P172 Spatial Transcriptomics Characterization of S1P Pathway Genes in Ulcerative Colitis and Crohn’s Disease Colon Tissues

Abstract

Abstract Background Inflammatory bowel diseases (IBD), such as ulcerative colitis (UC) and Crohn’s disease (CD) are chronic inflammatory diseases of the gastrointestinal tract, related to the confluence of environmental and immunological factors in genetically predisposed individuals. Activated T and B cells migrate from the lymphoid tissue into the circulation through the interaction of Sphingosine-1-phosphate (S1P) and the S1P1 receptor (S1P1), which can perpetuate inflammation and lead to tissue damage. Targeting of cellular migratory pathways has emerged as a novel therapeutic paradigm in IBD. The aim of this study is to characterize the S1P pathway-related genes and signaling pathways driving the pathogenesis of UC and CD. Methods Spatial transcriptomics analysis was performed in health volunteer (HV, n=2), UC (n=4) and CD (n=2) FFPE colon tissues using the GeoMX platform and NanoString whole transcriptome atlas (WTA) assay. The WTA panel was run on 8 samples stained with antibodies to S1P1, pan Cytokeratin, and CD45. Six regions of interests (ROIs) were selected in each sample based on the staining and each ROI were split into two areas (CD45+ or CD45-). Differential gene expression and enriched pathways analysis including S1P pathway genes were performed in CD45+ and CD45- segments in HV, UC and CD colon tissues. Results A total of 6085 and 6054 differentially expressed genes were identified from the CD45+ segments in UC and CD respectively, compared to HV colon (P=0.05), including the genes that are involved in T cell activation (e.g., HLA-DPA1, CCDC13), immune cell migration (e.g., ADAM15, CCL5) and tissue damage (e.g., FABP6, PDK4). Interestingly, significant differences were identified in UC and CD in S1P pathway gene expression. Specifically, SMPD1, a gene involved in generating ceramide and regulating inflammatory responses, was the most significantly up-regulated gene from both CD45+ and CD45- compartments in UC compared to HV colon. While CERS2 and CERS6, genes related to S1P metabolism, were significantly down-regulated genes in CD45+ and CD45- compartment in UC respectively, as compared to HV colon. Additionally, RTN4 (participates in the intestinal epithelial barrier function) and PLPP3 (dephosphorylates extracellular S1P to sphingosine) were most significantly down-regulated genes from CD45+ segments in both UC and CD compared to HV colon. Conclusion In summary, our study successfully validated the GeoMx transcriptome analysis approach in FFPE colon tissue and assessed the S1P pathway gene signature difference in HV, UC and CD colon tissues supporting the pathway’s role in IBD. Results could also facilitate the identification of potential S1P pathway UC and CD disease biomarkers.