Effect of Steroids on Interleukin-1beta and Tumor Necrosis Factor-alpha Expression due to High Tidal Volume in the Rat Ventilator-induced Lung Injury Model

ABSTRACT

PURPOSE: Although mechanical ventilation is used to improve oxygenation, this strategy can impose injurious mechanical stress on lung tissue. This is recognized as ventilator-induced lung injury (VILI). Recently, several studies have reported that inflammatory cells and mediators play an important role in the progression of VILI. This study was designed to investigate, in a rat model, the expression of interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha, as well as the anti-inflammatory activity of steroids in VILI. METHODS: Male Sprague-Dawley rats were divided into 3 groups. The control group received low tidal volume (6ml/kg) ventilation. The second group received high tidal volume (25 ml/kg) ventilation and the third group received high tidal volume (25 ml/kg) ventilation with methylprednisolone (30 mg/kg) treatment. After 60 minutes of mechanical ventilation, the animals in each group were sacrificed. Resected lungs were immunostained with antisera for IL-1beta and TNF-alpha. The stained areas were evaluated with an image analyzer. RESULTS: In the groups that received a high tidal volume, the number of positive pixels in IL-1 beta and TNF-alpha was significantly higher than it was in the low tidal volume group. The high tidal volume group showed greater expression of I L - 1beta and TNF-alpha,but this was significantly decreased by methylprednisolone. CONCLUSION: Our study suggests that an inflammatory response related with IL-1beta and TNF-alpha is involved in the development of VILI. The expression of IL-1beta and TNF-alpha was lessened by treatment with methylprednisolone, which might have contributed to improving lung dysfunction after mechanical ventilation.