Persistent Inflammation of the Rectum in Perianal-Fisulizing Crohn's Disease Associates with Goblet Cell Function
Perianal Fistulizing Crohn's Disease (perianal-CD) is a debilitating form of CD typically associated with prolonged periods of morbidity. Leveraging single-cell RNA sequencing, rectal mucosal tissue was sequenced from individuals following anti-TNF biologic therapy having either active perianal-CD and inflamed rectal mucosa or healed perianal-CD but non-inflamed mucosa. Single cell transcriptomic profiles of the inflamed and non-inflamed tissue were contrasted to test for specific cellular subsets of rectal epithelial and immune cell compartments associated with inflamed perianal disease. We identified eight broad classes of epithelial, six of immune, and a small population of stromal cells in the rectal mucosa. There was an increase in colonocytes in the non-inflamed tissue compared to the inflamed tissue, and an increase of naïve b cells and plasma cells associated with inflamed tissue. The cell type proportions of immune cells, highlighted patient heterogeneity of cell type abundance and potential dysregulation of both the immune and epithelial compartment. We also note enrichment of IgG plasma cells in inflamed tissue of two donors and expansion of IgA plasma cells of non-inflamed tissue in two donors. Differential gene expression analysis of goblet cells revealed enrichment of inflammatory pathways, such as IL6 and interferon gamma signaling, in inflamed tissue. These inflammatory pathways might affect tight junctions between epithelial cells leading to increased permeability and potentially affect fistula formation. Our findings suggest dysregulation of crypt maturation during persistent inflammation and over-abundance of goblet cells and colonocyte precursors in inflamed tissue of perianal-CD. Overall design: Single cell transcriptomic profiles of inflamed or non-inflamed rectal mucosal biopsies of individuals diagnosed with Perianal-Fistualizing Crohn's Disease. There is one non-IBD control.