Inhibition of nuclear factor-κB activation by IRFI 042, protects against endotoxin-induced shock

Abstract Background: The aim of our study was to investigate the effect of IRFI 042, a novel dual vitamin E-like antioxidant, on nuclear factor-κB (NF-κB) activation, TNF-α gene priming and on the release of the mature protein during endotoxin shock. Methods: Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg kg−1 of Salmonella enteritidis lipopolysaccharide (LPS). Survival rate, mean arterial blood pressure, serum TNF-α and plasma malondialdehyde (MAL) levels were investigated. We then evaluated in the liver TNF-α mRNA levels, NF-κB binding activity and the inhibitory protein IκBα. Moreover we studied in LPS stimulated (50 μg ml−1) peritoneal macrophages (Mφ), NF-κB activation, cytoplasmic IκB-α degradation, the message for TNF-α, and TNF-α and MAL levels. Results: LPS administration reduced survival rate (0%, 72 h after LPS administration), decreased mean arterial blood pressure, augmented serum TNF-α (60±11 ng ml−1) and enhanced plasma malondialdehyde (MAL) levels (55±7.1 nmol l−1). LPS shocked rats also had increased TNF-α mRNA levels, augmented liver NF-κB binding activity in the nucleus and decreased levels of the inhibitory protein IκBα. In addition, in vitro LPS stimulation (50 μg ml−1) significantly induced NF-κB activation and cytoplasmic IκBα degradation in Mφ, enhanced TNF-α mRNA levels and increased Mφ TNF-α and MAL. Treatment with IRFI 042 (20 mg kg−1, i.v., 5 min after endotoxin challenge) protected against LPS-induced lethality (90% survival rate 24 h and 80% survival rate 72 h after LPS injection, respectively), reduced hypotension, blunted plasma MAL (9.0±0.9 nmol l−1) and decreased serum TNF-α (15±3 ng ml−1). The antioxidant also inhibited the loss of IκBα protein from the hepatic cytoplasm, blunted the increased NF-κB binding activity in the liver and decreased hepatic liver mRNA for TNF-α. Furthermore 'in vitro' IRFI 042 (50 μM) significantly inhibited activation of NF-κB through inhibition of IκBα degradation, reduced the amount of TNF-α mRNA, decreased LPS-induced TNF-α release and blunted lipid peroxidation (MAL) in LPS stimulated Mφ. Conclusions: These data suggest that IRFI 042 blocks the activation of NF-κB, reduces TNF-α mRNA levels, and finally reverses endotoxic shock.