Background: Accurate biomarkers for disease activity and progression in patients with inflammatory bowel disease (IBD) are a prerequisite for
individual disease characterization and personalized therapy. We show that metabolic profiling of serum from IBD patients is a promising approach
to establish biomarkers. The aim of this work was to characterize metabolomic and lipidomic serum profiles of IBD patients in order to
identify metabolic fingerprints unique to the disease.
Methods: Serum samples were obtained from 55 patients with Crohn’s disease (CD), 34 patients with ulcerative colitis (UC), and 40 healthy
control (HC) individuals and analyzed using proton nuclear magnetic resonance spectroscopy. Classification of patients and HC individuals was
achieved by orthogonal partial least squares discriminant analysis and univariate analysis approaches. Disease activity was assessed using the
Gastrointestinal Symptom Rating Scale.
Results: Serum metabolome significantly differed between CD patients, UC patients, and HC individuals. The metabolomic differences of
UC and CD patients compared with HC individuals were more pronounced than the differences between UC and CD patients. Differences in
serum levels of pyruvic acid, histidine, and the branched-chain amino acids leucine and valine were detected. The size of low-density lipoprotein
particles shifted from large to small dense particles in patients with CD. Of note, apolipoprotein A1 and A2 serum levels were decreased in CD
and UC patients with higher fecal calprotectin levels. The Gastrointestinal Symptom Rating Scale is negatively associated with the concentration
of apolipoprotein A2.
Conclusions: Metabolomic assessment of serum samples facilitated the differentiation of IBD patients and HC individuals. These differences
were constituted by changes in amino acid and lipoprotein levels. Furthermore, disease activity in IBD patients was associated with decreased
levels of the atheroprotective apolipoproteins A1 and A2.