2008 Annual Report
1a.Objectives (from AD-416)
1) To identify the mechanisms of local type 1 and type 2
cytokine-dependent alterations in gut function in the colon and in
unaffected areas in the small intestine..
2) Determine the impact of
specific nutritional deficiencies alone (Vitamin E and Selenium) on
baseline levels of cytokines and cytokine receptor expression and on gut
3)Determine the impact of specific nutritional deficiencies
(Vitamin E and Selenium) on immune-induced alterations in gut function.
1b.Approach (from AD-416)
Experiments will compare responses in Wild Type mice or mice deficient in
the signaling factors Stat4 or Stat6 after treatment with agents known to
elevate Th1 (inflammation using trinitrobenzene sulfonic acid) or Th2
cytokines (enteric helminth infection). Specific nutritional deficiencies
that impact these responses and affect gut function will be examined;
treatment groups will include.
and Se deficient diet). Molecular (real time RT-PCR) will be used to
determine diet-induced alterations in cytokine profiles and histological
evaluation will be performed to identify modifications in infiltrating
cells as a result of the diet deficiencies. Laser capture microscopy
(LCM) will be used to localize cytokine receptors to specific cell types
including epithelial mucosa, smooth muscle and nerves. Preliminary data
indicate that diets deficient in both VE and Se impair the ability of the
intestine to clear enteric nematodes and affect intestinal function.
Function is defined as changes in epithelial cell secretion and
absorption in vitro (Epithelial cell transport in Ussing chambers) and
smooth muscle contraction in vitro (Isometric smooth muscle contraction).
Evaluation of histological changes and assessment of cytokine and
cytokine receptor expression will be determined routinely using LCM and
tissue cytokines using RT-PCR.
Models of natural parasitic infection of the intestinal tract of mammals are useful to understand the mechanisms that link immunity to intestinal function since the parasite host model is an evolutionary adaptation to control the intensity of inflammation to the benefit of the host. External provocation of the intestine triggers immunity, and the response is orchestrated by the nature of the provocateur (in this case, a parasite). Parasite infection induces a patterned response that is physiologically and immunologically similar to that activated by food allergens, while chemical inducers of inflammation such as tri-nitrobenzene sulfulfuric acid (TNBS) induce a patterned response more like that resulting from bacterial and viral infections. These systems were studied to evaluate actions of the host cytokines and cytokine receptors (compounds involved in immune response) that regulate immune activity against the provocateur, but also engage non-immune physiological pathways in the intestine that influence nutrient absorption and smooth muscle contractility (the predominant muscle-type found in the intestine). The importance of the model is that it demonstrates the interplay of various external stimulators (provocateurs) within a more generalized inflammatory response that can interfere with normal intestinal function if not corrected. The work supports the National Program for Human Nutrition-107 Action Plan Component 6, Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle and Component 7, Health Promoting Intervention Strategies for Targeted Populations.
Parasite-induced interleukin (IL)-13 influences the development of alternatively activated macrophages in the intestine that alter smooth muscle function. The role of macrophages has been largely assigned to functions that destroy intracellular pathogens and regulate the presentation of antigens to lymphocytes that generate acquired immunity to pathogens. The results from studies conducted this year demonstrate that the functional expression pattern of macrophages is dependent on the type of infectious agent and that these cells can interact with non-immune systems like the smooth muscle of the intestine to regulate muscle contractility patterns and control the level of tissue inflammation. Part of the induction and development of this patterned response is through the induction of IL-13, which is a cytokine or protein hormone with receptors that activate functional responses in many different cell and tissue types. It is characteristically induced by parasitic infection, but also by conditions that convert food proteins into activators of allergic disease. The impact of the work is that a component of the response of the macrophage is determined by the metabolism of arginine through either nitric oxide synthase or arginase-1 (two enzymes involved in arginine synthesis), and the metabolites are directly involved in the regulation of smooth muscle function. This mechanism has not been systematically examined and points to a strategy to control responses to parasitic infection and similar changes induced by food allergens. The work supports the National Program for Human Nutrition-107 Action Plan Component 6, Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle and Component 7, Health Promoting Intervention Strategies for Targeted Populations.
5.Significant Activities that Support Special Target Populations
|Number of Non-Peer Reviewed Presentations and Proceedings||3|
Zhao, A., Urban Jr, J.F., Anthony, R.M., Sun, R., Stiltz, J., van Rooijen, N., Wynn, T.A., Gause, W.C., Shea-Donohue, T. 2008. Th2 cytokine-induced alterations in intestinal smooth muscle function depend on alternatively activated macrophages. Gastroenterology. 135(1):217-225.
Noland, G.S., Urban Jr, J.F., Fried, B., Kumar, N. 2008. Counter-regulatory anti-parasite cytokine responses during concurrent Plasmodium yoelii and intestinal helminth infections in mice. Parasite Immunology. 119(2):272-278.
Sutton, T.L., Zhao, A., Madden, K.B., Elfrey, J.E., Tuft, B.A., Sullivan, C.A., Urban Jr, J.F., Shea-Donohue, T. 2008. Anti-inflammatory mechanisms of enteric Heligmosomoides polygyrus infection on TNBS-induced colitis in a murine model. Infection and Immunity 76(10):4772-82.
Liu, Q., Liu, Z., Whitmire, J., Hossein, A., Vannoy, J., Urban Jr, J.F., Gause, W.C. 2007. The role of B cells in the development of CD4 effector T cells during a polarized TH2 immune response. Journal of Immunology. 179(6):3821-30.
Ramalingam, T.R., Pesce, J.T., Sheikh, F., Cheever, A.W., Mentink-Kane, M.M, Wilson, M.S., Stevens, S., Valenzuela, D.M., Murphy, A.J., Yancopoulos,G.D., Urban Jr, J.F., Donnelly, R.P.,Wynn, T.A. 2008. Unique functions of the type-II interleukin 4 receptor identified in mice lacking the interleukin 13 receptor alpha 1 chain. Nature Immunology. (1):25-33.