title: Plasma degradome affected by variable storage of human blood.
abstract: BACKGROUND
  The successful application of-omics technologies in the discovery of novel biomarkers and targets of therapeutic interventions is facilitated by large collections of well curated clinical samples stored in bio banks. Mining the plasma proteome holds promise to improve our understanding of disease mechanisms and may represent a source of biomarkers. However, a major confounding factor for defining disease-specific proteomic signatures in plasma is the variation in handling and processing of clinical samples leading to protein degradation. To address this, we defined a plasma proteolytic signature (degradome) reflecting pre-analytical variability in blood samples that remained at ambient temperature for different time periods after collection and prior to processing.
  
  
  METHODS
  We obtained EDTA blood samples from five healthy volunteers (n = 5), and blood tubes remained at ambient temperature for 30 min, 8, 24 and 48 h prior to centrifugation and isolation of plasma. Naturally occurred peptides derived from plasma samples were compared by label-free quantitative LC-MS/MS. To profile protein degradation, we analysed pooled plasma samples at T = 30 min and 48 h using PROTOMAP analysis. The proteolytic pattern of selected protein candidates was further validated by immunoblotting.
  
  
  RESULTS
  A total of 820 plasma proteins were surveyed by PROTOMAP, and for 4 % of these, marked degradation was observed. We show distinct proteolysis patterns for talin-1, coagulation factor XI, complement protein C1r, C3, C4 and thrombospondin, and several proteins including S100A8, A9, annexin A1, profiling-1 and platelet glycoprotein V are enriched after 48 h blood storage at ambient temperature. In particular, thrombospondin protein levels increased after 8 h and proteolytic fragments appeared after 24 h storage time.
  
  
  CONCLUSIONS
  The overall impact of blood storage at ambient temperature for variable times on the plasma proteome and degradome is relatively minor, but in some cases can cause a potential bias in identifying and assigning relevant proteomic markers. The observed effects on the plasma proteome and degradome are predominantly triggered by limited leucocyte and platelet cell activation due to blood handling and storage. The baseline plasma degradome signature presented here can help filtering candidate protein markers relevant for clinical biomarker studies.
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Oxford, OX3 7LJ UK.|NHS Blood and Transplant, Watford, WD24 4QN UK.|Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Kaisar
authors.affiliation: Surgical Research Laboratory, University Medical Center, University of Groningen, Groningen, 9713 GZ The Netherlands.
authors.forename: Leon F A
authors.initials: LFA
authors.lastname: van Dullemen
authors.affiliation: Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Marie-Laëtitia
authors.initials: ML
authors.lastname: Thézénas
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Oxford, OX3 7LJ UK.
authors.forename: M
authors.initials: M
authors.lastname: Zeeshan Akhtar
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Oxford, OX3 7LJ UK.|Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Honglei
authors.initials: H
authors.lastname: Huang
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Oxford, OX3 7LJ UK.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Rendel
authors.affiliation: Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Charles
authors.affiliation: Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Roman
authors.initials: R
authors.lastname: Fischer
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Oxford, OX3 7LJ UK.|NHS Blood and Transplant, Watford, WD24 4QN UK.
authors.forename: Rutger J
authors.initials: RJ
authors.lastname: Ploeg
authors.affiliation: Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ UK.
authors.forename: Benedikt M
authors.identifier: 0000-0002-8160-2446
authors.initials: BM
authors.lastname: Kessler
keywords: Ambient temperature; Biobank; Mass spectrometry; PROTOMAP; Plasma proteome; Pre analytical variability; QUOD