Comparing plasma and skin imprint metabolic profiles in COVID-19 diagnosis and severity assessment

As SARS-CoV-2 continues to produce new variants, the demand for diagnostics and a better understanding of COVID-19 remain key topics in healthcare. Skin manifestations have been widely reported in cases of COVID-19, but the mechanisms and markers of these symptoms are poorly described. In this cross-sectional study, 101 patients (64 COVID-19 positive patients and 37 controls) were enrolled between April and June 2020, during the first wave of COVID-19, in Sao Paulo, Brazil. Enrolled patients had skin imprints sampled non-invasively using silica plates; plasma samples were also collected. Samples were used for untargeted lipidomics/metabolomics through high-resolution mass spectrometry. We identified 558 molecular ions, with lipids comprising most of them. We found 245 plasma ions that were significant for COVID-19 diagnosis, compared to 61 from the skin imprints. Plasma samples outperformed skin imprints in distinguishing patients with COVID-19 from controls, with F1-scores of 91.9% and 84.3%, respectively. Skin imprints were excellent for assessing disease severity, exhibiting an F1-score of 93.5% when discriminating between patient hospitalization and home care statuses. Specifically, oleamide and linoleamide were the most discriminative biomarkers for identifying hospitalized patients through skin imprinting, and palmitic amides and N-acylethanolamine 18:0 were also identified as significant biomarkers. These observations underscore the importance of primary fatty acid amides and N-acylethanolamines in immunomodulatory processes and metabolic disorders. These findings confirm the potential utility of skin imprinting as a valuable non-invasive sampling method for COVID-19 screening; a method that may also be applied in the evaluation of other medical conditions.Key messagesSkin imprints complement plasma in disease metabolomics.The annotated markers have a role in immunomodulation and metabolic diseases.Skin imprints outperformed plasma samples at assessing disease severity.Skin imprints have potential as non-invasive sampling strategy for COVID-19.

Automated summary

In this study, skin imprints and plasma samples were analyzed to study the metabolomics of COVID-19. The results showed that plasma samples outperformed skin imprints in diagnosing COVID-19, while skin imprints were excellent for assessing disease severity. Specific lipid molecules were identified as discriminative biomarkers for identifying hospitalized patients through skin imprinting. This research confirms the potential utility of skin imprinting as a non-invasive sampling method for COVID-19 screening.