Dexamethasone inhibits ozone‐induced gene expression of macrophage inflammatory protein‐2 in rat lung

To address the potential role of the chemokine macrophage inflammatory protein‐2 (MIP‐2) in airway inflammation, we examined whether MIP‐2 may play a role in ozone‐induced neutrophilic inflammation of airways and its modulation by dexamethasone in rat lung. Following ozone exposure, MIP‐2 mRNA expression in the lung peaked at 2 h after exposure and slowly declined thereafter. Dexamethasone suppressed ozone‐induced MIP‐2 mRNA expression and neutrophil accumulation in the lung. We suggest that the MIP‐2 mRNA induction may switch on the neutrophilic influx observed in this model of lung inflammation. Furthermore, the MIP‐2 expression is regulated by dexamethasone which may represent one of the mechanisms by which glucocorticoids exert their potent anti‐inflammatory properties.