DOP61 Up-regulated Gremlin 1 in fibroblasts from Crohn’s Disease fibrotic strictures: A potential therapeutic target

Abstract

Abstract Background Fibrosis is a common complication in Crohn’s disease (CD), often leading to intestinal strictures that are refractory to available biologic drugs and require surgery. Addressing this complication remains a significant unmet need. This study aims to explore the transcriptomic signature of fibrostenotic ileal CD to identify novel therapeutic targets. Methods 9 CD patients undergoing surgery for fibrotic strictures were prospectively recruited. All patients underwent magnetic resonance enterography, ileoscopy, and assessment of C-reactive protein and faecal calprotectin. A multidisciplinary team adjudicated the presence of fibrotic strictures, warranting surgical resection. Resected specimens were harvested directly from the operating theatre and delivered fresh to pathologists, who dissected samples from the strictured area, and the proximal and distal non-strictured regions. RNA was extracted from all samples for bulk-transcriptomic and single-cell RNA sequencing (scRNAseq) analysis, using the 10x Chromium Controller® platform. Differentially expressed genes (adj. p-value <0.05) were identified. Machine learning analyses, including PCA and PLS-DA, were employed to compare gene expression patterns among different tissue segments. Pathway enrichment analysis pinpointed relevant pathways. Further, the random forest model was constructed to evaluate the predictive significance of genes in relation to strictures, and the resulting ranked list of genes was subsequently validated through qPCR, confirming the significance of selected genes. Results Bulk-transcriptomic analysis revealed 64 significantly up-regulated genes in strictures, associated with inflammation, matrix remodeling, adipogenesis and cellular stress. Furthermore, 17 down-regulated genes were linked to epithelial barrier integrity. Normalised gene expression of GREM1, SERPINE1, FGF2, HDAC1 AND LY96 showed high predictive value for strictures compared to distal and proximal segments. Notably, qPCR confirmed the significant up-regulation of GREM1 expression exclusively in the ileal stricture samples (non-stricture vs. stricture: AUC 0.88, 95% CI 0.77-0.95). scRNAseq linked up-regulated GREM1 exclusively to the fibroblast cell population (THY1+, COL1A1+,ACTA2+). Conclusion Bulk and single-cell transcriptomics, along with qPCR validation of resected CD ileal strictures, showed the up-regulation of GREM1 in fibroblasts within stricture compared to adjacent proximal and distal intestinal samples. These findings confirmed in ileal CD previous reports from animal models, highlighting the role of GREM1 in promoting intestinal fibrosis. Therefore, GREM1 emerges an attractive target for the treatment of fibrotic strictures in CD.