Plasma Glycoproteomics Reveals Sepsis Outcomes Linked to Distinct Proteins in Common Pathways*

Abstract

Objective Sepsis remains a predominant cause of mortality in the ICU, yet strategies to increase survival have proved largely unsuccessful. This study aimed to identify proteins linked to sepsis outcomes using a glycoproteomic approach to target extracellular proteins that trigger downstream pathways and direct patient outcomes. Design Plasma was obtained from the LacTATEs cohort. N-linked plasma glycopeptides were quantified by solid-phase extraction coupled with mass spectrometry. Glycopeptides were assigned to proteins using RefSeq and visualized in a heat map. Protein differences were validated by immunoblotting, and proteins were mapped for biological processes using Database for Annotation, Visualization and Integrated Discovery and for functional pathways using Kyoto Encyclopedia of Genes and Genomes databases. Setting Hospitalized care. Measurements and Main Results A total of 501 glycopeptides corresponding to 234 proteins were identified. Of these, 66 glycopeptides were unique to the survivor group and corresponded to 54 proteins, 60 were unique to the nonsurvivor group and corresponded to 43 proteins, and 375 were common responses between groups and corresponded to 137 proteins. Immunoblotting showed that nonsurvivors had increased total kininogen; decreased total cathepsin-L1, vascular cell adhesion molecule, periostin, and neutrophil gelatinase–associated lipocalin; and a two-fold decrease in glycosylated clusterin (all p < 0.05). Kyoto Encyclopedia of Genes and Genomes analysis identified six enriched pathways. Interestingly, survivors relied on the extrinsic pathway of the complement and coagulation cascade, whereas nonsurvivors relied on the intrinsic pathway. Conclusion This study identifies proteins linked to patient outcomes and provides insight into unexplored mechanisms that can be investigated for the identification of novel therapeutic targets. (Crit Care Med 2015; XX:00–00)

Reviewing Mechanistic Peptidomics in Body Fluids Focusing on Proteases

“…Indeed, the contribution of KLKB1 in defining the urinary peptidome is corroborated by the detection and quantification of the activity of this enzyme in the urine of patients with chronic kidney disease and nephrotic syndrome, with strong correlation with albuminuria . However, factors from cascade pathways such as the coagulation, kallikrein–kininogen, and complement are expected to be presented in blood‐derived fluids, the traditional samples used in their content assessment …”

Mass spectrometry for the discovery of biomarkers of sepsis

“…Previously detected markers of sepsis, including NGAL and VCAM, were found to be downregulated in non-survivors according to their glycopeptide levels. Although these proteins are found to be upregulated in sepsis, they may be part of a beneficial immune response that contributes to survival 105 .…”

Systematic Molecular Phenotyping: A Path Toward Precision Emergency Medicine?

“…For example, pharmacometabolomics and proteomics have been used to predict drug responsiveness in conditions like sepsis 8,27 and pain control 28 . One specific example of this is a post hoc study of patients in septic shock randomized to l-carnitine or placebo 29 .…”

“…This information could be used to rationally guide which patients would need specialized pain service follow-up after traumatic injury. DeCoux et al 27 Sepsis Proteomic Distinct proteins in common pathways predicted sepsis outcomes.…”