OBJECTIVETo study the expression of heme oxygenase-1 (HO-1) gene and protein and the effect of budesonide (BUD) on the HO-1 expression in lung tissues in rats with asthma.

METHODSFifty male Sprague-Dawley rats were randomly divided into 5 groups: normal control, asthma model, dexamethasone (DXM)-, hemin (HO-1 challenger)-or BUD-treated asthma. The asthma model was prepared by ovalbumin sensitization and challenge. The rats were sacrificed 24 hrs after the last challenge. The blood COHb content,and the total cell count and the percentage of differential cells in bronchoalveolar lavage fluid (BALF) were measured. The expression of HO-1 protein and mRNA in lung tissues was detected with immunohistochemistry and RT-PCR, respectively. The airway inflammation situations were evaluated by histopathology.

RESULTSThe airway inflammatory cell infiltration in the DXM-, hemin- and BUD-treated asthma groups was remarkably alleviated compared with that in the asthma model group. Compared with the normal control group, the expression of HO-1 mRNA and protein in lung tissues and the blood COHb content in the asthma model and the DXM-, hemin- and BUD-treated asthma groups were significantly up-regulated. The DXM-, hemin- and BUD-treated asthma groups showed significantly increased expression of HO-1 protein and mRNA in lung tissues compared with the asthma model group. The blood COHb content in the DXM-and the hemin-treated asthma groups was significantly higher than that in the asthma model group.

CONCLUSIONSThe expression of HO-1 protein and mRNA in lung tissues and blood HO-1 activity increased in rats with asthma,suggesting that HO-1 may be involved in the pathogenesis of asthma. HO-1 may have a protective effect against the airway inflammation in asthmatic rats. BUD and DXM can up-regulate the expression of HO-1 protein and mRNA, thus providing protective effects against the airway inflammation in asthmatic rats.