IBD risk locus rs1077773 is a pharmacogenomic eQTL for aryl hydrocarbon receptor activity and modulates immune cell function.

Introduction: The inflammatory bowel diseases (IBD) Crohn's disease (CD) and ulcerative colitis (UC) are disorders that cause chronic inflammation of the gastrointestinal tract. Both genetic and environmental factors contribute to the pathogenesis of IBD. There are currently >200 known genetic susceptibility loci for the development of IBD. The physiological impact of the majority of these loci remain a gap in our knowledge. One such locus is the single nucleotide polymorphism rs1077773, located ~56kbp downstream from the aryl hydrocarbon receptor ( Methods: All study procedures and reagents were approved by the Washington University Institutional Review Board (#202011003). Patient biopsies were collected at Barnes Jewish Hospital and genotyped using the IBD Genetics Consortium custom GSA SNP chip (Broad Institute) followed by imputation using TopMed Imputation Server at University of Michigan. Patient derived organoids (PDOs; N=3 G/G, N=4 G/A, N=5 A/A) were derived and maintained in 3D culture and supplemented with 50% L-WRN conditioned medium with passage every 3-4 days as previously described. PDOs were treated with AHR agonist 6-Formylindolo[3,2-b]carbazole (FICZ) or vehicle for 48h. Expression of Results: Conclusions: This work demonstrates that rs1077773 is an expression quantitative trait locus (eQTL) for AHR activity and modulates epithelial and immune cell function in vitro. Further mechanistic understanding of this locus and its correlates could improve our understanding of the molecular mechanisms of IBD susceptibility and may lead to novel personalized therapeutic approaches in IBD.