Fig. 3. Proteins and biological processes associated with mortality.

(A) Volcano plot of 229 quantified proteins. Significant differential proteins are above the dashed line (P < 0.05). Yellow and blue circles correspond to elevated and reduced levels in NS compared to S, respectively. (B) Frequency of influential proteins being selected by the elastic net multivariate analysis. Bars correspond to the percentage of the respective metabolite being selected by the model out of the 200 bootstrap samples. Influential proteins are those selected >70% (dashed line) of times, with bar color denoting mean concentration higher (yellow) or lower (blue) in NS compared to S. (C) Left: score plot of individuals (NS in yellow; S in blue) clustered by multilevel PLS-DA of 22 differential proteins. The interface between the white and the gray shaded area represents the classification decision line. The first two components explained 21% of the total variance of the 22 differential proteins. Model performance and validity measures were as follows: AUC = 0.86 ± 0.019, misclassification rate = 0.19 ± 0.024, DR² = 0.50 ± 0.02 and DQ² = 0.37 ± 0.04. Right: Correlations between the 22 differential proteins and PLS components. Arrows denote direction and magnitude of correlations. (D) Biological processes enrichment analysis of up-regulated proteins among NS associated with mortality. P value depicts the probability that a particular biological process is enriched in a group of proteins relative to other biological processes. (E) Standardized coefficients of inflammatory mediators. Color-filled bars represent significant cytokines associations with death (P < 0.05), with yellow denoting increase and blue denoting decrease in concentration in NS compared to S.