Fig. 4

Plasma proteins associated with COVID-19 severity in relation to immune response, clinical variables, and convalescence. A Volcano plot depicting the plasma proteome alterations in severe versus moderate COVID-19. The horizontal dashed line indicates the adjusted p values = 0.05. Colors indicate proteins’ PEA panel. B, C Heatmaps showing statistically significant correlations (Spearman’s, p < 0.05) between the 47 differentially altered plasma proteins in severe COVID-19 and clinical biomarkers of severity in (B) COVID-19 patients or (C) all CAP-sepsis patients. The bigger circle size and higher colour intensity represent higher correlations. D Diagram of the differentially altered plasma proteins in severe COVID-19 annotated by GO terms related to immune responses (based on STRING annotations [23]) and cell types (based on Human Protein Atlas [24]). E–G Average protein expression (± SEM) during acute and convalescence phases of selected proteins that had higher levels in severe COVID-19 compared to moderate. Proteins were labelled with gene names. E The only two proteins that had higher levels in severe COVID-19 in both acute and convalescence phases, as compared to healthy. F Proteins correlated (Spearman’s ρ > 0.7) with both KRT19 and HGF. G The only protein among the COVID-19-unique proteins (see Fig. 2J) that was higher in severe COVID-19. H Proteins that had lower levels in severe versus moderate (COVID-19)