Pancreas and gastrointestinal (GI) tract development is guided by several transcription factors, including pancreatic and duodenal homeobox gene-1 (PDX1). While it is well known that PDX1is essential for pancreatic development and beta cell function, its role in GI development and function is not fully understood. We identified a patient with a homozygous point mutation in PDX1 causing total loss of PDX1 protein resulting in pancreatic agenesis. We differentiated induced pluripotent stem cells from the patient into human antral gastric (HAGO) and intestinal (HIO) organoids as a novel diagnostic approach to identify new GI pathologies. Immunofluorescence staining revealed that portions of the PDX1-null HAGOs lost the gastric marker claudin18 and increased intestinal villin1 expression, signifying that regions of the antrum are converting to an intestinal phenotype. Similarly, PDX1-null HIOs lost the intestinal marker cadherin17 and increased claudin18, indicating that regions of the intestine are undergoing gastric metaplasia. Examination of functional markers revealed an increase in acid producing parietal cells, complete lack of gastrin producing endocrine cells in HAGOs, and an increase in gastric surface mucin in HIOs. These in vitro results were further validated using endoscopy biopsies from two patients with PDX1 mutations, which showed a similar disruption in gastric and intestinal identity. CRISPR/Cas9-mediated correction of the PDX1 mutation reversed the observed PDX1-null metaplasic phenotypes in HAGOs and HIOs and also allowed for the successful generation of pancreatic tissue indicating unambiguously that the PDX1 mutation is responsible for these pathologies. Based on these findings, these PDX1-null patients will have additional screening to monitor the progression of metaplasia into gastric and intestinal cancer. This study further demonstrates the utility of organoids in improving patient diagnoses and treatment.
M. Krishnamurthy: None. T.R. Broda: None. D.O. Kechele: None. X. Zhang: None. J.J. Palermo: None. M.H. Collins: None. I.H. Thomas: None. A. Heider: None. A. Dauber: None. J. Wells: None.
American Diabetes Association (1-19-PDF-036 to M.K.)