Oxidative stress is characterized by excessive concentrations of reactive oxygen and reactive nitrogen species (ROS and RNS). Excessive oxidative damage has been implicated in the pathogenesis of numerous degenerative diseases including coronary vascular diseases (CVD). A current hypothesis suggests that ROS, RNS and oxidized LDL (ox-LDL) induce the expression of atherogenic genes via redox-sensitive signaling pathways. The oxidative stress-induced gene expression has been shown to be mediated via the activation of redox sensitive transcription factors such as nuclear factor- kappaBeta (NFkB), and redox-sensitive transduction pathways such as those involving members of the mitogen activated protein kinase (MAPK) family as well as members of the Src family. Genes regulated by NFkB activation encode for proteins implicated in acute phase and inflammatory responses including certain cytokines and chemokines, cell adhesion molecules and inflammatory enzymes; several of these molecules are involved in the pathogenesis of atherosclerosis. Similarly, studies have shown that JNK, BMK-1 and cSrc are involved in signaling events stimulated by ROS that contribute to atherosclerosis such as smooth muscle cell proliferation. It is well known that diet plays a important role in a large number of chronic diseases. The investigators suggest that this is due in part to an effect of diet on a individual's antioxidant status. Vitamins and minerals contribute to the oxidative defense system because: (1) they are antioxidants (vitamins E, C and B-carotene); (2) they are essential for the function of enzyme antioxidants (Zn, Cu, Fe, Mn, Se and riboflavin); or (3) they act to maintain low levels of potentially pro-oxidant molecules (vitamins B12, B6 and folate). On the other hand, the cardio-protective effects of flavonoids result in part from their antioxidant properties, and their ability to modulate the activity of a wide spectrum of enzymes. The researchers propose to investigate the hypothesis that diet may influence vascular redox-mediated signaling and transcriptional activities. Using the mouse model, they will test the hypothesis that a diet marginal in select micronutrients will induce a pro-oxidative state that will worsen the pathophysiological state of atherosclerosis. Finally, they will test the hypothesis that addition of flavonoids to diets marginal in antioxidants will attenuate the atherogenic effect of the pro-oxidative effect of micronutrient deficiency and hypercholesterolemia. These issues will be addressed using mutant mice in which the LDL receptor (LDLr) has been inactivated. The researchers will measure the progression of atherosclerosis in LDLr +/+ and -/- mice fed a high fat-micronutrient adequate diet, or a high fat-micronutrient marginal diet, supplemented or not with the flavonoids, quercetin and catechin. They will use biochemical markers and immunohistochemistry to evaluate antioxidant capacity and redox status in the LDLr mice, and correlate these with the severity of atherosclerosis determined by lesion progression and atherogenic gene expression. Finally, they will examine the effects of the diets on the activation of NFkB and cell signaling pathways.
