Location: Diet, Genomics and Immunology Laboratory2018 Annual Report
Objective 1: Determine whether bioactive food components, such as vitamins A and D or lycopene, acting via vitamin A and D-receptor-mediated pathways and nuclear factor-kappaB signaling, exhibit dose-dependent inhibitory effects on macrophage-mediated remodeling of adipose tissue toward a pro-inflammatory phenotype in response to high fat diets in a swine model. [NP 107 Component 3, Problem Statement 3B]. Objective 2: Determine whether bioactives from food, including selenium, vitamin A, and thiol compounds, alter the immune response to model infectious organisms in mice through epigenetic changes, redox sensitive signaling pathways, and tissue remodeling by controlling cellular thiol levels, redox tone, and/or mitochondrial function. Compare responses of wild-type and genetically engineered mice with altered expression of one or more selenoproteins or proteins important for vitamin A or redox function, to identify specific proteins or pathways important for the effect of the nutrients under study on immune function and tissue remodeling. [NP 107 Component 3, Problem Statement 3B]
For Objective 1, in vitro and in vivo porcine models will be used to test the hypothesis that vitamin A or vitamin D or metabolites of dietary compounds that signal through retinoic acid receptor signaling pathways, such as lycopene, will promote an anti-inflammatory phenotype of adipose tissue macrophages and inhibit pro-inflammatory responses of adipose tissue macrophages to inflammatory ligands via inhibition of NF-kappaB signaling and epigenetic regulation of macrophage polarization. For Objective 2, a mouse model will be used to test the hypothesis that bioactives from food, including selenium, vitamin A, and thiol compounds, alter the immune response to model infectious organisms in mice through epigenetic changes, redox-sensitive signaling pathways, and tissue remodeling by controlling cellular thiol levels, redox tone, and/or mitochondrial function. Responses of wild-type and genetically engineered mice with altered expression of one or more selenoproteins or proteins important for vitamin A or redox function, will be used to identify specific proteins or pathways important for the effect of the nutrients under study on immune function and tissue remodeling.
A molecular marker of both pig and human anti-inflammatory cells is activated by metabolites of vitamin A. The most bioactive vitamin A metabolite, all-trans retinoic acid (ATRA), potentiated genes induced by the a signaling molecule called IL-4 to activate a macrophage cell (M2a) that has anti-inflammatory properties. These responses are necessary to maintain immune homeostasis and limit inflammation. We have recently demonstrated that the pig M2a and human THP-1 cells respond to both IL-4 and ATRA to produce an important enzyme called transglutaminase 2 (TGM2) that is a marker for both pig and human cells. In addition, the combination of ATRA and IL-4 synergistically increased a protein called IL1RN that binds to certain cell receptors and inhibits the action of selective proinflammatory proteins. These experiments suggest novel ways to inhibit or enhance inflammatory responses mediated by cells that regulate the appropriate control of inflammation in pigs and humans. Tools were developed to better characterize the genome of pigs. A correct and annotated genome is essential for high throughput methods of gene and protein analysis, as well as to compare genes from animals used to model humans. ARS scientists at the Beltsville Human Nutrition Center, Beltsville Maryland previously demonstrated the utility of our manual annotation process to identify errors and improve the annotation of an early version of the porcine genome. Version 11.1 of the porcine genome was recently released and we have now applied the same tools to 2,800 targeted genes in the latest version (11.1) of the pig genome and found that many errors exist in gene assembly and annotation. For example, only half of the gene sequences were correctly assembled and annotated, and a small but significant number of genes were not represented in the genome. Chief among these were genes in the interleukin 1 family which express proteins critical to controlling inflammation. We have continued assembling a non-redundant library of manually verified RNA (11,250) and protein (8,677) sequences and intend to continue this work in conjunction with our domestic and international partners. Similarities and differences were found in nutritional-related genes in