Can serum metabolomics discriminate the Crohn’s disease fibrostenotic phenotype?

Abstract

Background: Crohn’s disease (CD) patients are highly prone to develop fibrotic strictures, for which surgery is the only treatment option. Therefore, an unmet need exists for convenient diagnostic tools and clinical markers to assess onset and progression of this life-threatening complication. Aim: This study aimed to identify discriminating metabolic markers in the serum of CD patients with and without fibrostenosis. Methods: Samples of 66 CD patients with (n=28) and without (n=38) ileal fibrotic strictures were selected from a local biobank (UZ Gent, BB190100). Fibrostenosis was defined as a narrowing of lumen and prestenotic dilation on CT/MRI. Metabolomics analysis was performed applying UHPLC-Q-Orbitrap-HRMS. The in-house method for metabolite extraction and mass spectrometry analysis was validated for serum compatibility. Statistical analysis of the untargeted MS data was performed using SIMCA 15.0 and MetaboAnalyst 4.0, allowing multivariate statistical modelling through Principal Component Analysis and sparse Partial Least-Squares Discriminant Analysis (sPLS-DA). Results: Validation of serum metabolomics analysis, including instrumental precision, intra-assay, and inter-day analyses, showed excellent coverage of the measured metabolites. After analysis, CD samples yielded 5,959 features in total. Using sPLS-DA models, 1,000 features were retained to build an Orthogonal PLS-DA model which had R2Y of 0.99 and Q2 of 0.83, suggesting excellent predictivity and fitting of the existent data. After further filtering, 47 most differentiating features were determined. Conclusion: Our comprehensive metabolomics approach unveiled a discriminative metabolic fingerprint in the serum of fibrostenotic CD patients which has clinical application potential as novel diagnostic tool. Identification and validation of these metabolites is ongoing