T-bet is induced by interferon-γ to mediate chemokine secretion and migration in human airway smooth muscle cells

Singer CA. T-bet is induced by interferon-gamma to mediate chemokine secretion and migration in human airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 300: L633-L641, 2011. First published January 14, 2011; doi: 10.1152/ajplung.00163.2010.-An inappropriate balance between T-helper (Th)1 and Th2 cytokine production underlies inflammatory changes that result in airway disease. Expression of the T-box transcription factor T-bet regulates differentiation of Th cells and production of Th1 cytokines, particularly IFN gamma. T-bet-deficient mice develop airway hyperreactivity, undergo airway remodeling, and exhibit defects in IFN gamma production while overproducing Th2 cytokines. T-bet is also reduced in the airways of asthmatic patients, suggesting loss of T-bet expression or activity promotes development of inflammatory airway disease. We present novel data demonstrating T-bet expression is induced in human airway smooth muscle cells (ASMC) by IFN gamma. This IFN gamma-stimulated expression of T-bet is dependent on signaling through JAK2 and signal transducers and activators of transcription 1 (STAT1) and activates T-bet-dependent DNA binding activity. Expression of T-bet stimulates IFN gamma-stimulated IFN gamma expression, secretion, and promoter activity, while inhibiting IFN gamma-stimulated release of chemokines including monocyte chemoattractant protein (MCP)-1/CCL2, regulated on activation normal T-expressed and secreted (RANTES)/CCL5, and eotaxin/CCL11. This is accompanied by changes in expression of the chemokine receptors CCR3 and IL12R beta 2 and TNF alpha. T-bet expression also reduces chemotactic migration of ASMC in response to serum and PDGF, which contributes to airway hyperplasia. These results are the first to identify T-bet expression and activity in a structural cell of the lung and may provide new insights into therapeutic targets for inflammatory airway disease.