Abstract Background Identifying biological pathways that are associated with poor disease course in IBD may improve early risk stratification and guide targeted therapeutic approaches. We therefore aimed to integrate multiomics data determined at disease onset to explore pathways associated with disease course in pediatric IBD, focusing on both microbial and host-derived signals. Methods Children with IBD were enrolled at disease onset and followed prospectively for18 months. Samples for whole exome sequencing (WES), serum metabolomics, stool metabolomics, and microbiome were analyzed using MaAsLin2 for differential expression and Random Forest for outcome prediction for single-omic. A late integration approach with Support Vector Machine was applied for multi-omics prediction. Severe outcome was defined as steroid-dependency, early or multiple biologics, or IBD-related hospitalizations/surgeries. Pathway enrichment analyses for each omic were assessed using Fisher’s exact test and odd ratio (OR) was calculated to asses the enrichment magnitude. Results Altogether, 182 children were enrolled (123 with CD (28% severe course) and 59 UC (39% severe course). Several pathways were differentially enriched in the severe group (Figure 1). Shared pathways across CD and UC included AGE-RAGE signaling, implicated in oxidative stress and inflammation (OR=36 [95%CI 3-459] in CD and OR=92 [7-1121] in UC), and choline metabolism in cancer, associated with lipid signaling, inflammation, and fibrosis (OR=37 [95%CI 4-382] and OR=66 [3-475]). CD-specific pathways included sphingolipid metabolism (OR=30 [95%CI 2-393]), linked to barrier dysfunction and chronic inflammation, glycerolipid metabolism (OR=11 [95%CI 1-160]), and fat digestion and absorption (OR=16 [95%CI 3-167]), highlighting disruptions in nutrient absorption and inflammation. UC-specific pathways included pathways in cancer (OR=23 [95%CI 3-263]), reflecting tissue remodeling and neoplasia risk, inflammatory regulation of TRP channels (OR=14 [95%CI 1-143]), contributing to colonic inflammation, sensory perception and purine metabolism (OR=5 [95%CI 0.4-58]). Random Forest machine learning models showed modest to no predictive performance of the different omics (area under ROC curve ranged between 0.41-0.67 in CD, and 0.38-0.72 in UC; Table 1). Conclusion Key biological pathways were identified in association with severity of disease course in pediatric IBD, utilizing large datasets of genetics, metabolomics and microbiome. The findings offer insights into mechanisms underlying pediatric IBD and highlight potential therapeutic targets as well as biomarkers for early intervention.
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