IL-5 Up-Regulates Cysteinyl Leukotriene 1 Receptor Expression in HL-60 Cells Differentiated into Eosinophils

Abstract

The cysteinyl leukotrienes, leukotriene (LT) C4, LTD4, and LTE4, are lipid mediators that have been implicated in the pathogenesis of several inflammatory processes, including asthma. The human LTD4 receptor, CysLT1R, was recently cloned and characterized. We had previously shown that HL-60 cells differentiated toward the eosinophilic lineage (HL-60/eos) developed specific functional LTD4 receptors. The present work was undertaken to study the potential modulation of CysLT1R expression in HL-60/eos by IL-5, an important regulator of eosinophil function. Here, we report that IL-5 rapidly up-regulates CysLT1R mRNA expression, with consequently enhanced CysLT1R protein expression and function in HL-60/eos. CysLT1R 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 CysLT1R 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 CysLT1R expression on the cell surface, as assessed by flow cytometry using a polyclonal anti-CysLT1R Ab. They also showed enhanced responsiveness to LTD4, but not to LTB4 or platelet-activating factor, in terms of Ca2+ mobilization, and augmented the chemotactic response to LTD4. Our findings suggest a possible mechanism by which IL-5 can modulate eosinophil functions and particularly their responsiveness to LTD4, and thus contribute to the pathogenesis of asthma and allergic diseases.

Effects of a cysteinyl leukotriene receptor antagonist on eosinophil recruitment in experimental allergic rhinitis

“…5,20 Thus, cysLT1-R antagonism could be predicted to have effects on eosinophil differentiation, maturation and trafficking, as well as playing a role in allergic inflammation by acting upon other cell populations. 3,5,17,21,22 Indeed, our current study, in an experimental murine allergic rhinitis model, demonstrates that in vivo administration of a cys-LT1-R antagonist suppresses eosinophilopoiesis ex vivo in the presence of either IL-5 or GM-CSF, but not IL-3, with effects on indices of both differentiation (numbers of IL-5-responsive Eo ⁄Baso-CFU) and maturation (numbers of mature eosinophils in developing, methylcellulose colonies). Moreover, an in vitro dose-dependent suppression of LTD 4 and IL-5-mediated Eo ⁄Baso CFU formation by ML was observed, consistent with the direct or indirect involvement of cysLT1-R in the down-regulation or suppression of IL-5R ligation on eosinophilopoiesis.…”

“…Previous reports, in which in vitro suppression by a cysLT1-R antagonist of eosinophil differentiation and ⁄or maturation has been shown, include a study of eosinophil lineage commitment of an HL-60 cell line 22 and a recent report from our group on the role of cysLT1-R antagonism in abrogation of LTD 4 -and GM-CSF-induced Eo-Baso-CFU formation by marrow or blood progenitors taken from human asthmatic subjects. 23 Our results, from this murine study, provide the first evidence that administration of cysLT1-R antagonist can cause changes in eosinophil accumulation in vivo, as well as ex vivo effects on eosinophilopoiesis.…”

Up-Regulation of Cysteinyl Leukotriene 1 Receptor by IL-13 Enables Human Lung Fibroblasts to Respond to Leukotriene C4 and Produce Eotaxin

“…Thivierge et al (19) showed that IL-5 upregulates CysLT1R expression and enhances responsiveness to LTD 4 in HL-60 cells. They also reported that IL-13 and IL-4 enhance the expression of CysLT1R in monocytes/macrophages (20).…”

“…The in situ hybridization pattern of CysLT1R in normal human lung is characterized by strict localization to smooth muscle cells (SMC) and some macrophages (18). Thivierge et al (19) showed that Th2 cytokines such as IL-4, IL-5, and IL-13 have a regulatory role in CysLT1R expression in monocytes/macrophages (20) or HL-60 cells.…”

The CysLT1 Ligand Leukotriene D4 Supports α4β1- and α5β1-Mediated Adhesion and Proliferation of CD34+ Hematopoietic Progenitor Cells

“…There is a considerable amount of evidence that points toward interactions between lipid mediators and peptides, and above all between LTs and cytokines, including IL-3. Indeed, IL-3 and other cytokines have been shown to enhance LT production and receptor expression in vitro in various cell types (53,54), including monocytes/macrophages (55) and HL-60 cells differentiated into eosinophils (56). Moreover, treatment of patients with IL-3 leads to an increase in the endogenous LT production (54).…”