The Interplay of Host Genetic Variation and the Gut Microbiome in Crohn's Disease

ABSTRACT Crohn’s Disease (CD) is an autoimmune disease which leads to chronic inflammation and scarring of the digestive tract. The available treatments involve immunosuppressants and surgery which are costly, with many individuals still experiencing a decreased quality of life. The cause of CD is unknown, but is believed to occur due to both genetic and environmental factors, including diet. The gut microbiome is altered in individuals with CD, leading to dysregulation of the host and microbial transcriptional and metabolic landscape. Furthermore, many genetic risk variants associated with CD are in host genes known to function in host response to the microbiome. Thus, characterizing host-microbiome interactions in CD is imperative for understanding the pathogenesis of CD and identifying potential new therapeutic routes. In this proposed research, I aim to characterize the interactions between host genetic variation and the gut microbiome that regulate host gene expression in CD. I will use two complementary approaches. I will use a microbiome/intestinal organoids co-culturing approach to identify host gene expression changes in response to CD-derived microbiomes, and host genetic variants that modulate these changes using allele-specific expression analysis. I will also utilize data available through the Human Microbiome Project Inflammatory Bowel Disease Multi’omics Database to perform eQTL mapping, and integrate all of my findings with GWAS and TWAS to validate the significance of GxM for CD risk. These studies will provide insight into host-microbiome interactions that modify genetic risk for Crohn’s Disease. Furthermore, I will identify specific microbes that could become potential therapeutic targets for CD.