83.05 Creeping fat-derived mechanosensitive fibroblasts drive intestinal fibrosis in Crohn’s disease strictures

K. Bauer-Rowe¹, B. Pham¹, M. Griffin¹, A. Kim¹, N. Liang¹, M. Korah¹, M. Longaker¹, J. Hyun^{1  1}Stanford University, Palo Alto, CA, USA

Introduction:  Intestinal strictures are characterized by fibrotic bowel wall thickening and are a significant complication in Crohn’s disease (CD). Creeping fat (CF) is pathognomonic for CD and forms around intestinal strictures. Previously, we developed a colotomy-based mouse model of intestinal fibrosis and CF that phenocopies key features of human strictures and identified Postn+ pro-fibrotic, mechanosensitive fibroblasts by scRNA-seq. Here, we provide direct evidence that CF-derived mechanosensitive fibroblasts promote intestinal fibrosis progression.

Methods:  We first generated Col1a2-CreERT2; YAP^lox/+; TAZ^lox/+; ZsGreen+ heterozygous (Het) controls or Col1a2-CreERT2; YAP^lox/lox; TAZ^lox/lox; ZsGreen+ knockout (KO) mice to label fibroblasts and knock out YAP/TAZ signaling. To perform localized lineage tracing of MAT-derived fibroblasts, we generated liposome-encapsulated 4-hydroxytamoxifen (LiTMX). We then created colotomies in the mice and injected LiTMX into the mesentery adjacent to the colotomies (Figure 1A). We stained for collagen deposition using Masson’s trichrome.  We measured fibrosis by quantifying bowel wall (BW) thickness, and MAT circumference around the BW. Finally, we stained colotomies for nuclear YAP+GFP+POSTN+ MAT-derived, mechanosensitive fibroblasts.

Results: Knockout of YAP/TAZ signaling reduced gross MAT wrapping around the colotomy site (Figure 1B). The MAT-BW interface (IF) in Het mice but not KO mice had a thick area of thick fibrosis (Figure 1C). BW thickness and CF circumference both decreased in KO compared to Het mice. Finally, nuclear YAP+GFP+POSTN+ MAT-derived, mechanosensitive fibroblasts were present in the IF of Het mice but not in the KO mice.

Conclusion: CF-derived, mechanosensitive fibroblasts invade the BW and contribute to intestinal fibrosis progression in a YAP/TAZ dependent manner. Anti-fibrotic therapies targeting CD strictures may require also targeting CF-derived fibroblasts.