Date Available
5-6-2026
Year of Publication
2025
Document Type
Doctoral Dissertation
Degree Name
Doctor of Philosophy (PhD)
College
Agriculture, Food and Environment
Department/School/Program
Veterinary Science
Faculty
Dr. Carrie Shaffer
Faculty
Dr. Ted Kalbfleisch
Abstract
One major limitation to the study of equine disease is the lack of in vitro models that accurately reflect the dynamic physiology of the horse. Thus, there is a pressing need to develop in vitro systems that recapitulate diverse equine tissue and organ microenvironments. To overcome this deficiency, we developed multiple biomimetic equine organoid systems that can be employed for a variety of investigations aimed at resolving outstanding questions in infectious disease pathogenesis, therapeutic development and drug metabolism, host defense mechanisms, immune-modulated disease, and equine developmental biology. Our innovative platform incorporates novel equine intestinal enteroid and airway organoid models derived from thoroughbred and mixed breed tissues. Using functional assays and microscopy analyses, we show that these systems recapitulate complex tissue architectures, specialized and differentiated cellular function, and support host-pathogen interaction studies. A major threat to the equine industry is the impact of respiratory and gastrointestinal infectious diseases. Intestinal illnesses remain a significant cause of equine morbidity and mortality, and colic remains a leading cause of death in adult horses. While there are many causes of intestinal disruption in the horse, investigations into infectious causes have been limited by the lack of in vitro models that recapitulate the intestinal microenvironment and provide access to the luminal surface of the mucosal epithelium. Thus, we developed methods to transition our three-dimensional (3D) equine enteroids into two-dimensional (2D) polarized monolayers that differentiate into relevant cell types including enterocytes, goblet, and enteroendocrine cells. We demonstrate that the enteroid-derived pseudostratified epithelium exhibits tight barrier formation, brush border enzyme activity, and observable mucus production. Using these polarized models, we explored microbial pathogenesis induced by bacterial and viral causes of equine diarrheal disease. RNA-seq studies to understand the role of Salmonella enterica Typhimurium type III secretion system (T3SS) activity in gastrointestinal colonization revealed robust immune responses elicited in response to T3SS-dependent bacterial invasion and intracellular replication. We next extended our enteroid infection model to explore the replication and pathogenesis of equine rotavirus B (EqRVB) which cannot replicate in traditional transformed cell lines. Our results demonstrate that polarized enteroid models support EqRVB replication and mount antiviral programs, representing a critical experimental step that will enable future vaccine development. Finally, building on our success, we developed lineages of equine airway organoids that exhibit lung- and trachea-specific characteristics, including cellular differentiation, coordinated ciliated cell beating, and mucus production. We are using these systems to model equine respiratory disorders and communicable pneumatic diseases including equine herpesvirus and equine influenza. Collectively, our innovative equine organoids provide biologically-relevant in vitro models that will ultimately reduce animal experimentation and enable high impact studies to understand mechanisms underlying equine microbial pathogenesis, inflammation, and host-microbiome interactions.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2025.189
Funding Information
University of Kentucky Department of Veterinary Science/Lincoln Memorial University College of Veterinary Medicine Assistanship 2020-2025
Recommended Citation
Leedhanachoke, Lynn M., "ENGINEERING NOVEL BIOMIMETIC MODELS OF EQUINE HOST-MICROBE INTERACTIONS" (2025). Theses and Dissertations--Veterinary Science. 70.
https://uknowledge.uky.edu/gluck_etds/70