mice, pigs and humans to improve modeling. ARS scientists at the Beltsville Human Nutrition Center, Beltsville, Maryland have recently published 4 comparative analyses focusing on the comparative aspects of pig, mouse and human genes and proteins involved in immunity and inflammation (the immunome). Genes between humans and pigs were generally similar, but several were unique to humans and mice. The analysis was extended to genes and proteins involved in nutrition and metabolism with a focus on questions related to the nutritional regulation of physiology of the mouse, pig and human. Are these genes 1) in specific pathways, 2) structurally and functionally similar, 3) expressed in similar cell types, and 4) regulated in a similar manner to stimuli? Pigs had roughly 4-fold less unique genes than mice or humans. When a gene is missing from one or more genomes, the frequency and similarity of gene preservation between pigs and humans is overwhelmingly similar. Notably, physiological differences such as the lack of porcine salivary lipase and amylase activities is likely related to the absence of these genes in the porcine genome. This analysis suggests that evaluating nutrition interventions in pigs will provide useful data to bridge the gaps found in using mice as nutritional models for humans. Studies were performed to determine if the knock out (KO) of selenoproteins in specific cell types mimicked the effect of feeding a selenium deficient diet using our two infectious disease models. Deleting selenoproteins in one immune cell type (macrophages, dendritic cells, or lymphocytes) did not replicate what is observed in mice fed a selenium-deficient diet and infected with bacteria. A lack of an effect was also observed in worm-infected mice with selenoproteins deleted in macrophages or dendritic cells, but preliminary results indicate that the deletion of selenoproteins in lymphocytes may have an effect on worm clearance. Of note, it has not been possible to successfully generate KO of selenoproteins in intestinal epithelial cells by crossing TRSP floxed mice (KO of all selenoproteins) or GPX4 floxed mice (KO of only GPX4). Only mice with one allele KO for TRSP or GPX4 are produced and will be tested further. Diets deficient in vitamin A (VA) produced statistically significant changes in bacterial populations in the fecal microbiome. A more in-depth analysis of the data is underway. Bacterial infection of VA deficient mice express increased pathology, bacterial load, delayed clearance, and enlarged goblet cells with greater amounts of mucus, and higher levels of tissue associated bacteria. Studies using labels for sugar motifs on glycoproteins in mucus showed alterations in the types of mucus produced by VA deficient mice. In addition, the hosts of genes associated with mucus production and goblet cell function were down-regulated by VA deficiency. This is important in understanding how diet deficiencies effect the health of the intestine. Pomegranate peel extract (POM) reduced the pathogenicity of an intestinal bacterial infection. ARS scientists from the Environmental Microbial and Food Safety (EMFSL), Invasive Insect Biocontrol and Behavior Laboratory (IIBBL) and Beltsville Human Nutrition Center, Beltsville, Maryland tested the effect of POM on infectious colitis. The results demonstrate that POM reduced colonic pathology, development of a systemic bacterial infection, mortality, colonic mucosa damage and bacterial translocation. It does not alter peak bacterial load, clearance, or the immune response to infection indicating that the health effect is on intestinal barrier function that may be related to expression of the Ang4 gene. In addition, POM treatment decreased the loss of goblet cells and mucin production, which likely ablates the severity of the infection. Dietary supplements improve glucose tolerance and reduce bacterial infection. ARS scientists at the Beltsville Human Nutrition Center, Beltsville, Maryland and colleague at the University of Maryland-Baltimore Medical School treated mice with a genetic and high-fat diet induced obesity with an immune protein called IL-25. There was decreased weight gain and improved glucose tolerance in both genetic and diet-induced obesity in mice given IL-25. In another study, the effects of feeding indole 3-carbinol mice with a bacterial infection was studied and showed to ameliorate the pathological effects of infection. This work demonstrates the utility of mouse models of metabolic and infectious disease to screen for bioactive components that can improve health.
