Acute lung injury (ALI) is characterized by diffuse alveolar damage, inflammation, and transmigration and activation of inflammatory cells. This study evaluated if intravenous dexamethasone can influence lung inflammation and apoptosis in lavage-induced ALI. ALI was induced in rabbits by repetitive saline lung lavage (30ml/kg, 9±3-times). Animals were divided into 3 groups: ALI without therapy (ALI), ALI treated with
dexamethasone i.v. (0.5mg/kg, Dexamed; ALI+DEX), and healthy non-ventilated controls (Control). After following 5 h of ventilation, ALI animals were overdosed by anesthetics. Total and differential counts of cells in bronchoalveolar lavage fluid (BAL) were estimated. Lung edema was expressed as wet/dry weight ratio. Concentrations of IL-1ß, IL
-8, esRAGE, S1PR3 in the lung were analyzed by ELISA methods. In right lung, apoptotic cells were evaluated by TUNEL assay and caspase
-3 immunohistochemically. Dexamethasone showed a trend to improve lung functions and histopathological changes, reduced leak of neutrophils (P<0.001) into the lung, decreased concentrations of pro-inflammatory IL
-1β (P<0.05) and marker of lung injury esRAGE (P<0.05), lung edema formation (P<0.05), and lung apoptotic index (P<0.01), but increased
immunoreactivity of caspase-3 in the lung (P<0.001). Considering the action of dexamethasone on respiratory parameters and lung injury, the results indicate potential of this therapy in ALI.
Damage of alveolar-capillary barrier, inflammation, oxidative
injury, and lung cell apoptosis represent the key features of acute
lung injury (ALI). This study evaluated if selective
phosphodiesterase (PDE)-4 inhibitor roflumilast can reduce the
mentioned changes in lavage-induced model of ALI. Rabbits with
ALI were divided into 2 groups: ALI without therapy (A group)
and ALI treated with roflumilast i.v. (1 mg/kg; A+R group). One
group of healthy animals without ALI served as ventilated
controls (C group). All animals were oxygen-ventilated for further
4 h. At the end of experiment, total and differential counts of
cells in bronchoalveolar lavage fluid (BALF) and total and
differential counts of white blood cells were estimated. Lung
edema formation was assessed from determination of protein
content in BALF. Pro-inflammatory cytokines (TNFα, IL-6 and
IL-8) and markers of oxidation (3-nitrotyrosine, thiobarbituricacid reactive substances) were detected in the lung tissue and
plasma. Apoptosis of lung cells was investigated
immunohistochemically. Treatment with roflumilast reduced leak
of cells, particularly of neutrophils, into the lung, decreased
concentrations of cytokines and oxidative products in the lung
and plasma, and reduced lung cell apoptosis and edema
formation. Concluding, PDE4 inhibitor roflumilast showed potent
anti-inflammatory actions in this model of ALI.