2011 Annual Report
1a.Objectives (from AD-416)
1. Identify bioactive food components and food patterns that inhibit
atherosclerosis and angiogenesis using cell culture, animal models and human subjects under the following sub-objectives:
a) Determine bioavailability of avenanthramides from oats and characterize their
potency and molecular mechanism of inhibition of vascular smooth muscle cell
proliferation using cell culture systems and the femoral artery injury mouse model.
b) Elucidate the molecular mechanism of catechins and curcumin and other dietary
bioactive compounds on the inhibition of angiogenesis associated with adipose tissue growth and obesity.
c) Determine the comparative bioavailability and biopotency of tocopherols versus
tocopheryl phosphate on the inhibition of femoral artery injury model of vascular
atherosclerosis and restenosis.
2. Determine the anti-inflammatory and anti-proliferative effects of avenanthramides of oats and derivatives on several colonic cancer cells lines and mouse models of inflammatory bowel disease and colon cancer.
1b.Approach (from AD-416)
The main objective of this project plan is to determine bioavailability, potency and mechanism of action of several bioactive food components, including avenanthramides(Avns) of oats, curcumin of turmeric, catechins of green tea and isomers of tocopherol in the prevention of atherosclerosis and angiogenesis as they relate to CVD, obesity and cancer. Specifically, we will determine bioavailability of Avns from oats and characterize their potency and mechanism of inhibition of vascular smooth muscle cell proliferation using cell culture and the femoral artery injury mouse model. Further, we will investigate the anti-inflammatory and antiproliferative effects of Avns of oats and derivatives on several cancer cells lines and mouse models of inflammatory bowel disease and colon cancer. We will also elucidate the molecular mechanism of catechins and curcumin and other dietary bioactive compounds on the inhibition of angiogenesis associated with adiposity and obesity. We also plan to investigate the comparative biopotency of' alpha-tocopherol (alpha-T) versus alpha-tocopheryl phosphate (alpha-TP) on the inhibition inflammatory cytokines and monocyte adhesion in cell culture systems and on comparative bioavailability and efficacy of alpha-T vs. alpha-TP on femoral artery injury model of atherosclerosis.
The progress described below is related to problem statements NP107- 2A Identify Roles of Food, Nutrients, Food Components, and Physical Activity in Promoting Health and Preventing Disease and 3B Develop and Evaluate Strategies to Prevent Obesity and Related Diseases.
We have further investigated the biological activity of curcumin, a bioactive component of turmeric spice, both in vitro and in vivo. We investigated whether curcumin can modulate the accumulation of lipids in monocytes/macrophages. We found that curcumin increased the expression of two lipid transport genes (CD36/FAT and the FABP4/aP2), leading to increased lipid levels in macrophage-like cells. Curcumin increased the expression of FOXO3a (a transcription factor centrally involved in regulating several stress resistance and lipid transport genes)-mediated gene by 2-fold, possibly by its translocation from nucleous. Thus, the up-regulation of FOXO3a by curcumin could be a mechanism to protect against oxidant- and lipid-induced damage in the inflammatory cells of the vascular system. Curcumin derivative, (tetrahydrocurcumin ,THC), with similar antioxidant activity as curcumin, had no effects indicating that the impact of curcumin is mediated through a non-antioxidant activity. In contrast to the in vitro results, dietary curcumin reduced lipid levels and aP2 expression in peritoneal macrophages in LDL receptor knockout (LDLr-/-) mice fed a high fat diet for 4 mo, suggesting that additional regulatory mechanisms are involved in its in vivo effect. We also observed that in LDL-/- mice curcumin prevented high fat diet induced atherosclerosis, in part through inhibition aP2 and CD36 in macrophages, which is a necessary step in foam cell formation and atherogenesis. Furthermore, curcumin suppressed accumulation of fat in liver, thus it may prevent disorders associated with fatty liver such as liver cancer.
Fallowing determination of the bioavailability of alpha TP to monocytes in blood circulation, we investigated its cellular effects and molecular mechanisms in human THP-1 monocytes. Our data suggest that alpha TP may bind to CD36, a receptor on macrophages for lipid uptake, trigger its internalization, leading to inactivation. Our gene array analysis showed that more genes are regulated by alpha TP than by alpha T. Among these genes, the expression of the vascular endothelial growth factor (VEGF) and production of reactive oxygen species (ROS) by ¿alpha TP were observed to be mediated through phosphorylation and activation of sets of genes that are involved in cell proliferation. These effects of alpha TP were attenuated by alphaT. It is concluded that alpha TP and alpha T influence cell proliferation, ROS production in an antagonistic manner. In addition, in preadipocytes and adipocytes cell lines derived from mice¿alpha TP activated several genes with a regulatory role in nutrient metabolism and glucose and lipid homeostasis important for diabetes, obesity and the metabolic syndrome. These findings demonstrate for the first time that vitamin E may impact diabetes and metabolic syndrome through a novel mechanism, which might not be related to its antioxidant capacity.
Natural vitamin E analogue, alph-tocopheryl phosphate (alpha-TP), modulates inflammation associated with atherosclerosis more efficiently than alpha-tocopherol (alpha-T). ARS-funded researchers at JMUSDA-HNRCA at Tufts University, Boston, MA, showed that alpha-TP, a natural bioactive form of vitamin E (alpha-Tocopherol) modulates inflammatory processes associated with atherosclerosis more efficiently than alpha-T through non-antioxidant activity. Alpha-TP may bind to a cell surface receptor (CD36) and/or trigger its internalization, resulting in its inactivation. Their gene array analysis showed that alpha-TP stimulate production of protein called vascular endothelial growth factor that stimulate formation of new blood vessels (angiogenesis), which may promote wound healing and blood perfusion following ischemia. Their observations have indicated that increasing alpha-TP status, the natural bioactive analogue of vitamin E may be beneficial for promotion of health where inflammation and angiogenesis are the major players.
Curcumin, bioactive component of turmeric spice inhibits obesity and atherogenesis. Obesity and associated disorders including cardiovascular disease (CVD) are prevalent in US. ARS-funded researchers at JMUSDA-HNRCA at Tufts University, Boston, MA, continued further investigation of curcumin, the bioactive component of turmeric spice for its biological activity within the context of, obesity, atherosclerosis and angiogenesis. They demonstrated, in an animal model fed high fat diet, that curcumin can prevent body weight gain, adiposity, atherosclerosis, and fatty liver formation. They further showed that curcumin exerts this effect through several mechanisms, including: up-regulating basal metabolism and burning body fat, and by suppressing growth of new blood vessels (angiogenesis) in fat tissue, which is needed for fat tissue growth and expansion. In addition, curcumin may prevent development of CVD by suppressing atherogenesis as observed in mouse model of human atherosclerosis. They have elucidated these important health effects of curcumin on obesity and CVD by investigating its mechanisms of effect at cellular and molecular levels. These findings provide a platform to translate their findings to humans.