2006 Annual Report
1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The research falls under the Human Nutrition Program (107) and within Action Plan 220.127.116.11 that addresses a continuing need to expand our understanding of the roles nutrients play in maintaining health and to identify those components of foods that are most beneficial. The research promotes several goals of Action Plan 3.1.1 including:.
1)the need to establish healthful intakes of specific nutrients;.
2)defining interventions for reducing disease risks; and 3)develop effective strategies, based on the results of sound human nutrition research, to lower the cost of health care by prevention of diseases.
A common dietary problem in Westernized societies is functional deficiencies in trace elements and vitamins due to poor eating behavior. There are also harmful environmental conditions that contribute trace mineral pollutants and contaminants that compete with essential trace elements for binding sites on functional proteins. Seventy-six million cases of food-borne illness occur each year in the United States at a cost of $3-7 billion annually, yet it is not clear how important micronutrients and trace elements are in the prevention of disease of the intestinal tract. Basic information on functional deficiencies is best explored through animal models as a vehicle for hypothesis testing of novel strategies and approaches. Mice are an excellent experimental model for testing the role of nutrition on immune function because there is a wide spectrum of reagents for marking and characterizing cells and cell products that regulate immune function, and genetic strains are available or can be created to measure the effect of gene deletions or genetic modifications. Mice will be used as a model to determine how specific nutritional deficiencies in vitamin E (VE) and selenium (Se) affect the intestinal response to inflammation and infection. The overall hypothesis of the proposed studies is that these deficiencies will impair the protective response of the intestine to inflammation or infection orchestrated by distinct cell populations and products that skew the intestinal response towards patterns that are particularly designed to neutralize different classes of pathogens. The hypothesis is that these polarized cytokine profiles induce stereotypic alterations in epithelial and smooth muscle cell function that are a critical part of host defense. The studies will focus on two nutrients, Se and VE, known to influence the oxidative status in the gut, to measure the effect of deficiencies in these nutrients on appropriate immunity to infection and inflammation. This work will provide definitive data on the requirements for antioxidants to provide adequate intestinal function to improve immunity and prevent microbial invasion or expansion. Any dietary considerations derived from this research could be used to define a health-promoting diet that would improve resistance or recovery from intestinal infections, have a broad impact on the large number of people affected by these illnesses, and could result in reduced health care costs.
2.List by year the currently approved milestones (indicators of research progress)
Milestone 1 (1 - 4 years): The research will.
1)determine the effects of type 1 and type 2 cytokine-dependent alterations in colonic function,.
2)determine changes in cytokine and cytokine receptor expression in enteric infection and inflammation, and.
3)determine the effect of induction of type 1 or type 2 cytokines in the colon on responses in the small intestine.
Milestone 2 (1 - 4 years): The research will.
1)determine the effect of VE, Se, and Mg deficiency alone on gut function; and.
2)determine the effect of VE, Se and Mg deficiency, alone, on cytokine expression and receptor distribution.
Milestone 3 (2 - 5 years): The research will.
1)determine the effects VE, Se, or Mg deficiencies on gut function in response to induction of type 1 or type 2 cytokines, and.
2)determine the effect of VE, Se, and Mg deficiency on cytokine expression and receptor distribution in response to induction of type 1 or type 2 cytokines, including physiological alterations that affect the infectious agent and the transport of nutrients across the intestinal surface.
4a.List the single most significant research accomplishment during FY 2006.
Stereotypical changes in intestinal function are dependent on intracellular signaling:
This accomplishment addresses research that falls under the Human Nutrition Program (107) and within Action Plan 18.104.22.168 to expand our understanding of the roles nutrients play in maintaining health and to identify those components of foods that are most beneficial. The use of infectious agents to study the role of immune events that affect non-immune tissues in the intestine has shown stereotypical patterns of gene expression that are regulated by key intracellular transcription factors. Infections that stimulate Th1-linked immune response work through the transcriptional factor Stat4 to change intestinal resistance and muscle hyperthropy, while those that induce Th2-linked response regulate epithelial cell absorption of glucose and secretion of ions, as well as smooth muscle contractility through the transcriptional factor Stat6. The cascade of changes now include expression of the serotonin receptor (5-HT2AR) and the protease activated receptor 1 (PAR-1) that respond to serotonin and protease, respectively. There is also a population of cells that express macrophage markers that are present in the muscle and lamina propria that change the metabolism of arginine and produce either nitric oxide or polyamines that have dramatic downsteam effects on intestinal resistance and muscle hyperplasia. The ability to modify the activity of these cells in the intestine could provide a target to control inflammatory diseases of the bowel and the intensity of responses to dietary allergens.
4b.List other significant research accomplishment(s), if any.
Selenium (Se) and vitamin E (VE) control distinct components of the protective response to intestinal parasitic infection:
This research supports Strategic Plan for Human Nutrition Requirements 22.214.171.124: To develop appropriate animal models that will be used to identify specific biomarkers that are associated with developmental effects or disease prevention. Parasite-infected animals with diets enriched with Se and VE could limit the severity of infection since Se and VE has been shown to control distinct components of the intestinal response to parasitic infection. Optimal performance of intestinal tissue includes adequate absorption of nutrients and prevention of infection by agents that continually challenge the epithelial cell border. Nutritional deficiencies in Se and VE affect the clearance and pathogenicity of RNA viruses and some protozoan parasites. This observation was extended to study the effect of Se and VE deficiency following exposure to more complex worm parasites that represent pathogens that infect over a quarter of the world's population and stimulate host responses that mimic responses to food allergens. The impact of micronutrient deficiencies on gut function should provide information on mechanisms to control infection and disease from multiple sources. The research showed that deficiencies in Se/VE increased the persistence and intensity of infection by delaying worm expulsion; however, only VE deficiency impaired the normal physiological response involved in worm expulsion indicating that Se and VE affected different mechanisms of action. There is a level of interaction and complexity with these two selected micronutrients that suggest unique pathways that are dependent on adequate dietary intake.
