Phosphorylated Stat-6 levels in human nasal epithelial (HNE) cells in acute and controlled asthmatic children

IL-4 and IL-13 signaling via IL-4Rα is a critical pathway in Th-2 mediated disease states such as asthma. The subsequent phosphorylation of Stat-6 is specific for transcription and gene expression induced by these cytokines. HNE cells were selected as a proxy for respiratory epithelium and activated Stat-6 levels were measured and evaluated as a biomarker of asthma. HNE samples were collected via cytobrush sampling of the inferior turbinate from three groups: controlled asthmatic children, children with an asthma exacerbation through the emergency department, and normal healthy children who were skin test negative to common aeroallergens. Cells were incubated with and without IL-4 (20 ng/ml), fixed and permeabilized. A monoclonal antibody specific for phosphorylated Stat-6 site was used to detect the presence of activated Stat-6 by flow cytometry. The percentage change with IL-4 stimulation, corrected for isotype control, was compared between groups via t-test. No significant difference between all asthma (n=45) and normals (n=9) was found (p=.97). The difference between controlled asthma (n=23) +1.4% and acute asthma (n=22) +6.1% was not statistically significant (p=0.24) but trended towards a larger percentage change in acute asthma. Although not statistically significant, slightly higher levels of phosphorylated Stat-6 were observed in acute asthma versus controlled asthma. This method of measuring a critical signaling molecule in a disease state warrants additional study. Furthermore, this data suggests that activated Stat-6 may have potential as a biomarker in the acute phase of asthma.