P008 Fibrostricturing Crohn’s disease is characterised by an imbalance in active eosinophils, Th1, Th2 and regulatory T cells

Abstract Background About one third of patients with Crohn’s disease (CD) develop strictures during their course requiring surgical resection. The immune landscape involved in this process is poorly understood. Therefore, we aimed to characterise the fibroblast phenotype, cells and mediators intestinal strictures. Methods We included 25 CD stricturing terminal ileum (TI) 10 controls colorectal cancer (CRC), all undergoing an ileocolonic Transmural samples from resection specimen TI were obtained. Macroscopically, tissue was divided into unaffected, fibrostenotic inflamed regions by experienced histopathologist. Next, mucosa separated deeper layers, after which single isolated fluorescently stained for flow cytometry. Protein levels determined via MesoScale Discovery (MSD) platform corresponding samples. Comparisons between CRC performed unpaired t-test or Mann-Whitney analysis corrected multiple testing. Results An increase active fibroblasts decrease inactive fibrotic (p=0.0002 p<0.0001) layers (p=0.003 p=0.02) when compared observed, confirming ongoing remodelling. enrichment eosinophils only seen (p=0.02), although T helper 2 (Th2) observed both (p=0.02 p=0.04). In contrast, 1 (Th1) decreased (p=0.03 (p=0.01 both). Regulatory significantly enriched (p<0.0001 p=0.0005) p=0.006) (figure 1). quantification confirmed a significant transforming growth factor-β3 (TGF-β3) (p=0.007) (p=0.0002) but not more superficial mucosa. Comparably, IL-1β increased (p=0.05) layers. A similar observation made basic factor (bFGF) (p=0.004), trend could be (p=0.08) 2). Conclusion characterized activated eosinophils, Th2 regulatory Th1 cells, as well many mediator cytokines. current immunological characterisation can help prioritise potential anti-fibrotic targets CD.