2014 — 2018 |
Gosain, Ankush |
K08Activity Code Description: To provide the opportunity for promising medical scientists with demonstrated aptitude to develop into independent investigators, or for faculty members to pursue research aspects of categorical areas applicable to the awarding unit, and aid in filling the academic faculty gap in these shortage areas within health profession's institutions of the country. |
Gastrointestinal Mucosal Immune Defects in Hirschsprungs Disease @ University of Wisconsin-Madison
DESCRIPTION (provided by applicant): The ultimate translational goal of my research is to discover critical knowledge of basic enteric nervous system and gastrointestinal mucosal immune system biology that will improve the treatment and quality of life of children with acquired or inherited gastrointestinal disease. The focus of this proposal is to develop a scientific foundation by expanding upon my background in cell biology and neuro-immune interaction through a mentored phase of study of enteric nervous system development and gastrointestinal mucosal immune function. The Mentored Clinical Scientist Research Career Development Award will provide me with the protected time to train in the areas of enteric nervous system and immune system development and study their role in gastrointestinal mucosal immunity. I will be mentored by Dr. Ken Kudsk, a world expert in gut mucosal immunology, and Dr. Miles Epstein, a world expert in enteric nervous system development, Dr. Will Burlingham, a world expert in autoimmunity, development of tolerance, and lymphocyte function, and Dr. Chris Coe, a world expert in neuro-immunomodulation during development and aging. Each of these individuals has experience in mentoring young scientists and will guide me in my Career Development. The research plan crafted by Drs. Kudsk, the mentorship team, and myself will contribute substantially to my development as an independent researcher. We will investigate a potential developmental link between the enteric nervous system and gastrointestinal mucosal immunity. Hirschsprung's disease (HSCR) is a congenital segmental absence of the enteric nervous system (ENS) in the distal gut that results from failure of neural crest cell migration to the distal hindgut and is invariably lethal if untreated. Although HSCR can be surgically treated with segmental resection of the aganglionic bowel, up to 60% of patients in both the pre- and post-operative periods develop life-threatening Hirschsprung's-associated enterocolitis (HAEC), the pathophysiology of which is poorly defined. We have performed preliminary studies in animals with a neural crest-specific deletion of EdnrB (EdnrB-null) that exhibit distal colonic aganglionosis and closely model human, neonatal HSCR. These animals develop HAEC and die by post-natal day 28. Our preliminary results indicate that EdnrB-null mice have smaller Peyer's Patches with fewer mature B-lymphocytes than their heterozygote littermates. Additionally, the EdnrB- null animals have decreased amounts of small bowel secretory immunoglobulin A (SIgA), which is the key effector of mucosal immune defense. Finally, microarray analysis of embryonic tissue indicates decreased expression of genes involved in B-lymphocyte function in EdnrB-null mice. We hypothesize that deletion of EdnrB in the neural crest results in altered endothelin expression outside the neural crest and defective B- lymphocyte development and/or function, resulting in increased susceptibility to HAEC. In order to test this hypothesis, we will (Aim 1) determine if expression of the endothelin axis in developing hematopoietic organs is altered in animals with a neural crest-specific deletion of EdnrB, (Aim 2) determine if neural crest specific deletion of EdnrB results in intrinsic or extrinsc defects in B-lymphocyte function, and (Aim 3) determine the extent of the contribution of physiologic stress to the development of the EdnrB-null immune phenotype. We expect that these studies will provide insight into potential immunomodulatory targets for prevention and treatment of Hirschsprung's-associated enterocolitis. Completion of these aims ensures that there will be a clearer understanding of the underlying mechanisms in HAEC and the relationship between enteric nervous system and gastrointestinal mucosal immune development. The long-term goal of our research is to gain an understanding of the interactions between the enteric nervous system and gastrointestinal immune system in both development and disease to permit the generation of novel neuro-immunomodulatory therapies that may potentially target a broad range of congenital and acquired pediatric gastrointestinal tract diseases.
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0.936 |
2017 — 2018 |
Gosain, Ankush |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Validating Intestinal Enteroids to Study Hirschsprung's Associated Enterocolitis @ University of Tennessee Health Sci Ctr
Project Summary/Abstract Hirschsprung?s disease (HSCR) is a common cause of neonatal bowel obstruction that results from failed development of the distal enteric nervous system (ENS). The pathophysiology, approach to diagnosis and surgical treatment of HSCR has been well-defined over the last 60 years. However, Hirschsprung?s-associated enterocolitis (HAEC), the most serious complication of HSCR, remains a frequent cause of pre- and post- operative morbidity and mortality in HSCR patients, with poorly defined pathophysiology and unchanged treatment guidelines over multiple decades. HAEC is the presenting symptom of HSCR in 25% of infants and mortality ranges from 1-10%, with the majority of deaths occurring in newborns prior to definitive operation. Our central hypothesis is that developmental deficiency of the ENS in HSCR is accompanied by defects in intestinal homeostasis, leading to increased susceptibility to HAEC. Advances in understanding the genetics underlying HSCR have allowed development of animal models which recapitulate the human HAEC phenotype. Over the last five years, studies from our laboratory utilizing the EdnrBNCC-/- model of HSCR/HAEC have allowed us to identify defects in intestinal homeostasis that contribute to HAEC. We have identified ENS alterations in the ?normal?, ganglionated colon of EdnrBNCC-/- mice which include decreased neuronal density and a shift in neurotransmitter phenotypes, with over-representation of relaxation neurotransmitters and under-representation of contractility neurotransmitters. Additionally, we have demonstrated that EdnrBNCC-/- mice develop colonic dysbiosis prior to HAEC. Most recently, preliminary data indicate alterations in colonic epithelial tight junctions preceding the development of HAEC. Furthermore, EdnrBNCC-/- intestinal segments have increased susceptibility to invasion by pathogenic E.coli, with decreased production of innate immune defense molecules. Finally, we have identified impaired cellular immunity (B-cell populations and decreased secretory IgA) in these animals. Taken together, intestinal homeostasis in EdnrBNCC-/- mice appears to governed by a four-way interplay between the enteric nervous system, luminal microbiota, the intestinal epithelial barrier, and the mucosal immune system, all of which appear to be perturbed in the setting of altered host genetics. However, our studies to date have not allowed us to distinguish which alterations in intestinal homeostasis are causative versus associated with HAEC. Recently, intestinal enteroids have emerged as a tool to model the complexity of the intestinal epithelium in culture, avoiding confounding influence from local and system non-epithelial sources. In order to advance our understanding of the complex dynamics that contribute to HAEC, we propose to develop an experimental paradigm of in vivo, ex vivo and in vitro methods that will allow combinatorial testing of the components of intestinal homeostasis. This proposal will evaluate the contributions of EdnrBNCC-/- microbiome dysbiosis and epithelial barrier dysfunction to the development of HAEC and will determine the suitability of intestinal enteroids as a novel system to study the pathogenesis of HAEC.
