P0172 Targeting the Stromal Switch: Single-cell profiles implicate the cGMP-PKG pathway in driving fibrosis and cancer progression in Ulcerative Colitis

Abstract Background Ulcerative colitis (UC) is a growing global health burden, with intestinal fibrosis and colitis-associated colorectal cancer (CAC) representing severe complications lacking effective therapies. This study investigates the cellular networks driving UC progression to identify novel therapeutic targets. Methods We performed SeekOne® DD single-nucleus RNA sequencing on clinical samples of UC with concurrent fibrosis and CAC. Computational analyses included Seurat for clustering, Monocle 2/3 for pseudotime trajectory, and CellChat for cellular communication. We established a murine model mimicking UC progression through cyclic dextran sulfate sodium (DSS) exposure with azoxymethane (AOM) initiation, evaluating the therapeutic effects of riociguat and sildenafil. Validation employed primary human intestinal fibroblasts, histopathology, Western Blotting (WB), and quantitative real-time PCR. Results Single-cell transcriptomics revealed dramatic epithelial hyperproliferation and mesenchymal transitions during UC progression to fibrosis and CAC. The diseased microenvironment exhibited CD8+ T-cell exhaustion, CD4+ T-cell dysfunction, B-cell depletion, and immunosuppressive, pro-fibrotic myeloid activity. Stromal cells emerged as central communication hubs, with the cGMP-PKG pathway-particularly PRKG1-identified as the master regulator of stromal-driven pathogenesis, which drived the transformation of resting fibroblasts into inflammatory and tumor fibroblasts. Therapeutic targeting with riociguat (guanylate cyclase activator) or sildenafil (PDE5 inhibitor) significantly attenuated both fibrosis and tumor development in vivo and suppressed fibroblast activation in vitro. Conclusion Our study provides a comprehensive single-cell atlas of the fibrotic and neoplastic UC microenvironment, establishing stromal cGMP-PKG signaling as a pivotal driver of disease progression. We demonstrate the therapeutic potential of repurposing cGMP-elevating drugs, offering a novel strategy to combat devastating UC complications. References: 1. Voelker R. What is ulcerative colitis? JAMA 2024; 331: 716. 2. Gros B, Kaplan GG. Ulcerative colitis in adults: a review. JAMA 2023; 330: 951-965. Conflict of interest: Dr. Chen, Shuze: No conflict of interest Chen, Ye: No conflict of interest