Changes in transforming growth factor-beta mRNA expressionin the lung in a dog model of cardiopulmonary bypass-induced acute lung injury

Abstract

Objective To observe the changes in the transforming growth factor-beta 1 (TGF-β1 ) mRNA expression in the lung in a dog model of cardiopulmonary bypass(CPB)-induced acute lung injury. Methods Thirty-six healthy adult mongrel dogs of both sexes weighing 15-16 kg were randomly assigned into control group and CPB group ( n = 18 each) . Lung injury was produced by CPB according to the method described by Williams. Six animals were killed at each of the following time points: before CPB (T0 ) and 30 and 60 min after termination of CPB (T1 , T2) in each group. Lung specimens were obtained for microscopic examination and determination of TGF-β1 mRNA expression (by RT-PCR) and MDA content. The lungs were lavaged and the protein concentration in the brancho-alveolar lavage fluid (BALF) was determined and pulmonary permeability index (PPI) was calculated. Results Microscopic examination showed massive inflammatory cell infiltration, alveolar capillary dilatation, congestion, widened alveolar septum, massive RBC in the alveolar space and focal atelectasis in the lung in CPB group. The TGF-β1 mRNA expression and MDA content and PPI were significantly higher in CPB group than in control group. The TGF-β1 mRNA expression and MDA was positively correlated to PPI (MDA: r = 0.867, P < 0.01; PPI: r = 0.821, P < 0.01) . Conclusion TGF-β1 mRNA expression in the lung is significantly up-regulated after CPB and is an important factor contributing to CPB-induced acute lung injury. Key words: Transforming growth factor beta; Cardiopulmonary bypass; Respiratory distress syndrome,adult