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INTRODUCTION Intestinal fibrosis is a serious complication of Crohn's disease (CD) and is caused by the excess deposition of extracellular matrix protein. There are no therapies to prevent or treat this and surgical intervention remains the only treatment option. 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. Human intestinal organoids (HIOs), derived from induced pluripotent stem cells (iPSCs), are comprised of both of these cell types; therefore iPSC-derived HIOs represent an approach in which an unlimited number of patient specific cells could be generated for such models. Our goal was to confirm the feasibility of using iPSC-derived epithelial and mesenchymal cells from CD patients to model intestinal fibrosis METHODS iPSCs from CD patients with and without 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 mesenchymal cells. Both cell types were cultured with TNFα and TGFβ, and responses were assayed after 8, 24 and 48 hrs. Further assessment on the transcriptomic profile of the cultures was conducted using the Nanostring nCounter Fibrosis Panel. RESULTS Mesenchymal cells treated with TNFα for 48 hrs showed a significant increase in MMP9 expression, whereas TGFβ elicited an upregulation in COL1A1 and COL5A1. Further analysis via Nanostring identified the upregulation of numerous other fibrosis-related genes in response to TNFα stimulation, mainly: CCL2, IL6, MMP7, and MMP9. In eHIO cultures, after 24 hrs of cytokine exposure, we detected a significant upregulation in EMT (NCAD, VIM, and SNAI2) and fibrosis genes (COL1A1, COL5A1, and MMP9), mainly in response to TGFβ and the combination TNFα/TGFβ. Nanostring further identified a total of 121 differentially expressed genes, mostly in response to these treatments, particularly: CCL2, IL11, MMP9, MMP10. Overall, Nanostring analysis found an upregulation in pathways associated with ECM production and remodeling, immunomodulation, and ligands associated with EMT and cell migration. CONCLUSION We have successfully generated a system to assay intestinal fibrosis in a patient-specific manner using iPSC-derived epithelial and mesenchymal cells from CD patients. Our model elicited a reliable and reproducible response to inflammatory and fibrogenic stimuli, measured by the differential expression of key fibrosis-associated genes. Future studies will focus on a broader analysis of these data via RNA-seq to investigate a potential fibrogenic phenotype and to identify novel genes/pathways that may play in role in the pathophysiology of intestinal fibrosis in CD.

We describe MIP-1 and MIP-2, novel paralogous C. elegans germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.