Single deficiencies in Se or VE affect intestinal immunity by different mechanisms:
The action of Se and VE appear to affect different components of the response that delays worm expulsion; VE but not Se blocks changes in glucose absorption that typically are reduced during worm expulsion. This affect is not related to altered cytokine gene expression and it suggests that a down stream component of cytokine-induced changes in physiological function is affected. Only the type 2 component of the immune response that initiates worm expulsion in the intestine has been examined. Infection with the gram negative bacteria Citrobacter rodentium has been selected to study modulation of type 1 immune response in the colon. The model has been expanded to cover immune-based alterations in intestinal physiology to both bacterial and worm infections in the gut. These studies are unique and should provide information on dietary changes that enhance intestinal health against a broad range of pathogens.
4c.List significant activities that support special target populations.
This project was approved in March 2004. Initial studies have shown that Se or VE deficiencies affect the local immune and physiological response to worm infection that results in more severe disease intensity. The target of the deficiency is related to changes in nutrient absorption that have not been previously described. Evaluating bacterial infections in the intestine will determine if Se and VE deficiency affects a broad response pattern to intestinal pathogens. Descriptions of several new pathways that alter intestinal metabolism through either Stat4- or Stat6-dependent activation events add a broad category of novel mechanisms that effect intestinal function and that may be susceptible to changes in diet; studies are in place to explore the interaction between diet and immune activation of intestinal function.
5.Describe the major accomplishments to date and their predicted or actual impact.
This research is from previous studies in NRFL that demonstrated that deficiencies in Se or VE increased the virulence of coxsackievirus B3 and influenza infections in somatic tissues, and supports Strategic Plan for Human Nutrition Requirements 126.96.36.199 to develop appropriate animal models that will be used to identify specific biomarkers that are associated with developmental effects or disease prevention.
Molecular analysis of the viruses isolated from the Se or VE deficient mice indicated that specific mutations had occurred within the viral genomes that are associated with the increased virulence. Since both Se and VE are important for the antioxidant defense of the host, it is believed that nutrient deficiency-induced oxidative stress is the driving force behind the rapid evolution of these viruses. This is the first attempt to examine changes in oxidative stress in the intestine against intestinal infections.
It is important to know if nutritionally-induced oxidative stress that has altered viral virulence and pathogenesis will affect other intestinal pathogens, including parasites and microbial pathogens. This could have implications for the appearance of new and more virulent pathogens that are not exclusively viral. The results of this research will provide health-care professionals and the public with information needed to determine if specific nutrients can improve disease resistance and intestinal function, and if the recommendation for adequate nutrient intake will have broad affects on the control of intestinal infection. New patterns that show control over intestinal metabolism and function by specific transcription factors and the description of a novel role for arginine metabolism in smooth muscle contractility and muscle hyperplasia will provide novel targets for the study of dietary changes that can regulate immune and physiological changes in the intestine. Milestones 1, 2, and 3 have been substantial met as the model is currently well defined and suitable for moving towards completion over the next 2 years of the project.
6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
This proposal is related to a research grant entitled "GI Nematode and Gut Functional Responses to Inflammation" with a cooperating scientist at the University of Maryland School of Medicine Mucosal Biology Division that was funded by the National Institutes of Health, TMP Section; period: April 2002 to March 2007.
7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Pesce, J., Kaviratne, M., Ramalingam, T., Thompson, R.W., Urban Jr, J.F., Cheever, A., Young, D., Collins, M., Grusby, M., Wynn, T. 2006. The IL-21 receptor auguments Th2 effector function and alternative macrophage activation. Journal of Clinical Investigation. 116(7):2044-2055.
Liu, Q., Liu, Z., Whitmire, J., Alem, F., Hamed, H., Pesce, J., Urban Jr, J.F., Gause, W. 2006. IL-18 stimulates IL-13 mediated INF-gamma sensitive host resistance in vivo. European Journal of Immunology. 36(5):1187-1198.
Morimoto, M., Morimoto, M., Zhao, A., Madden, K., Dawson, H., Finkleman, F., Mentink-Kane, M., Urban Jr., J.F., Wynn, T., and Shea-Donohue, T. 2006. Functional importance of regional differences in localized gene expression of receptors for IL-13 in murine gut. Journal of Immunology. 176(1):491-495.
Anthony, R.M., Urban Jr, J.F., Alem, F., Hamed, H.A., Boucher, J., Van Rooijen, N., Gauge, W.C. 2006. IL-4-producing memory T cells induce alternatively activated macrophages to mediate protection against nematode parasites. Nature (Medicine). 12(8):955-960.
Zhao, A., Urban, Jr, J.F., Morimoto, M., Elfrey, J., Madden, K., Finkelman, F., Shea-Donohue, T. 2006. Contribution of 5-HT2A receptor in nematode infection-induced murine intestinal smooth muscle hyper contractility. Gastroenterology. 131(2):568-578