1. Feeding probiotic reduced allergenic responses to worm infection. Infection in livestock such as the pig continues to be a problem for our food system, safety of food products and impacts human health. ARS scientists at the Beltsville Human Nutrition Center, Beltsville, Maryland, seek to elucidate beneficial effects of probiotics in feed to overcome infection in the pig. The effects of feeding the probiotic Bifidobacterium animalis subspecies lactis (Bb12) on parasitic nematode Ascaris suum infection in the pig were examined. Parasite-protective antibody responses in the serum and intestinal fluid were found to be significantly increased, and an inflammatory cell population in the small intestine was inhibited in infected pigs fed Bb12 without affecting the normal expulsion of the worm. The expression of genes associated worm-protective responses was enhanced along with certain anti-inflammatory genes after feeding Bb12 to worm infected pigs. Thus, feeding a probiotic can improve intestinal function during a worm infection by reducing components of a strong allergenic response without compromising normal worm expulsion and may benefit healthy livestock production.
2. Infection protective cells in the intestine are activated in response to diet and changes in gut microbiome. Tuft cells in the intestine are known to act as sentinels for infectious agents [e.g., helminths (worms) and bacterial microbiota] and express taste-signaling elements. In this work, the G protein-coupled receptor Sucnr1 was shown to be expressed specifically in tuft cells, but not in other intestinal epithelial cells. Dietary succinate and perturbations in the microbiota activate tuft cells, and subsequently type 2 immunity, via tuft cell-expressed Sucnr1. Modulating this pathway using dietary succinate or specific Sucnr1 agonists may be a strategy for fighting bacterial and parasitic infections or other type 2 immune-related metabolic disorders such as obesity.
3. Novel strategy for prevention of allergic airway inflammation identified using genetic deficient mice. Allergy and allergic asthma are significant health burdens and sound strategy to prevent these diseases are necessary. ARS scientists at the Beltsville Human Nutrition Center, Beltsville, Maryland, and colleagues at the Virginia Commonwealth University, Richmond, Virginia characterized a mouse strain with a conditional deficiency in the gene A disintegrin and metalloproteinase (ADAM) 10, and used the strain to understand the role of ADAM10 on selected immune cells during the development of allergic and anaphylactic responses. ADAM10 was found to be important in the immune response. This study provides science-based information to support that targeting ADAM10 represents a novel strategy for modulating allergic airway inflammation in the pathogenesis of allergy and allergic asthma.
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Damie, S.R., Martin, R.K., Cockburn, C.L., Lownik, J.C., Carlyon, J.A., Smith, A.D., Conrad, D.H. 2017. ADAM10 and Notch1 on murine dendritic cells control the development of type 2 immunity and IgE production. Allergy. 148(4):542-551. https://doi.org//101111/a11.13261.
Lei, W., Ren, W., Ohmoto, M., Urban Jr, J.F., Matsumoto, I., Margolskee, R.F., Jiang, P. 2018. Activation of intestinal tuft cell-expressed Sucnr1 triggers type 2 immunity in the mouse small intestine. Proceedings of the National Academy of Sciences. (21):5552-5557. https://doi.org/10.1073/pnas.1720758115.
Lorentsen, K., Cho, J., Luo, X., Zuniga, A., Urban Jr, J.F., Zhou, L., Gharaibeh, R., Jobin, C., Kladde, M., Avram, D. 2018. Bcl11b is essential for licensing Th2 differentiation during helminth infection and allergic asthma. Nature Communications. 9(1)1679. https://doi.org/10.1038/s41467-018-04111-0.
Martin, R.K., Damle, S.R., Zellner, M.P., James, B.N., Valentine, Y.A., Elkowich, A.J., Lownik, J.C., Demeules, M.M., Khandjian, L.M., Urban Jr, J.F., Conrad, D.H. 2018. B1 cell IgE impedes mast cell-mediated enhancement of parasite expulsion through B2 IgE blockade. Cell Reports. 22(7):1824-1834. https://doi.org/10.1016/j.celrep.2018.01.048.
Huang, Y., Mao, K., Chen, X., Sun, M., Kawabe, T., Li, W., Usher, N., Zhu, J., Urban Jr, J.F., Paul, W.E., Germain, R.N. 2018. S1P dependent inter organ trafficking of group 2 innate lymphoid cells supports host defense. Science. 359:114–119. https://doi.org/10.1126/science.aam5809.