Carbon Monoxide Protects against Ventilator-induced Lung Injury via PPAR-γ and Inhibition of Egr-1

• Published in: American journal of respiratory and critical care medicine Vol. 177; no. 11; pp. 1223 - 1232
• Main Authors: HOETZEL, Alexander, DOLINAY, Tamas, CHOI, Augustine M. K, VALLBRACHT, Simone, YINGZE ZHANG, HONG PYO KIM, IFEDIGBO, Emeka, ALBER, Sean, MURAT KAYNAR, A, SCHMIDT, Rene, RYTER, Stefan W
• Format: Journal Article
• Language: English
• Published: New York, NY American Lung Association 01.06.2008; American Thoracic Society
• Subjects: Airway Resistance - physiology; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Antimetabolites - therapeutic use; Biological and medical sciences; Blood Pressure - physiology; Carbon Monoxide - therapeutic use; D. Critical Care; Disease Models, Animal; Early Growth Response Protein 1 - physiology; Emergency and intensive respiratory care; Intensive care medicine; Male; Medical sciences; Mice; Mice, Inbred C57BL; Neutrophil Infiltration - physiology; PPAR gamma - physiology; Respiration, Artificial - adverse effects; Respiratory Distress Syndrome - etiology; Respiratory Distress Syndrome - metabolism; Respiratory Distress Syndrome - prevention & control; early growth response-1; Lung disease; Ventilator; Intensive care; Respiratory disease; peroxysome proliferator-activated receptor-γ; Inflammation; Carbon monoxide; ventilator-induced lung injury; Resuscitation
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200708-1265OC

Ventilator-induced lung injury (VILI) leads to an unacceptably high mortality. In this regard, the antiinflammatory properties of inhaled carbon monoxide (CO) may provide a therapeutic option. This study explores the mechanisms of CO-dependent protection in a mouse model of VILI. Mice were ventilated (12 ml/kg, 1-8 h) with air in the absence or presence of CO (250 ppm). Airway pressures, blood pressure, and blood gases were monitored. Lung tissue was analyzed for inflammation, injury, and gene expression. Bronchoalveolar lavage fluid was analyzed for protein, cell and neutrophil counts, and cytokines. Mechanical ventilation caused significant lung injury reflected by increases in protein concentration, total cell and neutrophil counts in the bronchoalveolar lavage fluid, as well as the induction of heme oxygenase-1 and heat shock protein-70 in lung tissue. In contrast, CO application prevented lung injury during ventilation, inhibited stress-gene up-regulation, and decreased lung neutrophil infiltration. These effects were preceded by the inhibition of ventilation-induced cytokine and chemokine production. Furthermore, CO prevented the early ventilation-dependent up-regulation of early growth response-1 (Egr-1). Egr-1-deficient mice did not sustain lung injury after ventilation, relative to wild-type mice, suggesting that Egr-1 acts as a key proinflammatory regulator in VILI. Moreover, inhibition of peroxysome proliferator-activated receptor (PPAR)-gamma, an antiinflammatory nuclear regulator, by GW9662 abolished the protective effects of CO. Mechanical ventilation causes profound lung injury and inflammatory responses. CO treatment conferred protection in this model dependent on PPAR-gamma and inhibition of Egr-1.