in vivo Cardiac Gene Transfer of Dominant Negative IKK-beta Reduces Myocardial Inflammation, Apoptosis, and Infarction after Ischemia-Reperfusion Injury

ABSTRACT

BACKGROUND AND OBJECTIVES: NF-kappaB transcription factors drive the expressions of many genes involved in inflammation and cell survival, which are both important in ischemia-reperfusion (IR) injury. IKK-beta can mediate NF-kappaB activation through the phosphorylation of IkappaB; however, alternative pathways of activation exist. MATERIALS AND METHODS: To test the role of IKK-beta in cardiac IR injury, cardiac gene transfer of dominant negative IKK-beta (dnIKK-beta) was performed in rats 48 hr prior to IR. RESULTS: Adenoviral gene transfer was found to result in regional transgene expression encompassing ~60% of the ischemic area. Ad.dnIKK-beta reduced the IR-induced NF-kappaB translocation and IkappaB-alpha degradation, and blocked induction of the NF-kappaB-dependent inflammatory chemokine, MCP-1, in the ischemic area compared to the Ad.EGFP.beta-gal treated rats (p<0.05). Neutrophil infiltration in the ischemic area (as indicated by myeloperoxidase activity) was decreased by 33% in the Ad.dnIKK-beta treated rats compared to the Ad.EGFP.beta-gal treated rats (p<0.05). Ad.dnIKK-beta also reduced IR-induced apoptosis, as reflected by the attenuated DNA laddering compared to rats injected with either buffer or Ad.EGFP.beta-gal. The ischemic area was not affected by dnIKK-beta expression. However, Ad.dnIKK-beta reduced infarction(%MI) by 57% compared to the Ad.EGFP.beta-gal treated rats (p<0.01). CONCLUSION: Thus, in vivo gene transfer of dnIKK-beta prevents the IR-induced activation of NF-kappaB. In this setting, abrogation of pro-inflammatory signals appears more important than loss of NF-kappaB dependent survival factors, resulting in an overall reduction in apoptosis and infarct size. These data suggest that IKK-beta may represent a valuable target for therapeutic intervention in IR injury.