Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Impact of β-Galactomannan on health status and immune function in rats LeeAnn Schalinske Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Allergy and Immunology Commons, Human and Clinical Nutrition Commons, Immunology and Infectious Disease Commons, and the Medical Immunology Commons Recommended Citation Schalinske, LeeAnn, "Impact of β-Galactomannan on health status and immune function in rats" (2015). Graduate Theses and Dissertations. 14508. https://lib.dr.iastate.edu/etd/14508 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Impact of β-Galactomannan on health status and immune function in rats by LeeAnn Schalinske A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Nutritional Sciences Program of Study Committee: Michael Spurlock, Major Professor Douglas Jones Marian Kohut Matthew Rowling Iowa State University Ames, Iowa 2015 Copyright © LeeAnn Schalinske, 2015. All rights reserved. ii TABLE OF CONTENTS Page LIST OF FIGURES ....................................................................................... iv LIST OF TABLES ......................................................................................... v NOMENCLATURE ....................................................................................... vi ACKNOWLEDGEMENTS ............................................................................. viii ABSTRACT………………………………. ...................................................... ix CHAPTER 1 LITERATURE REVIEW ........................................................ 1 Introduction to Gut Immunology……………………………………… .. 1 Gastrointestinal Architecture…………………………………….. ........ 1 Dendritic Cells……………………………………………………. ......... 3 Regulatory T-cells………………………………………………… ........ 6 The development of immune tolerance via Tregs……………….. ..... 7 Production of inhibitory cytokine IL-10………… ................... 8 Disruption of effector T-cells (CD4+)………………… ........... 8 Modification of dendritic cells………………………………… 10 Promotion of cytolysis………………………………………… . 10 β-Galactomannan………………………………………………………… . 11 Consumption of β-galactomannan elicits an immunogenic immune response………………………………………………………… . 12 Consequences of intestinal inflammation ............................. 14 Therapeutic effects of mannans……………………………… 16 Enzymatically modified β-GM may have anti-inflammatory effects and promote tolerance........................................................................... 17 Role of IL-10 in immune tolerance…………………………… 19 Pre-biotic role of hydrolyzed galactomannan……………….. 21 iii ............................................................................................. Page CHAPTER 2 EFFECTS OF PLANT DERIVED β-GALACTOMANNAN ON HEALTH AND IMMUNE STATUS OF SPRAGUE-DAWLEY RATS ..... 23 Abstract……………………………………………………………………… 23 Introduction………………………………………………………………… 24 Materials and Methods…………………………………………………… 25 Results……………………………………………………………………… . 28 Discussion………………………………………………………………… .. 29 Tables and Figures………………………………………………………. 34 REFERENCES ............................................................................................. 42 iv LIST OF FIGURES …. ......................................................................................................... Page Figure 1: Dendritic cell maturation………………………………………….. 5 Figure 2: β-galactomannan structure………………………………………... 11 Figure 3: β-galactomannan supplementation causes reduced weight gain and reduced dietary intake. ............................................. 35 Figure 4: Rats fed β-GM ate less throughout the three weeks study compared to control mice .......................................................... 36 Figure 5: β-GM did not alter ileal IL-10, IL-6, IL-12a, or IL-12b transcript abundance. .............................................................. 37 Figure 6: β-GM did not alter ileum mRNA transcript abundance of the PERK or ATF-6. .................................................................. 38 Figure 7: β-GM treatment reduced jejunum IL-12a mRNA transcript abundance. .............................................................................. 39 Figure 8: Neither dietary treatment significantly impacted IL-12b transcript abundance in the jejunum of rats. ............................ 40 Figure 9: IL-10 transcript abundance in the jejunum was greater in rats fed β-GM compared to control rats. …………………………. 