Methods: Plasma specimens were longitudinally obtained from peanut-allergic children (N=5) participating in an ongoing trial of short-term peanut oral immunotherapy (OIT) focused on identifying early changes indicative of desensitization. Cryopreserved samples were thawed and mixed with 0.9% saline solution in D2O. 1H NMR data were acquired in triplicate using a 700 MHz NMR. Data were manually phased, baseline-corrected, and referenced to formate. Processed spectra were binned using intelligent bucketing integration, and normalized to the total integral of each spectrum. Principle components analysis (PCA) was performed using pareto-scaling and mean centering in SIMCA 14.0 (Umetrics, Umeå, Sweden) software.
Results: PCA of all samples demonstrated high reproducibility, with analytical variability less than biological variability at each time point and substantial between-subject variation in metabolic profiles. This variation was evident prior to the initial challenge and may reflect differences in each Subject’s baseline IgE levels, indicative of their peanut sensitivity. Unsupervised multivariate analysis also clearly showed that over time, the individual metabolic profiles changed during peanut OIT.
Conclusions: NMR-based metabolomics identifies unique metabolic profiles with high reproducibility among children undergoing peanut OIT. The ability to work with small volumes of cryopreserved serum or plasma highlights the potential of this technology as an approach for biomarker discovery.