We have reported previously that components of
diesel exhaust particles (
DEP) differently affect
acute lung injury related to
lipopolysaccharide (LPS) in mice. This study examined the effects of components of
DEP on the lung expression of
cyclooxygenase (COX)-1 and -2 in the presence or absence of LPS. ICR mice were divided into six experimental groups that received vehicle, LPS (2.5 mg kg(-1)),
organic chemicals in
DEP (
DEP-OC) extracted with
dichloromethane (4 mg kg(-1)), residual carbonaceous nuclei after the extraction (washed
DEP: 4 mg kg(-1)),
DEP-OC (4 mg kg(-1)) + LPS (2.5 mg kg(-1)) or washed
DEP (4 mg kg(-1)) + LPS (2.5 mg kg(-1)) intratracheally. The expression of
mRNA for both COXs in the lung was evaluated 4 h after the intratracheal administration. The magnitude of COX-1
mRNA expression was not altered in each group. The LPS treatment enhanced the COX-2 gene expression compared with vehicle treatment. Washed
DEP combined with LPS further increased its expression compared with LPS alone. In contrast, combined treatment of
DEP-OC with LPS decreased COX-2 gene expression compared with LPS alone. These results suggest that the residual carbonaceous nuclei of
DEP predominantly enhance lung expression of COX-2 rather than the extracted
organic chemicals from
DEP in the presence of LPS, which is concomitant with the magnitude of
acute lung injury in our previous study.