Epidemiological and experimental studies have implicated that
diesel exhaust particles are involved in increases in morbidity and mortality from
lung diseases. Recently, we have demonstrated that
rosmarinic acid, a polyphenolic liquid component in perilla, inhibits
lung inflammation induced by
diesel exhaust particles in vivo, partly through its antioxidative property. We have also shown the antioxidative activities of volatile constituents of rosemary extract, the gaseous component in perilla, in vitro. The purpose of this study was to evaluate the effects of intratracheal administration of volatile rosemary extract on
lung inflammation induced by
diesel exhaust particles. ICR mice were treated with intratracheal administration of volatile rosemary extract before intratracheal exposure to
diesel exhaust particles. Twenty-four hr later,
diesel exhaust particles exposure elicited
lung inflammation characterized by the infiltration of neutrophils and eosinophils, which was confirmed by cellular profile of bronchoalveolar lavage fluid and histological examination.
Diesel exhaust particles enhanced the
protein expressions of
interleukin-1beta, macrophage inflammatory protein-1alpha, macrophage
chemoattractant protein-1, and keratinocyte
chemoattractant in the lung. Pretreatment with rosemary extract significantly inhibited the
diesel exhaust particles-induced
lung inflammation. Rosemary extract treatment also suppressed the
diesel exhaust particles-enhanced lung expression of macrophage inflammatory protein-1alpha, macrophage
chemoattractant protein-1, and keratinocyte
chemoattractant. These results suggest that intratracheal administration of rosemary extract can prevent
lung inflammation induced by
diesel exhaust particles. The preventive effect is mediated, at least partly, through the inhibition of the enhanced lung expressions of macrophage inflammatory protein-1alpha, macrophage
chemoattractant protein-1, and keratinocyte
chemoattractants.