Migration to draining lymph nodes is a critical requirement for dendritic cells (DCs) to control T-cell–mediated immunity. The calcium-activated potassium channel KCa3.1 has been shown to be involved in regulating cell migration in multiple cell types. In this study, KCa3.1 expression and its functional role in lung DC migration were examined. Fluorescence-labeled antigen was intranasally delivered into mouse lungs to label lung Ag-carrying DCs. Lung CD11chighCD11blow and CD11clowCD11bhigh DCs from PBS-treated and ovalbumin (OVA)-sensitized mice were sorted using MACS and FACS. Indo-1 and DiBAC4(3) were used to measure intracellular Ca2+ and membrane potential, respectively. The mRNA expression of KCa3.1 was examined using real-time PCR. Expression of KCa3.1 protein and CCR7 was measured using flow cytometry. Migration of two lung DC subsets to lymphatic chemokines was examined using TransWell in the absence or presence of the KCa3.1 blocker TRAM-34. OVA sensitization up-regulated mRNA and protein expression of KCa3.1 in lung DCs, with a greater response by the CD11chighCD11blow than CD11clowCD11bhigh DCs. Although KCa3.1 expression in Ag-carrying DCs was higher than that in non–Ag-carrying DCs in OVA-sensitized mice, the difference was not as prominent. However, Ag-carrying lung DCs expressed significantly higher CCR7 than non–Ag-carrying DCs. CCL19, CCL21, and KCa3.1 activator 1-EBIO induced an increase in intracellular calcium in both DC subsets. In addition, 1-EBIO–induced calcium increase was suppressed by TRAM-34. In vitro blockade of KCa3.1 with TRAM-34 impaired CCL19/CCL21-induced transmigration. In conclusion, KCa3.1 expression in lung DCs is up-regulated by OVA sensitization in both lung DC subsets, and KCa3.1 is involved in lung DC migration to lymphatic chemokines.

Angiopoietin (Ang)1 and Ang2 are ligands for Tie2 tyrosine kinase receptor (Tie2). Elevated levels of Ang1 and Ang2 in induced sputum of patients with asthma have been reported, with a positive correlation of Ang2 levels with the severity of airway occlusion. Although studies have shown Tie2-mediated regulation of nonvascular cells in some pathological conditions, current knowledge on Tie2 signaling in asthma is limited to the vasculature. We examined the expression pattern of Ang1, Ang2, vascular endothelial growth factor (VEGF), and Tie2 and their correlation with the degree of airway remodeling in the lung of ovalbumin (OVA)-sensitized and OVA-challenged mice with airway hyperresponsiveness. Lung tissues were isolated from Balb/c mice after OVA sensitization and challenge. Hematoxylin and eosin, periodic acid-Schiff, and trichrome staining were used to show the lung pathology. The expression of Ang1, Ang2, VEGF, and Tie2 was examined using immunofluorescence, Western blot, ELISA, and real-time PCR. In the lung of normal mice, Tie2 expression was detected only in the blood vessels. However, in the lung of OVA-sensitized and OVA-challenged mice, Tie2 was abundantly expressed in airway epithelial cells and in a subset of macrophages in addition to constitutive expression in pulmonary vessels. The increase in Tie2 expression correlated with the severity of airway remodeling. Macrophages and airway epithelial cells express Ang2 and VEGF only in allergic models. Ang1 was constitutively expressed, with a decrease in mRNA level in allergic models. In conclusion, increased expression of Tie2 and Ang2 in allergic airway epithelium and alveolar macrophages correlates with the severity of airway remodeling.