An exploratory multi-omics study reveals distinct molecular signatures of ulcerative colitis and Crohn's disease and their correlation with disease activity

Clinically heterogeneous spectrum and molecular phenotypes of inflammatory bowel disease (IBD) remain to be comprehensively elucidated. This exploratory multi-omics study investigated the serum molecular profiles of Crohn's disease (CD) and ulcerative colitis (UC), in association with elevated fecal calprotectin and disease activity states. The serum proteome, metabolome, and lipidome of 75 treated IBD patients were profiled. Single- and multi-omic data analysis was performed to determine differential analytes and integrative biosignatures for biological interpretations. We found that chronic inflammation, phosphatidylcholines and bile acid homeostasis disturbances underlined the differences between CD and UC. Besides, elevated calprotectin was associated with higher levels of inflammatory proteins and sphingomyelins (SM) and lower levels of bile acids, amino acids, and triacylglycerols (TG). Relative to the remission disease state, the active form was characterized by decreased abundances of SMs and increased abundances of inflammatory proteins and TGs. We also observed that molecular changes upon treatment escalation were putatively related to altered levels of inflammatory response proteins, amino acids, and TGs. ISM1, ANGPTL4, chenodeoxycholate, Cer(18:1;2 O/24:1), and TG were identified as candidates subject to further investigation. Altogether, our study revealed that disturbances in immune response, bile acid homeostasis, amino acids, and lipids potentially underlie the clinically heterogeneous spectrum of IBD.