Stat-3 is required for pulmonary homeostasis during hyperoxia

Abstract

Acute lung injury syndromes remain common causes of morbidity and mortality in adults and children. Cellular and physiologic mechanisms maintaining pulmonary homeostasis during lung injury remain poorly understood. In the present study, the Stat-3 gene was selectively deleted in respiratory epithelial cells by conditional expression of Cre-recombinase under control of the surfactant protein C gene promoter. Cell-selective deletion of Stat-3 in respiratory epithelial cells did not alter prenatal lung morphogenesis or postnatal lung function. However, exposure of adult Stat-3-deleted mice to 95% oxygen caused a more rapidly progressive lung injury associated with alveolar capillary leak and acute respiratory distress. Epithelial cell injury and inflammatory responses were increased in the Stat-3-deleted mice. Surfactant proteins and lipids were decreased or absent in alveolar lavage material. Intratracheal treatment with exogenous surfactant protein B improved survival and lung histology in Stat-3-deleted mice during hyperoxia. Expression of Stat-3 in respiratory epithelial cells is not required for lung formation, but plays a critical role in maintenance of surfactant homeostasis and lung function during oxygen injury. 29Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remain a common cause of morbidity and mortality in both infants and adults following infection, trauma, inhalation of toxicants, and drowning. The recent severe acute respiratory syndrome (SARS) outbreak emphasizes the severity of pulmonary outcomes associated with ALI (7). ARDS is associated with surfactant deficiency and dysfunction (8, 9), including abnormalities in surfactant lipids and proteins. Of the surfactant proteins, SP-B is required for maintenance of lung function in both newborn and postnatal periods (10, 11) and for adaptation to lung injury following infection or oxygen exposure. To assess the role of STAT-3 in lung function, we used a conditional system to express Cre-recombinase to selectively delete the Stat-3 gene in bronchiolar and alveolar epithelial cells of the mouse lung. MethodsGene construction and PCR. We generated SP-C-rtTA tg/-transgenic mice and (tetO) 7 CMV-Cre tg/tg or (tetO) 7 CMVCre tg/-mice as described previously (12, 13 -C-rtTA, (tetO) 7 CMV-Cre and Stat-3 flx genes using the primers 5′-GAC ACA TAT AAG ACC CTG GCTA-3′ and 5′-AAA ATC TTG CCA GCT TTC CC-3′ for SP-C-rtTA; 5′-TGC CAC CAA GTG ACA GCA ATG-3′ and 5′-AGA GAC GGA AAT CCA TCG CTCG-3′ for (tetO) 7 CMV-Cre; and 5′-CCT GAA GAC CAA GTT CAT CTG TGT GAC-3′ and 5′-CAC ACA AGC CAT CAA ACT CTG GTC TCC-3′ for Stat-3 flx . Triple transgenic (Stat-3 ∆/∆ ) and nondeleted littermate (Stat-3 flx/flx ) control mice were used for the experiments.Animal use and doxycycline administration. Transgenic Stat-3 ∆/∆ and control mice were kept in a pathogen-free vivarium according to institutional guidelines until oxygen exposure. Doxycycline was administered to the dams in the food at a concentration of 625 mg/kg (Harlan Teklad, Madison, Wisconsin, U...

GP130-STAT3 Regulates Epithelial Cell Migration and Is Required for Repair of the Bronchiolar Epithelium

“…Whereas GP130-STAT3 signaling regulates diverse aspects of acquired innate defense, for example, T-cell proliferation and B-cell differentiation, 11,46 GP130-STAT3 also regulates many airway epithelial cell processes, including surfactant homeostasis, cell survival, and apoptosis. 16,17 In the present study, we show that the GP130-STAT3 signaling functions in a cell-autonomous manner and plays a critical role in the repair of airway epithelium, influencing epithelial cell migration, density, and shape.…”

“…[13][14][15] Whereas pulmonary epithelial deletion of Stat3 did not perturb lung morphogenesis or postnatal lung function in the mouse, STAT3 was required for maintenance of alveolar function, surfactant homeostasis, and cell survival following hyperoxic and adenoviral infection-related alveolar injury. 16,17 To assess the potential role of STAT3 and GP130 in repair of the bronchiolar epithelium, we produced mice in which the genes were selectively deleted from respiratory epithelial cells in vivo. Cell migration and restoration of cuboidal-columnar cell shape following injury were dependent on STAT3 signaling in respiratory epithelial cells.…”

Stat3 regulates genes common to both wound healing and cancer

“…Tissue-specific Stat3 gene deletion mouse models have also defined an important role of Stat3 in tissue injury and wound healing in epithelial cells of the lung and skin (Sano et al, 1999;Gao et al, 2004;Hokuto et al, 2004;Severgnini et al, 2004). In lung epithelial cells, Stat3 is activated in acute lung injury and loss of Stat3 compromises survival following hyperoxia (Gao et al, 2004;Hokuto et al, 2004;Severgnini et al, 2004).…”

“…Stat3 is activated in lung tissues following either lipopolysaccharide (LPS) exposure or intrapulmonary deposition of IgG immune complexes (Gao et al, 2004;Severgnini et al, 2004). Selective Stat3 deletion in lung epithelial cells does not compromise postnatal lung function but mice exposed to hyperoxia develop rapid lung injury characterized by alveolar capillary leak and acute respiratory distress (Hokuto et al, 2004). Similary, selective loss of Stat3 in keratinocytes results in impaired wound healing and defects in keratinocyte migration (Sano et al, 1999).…”

Hyperoxia-induced signal transduction pathways in pulmonary epithelial cells☆

“…Transgenic mice, with the STAT3 gene selectively deleted in respiratory epithelial cell, exhibited significantly greater epithelial cell injury, inflammatory responses and mortality compared to the wildtype mice [99,100]. Heme oxygenase-1 (HO-1) is a cytoprotective enzyme and is highly inducible following exposure to hyperoxia and over-expression of HO-1 in pulmonary epithelial cells has been shown to protect animals and cells against oxygen toxicity [101].…”