Untargeted metabolomic profiling of sera from AMN-SARS-CoV-2
cases
Each serum sample underwent meticulous processing and analysis using
UHPLC-OE-MS for untargeted metabolomics, following a standardized
protocol. This approach encompassed the examination of both hydrophilic
and hydrophobic molecules via positive and negative ionization modes,
thereby ensuring a comprehensive assessment of diverse endogenous
biochemical classes. The analysis revealed a total of 15,585 metabolite
peaks, including 7,182 metabolites in the negative ion mode and 8,403
differential metabolites in the positive ion mode. Quality control (QC)
samples exhibited consistency within ± 2 standard deviations, thus
validating the precision, reliability, and consistent outcomes of the
experimental method employed. OPLS-DA plots visually depicted the
distinct clustering of AMN-SARS-CoV-2 and SARS-CoV-2-no AMN groups in
both discovery and validation cohorts (Figure 1A). Subsequent analysis
led to the identification of 498 metabolites through MS/MS spectra based
on the MS2 database (BiotreeDB), KEGG, and HMDB databases. Of these, 118
metabolites were significantly correlated with AMN-SARS-CoV-2 (Figure
1B; p < 0.05; VIP > 1). A volcano plot was
generated, revealing 76 significantly upregulated metabolites and 42
downregulated metabolites in the AMN-SARS-CoV-2 group compared to the
SARS-CoV-2-no AMN group (Figure 1C). Notably, several amino acids
exhibited marked changes among these significant metabolites.
Specifically, the AMN-SARS-CoV-2 group displayed significant
upregulation of L-asparagine, L-serine, L-pyroglutamic acid, glycine,
asymmetric-dimethylarginine (ADMA), ornithine, D-ornithine, L-proline,
sarcosine, L-threonine, citrulline, D-serine, N-acetyl-L-alanine,
N-acetyl-L-methionine, L-lysine, L-beta-aspartyl-L-threonine,
prolylhydroxyproline, and N-acetylserine (Figure 1D). Conversely,
leucyl-isoleucine, alanyl-leucine, serylalanine, leucyl-phenylalanine,
phenylalanylphenylalanine, and phenylalanyl-glycine levels demonstrated
significant downregulation (Figure 1E).