Clinical Blood Metabogram: Application to Overweight and Obese Patients

Abstract

Recently, the concept of a mass spectrometric blood metabogram was introduced, which allows the analysis of the blood metabolome in terms of the time, cost, and reproducibility of clinical laboratory tests. It was demonstrated that the components of the metabogram are related groups of the blood metabolites associated with humoral regulation; the metabolism of lipids, carbohydrates, and amines; lipid intake into the organism; and liver function, thereby providing clinically relevant information. The purpose of this work was to evaluate the relevance of using the metabogram in a disease. To do this, the metabogram was used to analyze patients with various degrees of metabolic alterations associated with obesity. The study involved 20 healthy individuals, 20 overweight individuals, and 60 individuals with class 1, 2, or 3 obesity. The results showed that the metabogram revealed obesity-associated metabolic alterations, including changes in the blood levels of steroids, amino acids, fatty acids, and phospholipids, which are consistent with the available scientific data to date. Therefore, the metabogram allows testing of metabolically unhealthy overweight or obese patients, providing both a general overview of their metabolic alterations and detailing their individual characteristics. It was concluded that the metabogram is an accurate and clinically applicable test for assessing an individual's metabolic status in disease.

Keywords: blood; clinical blood tests; diagnostics; mass spectrometry; metabogram; metabolomics; personalized metabolomics.

Figure 1

Workflow for designing a metabogram and its application as a clinical lab test. To design a metabogram, blood plasma samples are taken from healthy people (1), and after sample preparation, the mass spectra of blood metabolites are obtained by direct infusion mass spectrometry (DIMS) (2). The resulting mass peak lists are analyzed by principal component analysis (PCA) to identify the mass peak groups to form metabogram components (3). To characterize metabogram components, their composition was determined by identifying the chemical substances, with which they are enriched (by metabolite set enrichment analysis, MSEA) (4). Metabogram components are compared with clinical blood tests to reveal their functional characteristics (5). The design of the metabogram according to this workflow was conducted in previous work [24]. For routine application of the designed metabogram as a fast clinical test, characterized sets of mass spectrometry peaks corresponding to metabogram components are used (6). This workflow for applying the metabogram was used in this study and is the prototype for the clinical use of the metabogram as a laboratory-developed test (LDT). Color coding: red indicates upregulation in the corresponding metabogram component; yellow indicates downregulation in the corresponding metabogram component.

Figure 2

Metabogram data for normal (control), overweight, and obese patients. Z-score values are presented, which are a measure of the metabogram component (from −1.64 to +1.64 is the normal range; up- and downregulation correspond to higher and lower Z-score values, respectively). Color coding: red indicates upregulation in the corresponding metabogram component; yellow indicates downregulation in the corresponding metabogram component.

Figure 3

The frequency of deviations from the norm in the blood metabogram components for overweight and obese patients. The metabogram component deviates from the norm if its Z-score is less than −1.64 (the metabolites composing the metabogram component are downregulated) or above +1.64 (the metabolites composing the metabogram component are upregulated).

Figure 4

Correlation of metabogram components with each other and calculated for normal, overweight, and class 1–3 obesity patients.

Figure 5

Dendrograms of blood metabograms of overweight and obese patients involved in the study. Color coding: red indicates upregulation in the corresponding metabogram component; yellow indicates downregulation in the corresponding metabogram component.

Figure 6

Correlation of clinical tests and body parameters with metabogram components calculated for normal (control), overweight, and class 1–3 obesity patients.

Figure 7

Distribution of the metabogram types in overweight and obese men and women. The positive 1, positive 6, and negative 5 components (in one of them or their various combinations) have been downregulated or the positive 7 has been upregulated in a metabogram with a “typical deviation”. If the metabogram component(s) is close to the limit of the norm, the “close to a typical deviation” metabotype is detected (when retesting, a metabogram may fall into a group with a typical deviation). “Atypical metabograms” have component deviations that are not the same as those of typical metabograms.

Figure 8

An example of metabogram. “Var” superscript shows the percentage of the variance explained by the metabogram component. The Z-score value is a measure of the metabogram component (from −1.64 to +1.64 is the normal range). “Up-“ and “downregulation” correspond to higher and lower Z-scores, respectively. The frequently deviated components of the metabogram in overweight and obese patients are selected by color (red indicates upregulation in the corresponding metabogram component; yellow indicates downregulation in the corresponding metabogram component). To the left of the metabogram are the factors contributing to the development of obesity (adapted from [26]) and where they are mainly reflected in the metabogram. The reflection of the microbiota and genome in the components of the metabogram (indicated by the sign ‘?’) will be established in future studies. To the right of the metabogram is the relationship of obesity-related metabolites in the metabolic network (adapted from [27]) and in which metabogram components they may be reflected.