Abstract
Intestinal strictures significantly cause morbidity in Crohn’s disease (CD) patients. One major histological characteristic of strictures is the loss of epithelial architecture (Figure 1A). The cause of epithelial dysregulation in strictures is poorly understood. We hypothesize that the intestinal stem cell (ISC) niche secretes anti-regenerative signals, preventing epithelial regeneration.
Using publicly available and internally generated scRNA-seq human intestinal stricture data, we created a scRNA-seq CD atlas and characterized distinct fibroblast populations in strictures (Figure 1B-C). We utilized an anti-mesenteric colotomy model with mechanical tension to generate fibrosis and mesenteric adipose tissue (MAT) wrapping, mimicking human strictures, and performed Masson’s trichrome and scRNA-seq (Figure 1F-G). In human and mouse studies, we subclustered the fibroblasts and measured WNT agonist and antagonist expression (Figure 1D, 1H).
From our CD atlas, we identified a pro-fibrotic, mechanosensitive population of fibroblasts that expanded in strictures (Figure 1C) and expressed high levels of WNT antagonist genes (Figure 1D). We found that our mouse model could capture the epithelial loss found in human strictures (Figure 1F). scRNA-seq of our model demonstrated a similar upregulation of mechanosensitive fibroblasts in colotomy compared to sham (Figure 1G). We also observed an expansion of WNT antagonist genes from these fibroblast subpopulations (Figure 1H), mimicking our findings in human.
We observed an upregulation in WNT antagonism from mechanosensitive fibroblasts in both our human and mouse data which may be responsible for ISC dysregulation and epithelial loss in intestinal fibrosis. Targeting pro-fibrotic, mechanosensitive fibroblasts may be key to reestablishing the normal ISC niche and restoring epithelial regeneration in strictures.
Figure 1. Intestinal mechanosensitive fibroblasts secrete WNT antagonist. (A) Masson’s Trichrome of a pediatric stricture. (B) Outline of scRNA CD meta-analysis. (C) Uniform manifold approximation and projections (UMAP) of fibroblast from CD meta-analysis. (D) Dot plot of module scores for WNT antagonist and agonist from human fibroblast subclusters. (E) Schematic of mouse colotomy model of intestinal fibrosis. (F) Masson’s Trichrome of mouse intestine in sham and colotomy surgeries with epithelial loss highlighted in red. (G) UMAP of fibroblast
