An Epigenetic Basis for Sustained Inflammatory Epithelial Progenitor Cell States in Crohn's Disease.

BACKGROUND & AIMS: Defining consequential differences in intestinal epithelial stem cells in healthy humans vs those with inflammatory bowel disease (Crohn's disease and ulcerative colitis) is essential for the development of much needed therapies to restore the epithelial barrier and maintain its fidelity.

METHODS

We used single-cell transcriptomic and epigenomic approaches in matched patient tissues and organoids to investigate epithelial gene expression and function in children with no pathological diagnosis in the lower gastrointestinal tract and healthy adults compared with those with Crohn's disease.

RESULTS

We identify an inflammatory secretory progenitor (ISP) cell state present almost exclusively in patients with Crohn's disease compared with healthy subjects. ISPs exhibit gene expression profiles consistent with normal secretory progenitor cells but concomitantly express a suite of distinguishing pro-inflammatory genes. Mechanistically, ISPs exhibit open chromatin at ISP gene loci. Although ISP-specific genes are not expressed in intestinal stem cells, their chromatin is accessible in Crohn's disease stem cells, suggesting that ISP genes are epigenetically poised in stem cells and subsequently transcriptionally activated in ISPs in the presence of inflammatory stimuli. Consistently, Crohn's disease colonoids exhibit sustained ISP gene expression that can be elicited further with pro-inflammatory cytokines or via co-culture with pro-inflammatory macrophages.

CONCLUSIONS

We have defined differences in the epithelial stem and progenitor compartment of patients with Crohn's disease that suggest aberrant stem cell differentiation and inflammatory gene expression arise and persist during disease.