Alterations in transcriptional responses associated with vascular aging.

Vascular aging is an independent risk factor for cardiovascular disease that can occur in the absence of other traditional risk factors. Inflammation is a hallmark of vascular aging that ultimately leads to structural changes in the vessel wall including an increase in medial thickness and perivascular fibrosis. Several classes of transcription factors have been identified that participate in the regulation of cellular responses associated with vascular aging. Nuclear factor (NF)-kappaB is the prototypic example of a transcriptional activator in the setting of inflammation, being activated in response to multiple inflammatory mediators including pro-inflammatory cytokines and bacterial endotoxin. In contrast, the activation of the nuclear hormone receptor and transcription factor peroxisome proliferator-activated receptor-alpha (PPAR-alpha) results in its translocation from the cell surface to the nucleus where it exerts anti-inflammatory effects. Vascular aging is also associated with endothelial dysfunction. One important repair mechanism for improving endothelial function is the recruitment of endothelial progenitor cells (EPCs). In the setting of aging the number of EPCs diminishes which has been linked to a decrease in the activity and/or expression of the transcription factor hypoxia inducible factor (HIF)-1 alpha. A change in the balance of the activity of pro-inflammatory transcription factors versus those that inhibit inflammation likely contributes to the process of vascular aging. The purpose of this review is to summarize our current knowledge of these age-related changes in transcriptional responses, and to discuss the therapeutic potential of targeting some of these factors.