Harnessing The Biology of Intestinal Organoids To Accelerate Drug Discovery in Inflammatory Bowel Disease: A One Health Approach

Abstract

Rationale and SignificanceCanine inflammatory bowel disease (IBD) refers to a group of chronic gastrointestinal (GI) disorders of unknown cause and pathogenesis which mimic the spectrum of chronic enteropathies in human patients with IBD. There is currently no cure for IBD and many therapeutic interventions developed over the past 3 decades have consistently failed to demonstrate evidence of efficacy in clinical trials. There is, therefore, a critical need to develop robust drug screening tools to accelerate the availability of effective and safe therapeutic strategies for management of IBD. With the aim of modeling spontaneous GI disease in dogs and humans, intestinal stem cell (ISC)‐derived organoids are emerging as a promising ex vivo tool in the study of IBD pathogenesis. Our working testable hypothesis is that canine organoids will faithfully reproduce structural and functional changes of the intestinal epithelium in dogs with IBD, which will enable more accurate prediction of therapeutic drug efficacy and safety. Long‐term, this model will provide critical information for the design of canine clinical trials, and ultimately generate preclinical data for similar studies in humans with IBD. Altogether, we therefore expect to contribute to decreased morbidity/mortality, and improved quality of life in dogs and patients with IBD.MethodsISCs isolated from endoscopic biopsies of two healthy dogs and two dogs with active IBD were differentiated into intestinal organoids. Ileal organoids and matching tissues were probed by RNA in situ hybridization and immunohistochemistry for phenotypic changes in IBD. A panel of six phenotypic markers identified different epithelial cell lineages (LGR5+: intestinal stem cell, ALP: enterocyte, PAS: goblet cell, NeuroG3: enteroendocrine cell), epithelial barrier integrity (ZO‐1) and cell proliferation (Ki‐67). Functional features of IBD organoids were investigated by cystic fibrosis transmembrane conductance regulator (CFTR) organoid swelling assay to measure Cl− channel‐water conductance.ResultsOur preliminary findings suggest that IBD organoids exhibit increased cell proliferation, intestinal stem cells, enteroendocrine cells, and expression of tight junction protein as compared to healthy organoids. Similar trends were observed when comparing phenotypic marker expression in original intestinal tissues. Forskolin significantly (P < 0.05) increased swelling of IBD organoids after 1 and 4 hr vs. controls indicating functional CFTR in organoids.ConclusionOverall, our data show that ileal organoids derived from dogs with IBD recapitulate both the phenotypic and physiological features of diseased tissue compared to healthy tissue, demonstrating its utility as an ex vivo model for investigating mechanism and therapeutic strategies in IBD. These preliminary results will be further validated by additional intestinal biopsies from 14 dogs with IBD in an ongoing clinical trials.Support or Funding Information Research Support: IG BiosciencesPreliminary phenotypic characterization of IBD organoids.(Left) Representative RNA ISH of ALP and NeuroG3 staining in ileal organoids at x40 magnification (ratio of total area). Scale bar: 50 μm. (Right) Summary box plots of ALP and PAS expression in IBD vs. Control (CTR) organoids. Data from 10 distinct microscopic fields were aggregated per dog.Figure 1