表面CysLT1R表达增强。就钙离子动员而言，它们对LTD4的反应性也增强，但对LTB4或血小板活化因子无反应，并且对LTD4的趋化反应增强。我们的研究结果提示了一种可能的机制，通过该机制IL-5可以调节嗜酸性粒细胞的功能，特别是它们对LTD4的反应性，从而促进哮喘和过敏性疾病的发病机制。
