Genome expression profiling and network analysis of nitrite therapy during chronic ischemia: possible mechanisms and interesting molecules

Sodium nitrite is widely recognized to be a highly effective NO donor for the treatment of several ischemic tissue disorders. However, mechanisms by which nitrite confers cytoprotection during ischemic disorders remain largely unknown. In this study, we used genome expression profiling approaches to evaluate changes in gene expression in the hind-limb ischemia model using vehicle or sodium nitrite therapy. Sodium nitrite significantly restored ischemic tissue perfusion by day 3 post-ligation which returned to normal by day 7. Genesifter analysis of Affymetrix GeneChip data revealed a significant down-regulation of gene expression profiles at day 3, whereas gene expression profiles were predominantly up-regulated at day 7. Ingenuity network analysis of gene expression profiles at day 3 showed a strong decrease in gene expression from networks associated with immune functions such as acute inflammatory responses, antigen presentation, and humoral immune responses while networks containing increased gene expression profiles were associated with cardiovascular, skeletal, and muscle system development and function. Network analysis of day 7 gene array data revealed predominant up-regulation of genes associated with cell survival, tissue morphology, connective tissue function, skeletal and muscular system development, and lymphoid tissue structure and development. These data suggest that sodium nitrite elicits potent anti-inflammatory and pro-angiogenic gene responses at early time points which is later followed by up-regulation of genes associated with tissue repair and homeostasis.