Eicosatetraynoic Acid Regulates Pro-Fibrotic Pathways in an Induced Pluripotent Stem Cell Derived Macrophage:Human Intestinal Organoid Model of Crohn's Disease
Background: We previously reported Crohn's Disease (CD) ileal macrophage and fibroblast gene expression modules linked to future strictures, and identified small molecules which may reverse this gene signature. Here we developed a model system to test a lead candidate, eicosatetraynoic acid (ETYA), a Peroxisome Proliferator-Activated Receptor (PPAR) agonist.  Methods: CD patient induced pluripotent stem cells (iPSC) were differentiated into macrophages and human intestinal organoids (HIOs).  Macrophages and macrophage:HIO co-cultures were exposed to lipopolysaccharide (LPS) with and without ETYA pre-treatment. Cytospin and flow cytometry characterized macrophage morphology and activation markers, and RNA sequencing defined the global pattern of macrophage gene expression. TaqMan Low Density Array, Luminex multiplex assay, immunohistologic staining, and sirius red polarized light microscopy were performed to measure macrophage cytokine production and HIO pro-fibrotic gene expression and collagen content. Results: iPSC-derived macrophages exhibited morphology similar to primary macrophages and expressed inflammatory macrophage cell surface markers including CD64 and CD68. LPS-stimulated macrophages expressed a global pattern of gene expression enriched in CD ileal inflammatory macrophages and matrisome secreted products, and produced cytokines and chemokines including CCL2, IL1B, and OSM implicated in refractory disease. ETYA suppressed CD64 abundance and pro-fibrotic gene expression pathways in LPS stimulated macrophages. Co-culture of LPS-primed macrophages with HIO led to up-regulation fibroblast activation genes including ACTA2 and COL1A1, and an increase in HIO collagen content.  ETYA pre-treatment prevented pro-fibrotic effects of LPS-primed macrophages. Conclusions: ETYA inhibits pro-fibrotic effects of LPS-primed macrophages upon co-cultured HIO. This model system may be used to screen personalized effects of candidate small molecules upon inflammatory and fibrotic pathways implicated in refractory CD patients. Overall design: CD patient-induced pluripotent stem cells (iPSC) were differentiated into macrophages. These macrophages were exposed to lipopolysaccharide (LPS) with and without ETYA pre-treatment. Overall there were 6 macrophages controls with no treatment, 6