BACKGROUND: Sepsis is a potentially fatal syndrome mediated by an early [e.g., tumor necrosis factor-alpha (TNF-α)] and late [high mobility group box-1 (HMGB-1)] proinflammatory cytokine response to infection. Sepsis-induced acute kidney injury (AKI) is associated with a high mortality. C-Fos/activator protein-1 (AP-1) controls the transactivation of proinflammatory cytokines via AP-1 binding in the promoter region. T-5224 is a de novo small molecule inhibitor of c-Fos/AP-1 that controls gene expression of multiple proinflammatory cytokines. We investigated whether T-5224, a selective inhibitor of c-Fos/AP-1, improves survival in lethal lipopolysaccharide (LPS)-induced AKI by inhibiting early (TNF-α) and late (HMGB-1) proinflammatory cytokine response. METHODS: Mice were divided into four groups (control, LPS, LPS + T-5224, and T-5224 only). Control mice were administered polyvinylpyrrolidone (PVP) solution orally, immediately after intraperitoneal (i.p.) saline injection. LPS mice were administered PVP solution orally immediately after i.p. LPS (10 mg/kg) injection. LPS + T-5224 mice were administered T-5224 orally (300 mg/kg) immediately after i.p. LPS injection. T-5224 mice were administered T-5224 orally (300 mg/kg) after i.p. saline injection. Serum concentrations of TNF-α, HMBG-1, and interleukin (IL)-10 were measured by enzyme-linked immunosorbent assay (ELISA). Serum blood urea nitrogen (BUN) and creatinine concentrations were commercially analyzed. Finally, histological examination was performed on the kidney. RESULTS: Treatment with T-5224 decreased serum TNF-α and HMGB-1 levels and increased survival after LPS injection. Furthermore, T-5224 treatment decreased serum BUN and creatinine concentrations but increased serum IL-10 concentration. LPS-induced pathological changes in kidney were attenuated by T-5224 treatment. CONCLUSIONS: These results suggest that T-5224, a selective inhibitor of c-Fos/AP-1, inhibits expression of early and late proinflammatory cytokines, protecting mice from LPS-induced lethality. T-5224 is a potential approach for decreasing lethality in sepsis-induced AKI.