Direct Infusion Mass-Spectrometry of Human Blood Plasma Metabolome

Scientists currently use only a small portion of the information contained in the blood metabolome. The identification of metabolites is a huge challenge because only highly abundant and well-separated compounds can be easily identified in complex samples. However, new approaches that enhance the identification of compounds have emerged; among them, the identification of compounds based on their involvement in a particular biological context is a recent development. In this work, this approach was first applied to identify metabolites in complex samples and, together with metabolite set enrichment analysis, was used for the evaluation of blood plasma from obese patients. The proposed approach was found to provide a statistically sound overview of the biochemical pathways, thus presenting additional information on obesity. Obesity progression was demonstrated to be accompanied by marked alterations in steroidogenesis, androstenedione metabolism, and androgen and estrogen metabolism. The findings of this study suggest that the workflow used for blood analysis is sufficient to demonstrate obesity at the biochemical pathway level as well as to monitor the response to treatment. The current dataset contains mass spectra of venous blood collected at the Federal State Budgetary Institution “Nutrition and Biotechnology” (Moscow, Russia), from 100 volunteers (20 healthy subjects, 20 overweight subjects, and 60 subjects with stage 1, 2, or 3 obesity, according to the World Health Organization classification of obesity by BMI). The blood samples were analyzed by a hybrid quadrupole time-of-flight mass spectrometer (maXis Impact, Bruker Daltonics, Billerica, MA, USA) equipped with an electrospray ionization (ESI) source. The detailed Materials and Methods and experimental design are described at https://doi.org/10.3390/ijms21020568