A MODEL TO STUDY INTESTINAL FIBROSIS IN IPSC-DERIVED HUMAN EPITHELIAL AND MESENCHYMAL CELLS FROM CROHN’S DISEASE PATIENTS

Abstract

Abstract INTRODUCTION Intestinal fibrosis is a serious complication of Crohn's disease (CD) and is caused by the excess deposition of extracellular matrix (ECM) proteins. Numerous cell types, including intestinal epithelial and mesenchymal cells, are implicated in this but research efforts are impaired by a lack of in vitro models. To overcome this, we have previously developed a human model of intestinal fibrosis using iPSC-derived epithelial and mesenchymal cells generated from both control and CD patients. Using this model, we aimed to further characterize the transcriptomic signature associated with the fibrotic response as well as other functional hallmarks of fibrosis. METHODS iPSCs from 19 CD patients with (10) and without (9) fibrotic complications were directed to form HIOs. As iPSC-derived HIOs contain epithelial and mesenchymal cells, the organoids were dissociated to generate purified cultures of epithelial only-HIOs (eHIOs) and intestinal mesenchymal cells (MSCs). eHIO and MSC cultures were treated with TNFα and TGFβ, alone or in combination. We evaluated the transcriptomic profile of both cell types via RNA-seq and carried out additional studies via ELISA, ECM staining and scratch assay. RESULTS RNAseq analysis on the effects of cytokine induction in eHIOs lead to an enrichment in pathways associated with inflammation and regulation of the immune response. Furthermore, eHIOs from patients with fibrotic complications showed a significant upregulation of ORM1 regardless of culture conditions, which was subsequently confirmed at the protein level indicating an intrinsic difference between both patient groups. RNAseq analysis on MSC cultures found differentially expressed genes clustered in pathways associated with ECM production and remodeling, and cell migration and proliferation. Cell migration capacity of MSCs was assessed by measuring the reduction in scratch area and under basal conditions, MSCs from the fibrotic cohort had a lower rate of cell migration (40.81%) compared to the non-fibrotic cohort (20.97%); notably, the addition of TNFα appeared to accelerate the migration capacity of MSCs in both fibrotic (14.54%) and non-fibrotic (6.56%) samples. Finally, compared to untreated cultures, MSCs treated with TNFα/TGFβ exhibited a significant increase in ECM deposition (2.64- and 2.29-fold increase for non-fibrotic and fibrotic, respectively). CONCLUSION We have demonstrated the functionality of our model of intestinal fibrosis generated from iPSC-derived epithelial and mesenchymal cells from CD patients. Furthermore, we have identified both generalized and intrinsic differences in our cohort of patients with fibrotic complications. Future experiments on the role of ORM1 in intestinal fibrosis and its effects on mesenchymal cells could provide a deeper understanding of the events leading the development of intestinal fibrosis in CD patients.