In the rat model of
lung injury induced by
oleic acid (OA), we studied the effect of
corticosteroid therapy on
pulmonary inflammation and compliance at acute (1 day post OA) and recovery (3 and 7 days post OA) stages.
Methylprednisolone (MP) and
dexamethasone (DM) were examined for therapeutic benefit in this model. Histologic examination, lung compliance, and analysis of bronchoalveolar lavage (BAL) fluid were used to assess
lung injury. Our results demonstrated that, at 1 day post OA, both
steroids effectively reduced
pulmonary inflammation and restored lung compliance when compared to animals that received only OA. In comparison to
DM, MP was more effective in inhibiting the
pulmonary inflammation induced by OA, but was less effective in restoring lung compliance. However, at 3 and 7 days post OA, cell and/or
protein levels in BAL fluid from both MP- and DM-treated OA animals were significantly higher than levels observed in animals that received only OA. Lung compliance returned to normal by 3 days in animals that received only OA. This effect, however, was blocked in OA animals that were treated with either
steroid, MP, or DM. Our data suggest that
steroid therapy can be beneficial in the acute stage of OA-induced
lung injury, but appears to be detrimental during the early recovery stage, perhaps by inhibiting the repair process.