IRFI 042, a novel dual vitamin E-like antioxidant, inhibits activation of nuclear factor-kappa B and reduces the inflammatory response in myocardial ischaemia-reperfusion injury

Background: Nuclear factor-kappa B (NF-kappa B) is a ubiquitous rapid respo nse transcription factor involved in inflammatory reactions which exerts it s effect by expressing cytokines, chemokines, and cell adhesion molecules. Oxidative stress causes NF-kappa B activation. IRFI 042 is a novel dual vit amin E-like antioxidant and we, therefore, investigated its ability to prot ect the heart from oxidative stress and to halt the inflammatory response i n a model of myocardial ischaemia-reperfusion injury. Methods: Anaesthetize d rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5-h reperfusion (MI/R). Sham myocardial ischaemia rats (sham-operated rats) were used as controls. Myocardial necrosis, cardiac ou tput, cardiac and plasma vitamin E levels, myocardial malondialdehyde (MAL) , cardiac SOD activity and elastase content (an index of leukocyte infiltra tion), hydroxyl radical (OH .) formation, cardiac amount of mRNA codifying for ICAM-1 (evaluated by the means of reverse transcriptase polymerase chai n reaction) and ICAM-1 immunostaining in the at-risk myocardium were invest igated. NF-kappa B activation and the inhibitory protein of NF-kappa B, I-k appa B alpha, were also studied in at-risk myocardium by using electrophore tic mobility shift assay (EMSA) and Western blot analysis, respectively. Re sults: The ischaemia-reperfusion model produced wide heart necrosis (area a t risk-necrotic area=52+/-5%; necrotic area-left ventricle=28+/-3%), increa sed cardiac MAL, an index of lipid peroxidation (area at risk=62.5+/-3.9 nm ol/g tissue; necrotic area=80.3+/-5.1 nmol/g tissue), induced tissue neutro phil infiltration, and caused a marked decrease in endogenous antioxidants. Furthermore, myocardial ischaemia plus reperfusion caused in the area at r isk peak message for ICAM-1 at 3 h of reperfusion and increased cardiac ICA M-1 immunostaining at 5 h of reperfusion. NF-kappa B activation was also ev ident at 0.5 h of reperfusion and reached its maximum at 2 h of reperfusion . I-kappa B alpha was markedly decreased at 45 min of occlusion; peak reduc tion was observed at 1 h of reperfusion and thereafter it was gradually res tored. Intraperitoneal administration of IRFI 042 (5, 10, 20 mg/kg, 5 min a fter reperfusion) reduced myocardial necrosis expressed as a percentage eit her of the area at risk (18+/-4%) or the total left ventricle (11+/-2%), an d improved cardiac output. This treatment also limited membrane lipid perox idation in the area at risk (MAL=14.3+/-2.5 nmol/g tissue) and in the necro tic area (MAL=26.5+/-3.7 nmol/g tissue), restored the endogenous antioxidan ts vitamin E and superoxide dismutase, and inhibited detrimental hydroxyl r adical formation. Finally, IRFI 042 blocked the activation of NF-kappa B, r educed cardiac ICAM-1 expression, and blunted tissue elastase content, an i ndex of leukocytes accumulation at the site of injury. Conclusions: Our dat a suggest that IRFI 042 is cardioprotective during myocardial infarction by limiting reperfusion-induced oxidative stress and by halting the inflammat ory response. (C) 2000 Elsevier Science B.V. All rights reserved.