1a.Objectives (from AD-416)
The long-term goal of our research is to define the mechanisms by which micronutrients, particularly vitamin A and selected antioxidants, regulate immune function and inflammation. Vitamin A deficiency impairs immune function and increases the risk of disease, while moderate excesses in vitamin A intake may increase the risk of asthma. These risks cannot be adequately assessed without understanding the cellular and molecular mechanisms underlying the actions of vitamin A on immune function. Our specific objective is to define the effects of vitamin A on T-cell development of mice and to determine if men with marginal but 'adequate' vitamin A stores have impaired immune function. An additional goal is to determine how disruption of specific vitamin A receptors (RXR and RAR) affects T cell development. Since recent data indicate that unsaturated fatty acids may act via the RXR pathway the effect of dietary fat on RXR-mediated T cell development may also be investigated. Although many food-derived antioxidants have shown anti-cancer, anti-inflammatory, and anti-atherosclerotic activities, very few detailed studies of their beneficial or detrimental effects on the immune response have been performed. The specific goals here will be to understand how antioxidants found in foods may regulate lymphocyte activities and the immune response in general, and to define appropriate dietary intake levels of foods containing high concentrations of these antioxidants that would contribute to the production of a healthy immune system. Furthermore, the anti-inflammatory activity of these antioxidants will be analyzed to ascertain whether they may be useful in managing chronic inflammatory autoimmune disorders, such as autoimmune diabetes and multiple sclerosis.

1b.Approach (from AD-416)
For the investigation of vitamin A in T-cell development, we will use cellular, molecular, and transgenic animal techniques to conduct these studies in vitro and in vivo using DO11.10 T-cell receptor transgenic mice and mice in which RXR has been disrupted in T cells. For the human studies, we will use stable isotope dilution methods to assess whole body vitamin A stores as well as a variety of immunologic methods to measure the number and function of T cells, B cells, monocytes, neutrophils, and NK cells in the peripheral blood of human volunteers. The human studies will be conducted at the International Centre for Diarrhoeal Disease Research, Bangladesh. To study the effects of antioxidants on immune function, several parameters of the immune response will be evaluated, including lymphocyte subset profiling, regulation of cytokine expression, whether apoptosis or growth arrest is induced, and changes in cytolytic function. Adverse and/or advantageous actions of these antioxidants on the immune system will be analyzed utilizing mice, by using immune cells isolated from the blood of healthy volunteers, and by evaluating immune responses in volunteers who have added defined levels of antioxidants to their diet. Anti-inflammatory activity of food-derived antioxidants in autoimmune diseases, such as type I diabetes and multiples sclerosis, will be initially conducted in non-obese diabetic (NOD) mouse and experimental allergic encephalitis mouse models, respectively, and may lead to future applications in humans with these diseases.

3.Progress Report
No such projects.

4.Accomplishments
Vitamin A and experimental asthma. Asthma has been increasing in incidence in the US and other industrialized countries for several decades. A principal reason for this is thought to be the decreased level of immune stimulation from common childhood infections now experienced in such countries (relative to developing countries and past conditions in the industrialized countries). This decreased stimulation allows an exaggerated response to allergens. However, significant dietary changes have also occurred in the US during the period when asthma has been increasing. Increasing vitamin A intake could cause changes in immune function during early childhood that might also predispose to asthma. Researchers at Davis, CA WHNRC tested this hypothesis in the ovalbumin-induced mouse model of asthma and found that vitamin A deficiency blocked development of asthma symptoms relative to a control diet while high-level dietary vitamin A exacerbated these symptoms. These findings suggest that early childhood “over-nutrition” may have detrimental effects on the risk of chronic, immune-mediated disease. National Program 107, Human Nutrition, Component V:Health Promoting Properties of Plant and Animal Foods. No Problem Statements listed for NP107 Components.

Isolated fractions from strawberries induce cell death in high-risk leukemia. Strawberries contain phytochemicals with anti-cancer activity. Researchers at Davis, CA, WHNRC in collaboration with Dr. Navindra Seeram, UCLA, different components of strawberries were isolated and tested for anti-cancer activity against high-risk leukemia cell lines. We showed that two flavonoid phytochemicals quercetin and kaempferol were effective in killing the leukemia cells. These results show that strawberries contain potent phytochemicals that may be useful in the clinic for prevention of high-risk leukemia. These data address the National Program 107, Human Nutrition, Component V:Health Promoting Properties of Plant and Animal Foods. No Problem Statements listed for NP107 Components.

Carnosol from rosemary interferes with anti-cancer activity of chemotherapeutic drugs. Carnosol is a phytochemical found in the herb rosemary and has shown anti-cancer activity against a number of different cancers, including high-risk leukemia cells. Many phytochemicals can increase the responsiveness of cancer cells to the effects of chemotherapeutic agents used in the clinic. We tested whether carnosol would be useful to increase the effectiveness of three chemotherapeutic drugs used against high-risk infant leukemia. We found that carnosol increased the early events in cell death in combination with these drugs, but delayed the last stages of death. These results show that carnosol interfered with the action of chemotherapeutics and caution will be needed in the clinic when combining drugs with certain plant-derived compounds. These data address the National Program 107, Human Nutrition, Component V:Health Promoting Properties of Plant and Animal Foods. No Problem Statements listed for NP107 Components.

5.Significant Activities that Support Special Target Populations
We are evaluating dietary intake and vitamin D status of infants to determine if a significant risk of deficiency exists in North-Central California. Other studies suggest that African Americans are at significantly increased risk of vitamin D insufficiency and this study should help clarify and address this issue in Sacramento.

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings	2
Number of newspaper articles and other presentations for non-science audiences	4

Review Publications
Stephensen, C.B., Marquis, G.S., Douglas, S.D., Kruzich, L.A., Wilson, C.M. Glutathione, glutathione peroxidase and selenium status in hiv-positive and hiv-negative adolescents. American Journal of Clinical Nutrition. 85:173-181.