Metabolic Reprogramming in SARS-CoV-2 Infection Impacts the Outcome of COVID-19 Patients

Abstract

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection triggers inflammatory clinical stages that affect the outcome of patients with coronavirus disease 2019 (COVID-19). Disease severity may be associated with a metabolic imbalance related to amino acids, lipids, and energy-generating pathways. The aim of this study was to characterize the profile of amino acids and acylcarnitines in COVID-19 patients. A multicenter, cross-sectional study was carried out. A total of 453 individuals were classified by disease severity. Levels of 11 amino acids, 31 acylcarnitines, and succinylacetone in serum samples were analyzed by electrospray ionization-triple quadrupole tandem mass spectrometry. Different clusters were observed in partial least squares discriminant analysis, with phenylalanine, alanine, citrulline, proline, and succinylacetone providing the major contribution to the variability in each cluster (variable importance in the projection >1.5). In logistic models adjusted by age, sex, type 2 diabetes mellitus, hypertension, and nutritional status, phenylalanine was associated with critical outcomes (odds ratio=5.3 (95% CI 3.16-9.2) in the severe vs. critical model, with an area under the curve of 0.84 (95% CI 0.77-0.90). In conclusion the metabolic imbalance in COVID-19 patients might affect disease progression. This work shows an association of phenylalanine with critical outcomes in COVID-19 patients, highlighting phenylalanine as a potential metabolic biomarker of disease severity.

Keywords: COVID-19; SARS – CoV – 2; amino acids; metabolomics; phenylalanine.

Figure 1

Changes associated with COVID-19 clinical severity. (A) Radar plot of amino acid and SA profiles in the studied groups. (B) Radar plot of acylcarnitine profiles in the studied groups. The log2-normalized median fold-change in the levels of acylcarnitines was calculated and compared with the levels in HS. (C) Hierarchical clustering analysis heatmap illustrating the changes in serum metabolite abundance (average serum metabolites from each studied group) of the top 25 metabolites from HS and patients with mild, moderate, and critical COVID-19. The colored boxes on the right of the figure indicate the relative concentrations of the corresponding metabolite in each group under study, from less concentrated (dark blue) to most concentrated (dark red). ALA, Alanine; ARG, Arginine; CIT, Citrulline; GLY, Glycine; XLE-OHPro (Leucine, Isoleucine Alloisoleucine and Hydroxyproline); MET, Methionine; ORN, Ornithine; PHE, Phenylalanine; PRO, Proline; TYR, Tyrosine; VAL, Valine; SA, Succinylacetone; C0, Free-carnitine; C2, Acetylcarnitine; C3, Propionylcarnitine; C3DC, Malonylcarnitine; C4, Butyrylcarnitine; C4OH, 3-hydroxy-butyrylcarnitine; C4DC, Methylmalonylcarnitine; C5, Isovalerylcarnitine; C5:1, Tiglylcarnitine; C5DC, Glutarylcarnitine; C5OH, 3-Hydroxy-isovalerylcarnitine; C6, Hexanoylcarnitine; C6DC, Adipylcarnitine; C8, Octanoylcarnitine; C8:1, Octenoylcarnitine; C10, Decanoylcarnitine; C10:1, Decenoylcarnitine; C12, Dodecanoylcarnitine; C12:1, Dodecenoylcarnitine; C14, Tetradecanoylcarnitine; C14:1, Tetradecenoylcarnitine; C14:2, Tetradecadienoylcarnitine; C14OH, 3-Hydroxy-tetradecanoylcarnitine; C16, Hexadecanoylcarnitine; C16:1, Hexadecenoylcarnitine; C16OH, 3-Hydroxy-hexadecanoylcarnitine; C16:1OH, 3-Hydroxy-hexadecenoylcarnitine; C18, Octadecanoylcarnitine; C18:1, Octadecenoylcarnitine; C18:2, Octadecadienoylcarnitine; C18:OH, 3-Hydroxy-octadecanoylcarnitine; C18:1OH, 3-Hydroxy-octadecenoylcarnitine.

Figure 2

Three-dimensional score plot of selected components. (A) Partial least squares-discriminant analysis plot of differential metabolites from HS and patients with mild, severe, and critical COVID-19. The explained variances are shown in parentheses. (B) Metabolites with a variable importance in projection (VIP) score >1.5. The intensities of colors in boxes to the right (from blue to red) indicate the relative concentrations of the corresponding metabolite in each group under study. HS= healthy subjects. PHE, Phenylalanine; ALA, Alanine; CIT, Citrulline; PRO, Proline; SA, succinylacetone.

Figure 3

Normalized serum concentrations of the five metabolites with variable importance in projection of >1.5 from healthy subjects and patients with mild, severe, and critical COVID-19. Data are expressed as median with interquartile range.

Figure 4

Receiver operating characteristic (ROC) curves for phenylalanine. (A) Phenylalanine in mild vs. critical model, adjusted by covariates. (B) Phenylalanine in severe vs. critical model, adjusted by covariates (all p ≤ 0.003).

Figure 5

Phenylalanine (A) and tyrosine (B) metabolic pathways and observed metabolic changes in COVID-19 patients. AS, Aspartate synthetase; ASL, Argininosuccinate lyase; ARG, Arginase; NO, Nitric oxide; BH4, Tetrahydrobiopterin; BH2, Dihydrobiopterin; HS, Healthy subjects; SA, succinylacetone; TCA, tricarboxylic acid cycle.

Figure 6

Arginine and citrulline metabolic pathways and observed changes in COVID-19 patients. BH4, Tetrahydrobiopterin; BH2, Dihydrobiopterin; B6, Pyridoxine; HS, Healthy subjects; PHE, Phenylalanine; TYR, Tyrosine.