ObjectiveSepsis is a major cause of adult respiratory distress syndrome. In this study, we evaluated the effect of FR167653, which is a potent suppressant of tumor necrosis factor (TNF)-&agr; and interleukin (IL)-1 production, on lipopolysaccharide (LPS)-induced lung injury and lethality in rats, and we examined the involvement of p38 mitogen-activated protein (MAP) kinase in the action of FR167653.DesignProspective, randomized study.SettingAnimal research facility in a university.SubjectsMale Sprague-Dawley rats weighing 200–270 g.InterventionsAll the animals were assigned to one of the following four groups: control group, FR-only group, LPS-only group, and LPS/FR group. Animals in the LPS-only and LPS/FR groups received 6 mg/kg of LPS intravenously. The animals in the FR-only and LPS/FR groups also received an infusion of FR167653 at 0.2 mg·kg−1·hr−1, commencing 30 mins before the LPS (or vehicle) injection and continuing for 5.5 hrs.Measurements and Main ResultsLPS significantly induced the accumulation of pulmonary neutrophils and lung edema, both of which were significantly attenuated by treatment with FR167653. FR167653 also significantly decreased the LPS-induced lethality. Histologically, tissue damage was milder in the LPS/FR group than in the LPS-only group. Serum concentrations of TNF-&agr; and IL-1&bgr; and plasma concentrations of thromboxane B2were all suppressed in the LPS/FR group compared with the LPS-only group. Western blot analysis revealed that FR167653 inhibited the phosphorylation of p38 MAP kinase in lung tissues.ConclusionsFR167653 administration decreased serum TNF-&agr; and IL-1&bgr; concentrations, which was associated with decreased lung injury and lethality. The mechanism responsible for the decreased TNF-&agr; and IL-1 may be related to the inhibitory effect of FR167653 on p38 MAP kinase activation.