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0.936 |
2020 — 2021 |
Gosain, Ankush |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Dysbiosis in Hirschsprung Associated Enterocolitis Pathogenesis @ University of Tennessee Health Sci Ctr
Hirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of Hirschsprung Disease (HSCR), a common cause of intestinal obstruction in the newborn that results from incomplete development of the enteric nervous system (ENS). HAEC affects 30-60% of infants with HSCR, occurs with unchanged incidence pre- and post-operatively, and carries a mortality of 5-10%, with the majority of deaths occurring in newborns prior to definitive operation. A critical barrier in the field is that the etiology of HAEC is poorly defined and current treatment remains empiric (bowel rest, rectal washouts, broad-spectrum antibiotics) and directed toward alleviating acute symptoms rather than targeting underlying pathophysiology. The long-term goal of our research is to define the pathophysiology of HAEC in order to develop novel therapeutic approaches that reduce morbidity and mortality in HSCR patients. Our preliminary and published findings, reinforced by those of other laboratories, support the central hypothesis that perturbation of host-microbiome mutualism, including evasion of immune exclusion and reinforcement of intestinal stasis by dysbiotic microbiota, drives the development of HAEC. Our objectives are to 1) define the mechanisms for impaired IgA production and secretion in HAEC, 2) identify the disease-promoting members of the dysbiotic HAEC microbiome, and 3) determine how the HAEC microbiome reinforces intestinal stasis. The proposed research is innovative because it will utilize novel, preclinical models to establish a causative relationship between dysbiosis and HAEC pathogenesis and test potential therapeutic targets. Our group is uniquely qualified to complete the aims because of our expertise in HSCR & HAEC, host- microbiome interactions, microbial endocrinology, and intestinal epithelial cell biology. The expected outcome of these studies will be a deeper understanding of the pathophysiology of HAEC and identification of novel therapeutic approaches for prevention or treatment of HAEC.
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0.936 |
2021 |
Gosain, Ankush Pierre, Joseph F |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Modeling Host-Fungal Interactions in Hirschsprung-Associated Enterocolitis @ University of Tennessee Health Sci Ctr
Hirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of Hirschsprung Disease (HSCR), a common cause of intestinal obstruction in the newborn. HAEC affects 30-60% of infants with HSCR and carries a mortality of 5-10%, with the majority of deaths occurring in newborns prior to definitive operation. A critical barrier in the field is that the etiology of HAEC is poorly defined and current treatment remains empiric (bowel rest, rectal washouts, broad-spectrum antibiotics) and directed toward alleviating acute symptoms rather than targeting underlying pathophysiology. The long-term goal of our research is to define the pathophysiology of HAEC and develop novel therapeutic approaches that reduce morbidity and mortality in HSCR patients. Our prior investigations and those of other groups, utilizing mouse models of HSCR/HAEC as well as human HSCR/HAEC patient samples, have associated a dysbiotic microbiota with the development of HAEC but have not directly tested causation or identified targetable molecular mechanisms to prevent or treat the disease. While almost exclusive focus has been placed on gut bacteria (microbiome), other microbial kingdoms contribute to the diverse intestinal community, including fungal yeast and molds (mycobiome), but these have largely been overlooked. Here, we propose a focused investigation of the mucosal barrier responses, including IgA/IgG and epithelial defense, to fungal pathogens in HSCR/HAEC patient and murine disease specific tissues. Our central hypothesis that aberrant mucosal immune responses to fungal pathobionts trigger HAEC inflammatory episodes. Our objectives are to 1) identify the disease-promoting members of the dysbiotic HAEC mycobiome and 2) define the normal and HAEC mucosal immune response to fungal pathobionts to understand etiological triggers and targets. We are approaching this problem through a synergistic and long-standing collaboration between the MPIs laboratories. The proposed research is innovative because it will utilize novel, preclinical models to establish a causative relationship between dysbiosis of the mycobiome and HAEC pathogenesis. Our group is uniquely qualified to complete the aims because of our expertise in HSCR/HAEC, host-pathogen interactions, gnotobiotic expertise, and mucosal immunology. The expected outcome of these studies will be a deeper understanding of HAEC pathophysiology and identification of novel targets for prevention or treatment of HAEC.
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0.936 |