Up-Regulation of CysLT2 Receptor Expression and Cysteinyl Leukotrienes-Induced Calcium Signaling By Th2 Cytokines in Human Endothelial Cells

Recently we have shown that the nasal CysLT2 receptor localized exclusively in blood vessels and the expression level of the CysLT2 receptor in patients with nasal allergy was higher than that in patients with non-allergic rhinitis (Shirasaki et al. Allergol Int 2013). We hypothesized that Th2 cytokines could regulate CysLT2 receptor expression and its function in vascular endothelial cells. Human umbilical vein endothelial cells (HUVECs) were stimulated with interleukin (IL) -4 or IL-13 for 48 hours, and the levels of CysLT2 receptor expression were evaluated by western blot analysis. HUVECs in 96-well plates were loaded with Ca2+ indicator Fluo-4, and agonist-induced Ca2+ influx was measured by using fluorescence plate reader. CysLT2 receptor protein was augmented about 2-fold after treatment with IL-4 (10ng/ml) and IL-13 (10ng/ml) at 48 hours of incubation. In non-pretreated HUVECs, any significant changes in intracellular Ca2+ levels were not observed by the stimulation with CysLTs. On the other hand, cellular responses to leukotriene C4 and leukotriene D4 were occurred in Th2 cytokine-pretreated HUVECs. CysLT2 receptor expression in vascular endothelial cells can be regulated by Th2 cytokines at protein level. And Th2 cytokines may activate the functions of vascular CysLT receptors.