OP32 TWIST1-mediated fibroblast activation protein (FAP)-expressing fibroblasts drives fibrosis in Crohn’s Disease

• Published in: Journal of Crohn's and colitis Vol. 18; no. Supplement_1; p. i58
• Main Authors: Ke, B J, Abdurahiman, S, Verstockt, B, Biscu, F, Zanella, G, Zouzaf, A, van Baarle, L, De Simone, V, Stakenborg, M, Santhosh, S, Verstockt, S, De Hertogh, G, Vermeire, S, Matteoli, G
• Format: Journal Article
• Language: English
• Published: 24-01-2024
• ISSN: 1873-9946; 1876-4479
• DOI: 10.1093/ecco-jcc/jjad212.0032

Abstract
Background
Stricturing Crohn’s disease (CD) is a distinct clinical phenotype, characterised by the development of fibrotic strictures within the GI tract. These strictures result from chronic inflammation, leading to the accumulation of collagen and scar tissue, causing narrowing of the affected intestinal segments. Due to a lack of anti-fibrotic medication, up to 70% of patients with CD will require surgery in their lifetime, while up to 40% of patients need repetitive resections within 10 years.
Methods
To understand inflammation-induced fibrosis, full-thickness ileal punch biopsies from CD patients (n=10) and colorectal cancer (CRC) patients (n=5) undergoing ileocecal resection (ICR), were profiled using single-cell RNA sequencing (scRNA-seq) on the 10x Genomics platform. Flow cytometry was performed to confirm scRNA-seq findings. Intestinal fibroblasts were cultured in the presence of NicheNet-predicted cytokines or supernatant of FACS-sorted myeloid cells. To confirm the pro-fibrotic role of TWIST1 in fibroblasts, both Harmine (TWIST1 inhibitor)-treated wild-type mice and COL1A2CrexTWIST1fl/fl mice were subjected to chronic dextran sulphate sodium (DSS)-induced colitis.
Results
Using scRNA-seq, we identified a specific subset of FAP-expressing fibroblasts enriched in fibrotic surgical CD specimens. Flow cytometry confirmed a significant increase of these cells in the inflamed and stenotic ileum, compared to proximal uninflamed ileum and unaffected control ileum from CRC patients undergoing ICR. Computational methods identified TWIST1 as a key transcription factor, mediating fibroblast activation and extracellular matrix (ECM)-regulatory phenotypes. Myeloid cell-derived inflammatory signals were predicted to induce this specific fibroblast activation, resulting in collagen deposition and tissue fibrosis. Intestinal fibroblasts cultured with inflammatory monocyte supernatant or pro-inflammatory cues expressed higher levels of TWIST1, FAP, and COL3A1. After inhibiting TWIST1 with Harmine, collagen expression and ECM accumulation were decreased in fibroblasts. In addition, in chronic DSS colitis, wild-type mice treated with Harmine showed a reduction in collagen deposition. COL1A2CrexTWIST1fl/fl mice showed improved disease activity, compared to their littermate controls.
Conclusion
Our findings suggest that TWIST1 serves as a central mediator in the activation of fibroblasts, promoting excessive collagen deposition in ileal CD. Targeting TWIST1 may reduce tissue remodelling and prevent fibrosis in CD.