Mucosal and Plasma Metabolomes in New-onset Paediatric Inflammatory Bowel Disease : Correlations with Disease Characteristics and Plasma Inflammation Protein Markers

Background and Aims To advance the understanding of inflammatory bowel disease [IBD] pathophysiology, we compared the mucosal and plasma metabolomes between new-onset paediatric IBD patients and symptomatic non-IBD controls, and correlated plasma inflammation markers and disease characteristics with the altered metabolites. Methods Paired colonic and ileal biopsies and plasma from 67 treatment-naïve children with incident Crohn’s disease [CD; n = 47], ulcerative colitis [UC; n = 9], and non-IBD controls [n = 11] were analysed using ultra-performance liquid chromatography-mass spectrometry [UPLC-MS/MS]. Inflammatory plasma proteins [n = 92] were assessed. Results The metabolomes in inflamed mucosal biopsies differed between IBD patients and controls. In CD, mucosal levels of several lysophospholipids [lysophosphatidylcholines, lysophosphatidyletanolamines, lysophosphatidylinositols, and lysophosphatidylserines] were decreased, correlating with various plasma metabolites including amino acid analogues and N-acetylated compounds. In both CD and UC, mucosal sphingolipids, including ceramide [d18:2/24:1, d18:1/24:2], lactosyl-N-palmitoyl-sphingosine [d18:1/16:0], behenoyl sphingomyelin [d18:1/22:0], lignoceroyl sphingomyelin [d18:1/24:0], and/or sphingomyelin [d18:1/24:1, d18:2/24:0] were increased, correlating with sphingolipids, bile acids, and/or N-acetylated metabolites in plasma. Among proteins associated with CD, interleukin-24 correlated with plasma metabolites, including lactosyl-N-palmitoyl sphingosine [d18:1/16:0] and phosphatidyletanolamine [18:1/18:1], haemoglobin, and faecal calprotectin. In UC, interleukin-24, interleukin-17A, and C-C motif chemokine 11 correlated with several plasma metabolites, including N-acetyltryptophan, tryptophan, glycerate, and threonate, and with the Paediatric Ulcerative Colitis Activity Index, C-reactive protein, and faecal calprotectin. Conclusions Mucosal perturbations of lysophospholipids and sphingolipids characterised the metabolome in new-onset paediatric IBD and ...