Plasma Protein Signature during Ischemia-Reperfusion Injury in Clinical Heart Transplantation.

PURPOSE: Cardiac allografts are subjected to ischemic preservation before transplantation, and subsequent ischemia-reperfusion injury (IRI) after the surgery. IRI increases the risk for acute rejection, and more detailed detection methods for early allograft injury and rejection are therefore warranted. Systemic molecular phenotyping by proteomics is a novel method for investigating the underlaying pathophysiology. Plasma protein expressions reflect the ongoing clinical state of the patients, therefore enabling real-time screening of biomarkers for allograft injury or treatment efficacy. Here, we systemically analyze the proteomic signature of recipients within first 24h after transplantation.

METHODS: This study is a post hoc analysis of data collected from 50 heart transplant recipients that participated in a separate clinical trial. Plasma samples from 1 and 24 hours after transplantation were analyzed with quantitative label-free proteomics in high definition MSE mode (HDMSE).

RESULTS: With two or more unique proteins per identification, 463 proteins were quantified. A complete separation between 1h and 24h based on a set of 270 identified proteins (p-value <0.05) was seen in supervised and unsupervised classification techniques. Identified proteins were studied further by pathway, network, and protein-protein interaction analyses. Using orthogonal projections on latent structure-discriminant analysis, we identified a set of 13 proteins that most significantly separated recipients at 1h from 24h. These proteins were Hemoglobin subunit beta, Hemoglobin subunit alpha, Keratin type I cytoskeletal 9, Malate dehydrogenase, Electron transfer flavoprotein beta subunit lysine methyltransferase, Zona pellucida-binding protein 1, Carbonic anhydrase 1, 14- 3-3 protein epsilon, Rootletin, C-reactive protein, Serum amyloid A-1 protein, Leucine-rich alpha-2 glycoprotein and Alpha-1-antichymotrypsin.

CONCLUSION: We show the change in proteomic signature of the first 24h after heart transplantation in human blood samples with open-label proteomics. We will further compare the proteomics data to clinical parameters in order to search for prognostic factors for rejection and mortality.