This project proposes rodent models to provide molecular, genetic, and functional information to address the effects of nutrient requirements on mucosal immune responses to infectious pathogens, and pig models to provide physiologically relevant comparisons to human allergy and responses to probiotic bacteria. <P>
Common features are the use of targeted gene expression probes to elucidate innate and acquired immunity to both probiotic and pathogenic bacteria that activate Th1 responses, and allergies and worm infections that activate Th2 responses. <P>
The goal is to reveal interactions between dietary micronutrients and food components that modulate immune responses to food allergens, micro and macrobiotic organisms, and their products. <P>
Objective 1: To elucidate the role of vitamin A (VA) on the phenotype and function of alternatively activated macrophages and T regulatory cells, and identify macrophage-mediated modulation of localized nutrient delivery/partitioning in porcine models of allergy. <P>
Objective 2: To elucidate the mechanisms used by probiotic bacteria to improve respiratory and intestinal mucosal responses to allergens, and correlate intestinal microflora composition of pigs and humans with biomarkers of allergic and intestinal disease. <P>
Objective 3: To elucidate the mechanisms by which micronutrients affect gut physiology and immune competence in response to food-borne illness due to viruses, bacteria, and gastrointestinal parasites.
APPROACH: Studies will evaluate if pigs can be sensitized to peanut (PN) allergens by different routes of mucosal exposure without cholera toxin and orally challenge with over-the-counter unsalted dry-roasted PN; if Vitamin A (VA) via all-trans retinoic acid (ATRA) can exacerbate allergic disease via stimulation of Th2 dependent pathways at low doses of antigen; if alternatively activated macrophages (AAM) express retinal and retinol dehydrogenases leading to increased ATRA generation in vitro and in vivo; and if CD209 is a receptor for PN and parasite antigens that mediates functional polarization of AAM accompanied by generation of ATRA. Additional work will test if probiotic bacteria protect against allergy, and if changes in intestinal microflora in children affect the incidence of allergy and intestinal disorders such as chronic diarrhea. Finally, it will be determined if selenium (Se) deficiency impairs AAM function in a helminth-parasite infection model in mice, if chronic Se deficiency or genetic deficiencies in selenoprotein expression in immune cells or intestinal tissue alter immunity and pathology associated with Citrobacter rodentium; and if vitamin A status will alter gastrointestinal immunity to C. rodentium and Heligmosomoides polygyrus in mice.