41 v LIST OF TABLES ......................................................................................................... Page Table 1: Galactose to mannose ratio of different galactomannan Source ....................................................................................... 34 Table 2: Ingredient composition of the control and β-galactomannan diets ........................................................................................... 34 v i NOMENCLATURE GIT Gastrointestinal tract GALT Gut-associated lymphoid tissue IBD Inflammatory bowel disease LP Lamina propria IEC Intestinal epithelial cell MLN Mesenteric lymph node DC Dendritic cell APC Antigen presenting cell PAMP Pathogen-associated molecular pattern TLR Toll-like receptor PRR Pattern recognition receptor Treg Regulatory T-cell nTreg Natural regulatory T-cell iTreg Induced regulatory T-cell IPEX Immunodysregulation polyendocrinopathy enteropathy X- linked syndrome IBS Irritable bowel syndrome T1DM Type 1 Diabetes Mellitus IDO Indoleamine-pyrrole 2,3-dioxygenase β-GM Beta-galactomannan NSP Nonstarch polysaccharide SBM Soybean meal vii CTL C-type lectin receptor LPS Lipopolysaccharide PHGG Partially hydrolyzed guar gum GG Guar gum tDC Tolerogenic dendritic cell ER Endoplasmic reticulum UPR Unfolded protein response viii ACKNOWLEDGEMENTS I would like to thank my committee chair, Michael Spurlock, and my committee members, Douglas Jones, Marian Kohut, and Matthew Rowling, for their guidance and support throughout the course of this research. In addition, I would also like to thank my friends, colleagues, the department faculty and staff for making my time at Iowa State University a wonderful experience. I want to also offer my appreciation to Dr. Dawn Koltes and undergraduate assistants Paige Abbott, Taylor Dawson, and Kaylee Hahn for their assistance during experimental studies. Special thanks go to Dr. Schalinske, my father and the smartest man I know. He has supported me in all my academic endeavors and always set aside time to share his wealth of knowledge. Without his unwavering encouragement, this thesis would certainly not have existed. Finally, thanks to my family and friends for their encouragement and to my fiancé for his patience, respect and love during these last two years. ix ABSTRACT Intestinal health and the maintaining the integrity of the intestinal barrier are critical to maintaining overall health. Research conducted over the years has consistently shown an unhealthy gut is detrimental to one’s overall well-being and is associated with a number of disease states including obesity, autism, Inflammatory bowel disease, and other autoimmune disorders. Chronic intestinal inflammation is an innate immune response that can disrupt the intestinal barrier causing it to become leaky and leaving the host susceptible to a plethora of environmental pathogens. Inflammation is also an energy draining physiological process that also causes health complications. Consumption of nonstarch polysaccharides, such as the guar gum containing β-galactomannan, have been shown to stimulate the innate immune response characterized by high levels of inflammatory cytokines. In livestock, studies have regularly shown the negative side effects of soybean meal β- galactomannan on health and immune function including impaired nutrient absorption, stunted growth, and inflammation. In vivo studies have also elucidated the immunostimulatory effects of mannans. Gums containing β- galactomannan are commonly used as thickeners, stabilizers, and binders in food industry. Therefore, it is essential to elucidate the extent of inflammation β- galactomannan may cause in order to protect the health of consumers. Our study was conducted to further characterize the impact of guar gum derived β-galactomannan on health and immune status in Sprague-Dawley x rats. As expected, rats fed β-galactomannan gained less weight throughout the course of the study compared to control rats and also consumed less. These effects, however, were not accompanied by an increased inflammatory cytokine profile. Β-galactomannan consumption did not affect inflammatory cytokines IL- 12a, IL-12b, or IL-6 nor did it affect the anti-inflammatory cytokine IL-10 in the ileum. Even more perplexing was that in the jejunum, β-galactomannan increased IL-10 mRNA transcript abundance and decreased IL-12a mRNA levels. Based on our experiment, β-galactomannan did not stimulate an innate immune response 1 CHAPTER 1: LITERATURE REVIEW Introduction to Gut Immunology The gastrointestinal tract (GIT) functions to digest and absorb nutrients. However, because it is normally the first point of contact