K. E. Bauer-Rowe1, A. Kim1, B. Pham1, M. Griffin1, J. Guo1, D. Foster1, J. Norton1, M. Longaker1, J. Hyun1 1Stanford University, Palo Alto, CA, USA
Introduction:
Crohn’s disease (CD) is a subtype of inflammatory bowel disease (IBD) characterized by transmural inflammation and creeping fat formation. Creeping fat (CF) forms adjacent to strictures, but whether it promotes stricture formation is unclear. Yes-associated protein (YAP) mediates mechanotransduction in fibroblasts to drive fibrosis. Here, we show that CF-derived fibroblasts may promote stricture formation via mechanotransduction.
Methods:
We performed single cell RNA-sequencing and 10X Visium spatial transcriptomics (ST) on whole-thickness pediatric strictures (Figure 1A). We partitioned ST sections into domains: 1) Bowel: tissue closest to the lumen, 2) Interface: stroma between bowel and CF, and 3) CF: mesenteric adipose tissue. We deconvoluted the ST datasets using CytoSpace and applied CellChat to identify domain communication pathways. We quantified nuclear YAP in strictures and adjacent, uninvolved tissue by immunofluorescence. Finally, we performed mesenteric injections of vehicle or YAP inhibitor verteporphin adjacent to a colotomy to simulate intestinal stricture formation and quantified bowel wall thickness and trichrome-positive area.
Results:
We identified mechanosensitive (MS) CLU+ fibroblasts enriched for YAP targets (CTGF, CYR61) (Figure 1B-C). ST analysis and deconvolution revealed the enrichment of ECM genes and MS fibroblasts at the interface (Figure 1D-F). Spatial CellChat showed that the interface and CF have strong profibrotic cellular communication patterns (Figure G-H). Nuclear YAP was strongly enriched in CF and interface compared to uninvolved adjacent tissue (Figure 1I). Mesenteric injection of verteporphin reduced bowel wall thickness and trichrome area (Figure 1J-L).
Conclusion:
Integration of scRNA-seq with ST in combination with nuclear YAP staining revealed that the bowel-CF interface is a highly profibrotic environment enriched with mechanosensitive CLU+ fibroblasts compared to other areas of the stricture. Mesenteric administration of a YAP inhibitor ameliorated fibrosis in a mouse model of intestinal strictures. Targeting CF-derived MS fibroblasts may attenuate intestinal stricture formation.
