[Effect of budesonide on Clara cell secretory protein and its mRNA expression in a rat model of asthma].

OBJECTIVE

To investigate the effect of inhaled glucocorticoids on the expression of Clara cell secretory protein (CCSP) and its mRNA in lung tissue of a rat model of asthma.

METHODS

The rat asthmatic model was established by sensitizing and challenging SD rats with aerosolized ovalbumin (OVA). Rats were divided into a control, an asthmatic and a glucocorticoid groups. Budesonide aerosol was delivered by a jet nebulizer. The CCSP mRNA level in the lung tissue and the CCSP level in bronchoalveolar lavage fluid (BALF) were determined by RT-PCR and dot immuno-blotting, respectively.

RESULTS

The level of CCSP mRNA in the lung tissue was 0.65 +/- 0.04 in the control, 0.56 +/- 0.05 in the asthmatic and 0.63 +/- 0.04 in the glucocorticoid groups, respectively (asthma versus control, P < 0.01; glucocorticoid versus asthma, P < 0.05). The CCSP level in BALF was 60 +/- 5 in the control, 49 +/- 5 in the asthmatic and 57 +/- 5 in the glucocorticoid groups, respectively (asthma versus control, P < 0.01; glucocorticoid versus asthma, P < 0.05). Budesonide reduced the percentage of eosinophils in BALF and inhibited airway inflammation.

CONCLUSIONS

OVA challenge in the rat model decreased CCSP mRNA, resulting in a reduction in CCSP production, which may contribute to asthmatic airway inflammation. Inhaled glucocorticoids increased the expression of CCSP mRNA in lung tissue, which may be a mechanism for the suppression of airway inflammation by glucocorticoids.