Differentiation-dependent responsiveness of bronchial epithelial cells to IL-4/13 stimulation.
The Th2 cytokines interleukin (IL)-4 and IL-13 are thought to play critical roles in the airway inflammation and hyperresponsiveness that characterize asthma. Recent evidence indicates that IL-13 can mediate these effects by acting directly on airway epithelial cells. Here we evaluated early [signal transducer and activator of transcription (STAT)6 phosphorylation] and delayed [granulocyte/macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-beta(2) (TGF-beta(2)) secretion] responses of airway epithelial cells to IL-4 and IL-13 stimulation and the dependence of these responses on the culture technique employed. As expected, normal human bronchial epithelial cells grown on microporous inserts at an air-liquid interface (ALI) expressed a well-differentiated mucociliary phenotype; in contrast, cells grown on plastic in submerged cultures were poorly differentiated. When stimulated with IL-4 or IL-13, the magnitude and duration of STAT6 phosphorylation under the differing culture conditions were statistically indistinguishable. In contrast, cytokine secretion responses to IL-4 and IL-13 were highly dependent on the culture technique; cells cultured on plastic exhibited significant concentration-dependent increases in GM-CSF and TGF-beta(2) secretion, whereas cells grown at ALI showed no statistically significant response. These results demonstrate that the coupling between early signal transduction responses to IL-4 and IL-13 and downstream functions such as cytokine secretion may be critically dependent on the cell culture technique employed and the resulting differentiation status of bronchial epithelial cells.
Kikuchi
Tadashi
T
Pulmonary and Critical Care Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Shively
Jonathan D
JD
Foley
John S
JS
Drazen
Jeffrey M
JM
Tschumperlin
Daniel J
DJ
D001980:Bronchi / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D010766:Phosphorylation; D050800:STAT6 Transcription Factor; D013194:Staining and Labeling; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000096:biosynthesis; D053781:Transforming Growth Factor beta2
D018793:Interleukin-13; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; C509041:TGFB2 protein, human; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor