Metabonomics uncovers a reversible proatherogenic lipid profile during infliximab therapy of inflammatory bowel disease

Abstract

Background: One-third of inflammatory bowel disease (IBD) patients show no response to infliximab (IFX) induction therapy, and approximately half of patients responding become unresponsive over time. Thus, identification of potential treatment response biomarkers are of great clinical significance. This study employs spectroscopy-based metabolic profiling of serum from patients with IBD treated with IFX and healthy subjects (1) to substantiate the use of spectroscopy as a semi-invasive diagnostic tool, (2) to identify potential biomarkers of treatment response and (3) to characterise the metabolic changes during management of patients with tumour necrosis factor-α inhibitors.

Methods: Successive serum samples collected during IFX induction treatment (weeks 0, 2, 6 and 14) from 87 IBD patients and 37 controls were analysed by ¹H nuclear magnetic resonance (NMR) spectroscopy. Data were analysed with principal components analysis and orthogonal projection to latent structures discriminant analysis using SIMCA-P+ v12 and MATLAB.

Results: Metabolic profiles were significantly different between active ulcerative colitis and controls, active Crohn's disease and controls, and quiescent Crohn's disease and controls. Metabolites holding differential power belonged primarily to lipids and phospholipids with proatherogenic characteristics and metabolites in the pyruvate metabolism, suggestive of an intense inflammation-driven energy demand. IBD patients not responding to IFX were identified as a potentially distinct group based on their metabolic profile, although no applicable response biomarkers could be singled out in the current setting.

Conclusion: ¹H NMR spectroscopy of serum samples is a powerful semi-invasive diagnostic tool in flaring IBD. With its use, we provide unique insights into the metabolic changes taking place during induction treatment with IFX. Of distinct clinical relevance is the identification of a reversible proatherogenic lipid profile in IBD patients with active disease, which partially explains the increased risk of cardiovascular disease associated with IBD.

Keywords: Crohn’s disease; Diagnostics; Metabolomics; Serum; Ulcerative colitis.

Fig. 1

Markers of disease activity in patients with Crohn’s disease (CD). Changes in Harvey–Bradshaw (HB) scores, perianal disease activity index (PDAI) and biochemical markers (C-reactive protein and haemoglobin levels) of disease activity during treatment of CD patients with infliximab (IFX) measured at the time of IFX initiation (0) and at the fourth infusion (14). Rem remission, Res responder, NRes non-responder. * P < 0.05; *** P < 0.001; **** P < 0.0001

Fig. 2

Markers of disease activity in patients with ulcerative colitis (UC). Changes in Mayo scores and biochemical markers (C-reactive protein and haemoglobin levels) of disease activity during treatment of UC patients with infliximab (IFX) measured at the time of IFX initiation (0) and at the fourth infusion (14). Rem remission, Res responder, NRes non-responder. ** P < 0.01; *** P < 0.001; **** P < 0.0001

Fig. 3

O-PLS-DA score plots and loading plots. O-PLS-DA score plots and corresponding coefficient-coded loading plots obtained from metabolic profiles of ¹H NMR spectra of the serum samples. The score plots display the first PLS component and one orthogonal component for each model. A two-way separation of the samples is demonstrated in all plots. The corresponding back-scaled loading plots reflect the class differences in the NMR spectra. Upright peaks indicate a relatively increased intensity of metabolites, and downright peaks a decreased intensity of metabolites. The colours shown on the plot are associated with the significance of metabolites in separating the samples; red indicating significance at a level of P < 0.05. (0), before first infusion of infliximab; (2), before second infusion; (6), before third infusion; (14), before fourth infusion. Glc glucose, Gln glutamine, GPC glycerophosphocholine, Gly glycine, HDL high-density lipoproteins, His histidine, Lac lactate, NAG N-acetyl glycoprotein, Phe phenylalanine, U1, U2, U3 unknown metabolite, Val valine, VLDL very-low density lipoproteins, CD Crohn’s disease, UC ulcerative colitis, Rem remission